nadirah ismail iwa young water professionals 2015
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Removal of Colour From Dyes in
Water and Wastewater Using Leaves
of Plants as Adsorbents:
A Review of Pre-treatment Methods
Nadirah Ismail
Chemistry Department, Faculty of Science
Universiti Teknologi Malaysia
IWA
Young Water Professionals 2015
William Henry Perkins (1838–1907) Accidently discovered the first
synthetic dye (at 18 y.o)
Aniline purple
From chemicals derived from coal tar
From this grew the highly innovative chemical industry of synthetic dyestuffs
Definition
• Coloured substances that when applied to fibers, give them a permanent colour which is able to resist fading upon exposure to sweat, light, water, chemicals, oxidizing agents and microbial attack.
Characteristics
• Synthetic origin
• Complex aromatic structure
• Stable in the environment
• Metabolites are toxic
• Threat to environment and organisms
The Technologies
Treatment methods for textile effluents
Chemical methods Physical methods Biological methods
oxidation ozonationFiltration
Coagulation/
flocculation
adsorption
microbes
enzymes
Adsorption
Accumulation of the molecular species at the
surface rather than in the bulk of the solid or liquid is termed as adsorption.
The phenomenon of attracting and retaining the molecules of a substance on the surface of a liquid or a solid resulting into a higher concentration of the molecules on the surface is called adsorption.
A chemical process that takes place when adsorbateaccumulates on the surface of a solid (adsorbent), forming a molecular or atomic film.
It is a surface phenomenon.
Simplest
Low capital and operating costs
Rapid kinetics of adsorption and desorption
No sludge production
Can have good physical properties
Adsorbents are easily available
Activated Carbon
Well
established
Capable to
adsorb various
organics and
metals Porous
structure
High specific
surface area =
Large sorption
capacities*BUT, activated carbon for
commercial scale pollutant removal is
quite expensive!
Alternative adsorbents
“Depleting natural resources, growing environmental awareness and economic considerations are the major driving forces to utilize renewable resources such as biomass for various applications”
(Narendra Reddy & Yiqi Yang, Biofibers from agricultural byproducts for industrial applications, 2005)
Low cost alternative adsorbent
Originated from agricultural / domestic/ industrial waste.
Lignocellulosic wastes: plant biomass wastes that are consisted of cellulose, hemicelluloses and lignin.
Such as sawdust, grasses, stalks, nutshells, bagasse, leaves, and peelings.
Alternative AdsorbentsBanana stalk Peanut hull Plum kernels Mango seed
kernel
Coconut husk Neem leaf powder
Sugarcane dust
Tea waste
Rice hull Corn cob Sago waste Degreased coffee beans
Banana peel Duckweed Sugar beet pulp
Rice bran
Orange peel Apricotstone
Lemon peel Soybean hull
Guava leaf powder
Sunflower stalks
Jute stick Bamboo dust
Almond shell Cotton stalks
Raw barley straw
Hazelnut shell Rattan sawdust
Durian shell
Malachite
green
Crystal
violet
Methylene
blue
Nirgudi leaf,
Kammoni leaf,
Pineapple leaf
Mangifera Indica (Mango)
leaf, Calotropis procera
leaf
Gulmohar leaf,
Posidonia oceanica
leaf, Pineapple leaf
Pineapple
leaf
Mangifera
Indica
Calotropis
procera
Posidonia
oceanica
Application of plant leaf waste as biosorbent
X-ray Diffraction (XRD)
Scanning Electron Microscopy (SEM)
Surface area, pore size distribution
Fourier transform infrared
spectroscopy (FTIR)
Tools
Characterization of lignocellulosic materials
Chemical pretreatment
FormaldehydeSulphuric
acid
Hydrochloric acid
Nitric acid
Sodium hydroxide
Formaldehyde has
been applied to
Sargassum binderi
to avoid organic
leaching that may
lead to secondary
pollution that might
devastate the
biosorption process
(Pei et al., 2009).
The chemical
treatments
enhanced the
adsorption kinetics
of Reactive Red 228
compared to
untreated Posidonia
oceanica (Ncibi et al.,
2007).
In the case of
Posidonia oceanica,
four types of chemical
treatments were
introduced i.e.
modification with 0.2
M nitric acid, 0.2 M
phosphoric acid,
sodium hypochloride
and 30% (v/v)
hydrogen peroxide
(Ncibi et al., 2007).
With chemical modification, adsorbent will experience good enhancements in pores.
When tea waste being treated with 0.5M NaOH, gap between pores like honeycomb shape was observed under scanning electron microscope (Nasuha and Hameed, 2011).
COVERED WITH MB
Physicochemical pre-treatments Another activation route that could give improved leaves’
pore structure
Involves the chemical agents such as alkali and mechanical actions.
Milling or extrusion of lignocellulosic biomass with the aid of alkali.
Mainly to destroy lignin structure
Chemical treatment of adsorbent
Methanol to remove inorganic and organic matter from the surface of sorbents.
Deionizedwater
Acid treatment
Methanol
Untreated leaves has relatively smooth surface while the physico-chemically treated leaves exhibits rougher surfaces.
Therefore, was proved to be a good activating agent to develop high surface area adsorbent
Adsorption
pH of adsorbate
Adsorbent Dosage
Contact time
Factors affecting dye
adsorption onto adsorbent
High solution pH solution results in an increase in the percentage of cationic dye removal because the positive charge on the solution interface will decrease and the adsorbent surface appears negatively charged.
At higher solution pH, electrostatic repulsion is found between the negatively charged surface and dye molecules, thus decreasing the adsorption capacity and percentage removal of anionic dyes
pHLow pH solution results in an increase in the percentage of anionic dye removal because of the electrostatic attraction between anionic dye and the positive surface charge of the adsorbent
pH
In general, the dye removal percentage is increasing with the increase of the adsorbent dosage
When excess adsorbent dosage is used, a significant portion of the adsorption sites remain unsaturated. This obviously leads to low specific adsorption capacity.
DosageWhen the adsorbent dosage was lowered, the number of active sites saturated with dyes increased; therefore, specific uptake also increased
Dosage
At higher contact time, the rate of adsorption decreases, gradually leading to equilibrium due to decrease in total adsorbent surface area and less available binding sites
The decrease in dye removal with time may be due to aggregation of the dye molecules around the adsorbent particles.
Time
Plant leaves-based adsorbent offers many attractive features such as outstanding
adsorption capacity for many dyes, low in costing and environmental friendly.
FUTURE RESEARCH: Investigation of these materials with real industrial effluents,
recovery of used plant leaves-based adsorbent, regeneration study and
continuous flow study.
It offers significant advantages over currently available adsorbent and in
addition contribute to agricultural waste minimization strategy.
Conclusions
Thank You
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