The recovery of glycerine from spent soap lye has been done using soap lye samples obtained from the hot process of soap production using palm kernel oil (P.K.O). The main advantage of hot process is that exact concentration of the lye solution is not known, but to perform this with adequate success, the lye and fat are boiled together at 80 – 100⁰C at times above 100⁰C until saponification occurs. The overall weight of glycerine recovered per 100g of oil used was 9.0g. The quantity of spent soap lye obtained was 250ml, Acid value was 555.39, percentage free acid value was 5.6%, total fatty acid = 7.131, percentage free caustic acid = 0.14%, percentage free fatty acid obtained was 0.07131%, the specific gravity was 1.059, purity of glycerine was 92%. These parameters obtained were measured relatively to international standards with negligible error due to the type of equipment used. From the result, it is evident that the amount of glycerine recovered depends largely on the quantity of spent soap lye. Other processes the spend soap lye and the glycerine undergo as may be seen in other chapters includes, salting out, filtration, splitting and others.

TABLE OF CONTENTS

Title page i

Letter of Transmittal ii

Approval page/certification iii

Approval page iv

Dedication v

Acknowledgement vi

Abstract vii

Table of Contents viii

List of Figures/Tables xii

Definition of Terms/Nomenclature xiii

CHAPTER ONE

1.0 Introduction 1

1.1 Background of the study 1

1.2 Statement of the problem 4

1.3 Scope and limitation of the study 6

1.4 Purpose/aim/objectives of the study 6

1.5 Method of Research 7

1.6 Significance of the study 8

CHAPTER TWO

2.0 Literature Review 10

2.01 History of glycerine 13

2.02 Lye clarification 16

2.03 Recovery of glycerine from spent lye 25

2.04 Twitchel process 38

2.05 Autoclave saponification 48

2.06 Lime saponification 49

2.07 Acid saponification 52

2.08 Aqueous saponifictaion 54

2.09 Splitting fats with ferments 55

2.10 Krebitz porcess 59

2.11 Distillation of fatty acids 62

2.12 Glycerol detection and estimation 66

2.13 Glycerine as a by-product of soap

manufacture 75

2.14 Process description of soap production 78

2.15 Process summary 79

2.16 Step 1: oil preparation 79

2.17 Ion exchange 81

2.18 Soap removal 82

2.19 Composition of glycerine production 83

2.20 Physical properties of glycerine 87

2.21 Chemical properties of glycerine 88

2.22 Sources and types of lipids 90

2.23 Distinction between fats and oils 91

2.24 Uses of glycerine 93

2.25 Major types of saponification 95

2.26 Separation of glycerine and free fatty acid 99

2.27 Quantifying the phosphoric acid to be used 100

2.28 Metabolism 102

2.29 Application of glycerine in food 103

2.30 Application of glycerine in urethane polymers 104

2.31 Application of glycerine in drugs and cosmetics 104

2.32 Application of glycerine as a lubricant. 106

2.33 Application of glycerine in snuffs 106

2.34 Other uses of glycerine 107

2.35 Hyper osmotic effects 108

2.36 Basic raw material for flycerine production. 108

CHAPTER THREE

3.0 Experimental Procedure 111

3.01 The Saponification Process 112

3.02 Splitting Method 115

3.03 Determination of the viscosity of Glycerine 116

3.04 Titration 117

3.05 Percentage Free Alkaline (FCA) 118

3.06 Bleaching of Crude Glycerine 119

CHAPTER FOUR

4.0 Experimental Result and Analysis 121

CHAPTER FIVE

5.0 Discussion 128

5.1 Conclusion 128

5.2 Recommendation 129

References 131

Appendices 132

LIST OF FIGURES/TABLE

Table 2.0: Properties of glycerine 87

Table 2.1: Physical properties of glycerine 86

Table 4A: Glycerine producer association standard for Glycerine recovery 121

Table 4B: Estimation consumption of glycerol in various industries 122

Table 4C: Order of increment of the amount of % glycerine in all the samples. 124

Table 4D: Standard deviation table for percentage (%) salt and percentage glycerine 127

DEFINITION OF TERM/NOMENCLATURE

% = Percentage

N/4 = Quarter normal

Lbs = Pounds

C.C = Cubic centimeter

PZ = Paterson Zochonis

IEA = International Equitable Association

KSI = Kitchen Soap Industries

SSL = Laboratory Stimulated sample

V = Volume of Acid

FFA= Free fatty Acid

AV = Acid Value

SD = Standard Deviation

FCA= Free Caustic Alkali

CA = Percentage Concentration of Glycerol

Vs = Volume of NaOH added to the sample

Vb = Volume of NaOH

Added to the bank

Ws = Weight of Sample

% FAV = Percentage free Acid Value

CHAPTER ONE

1.0 INTRODUCTION

1.1 BACKGROUND OF THE STUDY

Glycerine, (otherwise known as propan 1, 2, 3 triol) is found dissolved in the soap lye and also as an impurity in the crude soap during the saponification of fats and oils with caustic soda. Customarily, the process of soap manufacture, from fats and oil yields glycerol to about 10% of the value of the soap formed and due to its varied uses, its recovery is pertinent to the manufacturing cost analysis for any soap making business. Glycerol being an important bye product of soap manufacture, many small scale and medium scale soap manufacturers normally discards the lye as an unwanted product.

Glycerol occurs in nature combined in the form of triglycerides (fats and oil) and is obtained during the saponification of these triglycerides. This process was the only means of producing glycerol commercially, until 1949 when synthetic glycerol was produced as the compound recovered as by-product from the soap manufacture was sufficient for the world consumption. Alternatively, glycerol is synthesized from propene by the alternate chlorination and hydroxylation process. It is also obtained from the fermentation of various sugars. Glycerine is also produced by various routes from propylene. The epichlorohydrin process is the most important; it involves the chlorination of propylene to give ally chloride which is oxidized with a strong base to give epichlorohydrin. This epichlorohydrin is then oxidized to give glycerine.

In biodiesel, glycerine is a waste, as a result, the market for glycerol is depressed and the old epichlorohydrin process for glycerol synthesis is no more economically viable.

Fats and oils are esters of glycerine with long-chain fatty acid such as stearic acid (C₁₇H₃₅COOH) Palmitic acid (C₁₅H₃₁COOH) and oleic acid (C₁₇H₃₃COOH). Since glycerine contains three –OH groups, it can form three series of esters thus;

Mono-ester di-ester and tri-esters

CH₂.OH CH₂.OH CH₂.O.OC.R

CH.OH CH.O.OC.R CH.O.OC.R

CH₂.O.OC.R CH₂.O.OC.R CH₂.O.OC.R

Mono=-ester di-ester tri-ester

Some of the major industrial applications of glycerol include the manufacture of alkyd resins and flexible polyurethane for the plastic industry. It is also an important ingredient in cosmetics and adhesive manufacture. Many pharmaceutical preparations such as glycerol phenol mixture which serves as tranquilizers utilize glycerol.

Glycerol residue has been reported to contain 20.2% glycerol, 6.6% fatty acids (as soap) and 64.3% salt. Thus 91.1% of it is potentially useful. It is obviously advantageous, both environmentally and economically, to recover the glycerol in the waste material from soap industries as a potential alternative for the production of glycerol using chemical methods.

1.2 PROBLEM STATEMENT

The method of analyzing glycerine is greatly varied due to the fact that glycerine contained impurities which acted so much like glycerine as to introduce serious errors in the determination of crude glycerine. This however led to the appointment of committees in the United States and Europe to investigate the method of glycerine analysis. It was concluded in the meeting of the International Committee set for this purpose, that acetin method should control the buying and selling of glycerine, but the more convenient bichromate method in a standardized form might be used in factory control and other technical purposes.

The quantity of recovered residual salt is dependent on the point of recovery and nature of lye treatment. Neutralizes of the acid and alkaline content of the soap lye helps to reduce the amount of salt originally combined with soap by precipitation, coagulation and flocculation. This is done through their pH adjustments.

The whole process becomes entirely cumbersome as absolute care is taken to ensure that glycerine passes through all the stages required to obtain pure glycerine devoid of impurities.