NAME: MUZIMKHULU NGWENYA

COURSE: APPLIED CHEMICAL TECHNOLOGY

LEVEL: NATIONAL DIPLOMA

CANDIDATE NUMBER: 1113002C0028

SUPERVISER: MR V. MWAPAURA

PROJECT TITLE

Utilisation of fly ash and used tyre rubber to develop a composite mixture adsorbent product for industrial and environmental pollution treatment use in Zimbabwe.

A project report in partial fulfilment of the requirements for a HEXCO Diploma in Applied Chemical technology

November 2015

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ABSTRACTThe main focus on the study was to convert fly ash and used tyre rubber into a cheap and

effective adsorbent product, in the form of a composite mixture powder and pellet product.

Laboratory tests were used to gauge whether the products adsorption capacity was good

enough to be implemented into industries and environmental management organizations. The

results showed that the composite mixture adsorbent was very effective and efficient based on

the laboratory results obtained, it was also established that studies on the two individual

components being used as adsorbents has been conducted but the combination of the two has

not been undertaken to come up with a complete adsorbent that can treat any kind of

pollutants in water. The chemical analysis of the product showed that the composite mixture

adsorbent had a high concentration of functional groups for adsorption as compared to many

adsorbents used internationally, this was analysed by Boehm titrations and a significant

difference was observed.

Abstract approval

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Project supervisor

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Date

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DEDICATION

I dedicate this project to God and my mother Mrs. M. Ngwenya who both inspired me to see this project right to its completion

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ACKNOWLEDGEMENTSI would like give my special thanks to the following people, who led to the success of this

study:

o My project supervisor, Mr V. Mwapaura whose constant advice, encouragement and

monitoring was very useful.

o Bulawayo Polytechnic applied science staff, especially the laboratory technicians who

supplied me with all the chemical reagents, apparatus and equipment l needed

o My entire friends who gave me moral support throughout the project process

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LIST OF TABLES

Table 2.3 list of contaminants and types of industries................................................................24

Table 2.3 list of contaminants and types of industries 25

Table 2.3 list of contaminants and types of industries................................................................26

Table 2.5 Classification of effluent discharged into surface water 27

Table 4.1 Methyline blue uv-vis test results................................................................................54Table 4.1 Methyline blue results..................................................................................................55Table 4.2 Iodine number titration results....................................................................................57

Table 4.3 Boehm titration weight of adsorbent in reaction flasks 59

Table 4.3 Boehm titration volumes.............................................................................................59

Table 4.3 Boehm titration concentration results 60

Table 4.4.1 Chromium back titration volumes.............................................................................61Table 4.4.2 Copper back titration volumes..................................................................................62Table 4.4.3 Iron back titration volumes.......................................................................................63Table 4.4.4 Nickel back titration volumes....................................................................................65Table 4.4.5 Chlorides back titration volumes...............................................................................66

Table 4.4.6 Sulphates uv-vis results 68

Table 4.4.6 Sulphates results.......................................................................................................69Table 4.4.7 Ammonia uv-vis results.............................................................................................70Table 4.4.7 Ammmonia results....................................................................................................72

LIST OF FIGURES

Figure 4.1 Calibration curve of methyline blue............................................................................55Figure 4.4.6 Calibration curve of sulphates..................................................................................68Figure 4.4.7 Calibration curve of ammonia..................................................................................71

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LIST OF APPENDIXESAppendix; Pictures on the experiments………………………………………………………………...79

Appendix; Pictures on the experiments………………………………………………………………...80

Appendix; Pictures on the experiments………………………………………………………………...81

TABLE OF CONTENTS

ABSTRACT

DEDICATION

ACKNOWLEDGEMENTS

LIST OF TABLES

LIST OF FIGURES

LIST OF APPENDIXES

CHAPTER 1: INTRODUCTION

1.1 INTRODUCTION...................................................................................................................91.2 BACKGROUND.....................................................................................................................91.3 AIMS & OBJECTIVES..........................................................................................................111.4 PROBLEM STATEMENT......................................................................................................121.5 PROJECT SIGNICANCE........................................................................................................121.6 PROJECT SCOPE & DELIMITATIONS...................................................................................131.7 RESEARCH QUESTION........................................................................................................131.8 BRIEF METHODOLOGY......................................................................................................141.9 DEFINITION OF TERMS......................................................................................................141.10 PROJECT LAYOUT.............................................................................................................151.11 CHARPTER SUMMARY.....................................................................................................15

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CHAPTER 2: LITERATURE REVIEW

2.1 INTRODUCTION.................................................................................................................162.2 ENVIRONMENTAL POLLUTION..........................................................................................16

2.2.1 Industrial effluents.......................................................................................................16 2.2.2 Used tyres.................................................................................................................... 21

2.2.3 Flyash............................................................................................................................222.3 INDUSTRIAL EFFLUENTS....................................................................................................23

2.4 WASTE WATER CONTAMINANTS......................................................................................23 2.5 EFFLUENT DISPOSAL REGULATIONS..................................................................................26 2.6 EFFLUENT TREATMENT TECHNOLOGIES............................................................................27 2.7 DRAWBACKS OF CURRENT TREATMENT TECHNIQUES.....................................................29

2.8 ADSORPTION.....................................................................................................................30 2.9 ADSORBENTS.....................................................................................................................31 2.10 PREPARATION OF ADSORBENTS.....................................................................................35 2.11 BOEHM TITRATIONS........................................................................................................38 2.12 IODINE ADSORPTION NUMBER......................................................................................39 2.13 METHLINE BLUE TEST......................................................................................................39 2.14 CHARPTER SUMMARY....................................................................................................40

CHAPTER 3: RESEARCH METHODOLOGY

3.1 INTRODUCTION.................................................................................................................413.2 INSTRUMENTATION AND APPARATUS.............................................................................41

3.3 REAGENTS..........................................................................................................................42 3.4 EXPERIMENTAL DESIGN.....................................................................................................42

3.5 ADSORBENT MATERIAL PREPARATION............................................................................423.6 SAMPLE PREPARATION.....................................................................................................433.7 BOEHM TITRATION ...........................................................................................................433.8 IODINE ADSORPTION NUMBER........................................................................................44

3.9 METHYLINE BLUE TEST...................................................................................................... 47 3.10 HEAVY METAL TITRATION...............................................................................................47

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3.10.1 Chromium titration...................................................................................................47 3.10.2 Copper titration........................................................................................................ 48

3.10.3 Iron titration.............................................................................................................49 3.10.4 Nickel titration..........................................................................................................50 3.10.5 Determination of Chlorides......................................................................................51 3.10.6 Determination of Sulphates.....................................................................................52 3.10.7 Determination of Ammonia.....................................................................................523.11 Data Processing and Analysis .........................................................................................53

CHAPTER 4: RESULTS, PRESENTATION AND ANALYSIS 54

4.0 INTRODUCTION.................................................................................................................544.1 METHYLINE BLUE TEST RESULTS.......................................................................................54

4.2 IODINE NUMBER RESULTS ................................................................................................57 4.3 BOEHM TITRATION RESULTS.............................................................................................59 4.4 HEAVY METAL TITRATION RESULTS..................................................................................61 4.4.1 Chromium back titration.............................................................................................61 4.4.2 Copper back titration...................................................................................................62 4.4.3 Iron back titration........................................................................................................63 4.4.4 Nickel back titration.....................................................................................................65 4.4.5 Chlorides titration........................................................................................................66 4.4.6 Sulphates test results...................................................................................................68 4.4.7 Ammonia test results...................................................................................................70

4.5 DISCUSSION OF RESULTS...................................................................................................72

CHAPTER 5: SUMMARY, CONCLUSION AND RECOMMANDATIONS 75

5.1 SUMMARY.........................................................................................................................755.2 CONCLUSION.....................................................................................................................755.3 RECOMMENDATIONS........................................................................................................76

REFERENCES 77

APPENDIX 79

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CHAPTER 1

1.1 INTRODUCTION Chapter one helps on explicating the aims and objectives dealt with in this project, addressing the problems to be resolved. It also incorporates a layout of the project, summarizing on how the project was done from chapter to chapter.

1.2 BACKGROUNG OF THE STUDY The current pattern of industrial activity introduces new chemicals into the environment every now and then polluting the environment. The rate at which industrial effluents are discharged in the environment especially water bodies have been on the increase as a result of urbanization. Most of these effluents contain toxic organic and inorganic substances including heavy metals that pollute the environment. The presence of heavy metals in the environment is of major worry because of their bio-accumulating tendency, toxicity, threat to human life and the environment at large. Another environmental industrial pollutant is used coal, every year, the nation’s coal plants produce tons of coal ash (fly ash) pollution, which is the toxic by-product that is left over after the coal is burned. All that ash has to go somewhere, so it’s dumped in the backyards of power plants across the nation, into open-air pits and precarious surface waste ponds. Many of these sites lack adequate safeguards, leaving nearby communities at risk from potential large-scale disasters like the massive coal ash spill and from gradual yet equally dangerous contamination as coal ash toxins seep into drinking water sources or are blown into nearby communities. Coal ash pollution contains high levels of toxic heavy metals such as arsenic, lead, selenium, and other cancer causing agents. The public health hazards and environmental threats to nearby communities from unsafe coal ash dumping have been known for many years, including increased risk of cancer, learning disabilities, neurological disorders, birth defects, reproductive failure, asthma, and other illnesses. Another environmental industrial product pollutant is used car tyres. Tyres basically consists of heavy metals and other pollutants so there are a potential risk for the (leaching) of toxins into the soil and groundwater leading to contamination of

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ground water and pollution of soil.. Shredded tyre pieces leach much more, creating a bigger concern, due to the increased surface area on the shredded pieces. Many organisms are sensitive, and without dilution, contaminated tyre water has been shown to kill many organisms. Burning of tyres also produces many harmful gases. In winters, for the purpose of heat poor people burn used tyres which are precursor of air pollution and produces harmful and toxic gases and particulate matters. One can fall seriously ill with the inhalation of these contaminants due to suffocation. It is better to recycle these used tyres and coal ash (fly ash) to promote secondary raw materials or product. This can also be considered as an efficient drive for a better and safe environment. More economic activity can be obtained from new products derived from wastes, while reducing waste stream without generating excessive pollution, By-Product Synergy (BPS) is the matching of under-valued waste or by-product streams from one facility with potential users at another facility to create new revenues or savings with potential social and environmental benefits. The resulting collaborative network creates new revenues, cost savings, energy conservation, reductions in the need for virgin-source materials, and reductions in waste and pollution. These are quantifiable benefits to the environment, economy and communities and emissions from recycling operation. The production of activated carbon adsorbent from solid waste is one of the most environmentally friendly solutions to transforming negative valued waste to valuable product. Waste tyres have in the past been studied and exhibit potential of being converted to activated carbon adsorbent. Studies have also shown that fly ash due to its alkalinity and adsorptive properties can also be converted to activated carbon. Both of these wastes can be used to make an activated carbon adsorbent that can be used to treat industrial effluents, environmental water bodies and environmental toxic spills and also solve the problem of their individual disposal by using them as cheap raw materials for producing activated carbon adsorbents for treating environmental pollutions.

With the economic hardships faced in Zimbabwe, many companies are driven to dispose of their effluents without fully processing it, probably due to treatment chemical expenses and many other factors. This has seen cases Lake Chivero, the largest water supply of the city of Harare experience problems of pollution and eutrophication. It is suspected the pollution in the lake was caused by nutrients and chemicals introduced by disposal of not properly treated sewage effluent on land or into rivers feeding the lake. These failures emanate the need of an advanced relatively cheap technology to help monitor and manage waste water quality and other environmental pollutants. In this case the application of a cheap adsorbent which will be a composite mixture of waste tyre rubber and fly ash for industrial and environmental pollution treatment for the good of the nation, coming up with by-product synergy alleviating the waste to make a useful new product.

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1.3 AIMS AND OBJECTIVES

1.3.1 Aim

The aim of this project is to study the possibility of using a mixture of fly ash and waste tyre rubber to develop a cheap and commercially effective activated carbon adsorbent product for industrial and environmental pollution treatment use in Zimbabwe.

1.3.2 Objectives

To effectively come up with a solution to convert fly ash and used tyres to a valuable product in a cheap and economic way

To develop and formulate a cheap economic adsorbent product for industrial use and environmental adsorption of toxic pollutants

To analyse its adsorption of heavy metals ,dyes and inorganic pollutants ions compared to a commercial adsorbent to see its feasibility in treating environmental water pollutions and industrial wastes in Zimbabwe

1.3.3 Assumptions

That any kind of waste tyre rubber can be used for this process That the fly ash sample collected is the true representative of fly ash from various other

power stations That the results of the analysis of water samples are the true representative of the

effect of the composite mixture adsorbent The research is mainly centred on the composite mixture adsorbent and not individual

component adsorbents That a ratio of 1:1 tyre rubber and fly ash mixture is the most efficient ratio for the

composite mixture adsorbent

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1.3.4 Limitations

Full analysis of the fly ash content could not be done due to unavailability of X-ray fluorescence spectrometer

Analysis of heavy metals was done by UV-Vis spectrometer and titrations, due to the unavailability of an AAS

1.4 Problem statement

Industries are the biggest polluters of the environment by releasing industrial process effluents into streams, by producing by-products like coal ash, as well as their finished products like waste tyres posing a problem in their disposal causing environmental pollution. A cheap and effective method of utilising these by-products like coal ash (fly ash) and used finished products like used tyre rubber is needed as well as a cheaper, efficient way to effectively treat industrial effluents is needed. In this case the use of a mixture of a by-product waste like fly ash and used finished products like waste tyres to make an activated carbon adsorbent which will be used to treat industrial effluents and environmental pollutions has to be investigated to benefit the companies, environment and the community at large.

1.5 PROJECT SIGNIFICANCE

This project is aimed at achieving a way of using some waste products like coal ash (fly ash) and used tyre rubber that are available locally abundantly to produce a useful adsorbent product for industrial and environmental pollution treatment. This project is also meant to come up with a useful way of utilising industrial wastes like fly ash and used tyres.

Such a project is useful

Industry- the success of the project benefits industry by developing a cheap, efficient reliable adsorbent for industrial effluent treatment and also develops a useful way of utilising coal ash and used tyres as by-product synergy for development of a new product.

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Community- the success of the project will help alleviate environmental pollutions like coal ash used tyres and prevent the polluting of water bodies by industries which benefits all living organism like plants, animals, fish and humans that utilise these environmental water bodies.

1.6 PROJECT SCOPE AND DELIMITATIONS

This project is based on analyzing the extent to which heavy metals, dyes and inorganic substances were adsorbed using the composite mixture adsorbent in comparison to a commercial adsorbent. Other properties like iodine number, methyline blue number, identification of adsorption functional groups and their concentration were determined to observe the adsorption capability of the composite mixture adsorbent to compare with a commercial adsorbent and other theoretical adsorbents used elsewhere. The effluent samples were prepared standard solutions of different metal salts, inorganic salts and dyes to be used as the test sample.

1.7 RESEARCH QUESTIONS

This research sought to answer the following questions:

How can the fly ash and used tyre rubber be used in the formulation of an activated

carbon adsorbent?

To what extent does the adsorbent meet adsorption capability required by industry?

To what extent does the structure of final product formed from the two raw

materials specify with industrial acceptance?

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Will be the adsorbent made from fly ash and used tyre rubber be of less cost, than the

commercial adsorbent made from red oxide?

1.8 BRIEF METHODOLOGY

Methodology used in this project is literature review and laboratory experiments. It is divided into two sections. The first section focuses on the preparation of the composite mixture adsorbent. The second section focuses on preparation of test samples and testing the adsorption capacity and removal efficiency of the composite mixture adsorbent vs commercial adsorbent on heavy metals, dyes, inorganic ions to see how it competitive it will be on the market.

1.9 DEFINITION OF TERMS

FLY ASH – usually refers to ash produced during combustion of coal, also known as flue-

ash, is one of the residues generated in combustion, and comprises the fine particles

that rise with the flue gases.

ADSORBENT – a material having capacity or tendency to adsorb other substances

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ACTIVATED CARBON– are high surface area and porous carbons which are widely used

as an adsorbent for separation, purification, decolorization and deodorization of

vegetable oils and fats, water purification and pollution treatment, air and gas

purification (cigarette filters, motor vehicles exhaust control) and the food and

pharmaceutical industries

ADSORPTION CAPACITY– is defined as the ability to accumulate solute molecules at the

surface of a solid. This capacity is directly proportional to the area of the surface

exposed and is dependent on the solute

1.10 PROJECT LAYOUT

This project is subdivided into 6 chapters. The introductory chapter that is chapter 1

gives a summary of the whole project. Chapter 2 is a compilation of researches and

reviews from other authors. Chapter 3 gives a fully detailed methodology used for the

success of this project. After analysis comes results and these are shown chapter 4.

Chapter aims on discussing results obtained, with information in chapter 2. The 6th and

last chapter gives the conclusion, recommendation and references.

1.11 CHAPTER SUMMARY

Chapter 1 is aimed on giving a brief of the whole project. It explained the main aim of

the project, stating the objectives to be attained during the course the project, and

justifying the importance of the importance of the project altogether

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CHAPTER 2: LITERATURE REVIEW

2.1 INTRODUCTION

In this chapter the author seeks to compile a thorough research and review from

the information obtained by various scientists on industrial effluent, fly ash and

waste tyre environmental pollution, and industrial effluent treatment, the use of

fly ash, waste tyres as adsorbents, formulating and preparation of a composite

mixture of fly ash and waste tyre rubber activated carbon adsorbent and testing

it in comparison with a commercial adsorbent in their treatment of test mixtures

to observe adsorption capability.

2.2 ENVIRONMENTAL POLLUTION

2.2.1 INDUSRTRIAL EFFLUENTSThere is a rapid increase in the pollution of our environment due to an increase in industrialization and developmental processes and other factors of pollution in the world today. If this increase is allowed, the problem of pollution of the environment will become more acute as the amount of pollutants being introduced to the environment continues to be on the increase. In other to keep this environmental risk in check, some safety measure must be applied. Environmental water pollution is introduction of foreign materials capable of deteriorating water into a water body, hence positing negative effect on aquatic lies and human health. Industrial effluents account for several point sources of water pollution. While developed nations adopt stringent water quality requirement to control river pollution from point and non-point sources, the situation is different in most developing countries like Zimbabwe. Waste water treatment in Zimbabwe is not given the necessary priority it deserves and therefore, industrial wastes

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are discharged into receiving water bodies without treatment and the consequences of which include among others, river pollution, loss of aquatic life uptake of polluted water by plants, diseases burden and shorter life expectancy in developing countries. Zimbabwe at the moment has established industries like soaps and detergents, food and beverages, breweries, textiles and apparels, building materials, timber products, and wood and leather works, metal works, chemicals and plastics, clay and other industries .All these Industries produce various effluents that are discharged into the environment. Most large cities in Zimbabwe are feeling the pinch of pollution from industrial effluents [3].It is needless to talk of tons of effluents disposed indiscriminately into the rivers and streams. It has been realized that discharges of untreated or incompletely treated wastes containing algal nutrients, non-biodegradable organics, heavy metals and other toxicants will hasten the deterioration of receiving water bodies. On a global scale, environmental pollution by food or related industries via effluent discharge has become a threat to plants and animals and may ultimately threaten the quality of human life. In 1956, cases of minimata disease were reported in Japan [4]. The disease affects the brain, causing insanity and leading to death, as a result of pollution of water by industrial effluents containing methyl-mercury. Also, the Itai-Itai disease caused by cadmium poisoning originated in a prefecture factory in Japan. This disease damages the joints, softens the bones and causes the body to shrink and the affected person dies painful death [5]. One time or the other, there were cases of outbreak of mercury poisoning in Iraq and Nigeria when a number of people ate bread made from wheat which had been treated with alkyl- mercury as a fungicide. Due to industrial effluent and municipal sewage discharge has been documented in literatures. The contamination of Cauvery River in India by heavy metals (lead (Pb), Chromium (Cr), Zinc (Zn), was reported and it was attributed to agricultural, industrial and anthropogenic activities around the river (Begum et al, 2009). High level of mercury (Hg) was found in amphibians, invertebrates and reptiles which revealed a strong influence from industrial effluent (Hsua etal, 2006). The characteristic qualities of five textile industries effluent was analysed and high level of chemical oxygen demand (COD), Total suspended solids (TSS), ammonia (NH3), Biological oxygen demand (BOD) and sulphide (S2–) that exceeded the federal environmental protection agency (FEPA) limit by several fold was reported (Yusuf and Sonibare, 2004). The characteristics of selected effluents from industries were analysed and it was reported that the concentration of effluent discharge is on the limit (Sangadoyin. 1995). High levels of blood lead was reported due to exposure to the environmental pollutant which can get into the human body through various sources (Orisikwe, 2009).However, characteristics of pollutants in effluent from five tannery industries were analysed and it was reported that effluent had significantly chromium concentration varied between 1.02±0.13 to 1.56 ±0.06 mgL–1 which are above the limit set by world health organization (WHO) and FEPA of 1.0mgL–1.Hafawa enterprise Tannery unique leather finishing had significantly high lead concentrations, while great Northern Tannery limited were found to be a potential source of iron contamination (Akan et al, 2007). Another study conducted by Akan et al, 2009, analysed effluent samples from tanneries and textiles industries from Kano industrial areas of Chalawa, Bompai and Sharada industries are and reported that the

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physicochemical parameters (BOD, COD, DO) anions, trace elements and heavy metals were higher than the limit set by WHO for the discharge of tanneries an textile effluents into river they concluded that based on the high levels of the above parameters/effluents, regular monitory of pollutant in the tannery and textile effluents are necessary to ensure proper discharge of these effluents into receiving rivers. A study on water quality in industrial effluents from Lagos and Abaekuta are discharged was conducted and it was reported that the level of turbidity, oil and grease, faecal, coliform and iron were very high in the sampling siles (Jaji et al, 2007). This has been managed with the weight of such bodies as UNICEP established in 1952 an water aid which began work in Nigeria in 1995 to assist with the vast water and sanitation needs found and has since been assisting the water and sanitation units (WASU) of Local Government Councils to deliver water and sanitation services to the poor.

The contamination of metals is a major environmental problem and especially in the aquatic environment. Some metals are potentially toxic or carcinogenic even at very lowconcentration and are thus, hazardous to human if they enter the food chain. Metals areusually dissolved into the aquatic system through natural or anthropogenic sources. Metal ions are distributed thoroughly during their transport in different compartments of the aquatic ecosystems, in biotic or abiotic compartment such as fishes, water, sediment, plant. Metals remain in contaminated sediments may accumulate in microorganisms which in return entering into the food chain and eventually affect human well being (Shakeri & Moore, 2010).In 2010, Shakeri & Moore conducted a study to evaluate the distribution and average concentrations of Cu, Zn, Ni, Mo, Pb, V, As Co and Fe in the sediment at the study site. The authors indicated that Al and Fe hydroxides and clay content play a significant role in the distribution and sorption of metals in sediments. This study noted that metal inputs have brought negative impact to the freshly deposited sediments and the accumulation of the metal on the sediment surface. Metal in sediment is affected by mineralogical and chemical composition of suspended material, anthropogenic influences by deposition, sorption, and enrichment in living organism or aquatic plant (Jain et al., 2005). Naturally, suspended and bed sediment are an important compartment to buffer metal concentration in an aquatic system especially by adsorption or precipitation (Jain & Ali, 2000; Jain, 2001; Jain & Sharma, 2002; Jain et al., 2004). However, the metal discharges from industry may change the role of sediment as it may not be able to act as a sink and buffer to higher concentration of metal. Metals contributed by man-made sources are possible to associate with organic matter in the thin fraction of the sediments, or adsorbed on metal hydrous oxides, or precipitated as hydroxide, sulfides and carbonates (Singh et al., 2005; Shakeri & Moore, 2010). In India, the discharge from fertilizer industry has not undergone any treatments, is one of the major sources of pollution to water reservoirs such as lakes, ponds, rivers and ocean. The discharge contains certain toxic components such as metals, nitrates and ammonia which might be responsible for causing metabolic impairment in the aquatic organisms. At times, the toxic components could even cause fatality in aquatic living organism (Bobmanuel et al., 2006; Yadav et al., 2007; Ekweozor et al., 2010). A study has been conducted by Yadav et al. (2007) on freshwater fish,

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Channa striatus which are exposed to fertilizer industry discharge. It is found that the toxicity of the fertilizer discharge on the fish tissues could be due to metals and ammonia. Heavy metals such as Zn, Cr, Cu and Pb in the fertilizer industry discharge can bind with certain proteins in fish and disrupting membrane integrity, cellular metabolism and ion-transports that will bring harm to the maintenance of homeostasis. The result showed that the average protein concentration in various tissues of the control fish is, in descending order: gills>liver>brain>muscle>kidney>heart. However, the protein level reduced in all fish tissues at a higher sublethal concentration of industrial discharge at 7% higher than control fishes, the values of tissue reduced in descending order: liver, brain, muscle, gills, kidney, and heart at 76.23%, 55.95%, 52.16%, 50.06%, 49.28%, and42.86%, respectively. When metals associate with other chemicals compound in the fertilizer discharge may cause distortion in the cell

organelles and inhibit the activity of various enzymes (Valarmathi &Azariah, 2003; Yadav et al.,2007), which may greatly disturb the physiological state of the exposed living organism. The heavy metals present in the fertilizer industry discharge are usually in dissolved state which could easily be uptaken by fish and enter human food chain. There have been studies showed that metals will cause damage to the human kidney and liver even at low concentration. The early studies suggested that higher concentration in metals can be carcinogenic and teratogenic (O’Brien et al., 2003; Yadav et al., 2007). Generally, carbohydrate metabolism is a major source of energy production and the activity of Lactate dehydrogenase (LDH). It has been a target for the action of various xenobiotics. The activity of LDH in different part of body tissues of C. striatus after exposing to the fertilizer industry discharge has been examined. In this study, the result showed that the exposure of C. striatus to fertilizer industry discharge resulted in a drastic reduction in the enzyme activity.on of elements such as Zn, Co, Ni, Sc, C and Fe

Rai & Tripathi (2009a) added that most metals in aquatic environment associated withparticulate matter, then settled and accumulated in the bed sediments. The accumulation of contaminant in the bed sediments and the remobilization of contaminant are the most important mechanisms of contaminant in an aquatic ecosystem regulation. Furthermore, under certain circumstances such as deficit in dissolved oxygen or decreased in pH, the bed sediments can be another source of secondary water pollution when the heavy metals from bed sediments are released.

Another study conducted in a kaolin refinery industry produces hazardous by-product such as Al, Fe, and Zn. In kaolin processing, sulphuric acid is used to improve the whitening (Jordao et al., 2002) is discharged to the river waters. This will influence the well being of aquatic organisms that adapted well at close to neutral pH. Also, in order not to affect the colour and whiteness of paper, impurities such as iron oxides is needed

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to be removed. This can be made through the reduction of Fe(III) to Fe(II) with metallic Zn. Therefore, Zn, Fe, Al are usually present in the discharge. The study examined the pH, conductivity and hardness values and various metals such as Al, Ca, Cd, Cr, Cu, Fe, Mg, Ni, Pb, and Zn. Excessive concentration of these parameters in discharges that flows into rivers may also cause adverse effects to human health (Jordao et al., 2002). The discharges from the industry without proper treatment will decreased the pH of the river water. This is due to the usage of sulphuric acid in the kaolin processing. The pH values will bring effects in flora and fauna nearby, change the taste of water and lead to heavy corrosion in pipe lines. High conductivity naturally indicates the presence of ionic substances dissolved in the river water. However, the result showed that 90% of the study site exceeded the data reported for non-contaminated rivers due to excessive metal ions within the water. At the site nearer to kaolin industry the conductivity is 852 times higher than the non-polluted study site. The industrial discharge also changed the hardness in river water. However, the result showed that the study site is not exceeded the maximum limit (500 mg CaCO3 L-1) of hardness for drinking water as recommended by the Brazilian government (Jordao et al., 2002).

The study conducted by Hiller et al. (2011) to investigate the concentrations, distributions, and hazards of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs). PCBs are used mainly as coolant and electronic industries (capacitors, transformers), paints, sealants for wood, cutting and lubricating fluids, plasticizers, and as dielectric fluids. Therefore, at the former site of PCB manufacturing area in Slovakia, high concentrations of PCBs are detected in soils, sediments, humans, and wildlife (Kocan et al. 2001; Petrik et al., 2001; Hiller et al., 2011).Due to their low aqueous solubilities, the PCBs and PAHs lay on the surface of soils and waters. PCBs and PAHs adsorb strongly to the organic fraction of soils (Girvin & Scott, 1997; Hiller et al., 2011). Soils contaminated with PCBs and PAHs are transported directly or indirectly by rivers to the water reservoir and are subsequently converted into the bed sediments. Therefore, soils could be considered as the primary sinks for these organic contaminants. PCBs and PAHs are persistent in the environment, resistant to degradation process, and accumulate in food chain. This will eventually bring health hazard to living organisms, including mutagenicity and carcinogenicity (Hiller et al., 2011).

Yadav et al. (2007) studied on fertilizer industrial discharge showed that some components in the discharge may interact with each other and produce toxic to aquatic organisms. For instance, the interaction between dissolved oxygen and ammonia changed the respiratory physiology in fresh water fish. In addition, results showed that the toxicity of the effluent in fish depends on concentration and duration of exposure. Several study showed that the excess concentration of ammonia, whether is ionized or unionized, is one of the major contaminants in fertilizer discharge and it is toxic to aquatic living organism. It could cause impairment to the cerebral energy in fish, such as O. niloticus and a hybrid catfish (Yadav et al., 2007; Ekweozor et al., 2010).

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Surprisingly the toxicity level of fertilizer industry discharge may influence by theenvironmental factors such as conductivity, temperature, pH, cardon dioxide (CO2), oxygen and elements. Through studies, these factors will influence the behavior and certain biochemical indices of the fish, such as C. striatus, by acting either in synergistic, antagonistic or simple additive manner (Yadav et al., 2005; Bobmanuel et al., 2006; Yadav et al., 2007). A high conductivity value indicates high concentration of dissolved ion within the industrial discharge. However, the conductivity value which recorded in this study was slightly below the required limit. Moreover, in this study the increased in fish mortality may due to the increased in water temperature, the increased uptake of industrial discharge components and low dissolved oxygen in the water (Yadav et al., 2007). Carmago et al. (1992) found that the rivers nearer industrial discharge point have adverse impact to the environment as well as to macrobenthic communities.

Toxic contaminants from surface runoff, sewage discharges and industrial discharge have caused negative impacts towards the freshwater macrobenthic communities. The presence of substance chemical such as ammonia, chlorine, cyanide, metals, PCBs, pesticides and phenols would caused a decline pattern on the number of species and changes in the species composition. Furthermore, when industrial discharge and river regulation interact, benthic macroinvertebrates will be highly exposed to the toxic contaminants. The living organism which will be deeply affected are shredders, which feed on coarse sedimentary detritus, and collector-gatherers, which feed on fine sedimentary detritus, were the macroinvertebrate functional feeding groups are most adversely affected. Furthermore, during the industrial process, high amount of hydrofluoric acid (HF) are used to separate different sandy materials which are subsequently used for manufacturing glass at industrial plants. Therefore, high concentration of fluoride ion and suspended inorganic matter discharged bythe industrial into the study site. Carmago et al. (1992) noted that short-term flowfluctuations, low concentration of dissolved oxygen and also the siltation of suspendedinorganic matter caused by industrial discharge contribute greatly to the changes insediment and directly affect the structure of macro invertebrate community. The highsiltation of suspended inorganic matter caused significant reductions in taxa richness and abundance of zoo benthic communities as it changes the natural structure of the substratum. Other than that, the fluoride pollution which generated by the industrial discharge was also contributed to adverse effects on the macro benthic community.

2.2.2 USED TYRES

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Tyres environmentally are not desired at landfills, due to their large volumes and 75% void space, which quickly consume valuable space. Tyres can trap methane gases, causing them to become buoyant, or bubble to the surface. This ‘bubbling’ effect can damage landfill liners that have been installed to help keep landfill contaminants from polluting local surface and ground water. Shredded tires are now being used in landfills, replacing other construction materials, for a lightweight backfill in gas venting systems, leachate collection systems, and operational liners. Shredded tire material may also be used to cap, close, or daily cover landfill sites. Scrap tires as a backfill and cover material are also more cost-effective; since tires can be shredded on-site instead of hauling in other fill materials. Tyre stockpiles create a great health and safety risk. Tyre fires can occur easily, burning for months, creating substantial pollution in the air and ground. Recycling helps to reduce the number of tyres in storage. An additional health risk, tyre piles provide harborage for vermin and a breeding ground for mosquitoes that may carry diseases. Illegal dumping of scrap tyres pollutes ravines, woods, deserts, and empty lots; which has led many states to pass scrap tyre regulations requiring proper management. Tyre amnesty day events, in which community members can deposit a limited number of waste tyres free of charge, can be funded by state scrap tyre programs, helping decrease illegal dumping and improper storage of scrap tires. Unfortunately, tyre storage and recycling are sometimes linked with illegal activities and lack of environmental awareness. Due to their heavy metal and other pollutant content, tires pose a risk for the (leaching) of toxins into the groundwater when placed in wet soils. Research has shown that very little leaching occurs when shredded tires are used as light fill material; however, limitations have been put on use of this material; each site should be individually assessed determining if this product is appropriate for given conditions. Ecotoxicity may be a problem. Studies show that zinc, heavy metals, a host of vulcanization and rubber chemicals leach into water from tires. Shredded tire pieces leach much more, creating a bigger concern, due to the increased surface area on the shredded pieces. Many organisms are sensitive, and without dilution, contaminated tire water has been shown to kill some organisms.

2.2.3 FLYASH

Environmental problem of fly ash are groundwater contamination since coal contains trace levels of arsenic, barium, beryllium, boron, cadmium, chromium, thallium, selenium, molybdenum and mercury, its ash contains these traces, and therefore cannot be dumped or stored where rainwater can leach the metals and move them to aquifers.

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In 2014, residents living near the Buck Steam Station in Dukeville, North Carolina, were told that "coal ash pits near their homes could be leaching dangerous materials into groundwater. Where fly ash is stored in bulk, it is usually stored wet rather than dry to minimize fugitive dust. The resulting impoundments (ponds) are typically large and stable for long periods, but any breach of their dams or bunding is rapid and on a massive scale. Fly ash contains trace concentrations of heavy metals and other substances that are known to be detrimental to health in sufficient quantities. Potentially toxic trace elements in coal include arsenic, beryllium, cadmium, barium, chromium, copper, lead, mercury, molybdenum, nickel, radium, selenium, thorium, uranium, vanadium, and zinc Approximately 10% of the mass of coals burned in the United States consists of unburnable mineral material that becomes ash, so the concentration of most trace elements in coal ash is approximately 10 times the concentration in the original coal. A 1997 analysis by the U.S. Geological Survey (USGS) found that fly ash typically contained 10 to 30 ppm of uranium, comparable to the levels found in some granitic rocks, phosphate rock, and black shale. In 2000, the United States Environmental Protection Agency (EPA) said that coal fly ash did not need to be regulated as a hazardous waste. Studies by the U.S. Geological Survey and others of radioactive elements in coal ash have concluded that fly ash compares with common soils or rocks and should not be the source of alarm. However, community and environmental organizations have documented numerous environmental contamination and damage concerns. A revised risk assessment approach may change the way coal combustion wastes (CCW) are regulated, according to an August 2007 EPA notice in the Federal Register. In June 2008, the U.S. House of Representatives held an oversight hearing on the Federal government's role in addressing health and environmental risks of fly ash.

2.3 INDUSTRIAL EFFLUENT

As defined by the Environmental Protection Agency (2013), is any waste water, treated

or untreated, that flows out a treatment, sewer or industrial outfall .In this project the

aimed effluent is that of industrial effluent. The nature of the effluent depends on the

type of processing and processing and chemicals used at each company. Table A2 (refer

to Appendix) gives a brief picture of some contaminants of their major sources.

2.4 WASTEWATER CONTAMINANTS

Removal of pollutants such as lead from wastewater has conventionally been accomplished through a range of chemical and physical processes (Kiran et al., 2007; Cesur and Baklaya, 2007). There are traditional methods of industrial wastewater

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treatment, such as precipitation, adsorption and coagulation methods. However, these processes can be expensive and not fully effective. Among the available techniques, sorption has been used as one of the most practical methods and recent studies have focused on the search for an inexpensive and efficient adsorbent (Yadanaparthi et al., 2009). A wide variety of materials such as chitosan, granular red mud (Zhu et al., 2007), sugar beet pulp (Pehlivan et al., 2008), rice husk (Wong et al., 2003), rice bran Montanher et al., 2005; Ajmal et al., 2003), activated carbon (Giraldo and Moreno-Piraján, 2008), Zeolite (Stylianou et al., 2007), sawdust (Asadi et al., 2008), cocoa shells (Meunier et al., 2003), Sargassum (Silva et al., 2003) and leaves (King et al., 2006) are examples of low-cost materials used in the removal of heavy metals. Duffus (2002) defines heavy metals as elements that exhibit metallic properties, and are categorized into transition metals, actinides, lanthanides, and some metalloids. According to Ryan and Harrison (2003), Heavy metals include antimony, arsenic, bismuth, cadmium, cerium, chromium, cobalt, copper, gallium, gold, iron, lead, manganese, mercury, nickel, platinum, silver, tellurium, thallium, tin, uranium, vanadium and zinc. Heavy metals accumulate in the body, building up in fat cells, bones, glands and hair leading to a dizzying array of symptoms and chronic diseases (Ryan and Harrison,2003)

The contaminant from the discharge is directly related to the nature of the industry. Forexample, in textile industry, the discharge is usually high chemical oxygen demand (COD), biochemical oxygen demand (BOD) and colour point; tannery industry is on the other hand, produces discharges which have high concentration of metal such as cadmium, and etc. The Table presents a summary of the types of contaminants discharged from different industries

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2.5 Effluent Disposal Regulations (Zimbabwe Environmental Management, 2007)

The table is a list of different classes of effluent disposal permits. It shows the class in

correspondence to its risk and reasons for classification of effluent discharge

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Table: Reasons for classification of effluent discharged into surface water

Classification Risk Reason for classificationBlue Safe Complies with blue standards

Green Low hazard Waste meets green standards or blue

license conditions not being met

Yellow Medium hazard Waste meets yellow standard or green

license conditions not being met

Red High hazard Waste meets red standard or the yellow

license conditions not being met

This table summarises some of the parameters and standards used by the

Environmental Management Agency to classify permits per companies discharge

2.6 EFFLUENT TREATMENT TECHNIQUES

(i) Chemical precipitation

Through company visits, the author learnt that chemical precipitation is one of

the most common ways of effluent treatment technique especially in tanneries.

In this technique, metal ions settle out of solution forming metal ion containing

sediment called precipitate. The precipitate is then filtered or separated from

the solution by the other methods. During formation and settling, the precipitate

can catch ions and particles from solution, increasing efficiency of the method.

For precipitation to occur, coagulants such as lime, aluminum sulphate (alum),

ferrous sulphate and ferric chloride are used. These coagulants cause small

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suspended matter to gather together into bigger aggregates. Precipitations

efficiency is affected by pH, metal ion concentration, temperature and ionic

strength.

(ii) Membrane purification

Membrane purification, also known as reverse osmosis, is based on a semi

permeable separation wall, where certain components pass through the

membrane, while preventing others to pass through. These methods include

membrane bioreactors (MBRs), reverse osmosis and tertiary membrane filtration

(iii) Electro Dialysis

In electro dialysis, ions moves from one solution through ion exchange

membranes to another solution under the influence of an applied electric

potential difference. Cations and anions move towards respective electrodes

when an electric potential is applied between the two electrodes. The major

limitation is clogging the membrane by metal hydroxide precipitation

(iv) Ion exchange

Ion exchange is a process in which ions of like charge are exchanged between

the water phase and the solid resin phase. With this basis, cation exchange can

be used for removal of certain heavy metals (WHO, 2006)

2.7 DRAWBACKS OF CURRENT TREATMENT TECHNIQUES

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Disadvantages of chemical precipitation

Production of sludge is one of the major drawbacks of chemical precipitation in

metal ion removal. The situation is worse if lime is used for primary treatment,

where volumes of sludge can increase up to 50%. Application of alum instead of iron

salts and especially, lime results in much smaller amount of sludge but doesn’t solve

the problem completely

Other drawbacks of chemical precipitation are (from EPA, 2000)

Usually calculations of accurate dosages of chemicals impossible because

of changing levels of alkalinity, different competitive reactions and other

factors. And so, it is necessary to make batch tests often to prove the

optimal treatment conditions. One should also keep in mind that

overdosing can overdosing can result in the reduction f the treatment

efficiency

There is increased concerns about operator safety chemical precipitation

can involve contact with corrosive chemicals

High prices for polymers that can be used

Necessity to transport large amounts of chemicals to the waste water

treatment facilities usually needed

Disadvantages of Membrane Purification

Expensive membrane replacement

Shorter economic life of membrane

High energy consumption in comparison to other methods

Larger amounts of sludge produced

2.8 ADSORPTION

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Adsorption is the adhesion of atoms, ions, or molecules from a gas, liquid, or

dissolved solid to a surface. This process creates a film of the adsorbate on the

surface of the adsorbent. This process differs from absorption, in which a fluid (the

adsorbate) permeates or is dissolved by a liquid or solid (the absorbent). Adsorption

is a surface-based process while absorption involves the whole volume of the

material. The term sorption encompasses both processes, while desorption is the

reverse of it. Adsorption is a surface phenomenon.

Similar to surface tension, adsorption is a consequence of surface energy. In a bulk material, all the bonding requirements (be they ionic, covalent, or metallic) of the constituent atoms of the material are filled by other atoms in the material. However, atoms on the surface of the adsorbent are not wholly surrounded by other adsorbent atoms and therefore can attract adsorbates. The exact nature of the bonding depends on the details of the species involved, but the adsorption process is generally classified as physisorption (characteristic of weak van der Waals forces) or chemisorption (characteristic of covalent bonding). It may also occur due to electrostatic attraction.

Adsorption is present in many natural, physical, biological, and chemical systems, and is widely used in industrial applications such as activated charcoal, capturing and using waste heat to provide cold water for air conditioning and other process requirements (adsorption chillers), synthetic resins, increase storage capacity of carbide-derived carbons, and water purification. Adsorption, ion exchange, and chromatography are sorption processes in which certain adsorbate are selectively transferred from the fluid phase to the surface of insoluble, rigid particle suspended in a vessel or packed in a column. Lesser known, are the pharmaceutical industry applications as a means to prolong neurological exposure to specific drugs.

Adsorption, the binding of molecules or particles to a surface, must be distinguished from absorption, the filling of pores in a solid. The binding to the surface is usually weak and reversible. Just about anything including the fluid that dissolves or suspends the material of interest is bound, but compounds with color and those that have taste or odor tend to bind strongly. Compounds that contain chromogenic groups (atomic arrangements that vibrate at frequencies in the visible spectrum) very often are strongly adsorbed on activated carbon. Decolorization can be wonderfully efficient by adsorption and with negligible loss of other materials.

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The most common industrial adsorbents are activated carbon, silica gel, and alumina, because they present enormous surface areas per unit weight. Activated carbon is produced by roasting organic material to decompose it to granules of carbon - coconut shell, wood, and bone are common sources. Silica gel is a matrix of hydrated silicon dioxide. Alumina is mined or precipitated aluminum oxide and hydroxide. Although activated carbon is a magnificent material for adsorption, its black color persists and adds a grey tinge if even trace amounts are left after treatment; however filter materials with fine pores remove carbon quite well.

A surface already heavily contaminated by adsorbates is not likely to have much capacity for additional binding. Freshly prepared activated carbon has a clean surface. Charcoal made from roasting wood differs from activated carbon in that its surface is contaminated by other products, but further heating will drive off these compounds to produce a surface with high adsorptive capacity. Although the carbon atoms and linked carbons are most important for adsorption, the mineral structure contributes to shape and to mechanical strength. Spent activated carbon is regenerated by roasting, but the thermal expansion and contraction eventually disintegrate the structure so some carbon is lost or oxidized.

Temperature effects on adsorption are profound, and measurements are usually at a constant temperature. Graphs of the data are called isotherms. Most steps using adsorbents have little variation in temperature.

2.9 ADSORBENTS

Adsorbents are used usually in the form of spherical pellets, rods, moldings, or monoliths with a hydrodynamic radius between 0.25 and 5 mm. They must have high abrasion resistance, high thermal stability and small pore diameters, which results in higher exposed surface area and hence high capacity for adsorption. The adsorbents must also have a distinct pore structure that enables fast transport of the gaseous vapors.

Most industrial adsorbents fall into one of three classes:

Oxygen-containing compounds – Are typically hydrophilic and polar, including materials such as silica gel and zeolites.

Carbon-based compounds – Are typically hydrophobic and non-polar, including materials such as activated carbon and graphite.

Polymer-based compounds – Are polar or non-polar functional groups in a porous polymer matrix.

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Silica gel is a chemically inert, nontoxic, polar and dimensionally stable (< 400 °C or 750 °F) amorphous form of SiO2. It is prepared by the reaction between sodium silicate and acetic acid, which is followed by a series of after-treatment processes such as aging, pickling, etc. These after-treatment methods results in various pore size distributions.

Silica is used for drying of process air (e.g. oxygen, natural gas) and adsorption of heavy (polar) hydrocarbons from natural gas.

Zeolites

Zeolites are natural or synthetic crystalline aluminosilicates, which have a repeating pore network and release water at high temperature. Zeolites are polar in nature.

They are manufactured by hydrothermal synthesis of sodium aluminosilicate or another silica source in an autoclave followed by ion exchange with certain cations (Na+, Li+, Ca2+, K+, NH4

+). The channel diameter of zeolite cages usually ranges from 2 to 9 Å (200 to 900 pm). The ion exchange process is followed by drying of the crystals, which can be pelletized with a binder to form macroporous pellets.

Zeolites are applied in drying of process air, CO2 removal from natural gas, CO removal from reforming gas, air separation, catalytic cracking, and catalytic synthesis and reforming.

Non-polar (siliceous) zeolites are synthesized from aluminum-free silica sources or by dealumination of aluminum-containing zeolites. The dealumination process is done by treating the zeolite with steam at elevated temperatures, typically greater than 500 °C (930 °F). This high temperature heat treatment breaks the aluminum-oxygen bonds and the aluminu temperature heat treatment breaks the aluminum-oxygen bonds and the aluminum atom is expelled from the zeolite framework.

Activated carbon

Activated carbon is a highly porous, amorphous solid consisting of microcrystallites with a graphite lattice, usually prepared in small pellets or a powder. It is non-polar and cheap. One of its main drawbacks is that it reacts with oxygen at moderate temperatures (over 300 °C).

Activated carbon can be manufactured from carbonaceous material, including coal (bituminous, subbituminous, and lignite), peat, wood, or nutshells (e.g., coconut). The

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manufacturing process consists of two phases, carbonization and activation. The carbonization process includes drying and then heating to separate by-products, including tars and other hydrocarbons from the raw material, as well as to drive off any gases generated. The process is completed by heating the material over 400 °C (750 °F) in an oxygen-free atmosphere that cannot support combustion. The carbonized particles are then "activated" by exposing them to an oxidizing agent, usually steam or carbon dioxide at high temperature. This agent burns off the pore blocking structures created during the carbonization phase and so, they develop a porous, three-dimensional graphite lattice structure. The size of the pores developed during activation is a function of the time that they spend in this stage. Longer exposure times result in larger pore sizes. The most popular aqueous phase carbons are bituminous based because of their hardness, abrasion resistance, pore size distribution, and low cost, but their effectiveness needs to be tested in each application to determine the optimal product.

Activated carbon is used for adsorption of organic substances and non-polar adsorbates and it is also usually used for waste gas (and waste water) treatment. It is the most widely used adsorbent since most of its chemical (e.g. surface groups) and physical properties (e.g. pore size distribution and surface area) can be tuned according to what is needed. Its usefulness also derives from its large micropore (and sometimes mesopore) volume and the resulting high surface area.

Activated carbon (AC) has proven to be an effective adsorbent to remove a wide variety of organic and inorganic pollutants dissolved in aqueous solutions or in gas streams. Because AC presents an exceptionally high surface area, it is an adsorbent widely used for wastewater treatment . Hence, the well-developed porous structure of AC and a wide range of surface functional groups are responsible for most adsorption mechanisms. Being a porous material, AC is able to distribute chemical compounds on its hydrophobic surface, making it accessible to other reagents.

Despite its widespread use in adsorption processes, the main drawback to its industrial application will principally depend on the nature of the pollutants adsorbed upon it and especially the ease with which they can be desorbed. Once its adsorption capacity has been exhausted, ACs can be deposited in landfills, incinerated or regenerated for reuse. However, the disposal of hazardous waste in landfills is becoming increasingly unacceptable due to growing concerns about the effect of pollutants on the environment and more stringent environmental standards. This has motivated the development of regeneration systems to allow broader application of AC adsorption and ensure its economic viability and environmental security. The worldwide demand for activated carbon was about 4.28 million tons in 2012, and it is expected to increase more than 10 % annually over the next five years. This increase in activated carbon demand is probably due to the restrictive pollution legislation established in the USA and China. For example, in China, there is a project called the Twelfth Five Year Plan (2011–2015), which aims to improve the quality of water and air through the use of more environmentally friendly processes. In this way, the AC application demand to

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reduce emissions and for wastewater treatment by adsorption processes will increase significantly.

The application of activated carbon in large scale can be observed in various fields such as: (i) purification of different types of liquid food ingredients, including edible oils, extracts, concentrates, additives, and acids; (ii) discoloration, deodorization, and reduction of contaminant liquids, including juice concentrates and spirit beds in beverages production; (iii) discoloration and purification of different kinds of processing liquid phase using fixed-bed columns for a wide variety of chemicals and chemical intermediates; (iv) purification of drinking water and reduction of geosmin and methyl isoborneol, flavor and odor components, total organic carbon (TOC), and herbicides such as atrazine. Other applications include air purification, control of organic vapors, odor control, corrosive acid gas and metal removal.

The treatment of gases, originated from municipal solid waste combustion, is another example of large-scale application. The process is practical and has a good efficiency; however, it generates large amounts of saturated activated carbon intended to controlled landfills.

Aikyo and Suzuki indicated some problems in large-scale application of activated carbon adsorption applied to municipal fuel gas, regarding the disposal of solid containing absorbed dioxins. Most owners or operators of municipal solid waste incineration plants often find that the cost of activated carbon, including the purchase and disposal costs, is expensive compared with other items of operation and management. Minimizing the cost of has activated carbon become an important issue, and from the viewpoint of engineering applications an interesting initiative would be to reduce the cost of operation.

The individual cost of adsorbents, i.e., activated carbon, depends on availability, processing necessary conditions, both local treatment and recycling issues, and lifetime. Cost will vary when the adsorbents are made in and for the developed, developing or underdeveloped countries.

Polymer adsorption

Adsorption of molecules onto polymer surfaces is central to a number of applications, including development of non-stick coatings and in various biomedical devices. Polymers may also be adsorbed to surfaces through polyelectrolyte adsorption.

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2.10 PREPARATION OF ADSORBENTS

Activated carbon adsorbent is carbon produced from carbonaceous source materials such as nutshells, coconut husk, peat, wood, coir, lignite, coal, rubber, and petroleum pitch. It can be produced by one of the following processes:

1. Physical reactivation: The source material is developed into activated carbons using hot gases. This is generally done by using one or a combination of the following processes:

o Carbonization: Material with carbon content is pyrolyzed at temperatures in the range 600–900 °C, usually in inert atmosphere with gases like argon or nitrogen

o Activation/Oxidation: Raw material or carbonized material is exposed to oxidizing atmospheres (oxygen or steam) at temperatures above 250 °C, usually in the temperature range of 600–1200 °C.

2. Chemical activation: Prior to carbonization, the raw material is impregnated with certain chemicals. The chemical is typically an acid, strong base, or a salt (phosphoric acid, potassium hydroxide, sodium hydroxide, calcium chloride, and zinc chloride 25%). Then, the raw material is carbonized at lower temperatures (450–900 °C). It is believed that the carbonization / activation step proceeds simultaneously with the chemical activation. Chemical activation is preferred over physical activation owing to the lower temperatures and shorter time needed for activating material.

Activated carbon can be manufactured from any organic material. Commercial carbons are made from sawdust, wood, charcoal, peat, lignite, petroleum coke, bituminous coal, tyre rubber, and coconut shells. We use activated coal carbon and activated coconut carbon in the sintering process for metal clay. Activated carbon is a carbon which is chemically treated, or steamed to enhance its absorbing properties.

Coal ActivationAccording to Calgon Carbon, a manufacturer of activated carbon, “the coal is pulverized to a very fine particle, about the size of talcum powder. The powdered coal is mixed with a binder to "glue" it back together and pressed into briquettes. These in turn are crushed and classified to the size of the desired end product. The coal is heated in an oxygen free oven to remove the unstable components of the coal. The carbon is then activated by heating it again in an oxygen and steam environment. The activation process creates a highly porous coal with remarkable surface area.

Chemical Activation

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Wood type products are activated using chemical activation. The material is mixed with activating and dehydrating chemicals (acids) and then heated between 932 - 1472˚F. The acid causes the wood to swell, opening the cellulose structure and stabilizes this structure, keeping it open. The acid is then washed out of the carbon.2

Steamed ActivationPeat, coal, coconut shells, lignite, anthracite, rubber, and wood are activated using steam activation. The material is converted to carbon through heating. Then it is cut into 0.35nm thick chips (looks like potato chips). They are placed in a jumbled pile and are heated to 1835˚F and at the same time they are blasted with steam heated to 266˚F. The steam creates pores in the carbon. Depending on the original material used the pores are very small or can be large. The pores in hard coconut shell carbon are very small, micro pores. The pores formed in peat are usually meso sized pores.2

The performance of a carbon is based upon the types and number of internal pore sizes, the internal surface area, and percent of ash in the carbon. The most important determining factor for carbon use and performance is pore structure.There are three sizes of pore measurements.

Micropores have a radius of less than 1 nanometer* (nm) and are the smallest of openings in the carbon or less than 40 angstroms.**

Mesopores have a radius of 1 -25 nm. Macropores have a radius of larger than 25nm or above 5,000 angstroms.

Since the carbon we use is pulverized, it only has micro and meso pores.Carbon is pulverized into various mesh sizes. On her blog site, Hadar Jacobson3 refers to using a size 12 x 40 coconut shell-based carbon, such as what the PMC Connection sells. Additionally, she states, “…we want carbon that does not produce a lot of ash and does not stay hot a long time after firing.”

Over time the carbon pores fill up with the contaminant (now called adsorbate) and its absorbing power is gone. The carbon is “spent,” and no longer works. Reactivation is a process of cleaning the pores so that the carbon can work again. There are three processes used for reactivation.

Use heat (thermal recycling).The heat vaporizes or burns off the adsorbate inside the pores. The carbon is reactivated between 1292 - 1832˚F. 2

Use steam (steam recycling). Steam is hard for the amateur to process at home. Using boiling water. 2

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To reactivate the carbon using heat, place it inside the stainless steel container, cover with the lid, and fire for 30 minutes at 1750°F. Allow it to cool in the oven with the lid on. Then sift out the ash by pouring it from pan to pan while blowing on it lightly, or take it outside with a light breeze blowing and pour it from pan to pan.

To reactivate the carbon with boiling water, place it into a sauce pan of boiling water (ratio 2 to 1), stir with a spoon. Soak the carbon until it sinks to the bottom of the pan and then pour off excess water. Repeat 4 - 5 times. Place the carbon again into boiling water and allow soaking it for 24 hours. Dry the carbon by placing it on flat tray in the kitchen oven or toaster oven and heat at a low temperature (150˚F) until dry.

Commercial activated carbon is regarded as the most effective material for controlling the organic load. However, due to its high cost, and the fact that about 10 to 15 percent is lost during regeneration, unconventional adsorbents like flyash, peat, lignite, bagasse pith, wood and saw dust have been widely investigated for the removal of refractory materials (Pandey et al., 1985), with varying degree of success. Several investigations (Mott and Weber, 1992; Viraraghavan and Dronamraju, 1992) explored the use of flyash as an adsorbent for the treatment of wastewater to remove a variety of organic compounds and color. Gupta et al. (1990) used flyash for the removal of chrome dye from aqueous solutions and found that the mixture of flyash and coal (1:1) may substitute the activated carbon. Each of them concluded that flyash has a significant capacity for adsorption of organic compounds from aqueous solutions. It was reported that the carbon content of flyash plays a significant role during the adsorption of organic compounds by flyash (Banerjee et al., 1995). The adsorption capacity increases with the increasing carbon content of flyash. However, a review of the literature showed that very little investigation has been conducted to find out the suitability of synthetic sorbents like PTS or flyash for the removal of COD from domestic waste

Basically, there are two uses of tyre chars: as reinforcing filler and an adsorbent. Usually commercial carbon black is used for filling polymers and vulcanizates. Use of the tyre char as an end product for the tyre and printing ink industries has been reported to be unsatisfactory. This is due to the high ash content of the tyre char. Chars from tyre pyrolysis contain as much as 15 wt. % of ash, with the majority of this ash being zinc oxide. A means of removing the ash from tyre char is an important issue in the process of producing useful carbon black from waste tyres. Carbon as an adsorbent is usually evaluated by its surface area. Measurement of surface area can be obtained by a gas adsorption method, for example nitrogen BET. Tyre chars which had not been activated served well in removing mercury compounds from aqueous solution. The surface area

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of tyre char is in the range of 30-90 m2/g, which is comparable with those of carbon blacks used in rubber products. Therefore, an activation process is required to produce activated carbon from tyre char. Carbons can be activated by mild oxidation with steam or carbon dioxide at high temperatures to develop internal surface area. The slow gasification kinetics of carbons in steam or carbon dioxide allows gas molecules diffusing into the carbon micro pores to create or enlarge micro pores. The activation process usually follows hydrocarbon pyrolysis performed in an inert environment, but it is possible to accomplish pyrolysis and activation in one stage by pyrolyzing under mildly oxidizing conditions.

2.11 BOEHM TITRATIONS

Many applications of carbon materials are strongly influenced by their surfacechemistry. Thus, their uses in catalysis, adsorption in solution or electrochemicalprocesses are the examples of the influence of surface chemistry on Boehm titration is an acid-base titration method which is used the performance of materials. Many properties of carbon materials are decisively influenced by chemisorbed oxygen, which can be bound in the form of various functional groups. The surface of carbons is heterogeneous and consists of the faces of basal planes and of edges of such layers. The edge sites are much more reactive than the atoms in the interior of the basal planes, and they represent active sites for oxygen chemisorptions. Therefore, surface oxygen groups are predominantly located on the edges. Surface oxygen groups on carbon materials are usually determined by titrations in aqueous solutions. One of the standard methods is the Boehm method. to determine the amount of surface oxygen groups (acidic or basic) present on carbon surfaces (activated carbon, carbon black, graphene, carbon nanotubes, etc). There are several authors that perform the titration in various techniques direct titration, back titration and potentiometric titration. But the most common is a back titration technique, which consists of mixing the initial base with an excess of acid and titrating with base, while in the case of an initial acid, it is mixed with an excess of base and titrated with an acid. The method uses NaOH, Na2CO3, NaHCO3 and HCl and its main principle is that the number of acidic sites is determined under the assumptions that NaOH neutralizes carboxylic, lactonic and phenolic groups on the carbon surface; that Na2CO3 neutralizes carboxylic and lactonic groups; and that NaHCO3 neutralizes only carboxylic groups. Boehm titration has been adopted as one of usual methods to characterize surface functionality of carbon adsorbents. To characterize the representative functionalities such as carboxylic, lactonic and phenolic hydroxyl group, Boehm suggested selective neutralization of each functionality using different strength of base solutions called reaction bases; ie, sodium hydroxide (NaOH) neutralize all of three functionalities while sodium carbonate (Na2CO3) neutralize carboxylic and phenolic groups, and sodium bicarbonate (NaHCO3) only neutralize phenolic groups. However, there are a few sophisticated issues involved in Boehm’s titrations. When carbon adsorbents are acid-

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oxidized, the side walls concurrently disintegrate to some extent to yield acidic carbon fragments with phenolic and/or carboxylic functional groups on the periphery of aromatic core. Under this circumstance, it becomes very important to discern the functionalities. The surface oxygen groups on a carbon with acidic (carboxyl, lactone, phenol) as well as basic properties can be determined by the Boehm method. Thesegroups differ in their acidities and can be distinguished by neutralisation with differentsolutions:HCl (for basic groups) and NaHCO3, Na2CO3 and NaOH (for acidic groups).

2.12 IODINE ADSORPTION NUMBER

Many carbons preferentially adsorb small molecules. Iodine number is the most fundamental parameter used to characterize activated carbon performance. It is a measure of activity level (higher number indicates higher degree of activation), often reported in mg/g (typical range 500–1200 mg/g). It is a measure of the micropore content of the activated carbon (0 to 20 Å, or up to 2 nm) by adsorption of iodine from solution. It is equivalent to surface area of carbon between 900 m²/g and 1100 m²/g. It is the standard measure for liquid phase applications.

Iodine number is defined as the milligrams of iodine adsorbed by one gram of carbon when the iodine concentration in the residual filtrate is 0.02 normal. Basically, iodine number is a measure of the iodine adsorbed in the pores and, as such, is an indication of the pore volume available in the activated carbon of interest. Typically, water treatment carbons have iodine numbers ranging from 600 to 1100. Frequently, this parameter is used to determine the degree of exhaustion of a carbon in use. However, this practice should be viewed with caution as chemical interactions with the adsorbate may affect the iodine uptake giving false results.

2.13 METHYLENE BLUE TEST

Methylene blue Adsorption: Some carbon have mesopores structure which adsorb medium size molecules such as dye Methylene blue. Methylene blue adsorption is reported in g/100g ( range of 11-28g/100g) (Elliot et al., 1989). Methylene blue was chosen in this study because of its known strong adsorption onto solids and its recognized usefulnessin characterizing adsorptive material Methylene blue has a molecular weight of 373.9 x 10-3 kg mol-1Principles: The Langmuir equation was used to calculate the specific surface area of the sorbents. The general form of Langmuir isotherm is as Eqn. 1:Y=KC/(1+KC) - - (1)

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where Y is the fraction of sorbent surface covered by adsorbed methylene blue molecules, K is a constant, and C is the equilibrium methylene blue solution concentration. In this research,

Y = N/Nm ,where N represents the number of moles of methylene blue adsorbed per gram sorbent at equilibrium concentration, C, and Nm is the number of moles of methylene blue per gram of sorbent required to form a monolayer. After making the substitution andNrearranging Eqn. 2, we obtain :

C/N=C/NM + 1/KNM

For all adsorption isotherms of methylene blue. A plot of C/N vs. C gives a straight line with slope equal to 1/Nm, and intercept equal to 1/KNm. Therefore, the Langmuir isotherm is an adequate description of the adsorption of the methylene blue onto sorbents. The specific surface area was calculated by equation 3 (Chongrak et al.,1989):

SMB=(Ng х aMB х N х 10-20)/M - - (3)

where SMB is the specific surface area in 10 -3km2 kg-1; Ng is the amount of methylene blue adsorbed at the monolayer of sorbents in kg kg-1 .(In this research we defined experimental qe as Nm, which is the amount methylene blue adsorbed at the monolayer of sorbents in mg/g or 10-3 kg/kg), aMB is the occupied surface area of one molecule of methylene blue =197.2 Ų (Graham,1955) ; N is Avogadro’s number, 6.02 x 1023 mol-1; and M is the molecular weight of methylene blue,373.9 х 10-3Kg mol-1.

2.14 CHAPTER SUMMARY

The research and review so far obtained in this chapter clearly showed that fly ash and

waste tyre rubber can be utilised as an adsorbent. The next chapter titled methodology

uses this chapter’s information in making the composite mixture adsorbent and testing

its adsorption capacity

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CHAPTER 3: RESEARCH METHODOLOGY

3.1 INTRODUCTION

This chapter gives a fully detailed methodology used for the success of this project,

stating the instrumentation and reagents used by the author. Sampling, sample

preparation and effluent treatment procedures are all outlined, explaining ways used to

reduce errors

3.2 INSTRUMENTATION AND APPARATUS

UV-VIS SPECTROPHOTOMETER

ANALYTICAL BALANCE

OVEN

CRUCIBLES

SIEVES

FUNNEL AND WHATMAN FILTER PAPER

SEPARATING FUNNELS

BEAKERS

CONICAL FLASKS

BURRETE

VOLUMETRIC FLASKS

MEASURING CYLINDER

PARA FILM

TESTTUBES

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3.3 REAGENTS

FLY ASH AND TYRE RUBBER COMPOSITE ADSORBENT

COMMERCIAL ADSORBENT

STOCK SOLUTIONS OF FECl3, NiSO4NH4, CuSO4, KCr2O7

STOCK SOLUTIONS OF HCl, H3PO4, HNO3

DISTILLED WATER,

NaOH, Na2CO3, NaHCO3, NaNO3

METHYLINE BLUE

RESUBLIMED IODINE CRYSTALS

3.4 EXPERIMENT DESIGN

In order to reduce systematic errors, all chemicals used were of analytical grade and all

instruments were calibrated first before use.

3.5 ADSORBENT MATERIAL PREPARATION

The waste tyres were initially washed with detergent solution and dilute HCl in order to remove the earthen soil debris. After that, the cleaned and dried waste tyre was burned and the residue placed in a porcelain crucible and burnt completely at 250°C in an oven for 4 h. After cooling, a very dilute acidic solution (such as 0.001 mol L-1 HCl) was used to remove the salts of metals such as sodium, potassium and calcium. Then the mixture was filtered using Whatman grade 42 filter paper. The filtered solid was then washed with 100 mL of double distilled water and dried at 105ºC for 2 h before use.

The adsorbent flyash was sieved and washed with dilute (0.05N) HNO3 to remove

soluble metal oxides (CaO, MgO etc) filtered and washed again with distilled water until

it was free of acid. Then it was dried at 1000C and finally kept in polythene bottles

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The two adsorbent materials are mixed in the ratio of 1:1 before use

3.6 SAMPLE PREPARATION

The test samples used were prepared in the laboratory using different metal salts, FECl3,

NiSO4NH4, CuSO4, KCr2O7. 1g accurately measured and dissolved in 1litre volumetric flask

in distilled water to make a 1000ppm solution of the metal salts or 10g measured and

dissolved in 1 litre volumetric flask of distilled water to make 10000ppm solution of the

metal salt. The metal salts contained other ions besides the heavy metal, so the

adsorption of these ions was also tested.

3.7 BOEHM TITRATIONSBoehm titration is an acid-base titration method which is used to determine the amount of surface oxygen groups (acidic or basic) present on carbon surfaces eg (activated carbon adsorbents, carbon black etc). There are several authors that perform the titration in various techniques direct titration, back titration and potentiometric titration. But the most common is a back titration technique, which consists of mixing the initial base with an excess of acid and titrating with base, while in the case of an initial acid, it is mixed with an excess of base and titrated with an acid. The method uses NaOH, Na2CO3, NaHCO3 and HCl and its main principle is that the number of acidic sites is determined under the assumptions that NaOH neutralizes carboxylic, lactonic and phenolic groups on the carbon surface; that Na2CO3 neutralizes carboxylic and lactonic groups; and that NaHCO3 neutralizes only carboxylic groups.

1.5g of adsorbent was added to 4 separate flasks each containing 50mL of 0.05M NaOH, Na2CO3, NaHCO3 and HCl (these solutions are called the reaction bases or acid). The flasks were sealed and kept in a water bath at room temperature for 24hrs. After 24hrs, the carbon was filtered out. 10mL aliquot of NaOH reaction base was taken and an excess of 20mL of 0.05M HCl was added with 2 drops of Phenolphthalein indicator. The mixture was titrated against 0.05M NaOH and the volume of NaOH required to reach the endpoint was noted. Each titration was repeat twice. Similar was done for NaHCO3 reaction base, while for Na2CO3 reaction base an excess of 30mL of 0.05M HCl was added (rather than 20mL, due to the diprotic property of the base to ensure complete reaction with the acid). As for the HCl reaction acid, 20mL of 0.05M NaOH was added and it was titrated against 0.05M HCl.

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mol carbon functionality = ( [R a or b]*Vr - ( [X]*Vx - [T]*Vt) ) / m

[R a or b] is the concentration of the reaction base or acid initially in the 50mL in units of mol/L Vr is the volume of reaction base or acid initially which is 50mL or 0.05L [X] is the concentration of excess acid or base added to the 10mL aliquot in mol/L Vx is the volume of excess acid or base added in L [T] is the concentration of the titrant used in mol/L Vt is the volume of titrant required to reach the end point which is determined by experiment in L m is the mass of carbon used in g .The method uses NaOH, Na2CO3, NaHCO3 and HCl and its main principle is that the number of acidic sites is determined under the assumptions that NaOH neutralizes carboxylic, lactonic and phenolic groups on the carbon surface; that Na2CO3 neutralizes carboxylic and lactonic groups; and that NaHCO3 neutralizes only carboxylic groups. The number of basic sites is calculated from the amount of HCl required in the titration

3.8 IODINE ADSORPTION NUMBER

Iodine adsorption number: This is the most fundamental parameter used to characterize activated carbon performance. It is a measure of activity level (Higher degree indicates higher activation), often reported in mg/g (with typical range of 500 – 1200mg/g). It is a measure of the micropore content of the activated carbon (values > 0 to 20 AO, or up to 2nm) by adsorption of iodine from solution. It is equivalent to surface area of activated carbon between 900m2/g and 1100/mo/g and. (Elliot et al., 1989). It tells of carbons that preferentially adsorb small molecules.

Preparation of 0.1M sodium thiosulphate solution.Procedures: About 500cm3 of distilled water was boiled for 15mins and allowed to cool followed by the dissolution of 25g Sodium thiosulphate (NaS2O2.5H2O) in it. The resulting solution was further made up to the mark in a 1L volumetric flaskwith distilled water. The solution was used immediately and so this precluded its usualpreservation treatment by adding 0.1g Sodium carbonate (Na2CO3), 3 drops of Chloroform andstorage in a dark place (Aziza et al., 2008, Igwe and Abia, 2003).

Preparation of 0.02M Potassium iodate.Procedures: 4.28g Potassium iodate was accurately weighed and dissolved in a minimum of distilled water in a 250ml beaker. The solution was finally made to the 1litre-graduated mark to give a 0.02M solution (Aziza et al., 2008, Igwe and Abia, 2003).

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Standardization of sodium thiosulphate solution.Procedures: A 25ml aliquot of the prepared standard was pipetted into a 25ml Erlenmeyer flask. 1g of KI was added and the mixture was swirled for dissolution. 3cm3 of 1M H2SO4 was added and the liberated Iodine was immediately titrated with the Thiosulphate solution, with a constant shaking until the solution becomes pale yellow. The solution was then diluted to 100cm3 followed by the addition of 2ml freshly prepared starch indicator solution.Titration of the resulting blue black solution was resumed with constant swirling to the disappearance of the blue black coloration. The entire procedure was repeated 3 more times for each set of sample. The concentration of the thiosulphate was determined from the average titre value and the concentration of iodate the stoichiometry of the reaction equation(Aziza et al., 2008, Igwe and Abia, 2003).

Preparation of 0.02M iodine solutionProcedure: 20g iodate free KI was dissolved in 40ml distilled water in a glass stoppered 1000cm3 volumetric flask 12.7g of Iodine was weighed and transferred by means of small dry funnel into the concentrated KI solution. The flask was stoppered and shaken while still in cold until all the Iodine dissolved. The solution was allowed to attain room temperature and made to the mark with distilled water (Aziza et al., 2008).

Preparation of 1% starch indicatorProcedure: A paste was made of 1g Starch with little water and poured with constant stirring into 100ml of boiling water and allowed to boil for 1 minute. The solution was allowed to cool and stored. (Aziza et al., 2008; Igwe and Abia, 2003).

Standardization of iodine solutionProcedure: 25cm3 portion of iodine was transferred by means of measuring cylinder to a 250cm3 Erlenmeyer flask. The contents of the flask were diluted to 100ml and titrated with standardized thiosulphate solution from a burette until the solution turn pale yellow. 2ml of freshly prepared starch indicator were added and the titration w

Determination of iodine adsorption number ofsorbent

0.5g AC from each precursor was weighed into a beaker and 25ml of standard Iodine solution confirmed concentration after standardization was added. The mixture was

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swirled vigorously for 10mins and filtered by means of a funnel impregnated with clean filter paper. 20ml of the clear filtrate was titrated with the standard (0.1115M) thiosulphate confirmed concentration after standardization to a persistence of a pale yellow color. 5ml of freshly prepared Starch indicator solution was added and titration resumes slowly until a colorless solution appeared, the procedure was repeated for two more times. The titration was also repeated with 20cm3 portions of the standard iodine solution (not treated with AC from the precursor) to serve as blank titration.

The iodine adsorption number (IAN) was calculated from the relationship as

IAN = Ms (Vb - Vs) / 2Ma

Where: Ms = molarity of thiosulphate solution (mol/dm3).Vs = volume of thiosulphate (cm3) used for titration of the PAC aliquot.Vb = volume of thiosulphate (cm3) used for blank titration.Ma = mass of AC (g).

The iodine number (IN) was calculated from the relationship as:

The conversion factor can be calculated as follows:

(Mol.wt of Iodine × Normality of Iodine × Volume of analyte/ Wt. of activated carbon)

C= Blank reading – volume of hypo consumed after the adsorption of Activated carbon.

Iodine number = C ×Conversion factor (mg/g)

measurements extending from 2 to 12 hours at 27±2°C on reference carbon It was noted that the curve seems to reach complete equilibrium (least absorbance or highest adsorption value) in about 8 hours, then, fluctuations in plateau sets in before the 10th hour of adsorption. Therefore, we suppose that the adsorption of iodine onto the adsorbent has reached its maximum capacity. Consequently, this time was chosen as interaction time for adsorption of all samples.

Iodine Number is accepted as the most fundamental parameter used to characterize activated carbon performance. It gives the measure of activity level (higher number indicates higher degree of activation).

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3.9 METHYLENE BLUE TEST

Methylene blue stock(1000mgl-1) and standard solution

Procedure: Methylene blue was dried at 110°c for 2 hours before use. All of the Methylene blue solution was prepared with distilled water. The basic dye (Methylene blue) was used without further purification.

(i) A stock solution of 1000mgl-1 was prepared by dissolving 1.127g Methylene blue in 1000ml distilled water (Omomnhenle et al., 2006). This gives the Methylene stock. The experimental solution was prepared by diluting the stock solution with distilled water to between 10 and 160mgl-1, 1g of adsorbent was weighed into a test-tube and 25ml of standard methyline blue agitated in it until adsorption equilibrium is reached. The concentration of MB was determined at 630nm by the UV – visible spectrophotometer (Chongrak et al.,1998).(ii)A calibration curve of optical densities against methylene blue concentrations was obtained by using standard methylene blue solutions of known concentrations at pH values between 7 and 8. This was done to verify the wavelength for a 160mg/L concentration. An adsorption study was carried out to find the equilibrium time. This time was determined by a series of absorbance

3.10 HEAVY METAL TITRATION

3.10.1 CHROMIUM TITRATION

Analytical reagent grade standard solution is required. This solution is potassium dichromate solution that meets hexavalent chromium Preparation of a potassium dichromate standard for redox titration analysis requires that 25 ml of the analytical reagent grade standard solution is diluted to about the 200-ml mark with deionized water in a 400-ml beaker. In addition, 5 ml of concentrated sulfuric acid, 5 ml of concentrated phosphoric acid, a stirring bar, and five drops of the redox indicator are added to the beaker. The redox titrant is titrated to a green endpoint recording the amount of titrant dispensed. Preparation of test sample solution for hexavalent chromium analysis by redox titration requires that 10 ml of sample solution is pipette into a 500-ml volumetric flask which is filled to the mark with deionised water and mixed. Then 25 ml of this solution is pipetted in the flask into a 400-ml beaker and deionised water added to about the 200-ml mark of this beaker. As before. 5 ml of

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concentrated sulfuric acid, 5 ml of concentrated phosphoric acid, a stirring bar, and five drops of the redox indicator are added to the beaker. The redox titrant is titrated to a green endpoint recording the amount of titrant dispensed. Preparation of a test sample solution for total chromium analysis by redox titration requires that 10 ml of sample solution is pipetted into a 500-ml volumetric flask filled to the mark with deionized water and mixed. Then 25 ml of this solution is pipetted in the flask into a 400-ml beaker and deionised water added to about the 200-ml mark of this beaker. As before, 5 ml of concentrated sulfuric acid and 5 ml of concentrated phosphoric acid are added to the beaker. In addition, 0.05 ± 0.01 grams of manganese sulfate (a grain),3.0 ± 0.1 grams of ammonium persulfate, 5 ml of the reagent grade silver nitrate solution, and a stirring rod are added to the 400-ml beaker. This solution is boiled until a steady red color occurs, and then 5 ml of concentrated hydrochloric acid is added, making the solution in this beaker turn yellow. This solution is boiled again until it is clear, with the exception of the silver chloride precipitate, and then the solution is cooled to room temperature. Finally, a stirring bar and five drops of the redox indicator are added to this solution and titrated using the redox titrant to a green endpoint recording the amount of titrant dispensed. All standard and sample solutions are analyzed in triplicate. Trivalent chromium ion concentrations in the samples are determined by the difference between hexavalent chromium and total chromium and are calculated by simple proportion.

3.10.2 Determination of copper in copper sulphate (CuSO4.5H2O)

Theory:Copper sulphate reacts with potassium iodide according to the following equation:

2CuSO4 + 4KI → Cu2I2 + I2↑ + 2K2SO4

2Na2S2O3 + I2 → Na2S4O6 + 2NaI

i.e. 2CuSO4 ≡ I2 ≡ 2Na2S2O3

The equivalent weight of copper sulphate = M. wt.

The equivalent weight of copper = atomic wt. = 63.5

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Procedure:

1- Transfer 10 ml of copper sulphate solution to a conical flask, and then add 10 ml

of potassium iodide solution (10%).

2- Titrate the liberated iodine with 0.1N thiosulphate solution till the color

becomes pale yellow.

3- Add 1 ml of starch solution and continue adding the thiosulphate solution till

the blue colour is discharged (a white ppt. of cuprous iodide remains).

4- Repeat the experiment twice.

Calculation:

1 ml 0.1N Na2S2O3 solution ≡ 0.1×63.5

1000 ≡ 0.00635 gm Cu

wt. of Cu = V(S2O3−2) x 0.00635 gm / 10 ml

or:

N . V (S2O3−2) = N . V (Cu)

N . V (S2O3−2) =

wt .of Cueq .wt x 1000

wt. of Cu (gm) = N .V (S2O3−2 )×eq .wt .

1000

3.10.3 Determination of ferric iron with EDTA

Theory:

Salicylic acid and ferric ions form a deep-colored complex with a maximum absorption

(λmax) at about 525 nm; this complex is used as the basis for the photometric titration of

ferric ion with standard EDTA solution. At a pH of 2.4 the EDTA-iron complex is much

more stable (higher formation constant) than the iron-salicylic acid complex. In the

titration of an iron-salicylic acid solution with EDTA the iron-salicylic acid color will

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therefore gradually disappear as the end point is approached.

Reagents:

1- EDTA solution 0.1 M .

2- Ferric iron solution 0.05 M ( Dissolve about 12.0gm, accurately weighed, of A.R.

ferric chloride in water to which a little dilute H2SO4 is added, and dilute the

resulting solution to 500ml in a volumetric flask).

3- Sodium acetate-acetic acid buffer ( Prepare a solution which is 0.2 M in sodium

acetate and 0.8 M in acetic acid. The pH is 4.0) .

4- Salicylic acid solution (Prepare a 6% solution of A.R. salicylic acid in A.R. acetone).

Procedure:

1- Transfer 10 ml of ferric iron solution to the conical Flask, add about 10 ml of the

buffer solution of pH = 4 and about 120 ml of dist. H2O.

2- Add 1.0 ml of salicylic acid solution.

3- Add the EDTA solution slowly until the color will decrease, then introduce the

EDTA solution in 0.1 ml aliquots until the color disappear.

4- Calculate the concentration of Ferric iron.

Calculations:

M .V (EDTA)= M' .V' (Fe+3)

wt. of Fe+3 =M .V(EDTA )×atm .wt . Fe+3

1000 = gm/10ml

3.10.4 Determination of nickel with EDTA

Theory:

EDTA complexes with nickel can be used to estimate it. The complex is formed rather

slowly and there are two methods for determining this ion. The direct method ; using

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murexide and the indirect method ; using Eriochrome Black T.

Indirect Method:

Procedure:

1- Pipette 10 ml of the Ni+2 solution in to a conical flask.

2- Add 25 ml of EDTA (0.01M) from the burette.

3- Add 3 ml of the buffer solution (pH=10) and 3 drops of Eriochrome Black T.

4- Titrate rapidly with standard 0.01 M MgSO4 solution until the color changes from

blue to wine-red.

5- Calculate the concentration of Ni+2 .

Calculations:

Volume of 0.01M EDTA added = 25 ml

Suppose that the volume of 0.01M MgSO4 taken n the titration = V1 ml

Excess 0.01M EDTA ≡ V1 ml 0.01M MgSO4

Volume of EDTA reacted with Ni+2 = 25 – V1 ml

wt. of Ni+2 = M .V(EDTA )×atm .wt .¿+2

1000

= 0.01×(25−V 1)×atm.wt .¿+2

1000= gm /10ml

3.10.5 DETERMINATION OF CHLORIDES

Reagents

0.02M AgNO3

Potassium Dichromate indicator

Procedure

To a 50ml of a sample whose pH is between 7 and 10 add 1ml K2Cr2O4 indicator

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Titrate against 0.02N AgNO3 until end point

Calculation

For a 50ml sample: Chlorides (mg/L) = titre of AgNO3 × 14.2

3.10.6 DETERMINATION OF SULPHATES

Reagents

0.02M H2SO4

Standard sulphate solution: dilute 10.41ml of 0.02M H2SO4 TO 100ml of water or

dissolve 147.9mg of anhydrous sodium sulphate to 1L of water

Procedure

Pipette 100ml of sample into a 100ml beaker

Place the beaker onto a magnetic stirrer and stir, add half a spatula full of BaCl2 and stir

for 30 seconds exactly

Stir again thorough for another 30 seconds to ensure that all the BaCl2 is completely

dissolved

Set spectrophotometer at wavelength at 520nm and zero the distilled water

Read values of standard solutions and plot a graph

3.10.7 DETERMINATION OF AMMONIA

Reagents

Nessler Reagents

Stock Aluminum solution

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Standard ammonium chloride solution

Sodium Hexametaphosphate

Procedure

Blank: add 50ml distilled water into a 100ml volumetric flask

Pipette 50ml of sample into 100ml volumetric flask. Into all the flasks add 1ml of the

10% sodium Hexametaphosphate

Followed by 1ml nessler reagent. Dilute to the mark with distilled water and stand for 15

minutes

Read absorbance on a UV/Vis spectrophotometer at wavelength 415nm

3.11 DATA PROCESSING AND ANALYSIS

The amount of metals absorbed and the removal efficiency was then calculated from

the titrations results. For the amount of the adsorbed metals per unit mass of the

adsorbent used , the following expression was used ( Mostafa and Youssef 1993)

qe = (CO - Cp / m) × V

Adsorption quantity at equilibrium

Removal efficiency of target elements by the adsorbent was calculated using the

following formula

Removal efficiency (%) = (Co-Cp/Co) × 100

Where ; Co is the initial metal ion concentration (ppm)

CP the final metal ion concentration (ppm)

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V the volume of the aqueous phase (l)

m the amount adsorbent used (g)

Results obtained were shown using tables and charts

CHAPTER 4: RESULTS, PRESENTATION AND ANALYSIS

4.0 INTRODUCTION

This chapter sets to present, analyze and discuss findings obtained during the

development of the composite mixture adsorbent. The findings were obtained from raw

data of experimental observations which were made in the previous chapter.

4.1 METHYLINE BLUE TEST RESULTS

SAMPLE ABSORBANCE CONCENTRATION

STANDARD 1 0,188 32ppm

STANDARD 2 0.348 64ppm

STANDARD 3 0.509 96ppm

STANDARD 4 0.671 128ppm

STANDARD 5 0.825 160ppm

Composite adsorbent 0.015 9.2ppm

Commercial adsorbent 0,026 11.2ppm

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0 20 40 60 80 100 120 140 160 1800

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Calibration curve of methyline blue test

methyline blue concentration (ppm)

abso

rban

ce

qe = adsorption quantity of dye at equilibrium

qe = (CO - Cp / m) × V

qe(composite adsorbent) = (160ppm-9.2ppm/1g) × 0.025L

=3.77(mg/g)

qe(commercial adsorbent)= ( 160ppm-11.2ppm/1.0017g) × 0.025L

= 3.71(mg/g)

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Removal efficiency (%) = (Co-Cp/Co) × 100

% RE (composite adsorbent) = (160ppm-9.2ppm/160ppm) × 100

= 94.25%

% RE (commercial adsorbent) = (160ppm-11.2ppm/160ppm) × 100

= 93%

SORBENT Absorbance Cp (g/dm 3 ) Co-Cp(g/dm 3 ) qe (mg/g) % RE

Composite 0.015 9.20ppm 150.8ppm 3.77 94.25

commercial 0.026 11.20ppm 148.8 3.71 93

SMB = (Ng× aMB × N × 10-23)/M

SMB= specific surface area of adsorbent methyline blue adsorbent

Ng= qe (mmol/g)

aMB= 197.2A2

N = 6.023× 1023

M= molecular weight of methyline blue

SMB( COMPOSITE ADSORBENT)=( 3.77× 197.2 × {6.023×1023} ×10-23)/ 319.85

= 13.999(Km2Kg-1)

SMB( COMMERCIAL ADSORBENT)=( 3.71× 197.2 × {6.023×1023} ×10-23)/ 319.85

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= 13.78(Km2Kg-1)

4.2 IODINE NUMBER RESULTS

TITRATION RESULTS

SORBENT WEIGHT VOLUME OF

THIOSULPHATE

BLANK

VOLUME OF

THIOSULPHATE

SAMPLE

Composite mixture

adsorbent

2g 31.5ml 21.1ml

Commercial

adsorbent

2g 31.5ml 22.8ml

The iodine adsorption number (IAN) was calculated from the relationship as

IAN = Ms (Vb - Vs) / 2Ma

Where: Ms = molarity of thiosulphate solution (mol/dm3).Vs = volume of thiosulphate (cm3) used for titration of the PAC aliquot.Vb = volume of thiosulphate (cm3) used for blank titration.Ma = mass of AC (g).

IAN (COMPOSITE ADSORBENT) = 0.1M (31.5ml-21.1ml)/2×2g

=0.26

IAN (COMMERCIAL ADSORBENT) = 0.1M (31.5ml-22.8ml)/2×2g

=0.2175

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Iodine Number results

The conversion factor can be calculated as follows:

(Mol.wt of Iodine × Normality of Iodine × Volume of analyte/ Wt. of activated carbon)

C= Blank reading – volume of hypo consumed after the adsorption of Activated carbon.

Iodine number = C ×Conversion factor (mg/g)

Conversion factor = (127g×0.032N×40ml/2g)

=81.28

C (COMPOSITE ADSORBENT) = (31.5ml-21.1ml)

=10.4ml

C (COMMERCIAL ADSORBENT) = (31.5ml-22.8ml)

=8.7ml

Iodine Number (COMPOSITE ADSORBENT) = 10.4ml×81.28

=845,312mg/g

Iodine Number (COMMERCIAL ADSORBENT) = 8.7ml ×81.28

=707.136mg/g

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4.3 BOEHM TITRATIONS

WEIGHT OF ADSORBENT IN REACTION FLASKS

NaOH Flask Na2CO3 Flask NaHCO3 Flask HCl Flask

Composite

adsorbent

1,519g 1.658g 1,528g 1.499g

Commercial

adsorbent

1,540g 1,548g 1,510g 1,556g

TITRATION VOLUMES

NaOH Flask Na2CO3 Flask NaHCO3 Flask HCl Flask

Composite

adsorbent

9.0ml 11.8ml 10.0ml 11.2ml

Commercial

adsorbent

9.7ml 12.4ml 10.2ml 12.6ml

The method uses NaOH, Na2CO3, NaHCO3 and HCl and its main principle is that the number of acidic sites is determined under the assumptions that NaOH neutralizes carboxylic, lactonic and phenolic groups on the carbon surface; that Na2CO3 neutralizes carboxylic and lactonic groups; and that NaHCO3 neutralizes only carboxylic groups. The number of basic sites is calculated from the amount of HCl required in the titration

mol carbon functionality = ( [R a or b]*Vr - ( [X]*Vx - [T]*Vt) ) / m

[R a or b] is the concentration of the reaction base or acid initially in the 50mL in units of mol/L Vr is the volume of reaction base or acid initially which is 50mL or 0.05L [X] is the concentration of excess acid or base added to the 10mL aliquot in mol/L Vx is the

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volume of excess acid or base added in L [T] is the concentration of the titrant used in mol/L Vt is the volume of titrant required to reach the end point which is determined by experiment in L m is the mass of carbon used

CONCENTRATION RESULTS mmol/g

NaOH Na2CO3 NaHCO3 HCl

Composite

adsorbent

1.2837 0.9589 1.3089 1.3742

Commercial

adsorbent

1.2889 1.0465 1.3311 1.36889

CONCENTRATION OF FUNCTIONAL GROUPS mmol/g

Phenolic Lactonic Carboxylic Basic

Composite

adsorbent

0.3248 0.3500 1.3089 1.3742

Commercial

adsorbent

0.2424 0.2846 1.3311 1.3689

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4.4 HEAVY METAL TITRATION RESULTS

4.4.1 CHROMIUM BACK TITRATION RESULTS

7.52ml of redox titrant gave an initial standard solution of the hexavalent chromium

equivalent to 846ppm based on theory. (After dilution and concentration of test sample)

SAMPLE TITRANT VOLUME AFTER ADSORPTION

Composite mixture adsorbent 6.63ml

Commercial adsorbent 7.03ml

By simple proportion, the concentration remaining after adsorption

composite mixture adsorbent = 6.63ml/7.52ml × 846ppm

=745.89ppm

Commercial adsorbent = 7.03ml/7.52ml× 846ppm

=790.88ppm

Removal efficiency (%) = (Co-Cp/Co) × 100

% RE (composite adsorbent) = (846ppm-745.89ppm/846ppm) × 100

=11,83 %

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% RE (commercial adsorbent) = (846ppm-790.88ppm/846ppm) × 100

= 6.51%

Composite mixture adsorbent has an adsorption capacity of 100.11ppm of

hexavalent chromium

Commercial adsorbent has an adsorption capacity of 55.12ppm of hexavalent

chromium

4.4.2 COPPER BACK TRATION RESULTS

1 ml 0.1N Na2S2O3 solution ≡ 0.1×63500

1000 ≡ 635 mg Cu

wt. of Cu = V(S2O3−2) x 635 mg / L

6.30ml of 0,1N thiosulphate titrant gave an initial standard solution of copper equivalent

to 4000ppm.

SAMPLE TITRANT VOLUME AFTER ADSORPTION

Composite 5.57ml

Commercial 6.13ml

By simple proportion, the concentration remaining after adsorption

Composite mixture adsorbent = 5.57ml/6.30ml × 4000ppm

=3537ppm

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Commercial adsorbent = 6.13ml/6.30ml× 4000ppm

=3892ppm

Removal efficiency (%) = (Co-Cp/Co) × 100

% RE (composite adsorbent) = (4000ppm-3537ppm/4000ppm) × 100

=11,57%

% RE (commercial adsorbent) = (4000ppm-3892ppm/4000ppm) × 100

= 2.7%

Composite mixture adsorbent has an adsorption capacity of 463ppm of copper

Commercial adsorbent has an adsorption capacity of 108ppm of copper

4.4.3 IRON BACK TITRATION

M .V (EDTA)= M' .V' (Fe+3)

wt. of Fe+3 =M .V (EDTA )×atm .wt . Fe+3

1000 = gm/10ml

6.16ml of 0,1M EDTA titrant gave an initial standard solution of Ferric iron equivalent to

3442,89 ppm.

SAMPLE TITRANT VOLUME AFTER ADSORPTION

Composite 2.84ml

Commercial 6.00ml

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By simple proportion, the concentration remaining after adsorption

Composite mixture adsorbent = 2.84ml/6.16ml ×3442.89 ppm

=1587.31ppm

Commercial adsorbent = 6.00ml/6.16ml× 3442.89ppm

=3353.46ppm

Removal efficiency (%) = (Co-Cp/Co) × 100

% RE (composite adsorbent) = (3442.89ppm-1587.31ppm/3442.89ppm) × 100

=54%

% RE (commercial adsorbent) = (3442.89ppm-3353.46ppm/3442.89ppm) × 100

= 2.6%

Composite mixture adsorbent has an adsorption capacity of 1855.58ppm of

ferric iron

Commercial adsorbent has an adsorption capacity of 89.43ppm of ferric iron

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4.4.4 NICKEL BACK TITRATION

wt. of Ni+2 = M .V(EDTA )×atm .wt .¿+2

1000

= 0.01×(36.92ml−V 1)×atm.wt .¿+2

1000= mg /10ml

36.34ml of 0,01M EDTA titrant gave an initial standard solution of Nickel equivalent to

34.04 ppm. (note a dilution factor of 100 was used so actual concentration is 3404ppm)

SAMPLE TITRANT VOLUME AFTER ADSORPTION

Composite mixture adsorbent 31.46ml

Commercial adsorbent 33.53ml

By simple proportion, the concentration remaining after adsorption

Composite mixture adsorbent = 31.46ml/36.34ml ×3404 ppm

=2946.88ppm

Commercial adsorbent = 33.53ml/36.34ml× 3404 ppm

=3140.78ppm

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Removal efficiency (%) = (Co-Cp/Co) × 100

% RE (composite adsorbent) = (3404ppm-2946.88ppm/3404ppm) × 100

=13.4%

% RE (commercial adsorbent) = (3404ppm-3140.78ppm/3404ppm) × 100

= 7.73%

Composite mixture adsorbent has an adsorption capacity of 457.12ppm of nickel

Commercial adsorbent has an adsorption capacity of 263.22ppm of nickel

4.4.5 CHLORIDES TITRATION

For a 50ml sample: Chlorides (mg/L) = titre of AgNO3 × 14.2

23.09ml of 0.02M AgNO3 titrant gave an initial standard solution of Chlorides equivalent

to 327.86 ppm. (Note a dilution factor of 20 was used so actual concentration is

6557.11ppm)

SAMPLE TITRANT VOLUME AFTER ADSORPTION

Composite mixture adsorbent 10.63ml

Commercial adsorbent 22.47ml

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By simple proportion, the concentration remaining after adsorption

Composite mixture adsorbent = 10.63ml/23.09ml × 327.86 ppm

=150.94ppm

Commercial adsorbent = 22.47ml/23.09ml× 327.86 ppm

=319.06ppm

Removal efficiency (%) = (Co-Cp/Co) × 100

% RE (composite adsorbent) = (327.86ppm-150.94ppm/327.86ppm) × 100

=53.96%

% RE (commercial adsorbent) = (327.86ppm-319.06ppm/319.86ppm) × 100

= 2.68%

Composite mixture adsorbent has an adsorption capacity of 3538,4ppm of

chloride ions

Commercial adsorbent has an adsorption capacity of 176ppm of chloride ions

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4.4.6 SULPHATES TEST RESULTS

SAMPLE ABSORBANCE CONCENTRATION

STANDARD 1 0.0780 1112ppm

STANDARD 2 0.1540 2224ppm

STANDARD 3 0.2320 3335ppm

STANDARD 4 0.2980 4447ppm

STANDARD 5 0.3670 5559ppm

Composite adsorbent 0.32253 4823ppm

Commercial adsorbent 0,34317 5140ppm

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0 1000 2000 3000 4000 5000 60000

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

concentration vs absorbance

concentration (ppm)

abso

rban

ce

qe = adsorption quantity of sulphates at equilibrium

qe = (CO - Cp / m) × V

qe(composite adsorbent) = (5559ppm-4823ppm/1g) × 1L

=736(mg/g)

qe(commercial adsorbent)= ( 5559ppm-5141ppm/1.g) × 1L

= 418(mg/g)

Removal efficiency (%) = (Co-Cp/Co) × 100

% RE (composite adsorbent) = (5559ppm-4823ppm/5559ppm) × 100

= 13.23%

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% RE (commercial adsorbent) = (5559ppm-5141ppm/5559ppm) × 100

= 7.52%

SORBENT Absorbance Cp (g/dm 3 ) Co-Cp(g/dm 3 ) qe (mg/g) % RE

Composite 0.32253 4823ppm 736ppm 736 13.23%

commercial 0.34317 5141ppm 418ppm 418 7.52%

Composite mixture adsorbent has an adsorption capacity of 736ppm of

sulphates

Commercial adsorbent has an adsorption capacity of 418ppm of sulphates

4.4.7 AMMONIA TEST RESULTS

SAMPLE ABSORBANCE CONCENTRATION

STANDARD 1 0.142 208ppm

STANDARD 2 0.169 417ppm

STANDARD 3 0.205 625ppm

STANDARD 4 0.272 833ppm

STANDARD 5 0.331 1041ppm

Composite adsorbent 0.2903 903ppm

Commercial adsorbent 0.3044 963ppm

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0 200 400 600 800 1000 12000

0.05

0.1

0.15

0.2

0.25

0.3

0.35

concentration vs absorbance

concentration (ppm)

abso

rban

ce

qe = adsorption quantity of ammonia at equilibrium

qe = (CO - Cp / m) × V

qe(composite adsorbent) = (1041ppm-903ppm/1g) × 1L

=138(mg/g)

qe(commercial adsorbent)= ( 1041ppm-963ppm/1.g) × 1L

=78 (mg/g)

Removal efficiency (%) = (Co-Cp/Co) × 100

% RE (composite adsorbent) = (1041ppm-903ppm/1041ppm) × 100

72 | P a g e

=13.26 %

% RE (commercial adsorbent) = (1041ppm-963ppm/1041ppm) × 100

= 7.48%

SORBENT Absorbance Cp (mg/dm 3 ) Co-Cp(mg/L) qe (mg/g) % RE

Composite 0.2904 903ppm 138ppm 138 13.26%

Commercial 0.3044 963ppm 78ppm 78 7.48%

Composite mixture adsorbent has an adsorption capacity of 138ppm of ammonia

Commercial adsorbent has an adsorption capacity of 78ppm of ammonia

4.5 DISCUSSION OF RESULTS

The methyline blue test showed that there was a significant difference in the % removal

efficiency of the composite mixture adsorbent from the commercial adsorbent, as it

was higher. The higher % removal was due to a higher surface area. This higher specific

surface area had an influence in the adsorption of the methyline blue as it was shown by

the test after evaluation of the two adsorbent products. The influence of specific surface

area on the adsorption of methyline blue (dyes) is supported by (Graham,1955 &

Chongrak et al.,1989) who indicates that specific surface area in adsorbents influences

adsorption capacity. The adsorption is also affected by particle size especially in powder

form. When we look at other adsorbents used internationally, groundnut shell activated

carbon has %RE 82%, sheanut shell adsorbent has %RE 81.37%, Zeolites and Kaolin have

a %RE between 80-94%, British commercial adsorbent has % RE 98.44%. Based on these

73 | P a g e

results it is evident that the composite mixture adsorbent is better than most

adsorbents available when it come to the adsorption of dyes from aqueous solutions.

The iodine adsorption number test showed that there was a significant difference in the

adsorption of the composite mixture adsorbent from the commercial adsorbent, as it

was higher. The higher adsorption was due to a higher activity level due to activation

level of the adsorbent. This higher activity level had an influence in the adsorption of

the iodine as it was shown by test after evaluation of the two adsorbent products. The

influence of micropores on the adsorption of iodine is supported by (Elliot et al., 1989)

who indicates that the surface area and micropores in adsorbents influences

adsorption capacity of iodine and tells of carbons that preferentially adsorb small

molecules . The adsorption is also affected by micropore size especially in powder form.

When we look at other adsorbents used internationally, groundnut shell activated

carbon has IAN of 2.17, sheanut shell adsorbent has 2.19, British commercial adsorbent

2.23. Based on these results it is evident that the composite mixture adsorbent is better

than most adsorbents available when it come to the adsorption of iodine because its

IAN was 2.6. Iodine adsorption number is the most fundamental parameter used to

characterize adsorbent performance. It is a measure of activity level (Higher degree

indicates higher activation), often reported in mg/g (with typical range of 500 –

1200mg/g). Composite mixture adsorbent had a value of 845.312mg/g which showed

very good activity level.

The Boehm titration test showed that there was a significant difference in the

concentration of chemical functional groups on the composite mixture adsorbent

compared to the commercial adsorbent. The higher concentration may be due to the

production process since the composite mixture adsorbent had acid treatment in its

activation. The higher functional group concentration had an influence in the adsorption

as seen by the results after evaluation of the two adsorbent products. This influence is

74 | P a g e

supported by (Hans Peter Boehm 1994) who indicates that chemical surface functional

groups in adsorbents influence adsorption capacity.. When we look at other adsorbents

used internationally, they in average generally contain Lactonic group 0.35mmol/g ,

Phenolic group 0.198mmol/g ,Carboxylic groups 1.575mmol/g ,based on these results it

is evident that the composite mixture adsorbent has a higher concentration in phenolic

groups and equal lactonic groups with most international level adsorbents. The locally

used commercial adsorbent only had a larger concentration in carboxylic groups.

In the heavy metal tests, Chromium, Iron, Nickel and Copper were determined by

classical methods (titrations). This posed a very huge challenge because titrations

cannot detect very minute quantities like the standard maximum permissible limits so

the test samples had excess heavy metal ions in them, way above the realistic

concentration limit that they are found in, in waste waters. Dilution and concentration

of the samples had to done in order to get result. From the results obtained the

composite mixture adsorbent had a higher adsorption capacity than the commercial

adsorbent used. The adsorption capacities being Fe-1855.58ppm, Cr-100.11ppm, Cu-

463ppm, Ni-457.12ppm. The maximum permissible levels of heavy metal contamination

in water being Fe-1.0ppm, Cr-0.1ppm Cu-2.0ppm, Ni-0.2ppm. From this data it is clear

that the adsorbent is more than capable of adsorbing all the heavy metals to

undetectable levels making it very very effective.

The composite mixture adsorbent also had better adsorption capacity for chlorides ,

ammonia and sulphates in water than the commercial adsorbent. Its adsorption

capacities were NH3-138ppm, SO4-736ppm, and Cl-3538.4 ppm. The maximum

permissible level being NH3-2.0ppm, SO4-500ppm, Cl-300ppm. This shows that the

adsorbent is more than capable of adsorbing all the inorganic pollutants to undetectable

levels making it very effective.

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CHARPTER 5: SUMMARY, CONCLUSION AND RECOMMENDATIONS

5.1 SUMMARY

The researcher approached the research in two angles. First the researcher had to prepare the adsorbent product by charring the waste rubber tyre and sieving out the fly ash from bulk ash received from the power station then acid washing both products in a suitable acid, then mixing the two in a ratio of 1:1 to make the composite mixture adsorbent of fly ash and waste tyre rubber. Secondly the researcher analysed the adsorption capacity of the composite mixture adsorption in comparison with a commercial adsorbent product as a standard to compare its efficiency. Universally used parameters like methyline blue test, iodine adsorption number were also used to compare its efficiency against other adsorbent products used worldwide based on these results. Heavy metal and inorganic water pollutants like sulphates, chlorides and ammonia adsorption were also analysed during the research.

5.2 CONCLUSION

The results obtained in the research laboratory analysis showed that the composite mixture

adsorbent product was a very big success because it has a higher adsorption capacity in all the

parameters investigated as compared to the commercial adsorbent that was used as a standard.

The results also show that the composite mixture is more effective as compared to the

individual components being used separately because fly ash has a good adsorption capacity for

dyes but is average when it comes to heavy metal adsorption whereas waste tyre rubber has a a

good adsorption capacity for heavy metals but average when it comes to adsorbing dyes but the

mixture of the two products makes a complete adsorbent product that can absorb any pollutant

in waste water with a high degree of adsorptivity. The researcher was also able to come up with

a very cheap and easy formulation to make an effective adsorbent product that can be used in

agitation tanks in waste water treatment as well as decolourising during industrial processes

even in adsorption of toxins and deodorizing in environmental concerns.

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5.3 RECOMMENDATIONS

The following recommendations are extended from the findings of the study on the

utilisation of waste tyre rubber and fly ash to make composite mixture adsorbent

product. These recommendations are based on experimental facts the research

provided and aims at addressing the problems that incited the undertaking of this

research study.

o During the washing process other chemical reagents like zinc chloride, phosphoric acid

and nitric acid should be used to see if it improves the adsorption capacity by activating

other functional groups in the adsorbent product

o In the formulation of the pellet ,kaolin should be used as a binder or diatomaceous

earth because they also have adsorptive properties but can work well as binding

material for the two components

o Industries that have agitation tanks technology should adopt this technology to see its

effectiveness and how cost saving it will be to their institutions

o The spent adsorbent can be used as an aggregate pozzolan in cement making for

hydraulic cement used for making dam walls

o Desorption properties should also be investigated for this adsorbent product

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Babel, S. and Kurniawan, T. A., Low cost adsorbents for heavy metals uptake from contaminated water. J. Hazard. Mater. 97, No. 1-3, 219 (2003). Hsu, T. C., Yu, C. C. and Yeh, C. M., Adsorption of Cu2+ from water using raw and modified coal fly ashes. Fuel 87, No. 7, 1355 (2008).

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APPENDIX

FLY ASH SIEVING CHARRING THE TYRE RUBBER

Boehm titration (adsorbents in reaction bases)

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BOEHM TITRATIONS

IODINE NUMBER AND HEAVY METAL TITRATIONS

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AGITATING THE TEST SAMPLES WITH ADSORBENT

RESULTS OF ADSORPTION BEFORE THEN AFTER (METHYLINE BLUE)

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UV-VIS AND UV –VIS ANALYSIS

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