Method Development for Evaluating Pitch

Dispersing Agents Used in the Kraft

Pulping Process

Emma Olsson Månsson

Sustainable Process Engineering, master's level

2020

Luleå University of Technology

Department of Civil, Environmental and Natural Resources Engineering

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ACKNOWLEDGEMENTS I wish to show my deepest gratitude for my supervisors at BIM Kemi, PhD Emma W Janco and Fredrik Nyhlén, for your guidance, feedback and trust through each stage of the process. I feel very fortunate to have had the opportunity to work with both of you.

I would like to thank my supervisor at LTU, PhD Leonidas Matsakas, for your support and encouragement along the way, and for the opportunity to include a brief study on the interesting topic of bio-surfactants.

I would like to thank my examiner Prof. Lars Gunneriusson for your time and participation of my thesis, and for being responsible of the Sustainable Process Engineering program at LTU of which I will soon be a proud alumnus. I also wish to show gratitude to Joakim Ländin, for your valuable insight in the wood chemistry

and pulping processes, and to Katayon Nedjabat, Besim Smakoli and Johan Berglund for helping me understand the current methods and equipment at the BIM Kemi laboratory. Finally, I would like to recognize Anna Wållberg Axelsson and Adrian Ott and your wonderful people skills which encouraged me to take this thesis opportunity at the LTU job-fair last year.

You, and the rest of the BIM Kemi employees I’ve had the pleasure of getting to know, all made me feel part of your community. I will be forever grateful of these months – thank you!

Gothenburg, February 2020 Emma Olsson Månsson

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ABSTRACT

Depending on wood species and the extractives of the wood, the paper and pulp processes might

suffer from problems caused by the formation of pitch deposits from calcium soaps. BIM Kemi

is a specialty chemical producer supplying the pulp and paper industry with dispersing agents,

which prevent these problems. The objective of this thesis was to develop an in-house laboratory

method for evaluating novel pitch dispersing agents. The resulting method aimed to be

quantitative, have a high repeatability and higher accuracy than the current method used at BIM

Kemi, which suffered from statistical variations and subjective interpretation. A filtration method

and a plastic film method were developed in conditions simulating the kraft process and tested

on birch pitch. The filtration method captured the aggregated pitch deposits when removing the

filter, and the weight of the deposits could then be quantified and compared. The plastic film

method captured pitch deposits on the film, which was scanned for image-analysis to quantify

area and amounts of deposits that had attached. Both methods quantitively compared a reference

test to a product test in order to evaluate the efficiency of the product in the methods. This thesis

shows that a promising method for evaluating dispersing agents was filtration with a filter bag in

polyester material. It gave quantitative results and had the lowest standard deviation of all method

set-ups.

Key words: pitch deposit, dispersing agent evaluation, method development, calcium soaps

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SAMMANFATTNING

Trä innehåller både kalcium och extraktivämnen som i pappers- och massaindustrin kan orsaka

problem med hartsavsättningar från bildade kalciumtvålar. BIM Kemi tillverkar specialkemikalier

och tillhandahåller pappers- och massaindustrin hartsdispergerande produkter vilka förhindrar

dessa hartsavsättningar. Målet med arbetet var att utveckla en labbmetod för utvärdering av dessa

hartsdispergerande produkter på BIM Kemi. Syftet med arbetet var att ta fram en kvantitativ,

repeterbar och mer tillförlitlig metod jämfört med tidigare använd metod, som begränsades av

statistiska avvikelser och subjektiv bedömning. I förhållanden likt kraftprocessen utvecklades och

testades en filtreringsmetod samt en plastfilmsmetod på björkharts. De bildade avsättningarna

fångades upp av filtret och vägdes innan samt efter försöken. Vikten på avsättningarna minskade

när produkt användes och effektiviteten kunde således beräknas. Avsättningarna fastnade på

plastfilmen som scannades in, dessa kvantifierades därefter med hjälp av bildanalys. Båda metoder

jämförde ett referenstest med produkttest och kunde jämföras kvantitativt med antingen vikt,

area eller antal för att utvärdera effektiviteten på produkten. Filtreringsmetoden resulterade i mest

lovande resultat med en nedsänkt filterpåse i polyestermaterial där kvantifieringen var tydlig och

standardavvikelsen var lägst.

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TABLE OF CONTENTS

ACKNOWLEDGEMENTS ..................................................................................................... i

ABSTRACT ........................................................................................................................ ii

SAMMANFATTNING ......................................................................................................... iii

1. INTRODUCTION ............................................................................................................ 1

1.1 Background .................................................................................................................................................... 1

1.2 Objective ........................................................................................................................................................ 3

1.3 Hypothesis ...................................................................................................................................................... 3

2. THEORY ........................................................................................................................ 4

2.1 Formation of pitch deposits ............................................................................................................................ 4

2.2 Mechanisms of dispersing agents .................................................................................................................... 4

2.3 Evaluation methods and analysis of dispersing agents ..................................................................................... 5

3. METHODOLOGY ............................................................................................................ 8

3.1 Overview and restrictions .............................................................................................................................. 8

3.2 Materials and preparation of chemicals and stock mixture ............................................................................. 8

3.3 Filtration experiment and gravimetrical analysis ............................................................................................. 9

3.4 Plastic film experiment and image-analysis................................................................................................... 10

3.5 Statistical analysis .......................................................................................................................................... 11

4. RESULTS AND DISCUSSION ........................................................................................... 12

4.1 Filtration method ......................................................................................................................................... 12

4.2 Plastic film method ....................................................................................................................................... 14

5. CONCLUSION ............................................................................................................... 18

6. FUTURE WORK ............................................................................................................. 19

7. REFERENCES ................................................................................................................ 21

APPENDIX 1 ...................................................................................................................... I

A.1 Calculation of the theoretical maximum weight of pitch deposits ................................................................. I

A.2 Raw data for the filtration and plastic film results ........................................................................................ II

APPENDIX 2 ......................................................................................................................V

B.1 Development of filtration method ................................................................................................................ V

B.2 Development of plastic film method ........................................................................................................... VI

APPENDIX 3 .................................................................................................................. VIII

C.1 Brief investigation of the bio-surfactants Rhamnolipid ............................................................................ VIII

C.2 Methodology ............................................................................................................................................ VIII

C.3 Results and discussion ................................................................................................................................. IX

C.4 Conclusion ................................................................................................................................................... X

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1. INTRODUCTION The pulp and paper industry appeared thousands of years ago and is still highly evident in our

society, with a comprehensive availability (UNEP IE, 1996). The products from the pulp and

paper industry, such as packaging materials and sanitary products, are essential for a developed

and healthy society. The industry is one of the largest parts of the Swedish economy of which

90% is exported, making Sweden the second largest exporter of the combined amount of pulp,

paper and sawn softwood after Canada by the year of 2017 (Swedish Forest Industries Federation,

2019). Sustainably managed forests are a renewable source of carbon-neutral raw materials for

not only pulp and paper products, but for the emerging industry of bio-based materials, chemicals

and fuels (Lanzafame, et al., 2017). This enables a mitigation of the climate change and has the

potential of replacing the finite fossil-oil (Hermann, Blok, & Patel, 2007).

In order to maximize the yield and quality of the pulp and paper industry, specialty chemicals

are added in the pulping process. The chemicals are necessary for separating, washing and

enhancing the fibers in the wood. Specialty chemicals such as dispersing agents preventes

problems caused by wood extractives, known as pitch deposits.

1.1 Background Wood can be classified into two categories: hardwoods, which are flowering, deciduous wood

species such as birch and oak; and softwoods, which are coniferous ever-greens such as spruce

and pine. The structural parts of a tree consist of the root, stem, branch, bark and foliage, of

which it is mainly the stem that is significant for wood utilization (Henriksson, Gellerstedt, &

Ek, 2009). Except for the main components cellulose, hemicellulose and lignin, the dry mass of

wood contains approximately 3.5 % of wood extractives. The composition and content of the

extractive components vary significantly depending on tree species (Back & Allen, 2000). The

wood extractives are non-structural wood constituents of both organic and inorganic

components (Yang & Jaakkola, 2011). The most significant wood extractives covered in this

thesis are the lipophilic compounds, however, wood extractives contain hydrophilic compounds

such as phenols as well. The lipophilic compounds are mainly organic aliphatic compounds such

as fats and fatty acids, steryl esters and sterols, terpenoids, and waxes (Yang & Jaakkola, 2011).The

aliphatic compounds and terpenes are present in the wood extractives (Figure 1), with chemical

composition and quantity varying depending on species and climatological factors. The wood

extractives are responsible for wood properties such as color and odor (Yang & Jaakkola, 2011),

and can be secreted for protection against wounds in the wood (Henriksson, Gellerstedt, & Ek,

2009). As softwoods contain tall oil, which has a natural dispersing effect of these extractives due

to the high amount of fatty and rosin acids, the problems with pitch deposits is more extensive

when using hardwoods such as birch, which contains no or little rosin acid and less fatty acids

(Dogaris, Henriksson, & Lindström, 2019). Therefore, extractives of birch will be investigated

in this thesis.

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Figure 1. Examples of sterols and triterpenes found in birch, and their molecular structure.

In wood utilization, raw wood material is converted into pulp by physically and chemically

liberating the cellulosic fibers from lignin, hemicellulose and extractives (Biermann, 1996). The

pulp is dispersed in water and can be reformed for making paper products. The different pulping

processes of chemical, semi-chemical, chemi-mechanical and mechanical pulping are currently

used in the industry and uses either chemicals or mechanical energy (or a combination) for

liberating the cellulosic fibers from the lignin, hemicellulose and extractives. The most

dominating process is the kraft process, a chemical pulping process which uses the chemicals

NaOH and Na2S in the cooking step for a fast delignification process in an alkaline environment

suitable for all types of wood species (Henriksson, Gellerstedt, & Ek, 2009). The lignin and

hemicellulose are dissolved in the water phase and removed in the washing step. However,

water-insoluble compounds such as the wood extractives may still be present in the pulp feed.

The wood extractives may cause major problems in the pulp production line in the form of pitch

deposits on process equipment, or during pulp screening and bleaching and attach to the final

products as dirt specks (Hillis, 1962) (Jansson & Wadsborn, 2005). This leads to production

downtime due to equipment cleaning and discarded final products. The losses are mainly

economical (Gutierrez, Rio, Martinez, & Martinez, 2001), however, the inefficient use of

resources needs to be considered as well. When reducing the amount of rejected final paper

product both economic and environmental sustainability can be achieved (Back & Allen, 2000).

Current methods for pitch control occur during seasoning and bark removal, and in the

washing step after the cooking. The seasoning of logs and chips reduces the concentration of

extractives in the wood by storage in the woodyard, as oxidative processes affect the number of

extractives. Bark contains a higher concentration of extractives than the wood itself (Back &

Allen, 2000) (Gutierrez, Rio, Martinez, & Martinez, 2001) and debarking is therefore a

significant step. Pitch controlling chemicals, such as physicochemical agents, can be added in the

washing steps to readily disperse the lipophilic wood extractives in the water phase (Back &

Allen, 2000). Available research on the production of bio-surfactants is attracting research interest

(Hruzová, et al., 2019), and a novel bio-surfactant was briefly evaluated in this thesis (Appendix

3). Water-solubility is achieved by dispersing the lipophilic wood extractives using surfactants

which prevents pitch formation. The wood extractives become water-soluble due to the

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surfactants which enables their successful removal (Back & Allen, 2000). Many different

laboratory methods for evaluating the effectiveness of such agents are available in the literature

and are presented in the Theory of this report.

BIM Kemi AB develops specialty chemicals for the pulp and paper industry and produces,

among other products, pitch dispersing agents. By properly evaluating the performance of the

pitch dispersing agents in a laboratory method, effective pitch dispersing agents can be developed.

However, the current method is time consuming and suffer from large statistical variations and

qualitative interpretations. Hence, a new method for evaluating the pitch dispersing agent needs

to be designed.

1.2 Objective

The objective of this diploma work was to design and develop an in-house laboratory method

for evaluating novel pitch dispersing agents. The resulting method aims to be quantitative, have

a high repeatability and higher accuracy than the current methods. The experimental part was

performed at the laboratory with the R&D department at BIM Kemi in Stenkullen, outside of

Gothenburg.

1.3 Hypothesis Evaluating novel pitch dispersing agents can be done:

1. quantitatively by gravimetry or image-analysis to scientifically calculate the effectiveness

of a product compared to a reference test

2. repeatably, with a standard deviation of maximum 10 %

3. more reliable, by capturing a larger extent of the formed deposits compared to the

current method

4. more time-efficiently by decreasing the volume of solution evaluated

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2. THEORY The theory section presents the pitch formation in pulping processes, the mechanisms of

dispersing agents and available methods for evaluating the effectiveness of such agents.

2.1 Formation of pitch deposits The fatty acids and the rosin acids of the extractives contain carboxyl acids which have a net

charge at a high pH. The molecules also contain a nonpolar hydrocarbon part and will therefore

form soaps (Dogaris, Henriksson, & Lindström, 2019). Calcium is the second most frequent

metal ion in wood and constitute a major part of the pitch deposits in kraft mills (Henriksson,

Gellerstedt, & Ek, 2009). The calcium is supplied by the entering wood, or from the recovered

cooking liquor. In alkaline environment the carboxyl acids from the fatty acids and rosin acids

form sodium soaps which have high solubility in water. The affinity for calcium is much higher

in pH above 6, thus calcium soaps are formed instead, which are not soluble in water and is

therefore precipitated (Sithole & Allen, 2002) (Yantasee & Rorrer, 2002) .The calcium ions react

with the fatty and rosin acids of the extractives which creates calcium soaps (Berglund, 2012)

which aggregate into pitch deposits. Other components of the wood pitch, such as the

triglycerides, steryl esters and waxes, are hydrolyzed due to the alkaline environment in the kraft

process. Due to different hydrolysis rates more esters may remain intact while the triglycerides

are dissolved.

2.2 Mechanisms of dispersing agents A surface-active agent, or surfactant, is an agent which reduce the interfacial tension between

liquid, gas and solid surfaces. Surfactants are molecules which are amphiphilic, meaning the

molecules consists of two parts: a polar, hydrophilic group (such as a carboxyl) and a nonpolar,

hydrophobic group (such as a hydrocarbon) as illustrated in Figure 2. This affects the tendency

of the headgroup to arrange in the water phase while the tail prefers non-water phases such as

the pitch deposits (Holmberg, Jönsson, Kronberg, & Lindman, 2003).

Figure 2. Composition of surfactants and behavior in the presence of pitch deposits.

Due to the amphiphilic nature of surfactants, a surfactant will always adsorb at interphases,

with the driving force of decreasing the free energy of that phase boundary (Holmberg, Jönsson,

Kronberg, & Lindman, 2003).

There exists a great number of surfactant molecules due to the many combinations of head

groups and tail. These are classified into either ionic or non-ionic surfactants, based on the net

charge of the head group. The ionic surfactants are further classified into anionic or cationic,

based on the net charge being negative or positive. The charge of the head group is affected by

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its counterion in the solution (Joshi, Aswal, Bahadur, & Goyal, 2002), which affects the solubility

of either the dispersed or the continuous phase. The most common type is anionic surfactants.

The second most common group is the non-ionic surfactants, while the cationic surfactants are

least common (Holmberg, Jönsson, Kronberg, & Lindman, 2003). The dispersing agent in this

thesis contains both anionic and non-ionic surfactants.

Ionic surfactants, in particular anionic, give rise to electrostatic stabilization when added in a

solution, which decreases the entropy of the system. The charge of the surfactants will be the

opposite of the particles that are to be dispersed in the system, in order to stabilize. The particles

acquire a surface electric charge in polar mediums, which will affect the ions closest to the

particles in the polar medium (Shaw, 1992). The ions will be either attracted or repelled towards

the surface depending on charge. For nonionic surfactants, the phenomenon is instead referred

to as steric stabilization. This too is considered a repulsive interaction, which yields a decreased

entropy but is instead caused by the entanglement of the chains from the deposits (Holmberg,

Jönsson, Kronberg, & Lindman, 2003). Both electrostatic and steric stabilization are illustrated

in Figure 3.

Figure 3. Schematic representation of electrostatic (left) and steric (right) stabilization.

In the case of this thesis, the hydrophobic tails of the added surfactant are attracted to the

surface of the water-insoluble calcium soaps, while the hydrophilic head is arranged in the water

phase. This stabilizes the solution and limits the formation of calcium soaps and thus the

aggregation of further deposits. The anionic surfactants in the dispersing agent will neutralize the

positive net charge of the pitch components, while the non-ionic surfactants will stabilize

sterically due to the composition and length of the molecule.

2.3 Evaluation methods and analysis of dispersing agents Evaluation methods are commonly used in laboratories for ascertaining the function and

effectiveness of products. When developing a product, such as a dispersing agent for limiting

pitch formation, the literature offers a variety of methods which are either qualitative or

quantitative. The qualitative analysis can give information about properties, behavior, size and

shape of the pitch formation and aggregates, which could suffer from subjective interpretation.

The quantitative can give a comparable value such as area or weight of the deposit (Back &

Allen, 2000) which do not suffer from subjective interpretation.

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The available methods for evaluation of dispersing agents (which in this section includes pitch

dispersing agents as well as detergent agents) involves replicating the real environment in a

controlled set-up. Synthetic pitch solutions or soils of a predetermined composition are applied

under controlled conditions to ensure repeatability. Repeatability is an important factor which

can be defined as the difference between two single test results obtained with identical method,

materials, conditions and execution (Monte, Sánchez, Blanco, Negro, & Tijero, 2012). The

standard deviation has in this thesis been used as an indication of the repeatability. Further, the

methods produce a reference test which is compared to a product test. Thus, the efficiency can

be calculated by dividing the fraction of the deposits or soil quantified in the product test with

the total amount of deposits or soil in the reference test (U.S Patent No. 4,529,880, 1985). For

example by dividing the mass of removed soil in the product test with the original mass of soil

in the reference test times 100 will give the amount of removed soil in percentage (Gambogi,

Arvanitidou, & Lai, 2005), which could be used as a measure of efficiency as higher percentage

soil removed indicate a better cleaning ability when comparing it to a reference test or other

products.

Gravimetrical examples can be found in the literature, such as deposition testers using a wire

(Doshi, Blanco, Monte, Negro, & Haynes, 2003). These are conducted similarly to the current

BIM Deposit Test (BDT) at BIM Kemi for evaluating dispersing agents. The current method,

BDT, mixes synthetic pitch and calcium ions in a water solution, with pH and temperature

adjusted for simulating the real conditions in the pulp process. At high pH and temperature, the

calcium ions react with the fatty acids and aggregate into pitch deposits. The solution is mixed

with a rotating wire in the center of the container, simulating the wire steps in the paper process,

which captures the pitch deposits. The amount of pitch deposits can be deducted from the

weight of the wire as it is weighed before and after the experiment. The weight of the deposits

is expected to decrease when repeating the experiment with an added dispersing agent, as the

solubilized calcium soaps are dispersed in the water and don’t aggregate to a size large enough

to be captured by the wire. For illustration of the set-up, see Figure 4.

a) b)

Figure 4. Illustration of the BIM Deposit Tester (BDT) method set-up (a) and the stirrer, on which the wire is attached (b).

A potential shortcoming arises as the deposits attach to the container instead of the wire. This

can be solved by qualitatively document the shape and size of these deposits; however, it may

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suffer from subjective interpretations which makes the method less repeatable. A large container

will also be time-consuming in regard to heating time of the solution, especially as it is not a

common laboratory equipment there can only be one experiment operating at a time, requiring

at least two tests to be done in a sequence to perform a reference and a product test.

Specialty chemicals industries also use plastic-films for evaluation of deposits. The method is

based on the tendency of small adhesive particles, stickies, to adhere to a hydrophobic surface,

such as a polyethylene film. The deposits are then quantified using an image-analysis software

which calculate the covered area in mm2, or percentage of total area, by the deposits (Monte,

Sánchez, Blanco, Negro, & Tijero, 2012).

Qualitative evaluations in the detergent industry may use a photographic catalogue as a

reference, scaling ‘cleanliness’ from e.g. 1-10 based on the amount of impurities that are removed

of e.g. a plate or a beaker of a specified contaminant (German Cosmetic, Toiletry, Perfumery

and Detergent Association (IKW), 2015). When evaluating the effectiveness of a detergent, the

amount of impurities is then subjectively compared to the photographic catalogue. The

shortcoming of this is lack of quantification and the difficulties repeating the method as it is

subjectively interpreted.

The turbidity is another parameter for evaluating the effect of the detergent. It is an optical

measurement which uses an optical scatter-detection technique in which light is scattered by

particles in a liquid (Fondriest, 2020). A high transmission of light is enabled in clear solutions,

such as clean water. A low transmission of light indicates a turbid solution with many smaller

particles. However, a turbid solution with low transmission will be measured both with very

finely divided colloidal pitch particles in the liquid, as well as with aggregates of deposits in the

liquid and the data has to be interpreted together with visual observation, which gives rise to

subjective interpretation. Consequently, this method needs to be complemented by a

quantifiable method for optimal and objective interpretation of the result. This method is also

used currently at BIM Kemi and is complemented by the BDT.

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3. METHODOLOGY The methodology consists of the final two methods that were developed during this thesis work:

a filtration method, and a plastic-film method. The development is presented in Appendix 2.

3.1 Overview and restrictions The current method BDT is based on gravimetrical analysis from a reference and product test

by using a rotating wire to capture the pitch deposits in the container, as explained in the Theory.

From the literature, two approaches were derived and continuously improved in order to fulfill

the aim of a high reliability, repeatability and quantification compared to the current method.

The first approach represents a filtration method which uses a gravimetrical analysis for

quantification. The second approach represents a plastic-film method and image-analysis for

quantification.

The experiments were limited to conditions with a constant temperature of 65 °C, pH 11 in

a solution of 500 ml distilled water and concentration of pitch (250 ppm), dispersing agent (200

- 300 ppm) and CaCl2 (1000 ppm). The conditions were replicating the kraft pulping process.

A synthetic pitch based on the extractive composition of birch pulp (determined using extraction

methods and gas chromatography at BIM Kemi) was prepared. Only one type of dispersing agent

was used during the experimental work, BIM AP 1707, denoted as the ‘product’ from now on.

The thesis work was limited to developing the evaluation method, not any dispersing agents.

3.2 Materials and preparation of chemicals and stock mixture The pitch solution was prepared using the chemicals in Table 1. The solid chemicals were

weighed and added first, followed by the liquid and finally the solvents. The product was diluted

to 5 % w/w by solving it in distilled water. The materials and chemicals used in the experiments

are listed in Table 2.

Table 1. List of pitch chemicals and solvents for preparing 200 g synthetic Swedish birch pitch.

Pitch solution

Chemicals Supplier Amount (g)

Palmitic acid (s) Acros Organics, Belgium 1.2

Linolenic acid (s) Aldrich Chemistry, US 3.5

Oleic acid (l) Fisher Scientific, UK 1

Steric acid (s) - 1

Abietic acid (s) Acros Organics, Belgium 2

Docosanoic acid (s) - 0.3

Triglycerides (l) - 0.8

β-sterols (l) Sigma Life Science, US 7

Betulinol (s) UPM Kymmere, Finland 1.8

Squalene (l) Acros organics Belgium 1.4

Solvents Amount (g)

Ammonium (l) Fisher Scientific, UK 16

Toluene (l) Fisher Scientific, UK 41

Iso-butanol (l) Acros Organics, Belgium 123

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Table 2. Material and chemicals used in the filtration and plastic-film methods.

Material

Filter bags (material: polyester, volume: 1M(3), pore size: 125 microns from (Allied Filter

Systems Ltd, UK)

Filter bags (material: nylon, volume: 1M(3), pore size: 125 microns from (Allied Filter Systems

Ltd, UK)

Transparent, heat resisting, plastic A4-sheets

Black A4-sheets

Chemicals

NaOH (5 % w/w)

Prepared pitch solution (10 % w/w)

Dispersing agent (5 % w/w)

CaCl2 (10 % w/w)

About 1000 ml of distilled water was used as the base for the stock mixture, in which NaOH

(10 % w/w) was added until a pH of 11 was reached. The stock mixture was then divided into

two 500 ml beakers and the temperature was increased to 65 °C. The pitch and stock mixture

preparation were identical for both the filtration and plastic-film experiments.

3.3 Filtration experiment and gravimetrical analysis The chemicals and stock mixture were prepared according to 3.2. Two filter bags were dried in

an oven at 105 °C for 10 min and cooled in a desiccator for 10 min. The filters were weighed

prior to submerging them into the solution. As the temperature of the solutions reached 65 °C,

250 ppm of pitch, 200 ppm of product and 1000 ppm CaCl2 were added in this sequence, as

illustrated in Figure 5, and stirred for 10 min at 200 rpm. Finally, the filters were removed, dried

in an oven and desiccated for 15 min each before weighing them. The experiment was repeated

without the addition of a product in order to get a reference test for comparison.

Figure 5. Illustration of filtration set-up.

The weight of the dried filter before the product experiment (M1) was subtracted from the

weight of the dried filter after the product experiment (M2) to get the weight of the captured

Prod

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deposits (M3). M3 was used together with the weight of the deposits in the reference test (Mref)

to calculate the efficiency, according to Equation 1.

𝐸𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦 (%) = (1 −𝑀3

𝑀𝑟𝑒𝑓) ∗ 100 (1)

3.4 Plastic film experiment and image-analysis The chemicals and stock mixture were prepared according to 3.2. As the temperature of the

solutions reached 65 °C, the plastic film was placed on the inside of the wall of the beakers,

overlapping in the same direction as the flow of the stirrer. Then, 250 ppm of pitch, 200 ppm

of product and 1000 ppm CaCl2 were added in this sequence, as illustrated in Figure 6, and

stirred for 10 min at 200 rpm. Finally, the film was removed, dried in an oven and desiccated

for 15 min each before the image-analysis. The experiment was repeated without the addition

of a product in order to get a reference test for comparison.

Figure 6. Illustration of plastic film set-up.

The plastic film was taped to a black sheet, and a clean A4-sized plastic film was taped on top

in order to protect the scanner from the deposits. The sheets were placed in a scanner (Canon

iR-ADV 3525/3530-AirPrint, Japan) with the settings 600x600 dpi, JPEG-file format in full-

color setting. The JPEG-files were opened in the image-analysis software Image Pro (Media

Cybernetics, US), and the picture was calibrated in order to get the area calculation accurately.

This was done in the software section: capture – create – quick calibration. A line was drawn

along the length of the scanned A4-sized sheet and the unit was entered (in mm) to 297, which

is the standard length of an A4. Only “system calibration” and “reference pattern” should be

marked in this window of settings.

The “region of interest” (ROI) should be marked in order to exclude anything outside of the

plastic film. This was done in the software section: select – regions of interest and select: 1.

Multiple ROIs, and choosing: 2. The polygonal tool. The whole plastic film was marked where

deposits of pitch could be found (e.g. the pieces of tape were excluded).

For the quantification, the section: count/size – segment – manual was entered, and the area

of the histogram was selected to the range of 80-225 on the histogram settings, and the

Prod

11

quantification was performed by pressing “count”. The data presented gave both the area and

the number of elements that met the required range of color intensity.

3.5 Statistical analysis Data was analyzed by standard deviation calculation using excel function STDEV.P. This calculates the standard deviation according to Equation 2, for data that represents the entire population (not sample of population).

𝜎 = √∑(𝑥𝑖−𝜇)2

𝑛 (2)

𝜎 – population standard deviation

𝜇 – mean value of population

𝑥𝑖 – each value from the population

𝑛 – size of the population

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4. RESULTS AND DISCUSSION In this section, the results from the final methods will be discussed, and the different set-ups will

then be compared.

4.1 Filtration method The final filtration method was outlined in the Methodology (3.3), in which two different filter

materials were used: nylon and polyester. A reasonable range for the resulting weight of captured

pitch deposit was decided to 0 g – 0.17 g, thus no negatives values for the measured deposits nor

any values exceeding 0.17 g were considered valid. Negative values indicated weight losses,

which theoretically could not be achieved. Deposits larger than 0.17 g were considered too

remote from the theoretical maximum weight of 0.14 g (Equation A1 in Appendix 1) and was

also considered invalid.

The nylon filters showed a larger variation in deposit weight for both the reference and

product test compared to the polyester filter. Four and two data points respectively were

considered invalid of the ten trials for nylon and polyester. When including the outlier data

points, the result in Figure 7 showed a mean pitch deposit weight of 0.11 g (± 57 % SD) and

0.12 g (± 57 % SD) for the reference tests of nylon and polyester filter respectively, and 0.092 g

(± 88 % SD) and 0.10 g (± 65 % SD) for the product tests respectively. The standard deviations

were significant for all tests including the outlier data points.

Figure 7. The mean weight difference including all data points for polyester and nylon, comparing the reference and the product tests (250 ppm). Error bars show the standard deviation from 5 independent measurements (n=5). Based on data from table A1 and A2 in Appendix 1.

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.2

Wei

ght (g

)

Pitch deposit weight (all data points included)

Reference Product

Nylon

Reference Product

Polyester

± 57 %

± 88 %

± 57 %

± 65 %

13

When excluding the invalid data points, the mean weight of deposits filtered in nylon is higher

for the product than in the reference test which was unexpected and is discussed further down.

For polyester filters the mean weight was still larger in the reference tests than the product tests,

as expected. When excluding the outlier data points, the result in Figure 8 shows a mean pitch

deposit weight of 0.089 g (± 53 % SD) and 0.086 g (± 11 % SD) for the reference tests of nylon

and polyester filter respectively, and 0.13 g (± 20 % SD) and 0.071 g (± 13 % SD) for the product

tests respectively.

Figure 8. The mean weight difference excluding invalid data points for polyester and nylon, comparing the reference and the product tests (250 ppm). Error bars show the standard deviation from 4 independent measurements (n=4).

Comparing the mean pitch deposit weight and standard deviations of both materials, the error

bars are significantly smaller for the polyester trials, indicating a higher repeatability (Figure 8).

This indicates that the pitch formation or dispersing agent was affected by the material, and to a

larger extent vary with a nylon filter than a polyester filter. The standard deviations are far too

high for considering nylon filter a repeatable method in this set-up, however polyester filters

show a more promising repeatability at a standard deviation of approximately 10 %.

The efficiency of the product was calculated according to Equation 1 in the Methodology

and are shown in Table A6 and A4 in Appendix 1. For nylon, the tests which included all trials

the dispersing agent had an efficiency of 19 %, while the efficiency of the tests which excluded

invalid trials had an efficiency of -47 %. For polyester, the tests which included all trials the

dispersing agent had an efficiency of 13 % while the efficiency of the tests which excluded invalid

trials had an efficiency of 18 %. A negative efficiency, which was calculated for the nylon filters,

± 53 %

± 20 %

± 11%

± 13 %

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.2

Wei

ght (g

)

Pitch deposit weight (invalid data points excluded)

Reference Product

Nylon

Reference Product

Polyester

14

indicates that the deposit weight was higher in the trials with added dispersing agent. The

behavior of the chemicals might have been affected by the increased surface area supplied by the

filter in combination with a certain affinity for the nylon material. This would potentially make

a substantial part of the dispersing agent, pitch or calcium chloride to attach to the filter and thus

add weight. A dosage of 200 ppm product in 500 ml corresponds to a weight of 0.10 g of product

which if an arbitrary amount would attach to the filter could be a plausible explanation of the

unexpected weight increase due to affinity. There were also difficulties when measuring the

weight of the filters due to their irregular shapes and size. The filter-bags were rather large,

relative to the size of the cabinet of the scale, and slight movements occurred when folding the

filters which affected the weight. This represents an error source and might explain the outlier

data points.

Furthermore, the data presented shows that the difference between the reference and the

product tests varies between the two filter materials. For nylon, the mean pitch deposit weight

in the reference tests was 0.089 g and for product tests 0.13 g (Figure 8). That is, an increase in

mass when using a dispersing agent, and as mentioned above this was unexpected as the product

was expected to decrease the formation of pitch deposit and thus the weight. However, the

errors bars are overlapping which indicates that the statistically significance should be

investigated. The result is therefore notably affected by the high standard deviation and a

conclusion about the actual influence cannot be drawn. For polyester, the mean pitch deposit

weight in the reference tests was 0.12 g and for product tests 0.086 g (Figure 8).

Finally, the mean amount of deposits attached to the filter in the reference tests account for

79 % of the theoretical maximum weight using nylon filters, and 86 % using a polyester filter.

This indicates that the vast majority of the pitch deposits were captured in the filter when

removing it from the solution. The theoretical maximum weight for the BDT in 15 L was

calculated to 4.1 g (Equation A2 in Appendix 1), with deposit weights on the wire during the

reference tests at a historical mean of 2.1 g (Table A5 in Appendix 1). The deposit weight in this

method corresponds to only 41 % of the theoretical maximum weight of the deposits, since a

larger extent was left in the container or the solution in the current BDT than in the developed

filtration method using a nylon filter bag.

4.2 Plastic film method The final plastic film method was outlined in the Methodology (3.4), in which two different

parameters were analyzed in the image-analysis software: area and quantity of deposits attached

to the plastic film.

Area of pitch deposits

As the dispersing agent should limit the amount of pitch deposits formed, the area was expected

to decrease when adding the product. Figure 9 presents the result from the area measurements

and shows the smallest area for the reference test at 350 mm2 (± 62 % SD), the highest area of

620 mm2 (± 27 % SD) at 200 ppm product and slightly lower area of 550 mm2

(± 35 % SD) at

300 ppm product. The standard deviations were significant for all three, especially for the

reference test, and a conclusion can hardly be drawn from these results. The raw data can be

found in Table A6 in Appendix 1.

15

Figure 9. The mean area covered by the pitch deposits at 0, 200 and 300 ppm of dispersing agent added. Error bars show the standard deviation from 6 independent measurements (n=6). Based on the data in Table A6 in Appendix 1.

There is a clear difference between the reference test and the product test (especially at 200

ppm) when calculating the area of the pitch deposits, which could indicate an effective method

for evaluation according to the hypothesis. The data shows that the area increases when adding

a dispersing agent. However, the standard deviations were far too high for considering this set-

up a repeatable method. Despite the clear difference in the mean that can be seen between the

reference test and the product test with 200 ppm, it was expected that the area would decrease

when adding a dispersing agent. As is evident in Figure A1 in Appendix 1, there were deposits

on the surface of the solution during the reference tests which did not attach to the plastic film.

This represent an error source which might have yielded a larger mean area for the reference

tests than presented in the data – which potentially could have shown the expected decrease in

area. Due to the high standard deviations, and the error sources, this was not considered a reliable

method and needs further development.

Number of pitch deposits

The result from the calculated number of pitch deposits attached to the plastic film varied

significantly, as presented in Figure 10. The least number of pitch deposits of 2900 (± 47 % SD)

attached at 200 ppm product, while the reference and 300 ppm product at 3900 (± 61 % SD)

and 4200 (± 80 % SD) respectively were similar in attached pitch behavior. The standard

deviations were significant for all three, especially for the 300 ppm product test, and a conclusion

can hardly be drawn from these results. The raw data can be found in Table A7 in Appendix 1.

± 62 %

± 27 %

± 35 %

0

100

200

300

400

500

600

700

800

900

Are

a (m

m2)

Area of pitch deposits

0 ppm 200 ppm 300 ppm

16

Figure 10. The mean number of pitch deposits attached to the plastic film at 0 (reference), 200 and 300 ppm of dispersing agent added. Error bars show the standard deviation from 6 independent measurements (n=6). Based on the data in Table A7 in Appendix 1.

There is no significant difference between the reference test and the product tests as shown

in Figure 10, which indicate an ineffective method for quantification. The number of pitch

deposits attached to the plastic films varied greatly and the deposits also varied in size, which was

observed visually. The image-analysis could perhaps be categorized in size ranges for a more

sophisticated quantification in which a larger difference might have been seen. The standard

deviations were also far too high for considering this set-up a repeatable method.

Observations from the reference tests showed that a large pitch deposit tend to float at the

surface of the solution (Figure A1 in Appendix 1), which did not stick to the plastic film and

thus not accounted for in the quantification by the software – which might be significant for the

result when quantifying the area, but not as much in the number of pitch. For example, a deposit

spot of 5 mm2 would constitute about 25 % of the mean area at 350 mm2 but only a fraction of

a percentage on the number of pitch deposits. Another observation of an effect that might

influence the quantification was the thick line of deposit that was formed on the plastic film in

the boundary between water, air and the solid plastic film (Figure A2 in Appendix 1). The thick

line would vary in width and especially depth. As with the floating deposit of the solution, this

will have a larger impact on the area count than the number of deposits. By excluding this thick

line, the quantification would only include the tendency of the random attachment to the plastic

film and not the systematic formation of a floating nor thick line at the surface. This could

potentially lead to lower standard deviations and thus a repeatable and reliable method.

Both quantification parameters regarding the plastic film method suffered from large statistical

variations and can therefore be considered an unsuccessful method. It would however be

interesting to further investigate a combination of amount and area if specific size ranges were

taken into account. As the product limits the formation and aggregation of larger deposits there

should be a larger fraction of large pitch deposits in the reference test, while the largest fraction

in the product tests in theory should consist of smaller pitch deposits. The scanned images of the

plastic films do not specify the depth of the deposits, i.e. the volume, which could be a parameter

0

1000

2000

3000

4000

5000

6000

7000

8000

Num

ber

of

pit

ch d

eposi

ts

Number of pitch deposits

0 ppm 200 ppm 300 ppm

± 61 %

± 47 %

± 80 %

17

of interest. According to the theory, the aggregation is limited due to the solubilized pitch

particles thus the height of the deposits should be lower when adding product compared to the

reference tests.

Finally, the standard deviation is lowest for the trials performed at a concentration of 200 ppm

of dispersing agent, which indicates a reliable dosage of dispersing agents for image-analysis,

although higher concentrations than 300 ppm should be investigated before drawing a

conclusion. However, evaluating the efficiency is yet to be established and needs further work.

18

5. CONCLUSION The conclusion of this thesis work can be summarized in accordance to the hypotheses that were

stated in the Methodology.

1. It was possible to quantitively compare the results gravimetrically from a product test to

a reference test in the submerged filter bag method using a polyester bag, as it showed

promising standard deviations. The plastic film method was quantitative, but image-

analysis results had large standard deviations which compromises the credibility.

2. A sufficient repeatability was almost reached with polyester in the submerged filter bag

method, which had the lowest standard deviations of the final set-ups. The plastic film

method did not reach a satisfactory level of standard deviations and was therefore not

considered repeatable.

3. The filtration method shows potential in becoming a more reliable method compared to

the BDT method as the filtration method captures a large part of the pitch deposits in

the submerged filter.

4. As the volume was decreased from 15 L in the BDT method to 0.5 L in the developed

methods, which decreased the time for the heating by approximately 50 % compared to

the BDT method. Also, as the method was no longer limited by using the designated

BDT container, a more time-efficient method was developed in which two or more

standard laboratory beakers could be used at once.

19

6. FUTURE WORK The thesis resulted in the development of a promising method. However, as the repetitions were

limited, there are some areas of work that could be investigated further to optimize the method.

General recommendations

1. As the standard deviations were slightly higher than desired, it would be interesting to

study the effect by increasing the volume to 1 L. This would add twice the amount of

pitch and dispersing agent as in 0.5 L, which may reduce the standard deviation even

further as the methods would be less sensitive.

2. The temperature was decreased in the developed methods due to convenience and time-

efficiency compared to the current method, however the effect on the pitch formation

was not investigated. An increased temperature and its potential effect of the pitch deposit

formation and dispersing effect would therefore be interesting to study.

3. As only one type of pitch solution and dispersing agent was used, it would be interesting

to study the application of the developed method on other pitch types and products as

well. The birch pitch that was used is complex, consisting of many different compounds

and might have affected the formation and dispersing of the pitch deposits.

4. The actual conditions in the pulp mill include pulp in the feed, consequently it would

be closer to the reality to evaluate the efficiency of the product using pulp in the solution.

It might be recommended to use the plastic film method instead of the filtration method,

as it would be harder to separate the weight of the deposits from the weight of the pulp

in a filter, while the deposits could be stained using a lipophilic dye. However, further

development on decreasing the standard deviations would probably be required.

Filtration method recommendations

5. An alternative filtration method, in which the solution is poured through a filter instead

of having a filter bag submerged as in the presented filtration method, could be

investigated further. Emptying the solution through a filter was investigated early in the

development of this thesis. However, as it resulted in a large amount of deposit attaching

to the beaker walls, it was decided to have a submerged filter to avoid this problem. As

this caused problems with unexpected weight increase for the nylon filter, and a standard

deviation no less than 11 %, it would be recommended to study the effect of a container

with a non-stick lining, as an alternative solution to that problem. A larger extent of

pitch deposits would thus be caught in the filter when emptying the solution, as they do

not attach to the beaker walls. Consequently, a higher repeatability and reliability could

be achieved compared to when submerging a filter. Furthermore, any possible

interference or effect of filter material properties would be avoided, as the filter would

not be submerged in the solution.

6. The filtration method was mainly investigating plastic materials of the filter; however, it

would be interesting to investigate filters in metal, Teflon or PTFE mesh for submersion

as this could reduce any potential interaction with the chemicals.

20

Plastic film method recommendations

7. Investigating the combined result of area and amount, and instead analyze the size

fractions would be a recommended approach to evaluate the efficiency of the product.

8. The “smart function” for calculating area and quantities in Image Pro was not fully

evaluated but could reduce the error margins further.

9. Excluding the line of pitch deposits formed at the surface of the water along the plastic

film might decrease the standard deviation and would thus be interesting to investigate.

21

7. REFERENCES Back, E. L., & Allen, L. H. (2000). Pitch Control, Wood Resin and Deresination. Atlanta:

Tappi Press. Berglund, J. (2012). Resin Profile in a Bleached Kraft Pulp Process. Stockholm: KTH. Biermann, C. J. (1996). Handbook of pulping and papermaking. San Diego: Academic Press.

Dogaris, I., Henriksson, G., & Lindström, M. (2019). Tall Oil Solubility in Industrial Liquors. Stockholm: Energiforsk.

Doshi, M. R., Blanco, A., Monte, M. C., Negro, C., & Haynes, R. D. (2003, November). Comparison of Microstickies Measurement Methods Part II: Results and Discussion. Progress in Paper Recycling, pp. 44-53.

Fondriest. (2020, January 24). Fondriest. Retrieved from Turbidity sensors meters and methods: https://www.fondriest.com/environmental-measurements/measurements/measuring-water-quality/turbidity-sensors-meters-and-methods/

Gambogi, J., Arvanitidou, E. S., & Lai, K.-Y. (2005). Light-duty liquid detergents. In K.-Y.

Lai, Liquid detergents (pp. 171-238). Boca Raton: CRC Press. German Cosmetic, Toiletry, Perfumery and Detergent Association (IKW). (2015).

Recommendations for the Quality Assessment of the Cleaning Performance of Dishwasher Detergents. Sofw Journal, 34-48.

Gutierrez, A., Rio, J. C., Martinez, M. J., & Martinez, A. T. (2001, September). The biotechnological control of pitch in paper pulp manufacturing. TRENDS in Biotechnology, pp. 340-348.

Henriksson, G., Gellerstedt, G., & Ek, M. (2009). Pulping Chemistry and Technology. Berlin: De Gruyter.

Henriksson, G., Gellerstedt, G., & Ek, M. (2009). Wood Chemistry and Wood Biotechnology. Berlin: De Gruyter.

Hermann, B. G., Blok, K., & Patel, M. K. (2007, October 8). Producing Bio-Based Bulk Chemicals Using Industrial Biotechnology Saves Energy and Combats Climate Change. Environmental Sciense and Technologoy, pp. 7915-7921.

Hillis, W. E. (1962). Wood Extractives and Their Significance to the Pulp and Paper Industries. Academic Press.

Holmberg, K., Jönsson, B., Kronberg, B., & Lindman, B. (2003). Surfactants and Polymers in Aqueous Solutions. Chichester: John Wiley & Sons.

Hruzová, K., Patel, A., Masák, J., Matátková, O., Rova, U., Christakopoulos, P., & Matsakas, L. (2019, October 19). A novel approach for the production of green biosurfactant

from Pseudomonas aeruginosa using renewable forest biomass. Science of the Total Environment, pp. 1-8.

Jansson, M. B., & Wadsborn, R. (2005). Equilibrium calculations for fatty acid calcium soaps in pulp washing. Innventia.

Joshi, J. V., Aswal, V. K., Bahadur, P., & Goyal, P. S. (2002). Role of counterion of the

surfactant molecule on the micellar structure in aqueous solution. Current Science, 47-49.

Lanzafame, P., Abate, S., Ampelli, C., Genovese, C., Passalacqua, R., Centi, G., &

Perathoner, S. (2017, November 23). Beyond Solar Fuels: Renewable Energy‐Driven Chemistry. Chemistry and Sustainability, pp. 4409-4419.

Meril, C. L., & Sanders, A. (1985). U.S Patent No. 4,529,880. Monte, M., Sánchez, M., Blanco, A., Negro, C., & Tijero, J. (2012, January 24). Improving

deposition tester to study adherent deposits in papermaking. Chemical Engineering Research and Design, pp. 1491-1499.

Shaw, D. J. (1992). Introduction to Colloid and Surface Chemistry. Oxford: Butterworth-Heinemann.

22

Sithole, B. B., & Allen, L. (2002). The Effects of Wood Extractives on System Closure. Pointe

Claire: Pulp & Paper Research Institute of Canada. Swedish Forest Industries Federation. (2019, October 31). Swedish Forest Industries .

Retrieved from Statistics - Gloval Forest Industry: https://www.forestindustries.se/forest-industry/statistics/

UNEP IE. (1996). Environmental Management in the Pulp and Paper Industry p21. Stockholm: United Nations Publication.

Yang, G., & Jaakkola, P. (2011). Wood chemistry and isolation of extractives from wood - Literature study for BIOTULI project. Lappeenranta: Saimaa University of Applied Sciences.

Yantasee, W., & Rorrer, G. L. (2002). Comparison of Ion Exchange and Donnan Equilibrium Models for the pH-Dependent Adsorption of Sodium and Calcium Ions Onto Kraft Wood Pulp Fibers. Journal of Wood Chemistry and Technology, 157-185.

I

APPENDIX 1

A.1 Calculation of the theoretical maximum weight of pitch deposits A theoretical maximum of pitch deposits formed in 0,5 L solution was calculated, based on the

following data and assumptions:

- Molar weight of calcium is 40 g/mol

- A mean molar weight based on the components of the pitch was roughly estimated to

280 g/mol

- As the pitch solution had a concentration of 10 %, thus, 0,125 ml represents pitch that

could form deposits

- The density of the pitch was assumed to that of water, at 1000 g/L

- The density of calcium is 1500 g/L

- All pitch component will bond with the calcium ions in the calcium chloride and form

deposits

- The pitch will behave uniformly, despite its different constituents, and be assumed to

behave as “pitch particles”

- Each calcium will bond with two pitch particles, due to its electron configuration (Ca2+)

The molar weight of calcium corresponds to 14 % of the pitch, and the density of calcium

represents 150 % of the density of pitch. This value of 21 % (0.21) is then divided by two as each

calcium will bond with two pitch particles. With these assumptions the theoretical weight of

pitch deposits was calculated to 0,14 g, using Equation A1.

𝑊𝑒𝑖𝑔ℎ𝑡 = 0,125𝑔 + (0,21

2) ∗ 0,125𝑔 = 0,138 𝑔 (A1)

The corresponding maximum weight for the current BDT method was also calculated, with a

theoretical maximum weight of 4,1 g, using Equation A2.

𝑊𝑒𝑖𝑔ℎ𝑡 = 3,75𝑔 + (0,21

2) ∗ 3,75𝑔 = 4,144 𝑔 (A2)

II

A.2 Raw data for the filtration and plastic film results Table A1. Deposit weight from nylon material in filtration method. Values arranged in an ascending order. The mean and standard deviation both including and excluding invalid values.

Dispersing agent (ppm)

Deposit weight (g) Mean StD StD (%)

Mean** StD** StD

(%)**

0 0.0411 0.0739 0.0746 0.168 0.212* 0.114 0.0649 56.9 0.0893 0.0472 52.9

200 -0.0633* 0.0955 0.110 0.147 0.164 0.0893 0.0472 87.9 0.131 0.0260 19.8

* Invalid points ** Invalid points excluded

Table A2. Deposit weight from polyester material in filtration method. Values arranged in an ascending order. Mean and standard deviation both including and excluding the outlier values.

Table A3. Efficiency calculations for nylon filter using data from Table A1 in Appendix 1.

NYLON Mean (all) Mean (valid)

Weight wire (g) M1 = 5.69 5.68

Weight wire + deposit (g) M2 = 5.79 5.81

Weight deposit (g) M3=M2 - M1 0.0925 0.131

Weight deposit (% ) M4=(M3/M1)*100 1.62 2.31

Deposit in reference test (g) Mref = 0.114 0.0893

Efficiency (% ) (1 - (M3/Mref))*100 18.8 -47.1

Table A4. Efficiency calculations for polyester filter using data from Table A2 in Appendix 1.

POLYESTER Mean (all) Mean (valid)

Weight wire (g) M1 = 4.40 4.39

Weight wire + deposit (g) M2 = 4.51 4.47

Weight deposit (g) M3=M2 - M1 0.104 0.0706

Weight deposit (% ) M4=M3/M1*100 2.37 1.61

Deposit in reference test (g) Mref = 0.120 0.0859

Efficiency (% ) (1 - (M3/Mref))*100 12.8 17.8

Table A5. Historical data of pitch deposit weight using BDT set-up for evaluating pitch. Deposits gathered in reference test, at 70 °C, pH 11 and with spruce pitch (source: Mätosäkerhet-BDT).

Reference Deposits (g)

Dispersing

agent (ppm) Deposit weight (g) Mean StD

StD

(%) Mean** StD**

StD

(%)**

0 0.0780 0.0787 0.0859 0.101 0.254* 0.120 0.0678 56.7 0.0859 0.00920 10.7

200 0.0598 0.0633 0.0783 0.0808 0.239* 0.104 0.0677 65.0 0.0706 0.00910 12.9

* Outliers ** Outliers excluded

III

Test 1 1.98

Test 2 2.05

Test 3 2.02

Test 4 2.16

Test 5 2.16

Table A6. Area of pitch deposit on a color scanned image calculated by image-analysis at 0, 200 and 300 ppm of dispersing agent, arranged in an ascending order.

Dispersing agent (ppm)

Area of the deposits (mm2)

Mean area

(mm2)

StD StD (%)

0 107 143 298 319 480 747 349 216 61.9

200 487 509 533 540 708 968 624 170 27.2

300 207 433 535 591 727 785 546 191 35.0

Table A7. Quantity of pitch deposit on a color scanned image calculated by image-analysis software Image Pro at 0, 200 and 300 ppm of dispersing agent.

Dispersing agent

(ppm)

Quantity of deposits

Mean

(quantity)

Standard deviation

(StD) StD (%)

0 1320 1710 2440 4360 5380 8150 3890 2380 61.2

200 1150 1610 2400 3110 3930 5170 2900 1370 47.2

300 1260 2290 2600 3540 4000 11300 4170 3310 79.6

IV

Figure A1. Pitch deposit formation floating on the surface of a plastic method reference test.

Figure A2. Scanned image of plastic film, visible line of deposits.

V

APPENDIX 2 This section provides a description of the developed methods before reaching the final version

for the filtration method and plastic film method.

B.1 Development of filtration method The filtration method was investigating different sorts of filtration throughout the development.

Due to restrictions or undesired results it was continuously developed. Methods from the

literature study and the current method BIM Deposit Tester (BDT) was considered the starting

points for the developments.

Different parameters were considered and altered throughout the development period, which

consisted of the majority of the time allocated for the thesis project. These have been illustrated

in Figure B1 below for better comprehension of the tests. By decreasing the volume of the

container, compared to the 15 L container used in the BDT, the experiment would be more

time-efficient, standard laboratory beakers could be used and a larger extent of the solution could

be analyzed. Therefore, the first step of optimization was to develop a method in a beaker of 50,

100 and 500 ml. The 50 ml trials were neglected early as the deposits formed were almost

negligible when weighing, while the result at 100 ml was varying a lot, thus 500 ml was used

for the remaining experiments. To increase the repeatability, and since the smaller volume now

allowed for it, distilled water was used for every test, instead of decarbonating warm tap water

as was done in the BDT. The temperature was reduced to 65 °C compared to 85 °C in the

BDT, allowing for a shorter heating-time which yields both time and energy-efficiency. As the

designated 15 L large container was no longer needed, two tests could be conducted at the same

time, thus decreasing the execution-time significantly. In order to still reach a high repeatability,

a stock mixture was prepared before each two tests allowing for the same pH to be set in both

test beakers, thus reducing error margins.

Different filtration methods were considered, which aimed to capture all deposits that were

formed in the solution. Therefore, a variety of parameters were briefly investigated, as illustrated

in Figure B1. Three different filter shapes were tested: a circular disc, a cone and bag-shaped

filter, illustrated in Figure B1a). The circular disc was discarded as the solution had a tendency

of flooding the filter, when emptying the solution in the beaker through the filter. In order to

avoid this problem, a cone filter was used. However, when emptying the solution through this

filter, it was noticed that a large amount of deposits was attached to the beaker wall and was

therefore not captured in the filter. This was solved by submerging the cone filter and the

chemicals were added within the filter. In this way, the deposits were formed within the bag,

and did not attach to the beaker wall. However, the cone bag was holding a very small volume

compared to the rest of the beaker and was exchanged for a larger filter bag, which better fitted

the dimensions of the beaker.

Different filter materials were briefly tested, illustrated in Figure B1b), and the plastics showed

low standard deviations and were thus the most promising. Metal also had a low standard

deviation but was not available in filter bag shaped. The micron ratings ranging from 125 um to

800 um (illustrated in Figure B1c), was also evaluated and the micron ratings of 125-150 um

showed the lowest standard deviations during the experiments.

VI

Figure B1. Illustration of the development of the filtration method. a) The effect of a disc shaped filter, a cone shaped filter and bag-shaped filter was evaluated. b) The effect of the materials paper, metal, nylon and polyester was evaluated. c) Testing of different pore sizes of the filter, ranging from 125 to 800 microns was also evaluated.

B.2 Development of plastic film method The second approach was derived from the literature study and inspired by other laboratory

methods at BIM Kemi. The principle of deposits attaching to a film within the beaker, and

quantification of image-analysis was used. The initial conditions and set-up of this method were

similar to the final filtration method while the applied image-analysis was quantifying the deposit

spots using a software.

An execution that fitted the improvements of the conditions, and the expected image-analysis,

was developed. Before adding the pitch, dispersing agent and CaCl2, a plastic film was inserted

along the inside of the wall of the beakers. The plastic film was made up of a transparent A4-

sized plastic page cut in half, which tolerates higher temperatures. For an optimal result, a large

difference in deposits attached was desired when comparing the reference and product tests, thus

different dosages of added dispersing agent were evaluated. The presence of a staining agent was

also evaluated, for maximum contrast to the plastic film, using the staining dye Sudan IV. The

dye stained too irregularly, and the contrast was achieved by attaching a black background sheet.

The analysis was developed thoroughly by optimizing the environment and method for

documenting the plastic films, such as lighting/reflections and camera settings. The procedure

in the software was also developed, with support from image-analysis experienced laboratory

personnel at BIM Kemi. After removing the plastic film from the beaker, it was taped onto a

VII

black sheet for maximum contrast to the white-yellow pitch deposits. A series of images from a

camera was analyzed and compared to each other to investigate how reflections and angles

affected the image-analysis. The issues of reflections on the plastic films required optimization of

the environment when photographing, which included the assembly of a “camera box” with

dark lining, a hole at the top of the box for the lens to be located at the same position each time,

as well as markings of the box bottom to place the plastic film identically for each test. The

plastic films were also scanned, and parameters such as color or gray scale, resolutions and file

formats were analyzed and compared in the software.

Development in the image-analysis software included the calibration of image, which was

required for accurate calculation of the area covered by the pitch on the plastic film. Also, the

selection of the “region of interest” was evaluated, to mark only the areas of the photographed/

scanned image where the deposits were located. A fixed setting in the software for identifying

the pitch deposit spots was developed in order to increase repeatability and consistency of the

method. The pitch deposit spots were identified and marked by changing the range of a color

intensity histogram, which was evaluated too.

The final method for the plastic film method is presented in the methodology and result

section of this report.

VIII

APPENDIX 3 This section summarizes a short evaluation test that was conducted on a bio-surfactant provided

by Luleå University of Technology at BIM Kemi AB.

C.1 Brief investigation of the bio-surfactants Rhamnolipid The test method used was using a TurbiScan, illustrated in Figure C1 and this introduction

and methodology is based on the work method for BIM Precipitation Tester (BPT) available at

BIM Kemi (Metod BIM precipitation tester BPT). The glass reactor is filled with a desired

amount of solution, and a heat jacket surrounding the glass reactor is controlling the temperature.

A peristaltic pump transports the solution through the closed system. A measuring cell uses an

optical sensor through which the solution is passing. A detector box receives the signals which

are displayed and transferred to the computer.

Figure C1. Schematic image of the TurbiScan set-up.

The measuring cell is emitting a pulsing infrared light (850 nm) and the transmitting (passing)

and back scattering (reflecting) light of the solution is detected using the optical sensors. This is

plotted over time and presented in the software TurbiScan On-Line on the computer. A solution

showing a high transmittance is considered transparent or vaguely turbid. A test with low

transmittance (and high back scattering) is considered turbid.

C.2 Methodology The chemicals and instruments used are presented in Table C1. The pitch was prepared according to the description in the methodology section 3.2 of this report.

Table 3. Chemicals and instruments for the BPT method.

Chemicals Instruments

Prepared pitch solution TurbiScan

NaOH (10 %) TurbiScan On-line software

Rhamnolipids

CaCl2 (10 %)

IX

The computer and the TurbiScan was turned in order to allow for the temperature to be

reached within time for the test. The reactor was then filled with 1 L hot tap water for rinsing

during circulation. The temperature was set to 65 °C. The solution was prepared by filling a

beaker with 2 L of distilled water. The beaker was placed on a heat stirrer and the water was set

to pH 11 using NaOH and covered in aluminum foil. The temperature on the heat stirrer was

set to 65 °C. When the solution and the TurbiScan both reached 65 °C 1 L of solution was

transferred to the TurbiScan. The software was turned on and a new ‘run’ was initiated. When

pressing ‘go’, the chemicals could be added in the following sequence: at T=40 sec 1 ml of the

pitch solution was added, at T=200 sec 5 ml of CaCl2 was added. After T=600 sec the test run

could be stopped. The same procedure was repeated in a new test run in which 1 ml of

rhamnolipids were added at 120 sec.

C.3 Results and discussion The measured transmission for both the reference test and the product test is presented in Figure

C2 below.

The initial drops of the transmission at 50 seconds represents the addition of pitch, the second

dip (only for the product curve) represents the addition of rhamnolipids while the third drop

represents the addition of CaCl2 which initiates the pitch formation. The rhamnolipids drops to

about the same level of transmission at 65 % before stabilizing. The reference test shows an

increased transmission after about 450 seconds, while the rhamnolipids are keeping the

transmission stable at approximately 60 %.

Figure C2. The transmission (%) measured for the reference test and with added Rhamnolipids.

Although the transmittance is presenting a minor difference between the reference and

rhamnolipid tests, the solution was visibly dispersed, as suggested in Figure C3 and C4 below.

0

10

20

30

40

50

60

70

80

90

100

0 100 200 300 400 500 600 700

Tra

nsm

issi

on (%

)

Time (s)

Transmission of rhamnolipids vs reference

Reference

Rhamnolipids

X

Figure C3. Photograph of reference test after 600 sec.

Figure C4. Photograph of rhamnolipid test after 600 sec.

C.4 Conclusion The results showed that the bio-surfactant successfully stabilized the pitch deposits and prevented

them from forming deposits. Further tests and evaluations are still recommended as only one

trial was performed due to time limitations.