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I hereby declare that I have read this thesis

and in my opinion this thesis is sufficient in terms of scope and quality for the

award of the degree of Bachelor of Chemical Engineering

Signature : ……………………………………………...

Name of Supervisor : Prof Dr Rosli Bin Mohd Yunus

Date : 16th May 2008

THE FORMATION OF EMULSIONS IN BIODIESEL PRODUCTION ;

EMULSION STABILITY AND DEMULSIFICATION

VIA MICROWAVE HEATING

FARADILA BT ROZALI

Thesis submitted to the Faculty of Chemical and Natural Resources

Engineering in Partial Fulfillment of the Requirement for the Degree of

Bachelor of Chemical Engineering Faculty of Chemical & Natural Resources

Engineering University Malaysia Pahang

MAY, 2008

I declare that this thesis entitled “The formation of emulsion in biodiesel

production; emulsions stability and demulsification study via microwave

heating” is the result of my own research except as cited in the references.

The thesis has not been accepted for any degree and is not currently

submitted in candidature of any other degree.

Signature : ..........................................................

Name : FARADILA BT ROZALI

Date : 14 MAY 2008..........................................................

ACKNOWLEDGEMENT

Praise be to God for His help and guidance that finally I am able to complete

this final year project as one of my requirement to complete my study.

First and foremost I would like to extend my deepest gratitude to all the

parties involved in this research. First of all, a special thank to my supervisor Prof Dr

Rosli Mohd Yunus and Dr Abdurahman H.Nour for their willingness in overseeing

the progress of my research work from its initial phases till the completion of it. I do

believe that all their advice and comments are for the benefit of producing the best

research work.

I am grateful to the staff of Faculty of Chemical and Natural Resources

Engineering of University Malaysia Pahang for their cheerfulness and

professionalism in handling their work. In preparing this thesis, I was in contact with

many people, researches, academicians and practitioners. They have contributed

towards my understanding and thoughts.

In particular, my sincere thankful is also extends to all my colleagues and

others who have provided assistance at various occasions. Their views and tips are

useful indeed. Unfortunately, it is not possible to list all of them in this limited space.

And last, but not least I thank my parents and other family members for their

continuous support while completing this thesis.

ABSTRACT

In production of biodiesel, emulsions resulted from washing process is

important as a method to remove sediment contaminant or by-product. Ironically,

there have been a few cases when oil becomes a stable emulsion during water

washing process. These situations normally cause by an aggressive washing biodiesel

in the presence of soap and water. Formation of these emulsions is costly, due to

chemical used and production losses. Therefore, the aim of this study is to

understand the stability of emulsions and to investigate the effectiveness of using

microwave radiation to break the stable emulsions. In order to accomplish the

objectives of the study, emulsions were prepared in a lab with water and biodiesel as

raw materials. Part 1 of experiment was investigated the formation and stabilizations

of emulsions by using two different emulsifying agent; Sodium Dodecyl Sulfate and

Triton X100. Concentration of emulsifier varied between 1.5% to 3% total volume

while water-to-oil ratio was varied from 30-50:70-50. The stability studies were

carried out by analyzes the viscosity using viscometer and visually observes on

separation layer. As a result, an existence correlation between the effect of using

different emulsifying agent, the emulsifiers concentration, and water-oil ratio with

emulsion stability were discovered. In term of demulsification study via microwave

radiation, it has been found that the effect of microwave power is proportional to the

separation efficiency of emulsions. Demulsification by using microwave is primarily

due to heat temperature; therefore as the rate power output of microwave oven is

increase, the temperature will increase and this lead to fast separation of water from

emulsions. Microwave has features of penetrating power; in which can distributes its

energy within the bulk of materials thus suspends water droplets in an emulsion.

ABSTRAK

Dalam penghasilan Biodiesel, emulsi terbentuk daripada proses “washing”

atau “pembasuhan menggunakan air” yang penting sebagai satu kaedah untuk

menyingkirkan sebarang bendasing.yang terbentuk semasa tindakbalas penghasilan

biodiesel. Walaubagaimanapun, sebaliknya wujud masalah lain disebabkan proses

pembasuhan ini dimana biodiesel produk bertukar kepada bentuk emulsi. Ini

disebabkan proses pembasuhan yg agresif dengan kehadiran air dan sabun.

Pembentukan emulsi ini mendatangkan masalah kerana ia meningkatkan kos dan

merendahkan produktiviti. Dengan itu kajian ini telah dijalankan bertujuan

memahami pembentukan dan kestabilan emulsi selain mengkaji potensi Microwave

sebagai satu kaedah pemecahan emulsi. Bagi memenuhi objektif kajian ini, emulsi

telah dihasilkan sendiri di makmal dimana air dan biodiesel sebagai bahan asas.

Bahagian pertama eksperimen akan mengkaji tentang penghasilan dan kestabilan

emulsi menggunakan dua jenis agent pengemulsi yang berbeza iaitu Triton X100 dan

Sodium Dodecyl Sulfate. Ratio air kepada minyak dibezakan diantara 30-50 : 70-50

selain kuantiti agen pengemulsi yang digunakan diantara 1.5% sehingga 3% daripada

jumlah isipadu campuran. Kajian tentang kestabilan emulsi ini dijalankan dengan

menganalisis kelikatan dan memerhati kestabilan ratio air-minyak dan kesan

penggunaan agen pengemulsi yang berbeza. Hasil dari eksperimen yg dijalankan,

wujud hubungkait antara kesan penggunaan agen pengemulsi yang berbeza,

kepekatan emulsi dan ratio air-minyak terhadap kestabilan emulsi. Dalam kajian

pemecahan emulsi pula, didapati kesan tenaga yang dibekalkan oleh Microwave

adalah berkadar langsung dengan keberkesanan pemecahan emulsi kepada minyak.

Ini disebabkan tenaga yang dibekalkan kepada microwave akan meningkatkan suhu

dan disebarkan ke seluruh bahagian emulsi dan dengan itu mempercepatkan

pemecahan emusi stabil kepada lapisan minyak dan air.

vi

TABLE OF CONTENTS

CHAPTER TITLE PAGE

TITLE i

DECLARATION ii

ACKNOWLEDGEMENT iii

ABSTRACT iv

ABSTRAK v

TABLE OF CONTENTS vi

LIST OF FIGURE xi

LIST OF TABLE xiii

LIST OF APPENDICES xiv

LIST OF ABBREVIATION xv

NOMENCLATURES xvi

1 INTRODUCTION 1

1.1 Introduction 1

1.2 Problem Statement 2

1.3 Objectives of the study 3

1.4 Scope of Research 3

2 LITERATURE REVIEW

2.1 Biodiesel

2.1.1 Biodiesel Production

2.1.2 Transesterification Reaction

4

4

7

2.2 Water and Contaminant in Biodiesel 8

vii

2 .2.1 Free Glycerols

2.2.2 Residual Alcohol and Catalyst

2.2.3 Water and Sediment

9 9

10

2.3 Emulsion

2.3.1 Emulsion Formation

2.3.1.1 Emulsions are created in two ways

2.3.2 Physico-Chemical Factors Affecting the

Formation of Emulsions

2.3.3 Emulsion Stability

2.3.3.1 Sedimentation

2.3.3.2 Flocculation

2.3.3.3 Coalescence

2.3.3.4 Partial Coalescence

2.3.3.5 Ostwald Ripening

11

12

13

14

14

15

16

18

18

19

2.4 Types of Emulsions

2.4.1 Based on dispersed phase

2.4.1.1 Water in Oil (W/O)

2.4.1.2 Oil in Water (O/W)

2.4.2 Based on size of liquid droplets

19

19

20

21

21

2.5 Surfactant

2.5.1 Surfactant are Amphiphilic

2.5.2 HLB Concept

22

22

24

2.6 Selection of Emulsifiers 24

2.7 Emulsion Breaking / Demulsification

2.7.1 Introduction to Microwave Theory

25

27

3 METHODOLOGY 28

3.1 Introduction 28

viii

3.2 Materials 28

3.3 Emulsifiers

3.3.1 Triton X100

3.3.2 Sodium Dodecyl Sulfate

29

29

30

3.4 Equipment

3.4.1 Microwave Oven

3.4.2 Stirrer (Three Blade Propeller)

31

31

33

3.5 Analyzing Sample

3.5.1 Viscometer Kinematic

3.5.2 Moisture Content

3.5.3 TLC Analysis

3.5.4 Test for Emulsion Type

33

34

35

36

37

3.6 Sample Preparation and Experimental Procedures 37

4 RESULTS AND DISCUSSION 39

4.1 Introduction 39

4.2 The Formation and Stabilization of Emulsions 39

4.2.1 Effect of Water-Oil Ratio on Emulsion Stability

4.2.2 Effect of Emulsifier Concentration on Emulsion

Stability

4.2.3 Effect of using different emulsifiers on Emulsion

Stability

4.2.4 Correlation between Viscosity and Emulsion

Stability

41

46

47

49

4.3 Demulsification

52

ix

4.4 Sample Analysis 60

4.4.1 TLC Analysis 60

4.4.2 Viscosity Analysis 61

4.4.3 Moisture Content Analysis 62

5 CONCLUSION AND RECOMMENDATION 63

5.1 Conclusions 63

5.2 Recommendation 65

6 REFERENCES 66

vi

LIST OF FIGURE

FIGURE NO TITLE PAGE

2.1 Process Flow Schematic for Biodiesel Production 5

2.2 Settling Particle Spheres in a dispersed medium 16

2.3 Flocculation 17

2.4 Coalescence 18

2.5 Water Droplet in oil showing stabilization by surfactants 23

3.1 Chemical structure of Triton X100 29

3.2 Chemical Structure of Sodium Dodecyl Sulfate 30

3.3 ELBA Domestic Microwave Oven Model : EMO 808SS 32

3.4 Three Blade Propeller 33

3.5 Viscometer Kinematics 34

3.6 Karl Fisher Titration 36

3.7 Method in preparation of emulsions 38

4.1 Volume of Water Layer VS Settling Time 41

(1.5% Emulsifier)


(2% Emulsifier)


(2.5% Emulsifier)


(2% Emulsifier)

4.5 Volume of Water Layer VS Settling Time (50-50 w/o) 44



4.8 Separation Efficiency VS Settling Time at Power 180Watt 53


vii




viii

LIST OF TABLES

TABLE NO TITLE PAGE

3.1 Different properties Triton X100 and Sodium Dodecyl 30

Sulfate

4.1 Viscosity of Emulsions (Triton X100) 50

4.2 Viscosity of Emulsions (Sodium Dodecyl Sulfate) 50

4.3 Demulsification at Rate Power 180 Watt 53





4.8 Temperature and Heating Rate 59

4.9 Rf Value of oil before and after demulsification 60

4.10 Viscosity of Oil before demulsification (Biodiesel) 61

4.11 Viscosity of Oil after demulsification 61

4.12 Moisture Content of oil before and after demulsification 62

ix

LIST OF APPENDICES

APPENDIX TITLE PAGE

A 1 Result of Emusion Stability using 69

Triton X100 (Bottom Layer)

2 Result of Emulsion Stability using 70

Triton X100 (Top Layer)

3 Result of Emusion Stability using 72

Sodium Dodecyl Sulfate(Bottom Layer)

4 Result of Emusion Stability using 73

Sodium Dodecyl Sulfate(Top Layer)

x

LIST OF ABBREVIATION

SDDS Sodium dedocyl Sulfate

Triton X-100 iso-octylphenoxy polyethoxy ethanol

HLB Hydrophilic-lipophilic-balance

W/O Water-in-oil emulsion

O/W Oil-in-water emulsion

Mic. Microwave

1

CHAPTER 1

INTRODUCTION 1.1 Introduction

Biodiesel is an important new alternative transportation fuel. The technical

concept of using vegetable oils or animal fats or even used oils as a renewable diesel

fuel is fascinating one. The concept itself may appear simple , but that appearance is

deceiving since the use of biodiesel is fraught with numerous technical issues.

Accordingly, many researchers around the world have dealt with these issues and in

many cases devised a unique solutions.

Water and sediment contamination are basically housekeeping issue for

biodiesel. During the transesterification process, intermediate glycerols, unreacted

triacylglycerols, free fatty acid, residual alcohol, soap and catalyst are formed in a small

amount which can remain and contaminate the final biodiesel product. Therefore, to

overcome the contaminant issues, water washing steps have been devised which aim to

remove all contaminant or by product in biodiesel which by the way has created another

problem; the formation of emulsions. Emulsions are found in a number of products,

including food, petroleum, pharmaceuticals and cosmetics. They result from the

admixture of two immiscible liquids, with one liquid dispersed in the other, which acts

as a continuous phase. In Biodiesel production, the types of emulsions present are

normally water in oil emulsions in which oil as a continuous phase. Being

thermodynamically unstable, emulsions rely on the addition of stabilizing agents that

2

lower interfacial tension, provide a viscoelastic film, and form a steric barrier or a

physical film. For effective physical stabilization, colloidal particles must provide

sufficient droplet coverage and favorable adsorption characteristics

The traditional ways of breaking emulsions include heating and chemicals

adding are disadvantageous both from economic and environment perspectives.

Therefore in this study, the microwave potentials in demulsification of water-in-oil

emulsions were investigated. It is aimed to investigate the effect of microwave radiation

in the breaking of the emulsion as to find an effective way of good separation, less

energy consumption and even cost effective.

1.2 Problem Statement

In the Industry, emulsions are resulted from washing process, which is important

as method to removed sediment contaminant or by-product. The contaminant can lead to

severe operational problems when using biodiesel such as engine deposits, filter

clogging or fuel deterioration.(Gerhard et al., 2005 ) Normally these situations (the

formation of emulsions) are cause by aggressively washing biodiesel in the presence of

water and soap. Soap molecules (a by-product of the biodiesel reaction created when

free fatty acids are neutralized with the catalysts) are long chain molecule that have one

end that is attracted to polar molecules (water) and the other end that is attracted to

nonpolar molecules (biodiesel). These long molecules will attach themselves to biodiesel

and then bunch together forming a "bubble" so that the ends of the soap molecules that

are attracted to water form the outside surface of a sphere with the biodiesel at the center

of the "bubble".

As the significant of this study, the stable emulsions that have been form in

Experiment Part1 will undergo treatment (demulsification) in order to break the

emulsions into oil and water. Formation of emulsion during Biodiesel production is a

3

costly problems both in term of chemical used and production loss. The tradition

methods normally used to break the crude oil emulsions can also applied in eliminating

emulsions in biodiesel production. But usually, these methods are expensive and require

high dosage of chemical to overcome the difficulty which leads to secondary pollutant

since the separated water may contain too much chemicals to be discharged to public

water. Therefore a most recent technology which has received lot of attention from

researchers has been used in this research. Microwave Radiation offer a fast heating

treatment with uniform temperature distribution to the subjected sample during

emulsion breaking process.

1.3 Objectives

This study is aimed to understand the stability of emulsion and investigate the

effect of microwave radiation in the breaking of the emulsion. The effect of adding two

different emulsifying agent in stability of emulsions also being investigates.

1.4 Scope of research work

The research is based on an experimental studies. In order to achieve the

objectives as mentioned earlier, two scoped have been identified ;

I. Part I Experiment : To study the formation , characteristic and stability of

emulsions.

II. Part II Experiment : To investigate the effect of Microwave Radiation in

breaking the emulsions.

4

CHAPTER 2

LITERATURE REVIEW

2.1 Biodiesel

Biodiesel is produced by chemically reacting a fat or oil with an alcohol, in the

presence of a catalyst. The product of the reaction is a mixture of methyl esters, which

are known as biodiesel and glycerol, which is a high value co-product. (Watanabe et al.,

2000)

2.1.1 Biodiesel Production Figure 2.1 shows a schematic diagram of the processes involved in the biodiesel

production. Alcohol, catalyst and oil are combined in a reactor and agigated for

approximately one hour at 60°C. Smaller plants often use batch reactors (Stidham et al.,

2000) but most larger plant (> 4 million liters/year) use continuous flow processes

involving continuous stired-tank reactors (CSTR) or plug flow reactors. The reaction is

sometimes done in two steps where approximately 80% of the alcohol and catalyst is

added to the oil in a first stage CSTR. Then the product stream from this reactor goes

through a glycerol removal step before entering the a second CSTR. The remaining 20%

of the alcohol and catalyst are added in this second reactor. (Gutsche et al., 1996)

5

Figure 2.1: Process Flow Schematic for Biodiesel Production

Following the reaction, the glycerol is removed from the methyl esters. Due to

the low solubility of glycerol in the esters, this separation generally occurs quickly and

may be accomplished with either a settling tank or a centrifuge. The excess methanol

tends to act as a solubilizer and can slow the separation. However, this excess methanol

is usually not removed from the reaction stream until after the glycerol and methyl esters

are separated due to concern about reversing the transesterification reaction. Water may

be added to the reaction mixture after the transesterification is complete to improve the

separation of glycerol (Stidham et al 2000)

(Saka et al. 2000) claim that it is possible to react the oil and methanol without a

catalyst, which eliminates the need for the water washing step. However, high

temperatures and large excesses of methanol are required. (Dasari et al. 2003) noted the

difficulty of reproducing the reaction kinetics results of other researchers and attributed

6

it to catalytic effects at the surfaces of the reaction vessels and noted these effects would

be exacerbated at higher temperatures. (Kreutzer 1984) has described how higher

pressures and temperatures (90 bar, 240ºC) can transesterify the fats without prior

removal or conversion of the free fatty acids. However, most biodiesel plants use lower

temperatures, near atmospheric pressure, and longer reaction times to reduce equipment

costs.

Returning to Figure 2.1, after separation from the glycerol, the methyl esters

enter a neutralization step and then pass through a methanol stripper, usually a vacuum

flash process or a falling film evaporator, before water washing. Acid is added to the

biodiesel to neutralize any residual catalyst and to split any soap that may have formed

during the reaction. Soaps will react with the acid to form water soluble salts and free

fatty acids. The salts will be removed during the water washing step and the free fatty

acids will stay in the biodiesel. The water washing step is intended to remove any

remaining catalyst, soap, salts, methanol, or free glycerol from the biodiesel.

Neutralization before washing reduces the water required and minimizes the potential

for emulsions to form when the wash water is added to the biodiesel. Following the

wash process, any remaining water is removed from the biodiesel by a vacuum flash

process. (Watanabe et al 2000)

The glycerol stream leaving the separator is only about 50% glycerol. It contains

some of the excess methanol and most of the catalyst and soap. In this form, the glycerol

has little value and disposal may be difficult. The methanol content requires the glycerol

to be treated as hazardous waste. The first step in refining the glycerol is usually to add

acid to split the soaps into free fatty acids and salts. The free fatty acids are not soluble

in the glycerol and will rise to the top where they can be removed and recycled. The

salts remain with the glycerol although depending on the chemical compounds present,

some may precipitate out. Mittelbach and Koncar describe a process for esterifying these

free fatty acids and then returning them to the transesterification reaction stream One

frequently touted option is to use potassium hydroxide as the reaction catalyst and

phosphoric acid for neutralization so that the salt formed is potassium phosphate, which

7

can be used for fertilizer. After acidulation and separation of the free fatty acids, the

methanol in the glycerol is removed by a vacuum flash process, or another type of

evaporator. At this point, the glycerol should have a purity of approximately 85% and is

typically sold to a glycerol refiner. The glycerol refining process takes the purity up to

99.5 to 99.7% using vacuum distillation or ion exchange processes. The methanol that is

removed from the methyl ester and glycerol streams will tend to collect any water that

may have entered the process. This water should be removed in a distillation column

before the methanol is returned to the process. This step is more difficult if an alcohol

such as ethanol or isopropanol is used that forms an azeotrope with water. Then, a

molecular sieve is used to remove the water. (Mittlebatch et al 1998)

2.1.2 Transesterification Reaction

To obtain biodiesel , the vegetable oil or animal fat is subjected to chemical

reaction termed transesterification. In that reaction , the vegetable oil or animal fat is

reacted in the presence of catalyst ( usually base ) with alcohol ( usually methanol) to

give corresponding alkyl esters ( for methanol-methyl esters @ fatty acid methyl ester -

FAME ) The product of the reaction is a mixture of methyl esters, which are known as

biodiesel, and glycerol, which is a high value co-product. (Gerhard et al., 2005 )

Transesterification sometimes called fatty acid chains. There are only five

chains that are common in most vegetable oils and animal fats (others are present in

small amounts). The relative amounts of the five methyl esters determines the physical

properties of the fuel, including the cetane number, cold flow, and oxidative stability

(Jeromin et al., 1987) Biodiesel can be used neat and when used as a pure fuel it is

known as B100. However, it is often blended with petroleum-based diesel fuel and when

this is done the blend is designated “BXX” where XX is the percentage of biodiesel in

the blend. For example, B20 is a blend of 20% biodiesel and 80% petroleum diesel fuel.

(Mike Osenga, 1993)

8

While virtually all commercial biodiesel producers use an alkali-catalyzed

process for the transesterification process, other approaches have been proposed

including acid catalysis and enzymes. (Foglia et al 1999) The use of acid catalysts has

been found to be useful for pretreating high free fatty acid feedstocks but the reaction

rates for converting triglycerides to methyl esters are very slow. Enzymes have shown

good tolerance for the free fatty acid level of the feedstock but the enzymes are

expensive and unable to provide the degree of reaction completion required to meet the

ASTM fuel specification Immobilization of the enzyme and use of multiple enzymes in

sequence may provide future opportunities in this area. (Shimada et al 1999 )

2.2 Water and contaminant in Biodiesel

There are a number of water-soluble impurities left in biodiesel after the reaction

and initial settling is complete. The contaminants include soaps, a small amount of

leftover methanol, a small amount of leftover lye, and some free glycerin. Washing the

fuel with water removes these contaminant. Washing also stops the very slow remaining

reaction that sometimes occurs in unwashed fuel where you can sometimes see glycerin

settle out over a period of weeks or months, and washing and removing methanol or lye

will stop this.

In biodiesel production, pretreatment process is introduced to remove dirt,

charred food and other non-toxic materials often found in waste cooking oil. Water is

removed as well because its presence causes the triglycerides to hydrolyze to give salts

of the fatty acids instead of undergoing transesterification to give biodiesel. (Gerpen et

al., 2005)

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