ABSTRACT
The potential use of extracted Vanillin from vanilla flavour for the chemical substitution of toxic carriers used in aqueous dyeing of polyester fabrics was assessed. The extracted vanillin was used to compare the dyeing of a woven polyester fabric with two synthesized azo disperse dye from 2-nitroso-1-naphtol and 1-nitrosol-2-naphthol and two commercial dyes C.I Disperse Yellow 56, and C.I. Disperse Yellow 50. When vanillin and the conventional carriers were used for dyeing at 3% shade at boil, the dye uptakes increased for both vanillin and the conventional carriers but were higher with the conventional carrier especially benzoic acid which gave 81.4% exhaustion and least for salicylic acid which gave 73% exhaustion, at 0.15g of vanillin and pH 4 and70.4% exhaustion for C.I Foron Yellow 50 and least on C.I Disperse Yellow 56 which gave 0.66% exhaustion pH 11. The wash, hot pressing and light fastness were determined, an excellent wash fastness was observed at both ISO2 and ISO3 wash fastness respectively for the conventional carriers and vanillin which gave an excellent rating of 4-5. More so, the light fastness test gives a high fastness rating at an average of 6-7 for both the conventional carrier and vanillin at the different pH and concentration used.The study confirms that vanillin can be used as a chemical substitute to conventional carriers withgood wash and light fastness properties.
TABLE OF CONTENTS
DECLARATION …………………………………………………………………………………………………………… ii
CERTIFICATION ………………………………………………………………………………………………………… iii
DEDICATION ……………………………………………………………………………………………………………… iv
ACKNOWLEDGEMENTS …………………………………………………………………………………………….. v
ABSTRACT ………………………………………………………………………………………………………………… vi
TABLE OF CONTENTS ……………………………………………………………………………………………… vii
LIST OF TABLES ……………………………………………………………….. Error! Bookmark not defined.
LIST OF FIGURES ……………………………………………………………………………………………………… xii
LIST OF SCHEMES …………………………………………………………………………………………………… xiii
LIST OF PLATES …………………………………………………………………………………………………………..xiv
LIST OF APPENDICES……………………………………………………………………………………………….. xv
CHAPTER ONE ……………………………………………………………………………………………………………. 1
1.0 INTRODUCTION ………………………………………………………………………………………………. 1
1.1 ACTION OF CARRIERS ………………………………………………………………………………. 2
1.2 VANILLIN ……………………………………………………………………………………………………. 3
1.3 STATEMENT OF THE RESEARCH PROBLEM ………………………………………….. 4
1.4 JUSTIFICATION OF THE STUDY……………………………………………………………….. 5
AIM AND OBJECTIVES …………………………………………………………………………………………. 5
1.5.1 Aim …………………………………………………………………………………………………………. 5
1.5.2 Objectives ……………………………………………………………………………………………….. 5
CHAPTER TWO …………………………………………………………………………………………………………… 7
2.0. LITERATURE REVIEW ………………………………………………………………………………. 7
2.1 DISPERSE DYES ………………………………………………………………………………………….. 7
2.2 CHEMICAL CONSTITUTION OF DISPERSE DYES …………………………………… 9
2.3 AZO DISPERSE DYES …………………………………………………………………………………. 9
2.4 ANTHRAQUINONE DISPERSE DYES ………………………………………………………..10
2.5 HYDROPHOBIC FIBRES ……………………………………………………………………………10
2.6 POLYESTER FIBRES ………………………………………………………………………………….10
2.7 PROPERTIES OF POLYESTER FIBRES …………………………………………………….11
2.7.1 Physical Properties ………………………………………………………………………………….11
2.7.2 Chemical Properties ………………………………………………………………………………..12
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2.8 AZO DYES …………………………………………………………………………………………………..13
2.8.1 Method of Synthesizing Azo Dyes ……………………………………………………………..13
2.8.2 Diazotization …………………………………………………………………………………………..13
2.8.4 Dyeing Techniques …………………………………………………………………………………..15
2.8.5 Carrier Dyeing …………………………………………………………………………………………15
2.8.6 High Temperature Dyeing …………………………………………………………………………16
2.8.7 Thermosol Dyeing ……………………………………………………………………………………17
2.8.8 Vanillin …………………………………………………………………………………………………..18
2.8.9 Occurrence ……………………………………………………………………………………………..19
CHAPTER THREE ………………………………………………………………………………………………………22
3.0 MATERIALS AND METHODS …………………………………………………………………………22
3.1 Materials ………………………………………………………………………………………………………22
3.1.1 Extraction of Vanillin ………………………………………………………………………………..22
3.1.2 Synthesis of 2nitroso1naphthol Coupling Component……………………………23
3.1.3 Synthesis of 1nitroso2naphthol …………………………………………………………..23
3.1.4 Diazotisation of 4nitro aniline …………………………………………………………………23
3.1.5 Diazotization of Aniline …………………………………………………………………………….23
3.1.6 General Procedure for Coupling 2-nitroso-1-naphthol …………………………………24
3.1.7 General Procedure for Coupling 1n 2naphthol ……………………………………..24
3.1.8 Percentage Yield ……………………………………………………………………………………..25
3.1.9 Purification ……………………………………………………………………………………………..25
3.2 Spectroscopic Analysis of the Dyes and Vanillin ………………………………………………26
3.2.1 UltravioletVisible (UVVIS) Spectroscopic Analysis of Synthesized Dyes ………26
3.2.2 Determination of Molar Extinction Coefficient of Synthesized Dyes ………………26
3.2.3 Application of the Dyes …………………………………………………………………………….26
3.2.4 Reduction Clearing …………………………………………………………………………………..27
3.2.5 Percentage Dye Exhaustion ………………………………………………………………………27
3.3 FASTNESS TEST …………………………………………………………………………………………27
3.3.1 Wash Fastness Test ………………………………………………………………………………….27
3.3.2 Determination of Light Fastness (ISO BOI: 1994) …………………………………………28
CHAPTER FIVE ………………………………………………………………………………………………………….62
5.0 RESULTS AND DISCUSSION …………………………………………………………………………..62
5.1 ASSESSMENT OF FT-IR ABSORPTION SPECTROSCOPIC PROPERTIES 62
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5.2 Physical Characteristics of the Dyes and Vanillin …………………………………………..62
5.2.1 Visible Absorption Spectra of the Dyes ………………………………………………………63
5.2.2 Effects of pH on Dye Exhaustion ………………………………………………………………..63
5.2.3 Effect of Carrier Concentration on Dye Exhaustion ………………………………………64
5.2.4 Comparison of conventional Carriers and Vanillin ……………………………………….64
5.2.5 Assessment of Wash Fastness …………………………………………………………………..65
5.2.6 Assessment of Light Fastness. …………………………………………………………………..66
5.2.7 Fastness to Heat Pressing …………………………………………………………………………66
CHAPTER SIX …………………………………………………………………………………………………………….68
6.0 SUMMARY, CONCLUSION AND RECONMENDATIONS …………………………….68
6.1 SUMMARY ………………………………………………………………………………………………….68
6.2 CONCLUSION …………………………………………………………………………………………….69
6.3 RECOMMENDATION …………………………………………………………………………………70
6.4 CONTRIBUTIONS TO KNOWLEDGE. ……………………………………………………….70
CHAPTER ONE
1.0 INTRODUCTION
In 2009, global production of polyester fibres reached 31.9million tonnes; about 45% ofworldwide fibre production (Oerlikon,2010). Polyester (polyethylene terephthalate (PET)) fibres havea growing importance, and are mainly used in clothing, geotextileand automotive industries. PET has excellent tensile strength andchemical resistance. However as PET is hydrophobic and has nochemically active groups, its dyeing in aqueous conditions is quitedifficult. Dyeing is achieved with disperse dyes having good diffusivityand solubility in PET fibre. Moreover, the highly crystallinestructure of PET fibre slows down the rate of dye diffusion into thefibre(Trotman, 1970).Dyeing of polyester fabrics can be achieved using three differentmethods depending on the quantity of fabrics to be dyed (Dupont,2002).
Thermosol process used for continuous dyeing of thousands of metres of polyester fabrics, is carried out by impregnation of the PET fabric in the dye bathfollowed by squeezing of excess dye bath and then subsequent dried(100-140°C) before dye fixation (at 200-225°C during 12-25sec.). This technique is however restricted to disperse dyes thatcan sublimate and penetrate inside the PET fibre in gaseous state.Thus, only a limited amount of colour shades can be obtained.When special shades are needed, dyeing of polyester fabricswith disperse dyes is achieved usingexhaustion method (deepdyeing)(Dupont,2002). The fabric to be dyed is immersed in the dye bath forlonger period (about 1hr.) under high temperature and pressure,under agitation, with or without addition of a carrier to allow dyediffusion inside the polyester fibre. Exhaustion method is used fordyeing of smaller quantities of polyester fabrics or for dyeing ofpolyester textiles in the form of fibres, yarns or knitted fabrics. Twoexhaust dyeing methods are used: Dyeing under
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atmosphericconditions (below 100°C) with the aid of carriers and dyeingunder high-temperature and pressure conditions (125-135°C) without carrier. Thelast method is the most commonly applied but it requires highenergy consumption because of high temperature conditions.Carriers are used for dyeing of PET fibres in order to improveadsorption and accelerate diffusion of disperse dyes into the fibre atlow temperature and pressure conditions. Nevertheless, most carriers are toxic e.g. phenol, naphthalene, dicloro benzene, etc., to humans and aquatic organisms (Murray andMortimer,1971). During dyeingand rinsing, a large amount of carriers is released into wastewater,but part remains entrapped in the fibre(Vigo,1994) andis likely to be emitted into air during drying, thermofixation andlater use (e.g. ironing).Chemical carriers include: phenolics, chlorinated aromatics,aromatic hydrocarbons and ether(Vigo, 1994). Some carriers aresaid to be “hydrophobic” and some are “hydrophilic”, and their mode ofaction differ accordingly. Hydrophobic carriers are more effectivethan hydrophilic ones (Burkinshaw,1995). In textile industry, hydrophobiccarriers such as dichloro and trichloro-benzene arealready substituted by hydrophilic carriers such as benzoic acid (Vigo,1994).
1.1 Action of Carriers
During the first stage of dyeing, adsorption of carriers on PETfibre takes place in a manner which is similar to that of dispersedyes. Interactions between PET fibre and carrier involve primarilydispersive forces acting between aromatic parts of the carrier andthe PET polymer (Murray and Mortimer, 1971). As the carrier molecules are smaller in size than the dye molecules,they diffuse more rapidly into the amorphous regions of fibreafter their adsorption onto PET fibre. There is then a swelling of PET fibre and creation of spaces between PET macromolecular chains.Amorphous regions
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then become more easily accessible to the dyemolecules. This swelling phenomenon causes a plasticization ofPET and therefore a reduction of glass transition temperature Tg(Murray andMortimer, 1971; Vigo, 1994; Burkinshaw, 1995). Thecarrier has thus the effect of accelerating dye diffusion inside PETfibre.“Hydrophilic” carriers have a different mode of action: they actas powerful dispersing agent, increasing solubility of the dispersedye inwater, (Burkinshaw, 1995), but their increasedsolubility in water decreases their diffusion inside the PET fibre.Carriers such as phenols have aromatic group which contributes totheir adsorption on the fibre (Balmforthet al., 1966).
1.2 Vanillin
Molecular structure of vanillin Fig. 1, is similar to that of traditionalcarriers, which confers to all of them a solubility parameter close tothat of PET. Hence it would be interesting to study the possibleuseof vanillin to substitute traditional toxic carriers. Naturally occurring vanillin in pods is very expensive and wasfor a long time replaced by petrochemical vanillin for its use in poultry feedsand perfumery, etc. There is nowa great concern for its productionusing biotechnological solution: Rhodia markets biosyntheticvanillin prepared by the action of microorganisms on ferulic acidextracted from rice bran and today lots of research is being undertakento synthesize vanillin from agro-resources such as lignin(McShan, 2005). Moreover, vanillin has antioxidant (Tai et al., 2011), antimicrobial and anti-mutagenic effects (Walton et al., 2003). In this research, the feasibility of substituting traditional carriersby vanillinis assessed, the fabric is dyed in atmosphericconditions using two differentcommercial disperse dyes having differing molecularweight and two synthesized azo dye. Thepurpose of this study is to assess the feasibility of substitutingtoxic molecules called
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carriers used for dyeing of polyester fabricsby vanillin from an extracted substance. “Foster Clark” vanilla flavour. Figure 1: Vanillin structure.
1.3 STATEMENT OF THE RESEARCH PROBLEM
Environmental issues are being increasingly taken into account in textile dyeing and finishing industries because of strict legislations and a growing ecological concern. Main environmental impacts of textile dyeing and finishing industries involve high water consumption, high energy use and also input of a wide range of chemicals (dyes, surfactants, carriers, etc.) Some of these chemicals are hazardous for both human health and environment(Szenteet al., 1998). And despite the obvious advantages associated with the chemical carriers in aqueous PETS, dyeing it has a major problem of toxicity on the environment. Thepurpose of this project is to assess the feasibility of substituting toxic molecules called carriers used for dyeing of polyester fabricswith vanillin whichare environmentally friendly and sometimes less expensive.
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1.4 JUSTIFICATION OF THE STUDY
Owing to the toxic nature of the chemical carriers used in the dyeing of polyester fabric, vanillin which is more ecofriendly and with a good solubility nature like the conventional type is used in the dyeing of a woven polyester fabric. Dye uptake was alsocompared to those of traditional carriers such as phenol, benzoic acid,salicyclic acid and naphthalene (Fig. 2 below). The research seeks to confirm the effect of vanillin as a chemical substitute to traditional carriers and evaluation of wash and light and heat pressing fastness properties.
Phenol Benzoic acid Salicyclic acid Naphthalene Figure 2:Chemical Formula of otherCarriers used in the Study
AIM AND OBJECTIVES
1.5.1 Aim
The aim of this research work is to assess the effect of vanillin as a substitute to the chemical carrier in the dyeing of polyester fabric.
1.5.2 Objectives
The specific objectives of this research include:
i. Extraction of vanillin from vanilla flavour.
ii. Characterization ofthe extracted vanillin using FTIR.
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iii. Syntheses of disperse dye from 2-nitroso-1-naphthol and 1-nitroso-2-naphthol
iv. Characterization of the dye using FTIR and UV- visible Spectrophotometre.
v. Assessment of the effect of vanillin on the dyeing of both commercial and synthesized dye on polyester fabric.
vi. Comparison of vanillin with other chemical traditional carriers.
vii. Assessment of pH and concentration on the dye absorption.
viii. Assessment of wash, heat and light fastness properties.
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