SOLVENT DYEING OF COTTON WITH ANIONIC DYES
by
J. VENKATA RAO
A thesis Submitted to the Indian Institute of Technology, Delhi
for the award of the Degree of
DOCTOR OF PHILOSOPHY
DEPARTMENT OF TEXTILE TECHNOLOGY INDIAN INSTITUTE OF TECHNOLOGY, DELHI
APRIL, 1982
01
CEERTIFIC TE
This is to certify that the thesis entitled
"SOLVENT DYEING OF COTTON WITH ANIONIC DYES",
submitted by Mr. J. Venkata Rao to the Indian
Institute of Technology Delhi, for the award of
degree of DOCTOR OF PHI10SOPHY is a record of the
bonafied research work carried out by him.
Mr. J. Venkata Rao has worked under my guidance for
the submission of this thesis, which to my knowledge
has reached the requisite standard.
The thesis or any part thereof, has not been
submitted to any other University or Institution for
the award of any Degree or Diploma.
(R.B. Chavan) Thesis Supervisor,
Department of Textile Technology, Indian Institute of Technology Delhi,
New Delhi 110016.
CURRICULUM VITAE
1970 , B. Tech (Text) in I Class, Madras University
1970-71 Supervisor, M/s Anglo French Textiles, Pondicherry.
1971-74 M. Tech. (Text) in I Class with Distinction
1971-74 Instructor, , Dept. of Textile Technology, A.C. College of Tech., Madras.
1974— Lecturer, onwards Dept. of Textile Technology,
A.C. College, Madras.
1979-82 Engaged in the present work.
k
AC KNOW WLEDGE EN TS
The "philosophy" that I learnt pursuing the
"Doctor of Philosophy" is that research is never a one man
act. Scores of people directly or indirectly were involved
in my research programme and, thank God, everyone had
facilitated me in my pursuit. I feel that I am lucky in
this respect and I bow to all of them, with a .;deep sense
of gratitude.
First and the foremost among them is my thesis
supervisor, Dr.. R.B. Chavan, Assistant Professor, Depart-
ment of Textile Technology, Indian Institute of Technology,
for his heuristic approach, for allowing complete freedom
of work, for initiating me into this "research culture" and
for warm heartedness.
To late Prof. S. Krishnamurthy and Perarignar Anna
University of Technology, Madras for having deputed me for
Ph.D Linder Quality Improvement Programme.
To Professor C.D. Shah, Head of Textile Technology
Department, Prof.. V.B. Gupta, Prof. (Miss) P. Bajaj and
Prof.. M. L. Gulrajani for their unfailing help in every
aspect, for providing all the facilities in the department
and for the valuable suggestions.
To Prof. S.R. Sivaraja Iyer, University Department
of Chemical Technology, Bombay, for the valuable discussions.
To Dr. Raj Kumar, ATIRA, Ahmedabad, Dr. S. Chopra and
Dr. H. Bohidhar, Department of Physics, I.I.T. Delhi and
Dr. A. Hussain,CMST, IIT Delhi, for helping in conducting
different experiments.
To all the technical staff of Textile Department,
for their ungrudging cooperation.
To my beloved parents and natural mother who always
prayed for me.
To my wife and sons, Shiva and Prasad who bore my
separation ungrudgingly and without distraction to my
research work.
To Mrs. and Mr. J.L. Bhatt and their children who
made me feel at home:during my three years stay in Delhi
and also for helping in the preparation of the manuscript.
To all my Shivalikites and research colleagues for
their never ending help.
To Mr. Rajesh K. Arora, for typing the manuscript
with speed and efficiency.
ii
A special word of thanks to my teacher,
Shri R.A. Quraishi, who was instrumental in inducting me
to this "research culture".
iii
(J. Venkata Rao)
ABSTRACT
An attempt was made to understand the dyeing mechanism
of water swollen-sovent exchanged (WSSE) cotton with anionic
dyes from dimethylformamide-trichloroethylene (DMF-TCE) sol-
vent mixtures. For this purpose three anionic dyes,
Naphthalene Red JS (CI Acid Red 88), Naphthalene Red EA
(CI Acid Red 13) and Naphthalene Scarlet 4R (CI Acid Red 18)
having the same structure but varying number of sulphonic
acid groups from 1 to 3 were selected. The dyeing of WSSE
cotton with anionic dyes was explained on the basis of the
electrokinetic character of cotton in the solvent medium,
analysis of adsorption isotherms, dyeing behaviour of oxidized
cotton and the use of solubility parameter concept. The
state of dye in solution was determined from the aggregation
behaviour of the dyes in DIIF-TCE solvent mixtures using a
new technique, namely, quasielastic light scattering.
SYNOPSIS
Water as a medium for chemical processing of textiles
is used universally. However, its use is not free from
problems such as effluent treatment, stream pollution and
high thermal energy required for evaporation. The use of
non-aqueous medium was therefore considered to be an alter-
native medium for chemical processing of textiles. Chlori-
nated hydrocarbons such as perchloroethylene, trichloro.-
c thylene, 1 ,1 ,1--trichloroethane etc. , were found to be more
suitable for this purpose on the basis of their non-inflamm-
ability, stability towards repeated recovery and low thermal
energy required for evaporation. Processes such as scouring
of natural And synthetic fibres have been commercialised
using these solvents. Considerable information is also
available on the dyeing of synthetic fibres such as
polyester with disperse dyes. This was possible because of
non ionic nature of the dyeing system. However dyeing of
natural fibres such as cotton with anionic dyes using
chlorinated hydrocarbons was not possible due to non-polar
nature of the solvents the fibre swelling was poor and the
anionic dyes were insoluble in such solvents. To overcome
these problems, it was essential to use a polar solvent
ii
like itiater or dimethyl formamide (DMF) at certain stage of
dyeing for fibre swelling and dye solubilization. Certain
systems have been reported in the literature based on the
above principle L-4,77 A more systematic study has been
reported by Chavan and Co-workers for the dyeing of cotton
with acid, direct and reactive dyes using polar and non-
polar solvent mixtures LT3-177. It was reported that a
reactive dye could successfully be exhausted and fixed on
cotton when the dyeing was carried out from dimethyl formaemide-
trichloroethylene (D AF-TCE) solvent mixture. This study is
of importance because hydrolysis of a reactive dye in aqueous
system is almost inevitable. If the presence of water in the
dye bath is reduced or elimin .ted, the dye hydrolysis could
be minimised or avoided leading to higher dye fixation on
cotton. Higher dye exhaustion and better fixation were
achieved when aqueous-alkaline -pre-swollen cotton wag dyed
in DMF-TCE solvent mixture 04,15, . acetone and the ,Mixtures
of acetone-TCE assisted by a small proportion of water or
DMP was also suggested for the application of reactive dyes
on water or aqueous-alkali-swollen cotton LT77. The work
on the application of acid and direct dyes on water swollen-
solvent exchanged (WSSE) cotton from DMF-TCE solvent mixture
revealed that with the increase in TOE content in the solvent
dye bath, the dye-uptake on the fibre was increased. This
iii
increase in dye uptake was attributed to "the decrease in dye
solubility in the solvent mixture. The present work is an
extension of the earlier study on the application of anionic
dyes on cotton from DMF-1E mixtures. For this purpose three
anionic dyes (CI _1A,cid Red 88, CI Acid Red 13 and CI Acid
Red 18) having the same structure but number of sulphonic
acid groups varying from 1 to 3 were specifically selected.
It was postulated that the transfer of the dye from external
phase to the internal liquid phase closely associated. with
the fibre (which was essentially DMF) takes place due to
solubility difference, followed by I ngmuir adsorption. The
above hypothesis was based on the experimental observations on
the electrokinetic character of cotton in the solvent mediui,
analysis of the adsorption isotherms and the dyeing behaviour
of oxidized cotton. An attempt was also made to 'explain the
dyeing observations on the basis of solubility parameter
concert. To understand the state of dye in solution the
aggregation behaviour of the dyes in DMF-TCE solvent
mixtures was also studied.
The thesis has been divided into seven chapters.
First chapter relates to the general introduction and a
review of literature.
In the second chapter the zeta potential existing at
the interface of W$SE cotton and DTMF,TCE and their mixtures
was determined using streaming potential technique, and its
effect on dyeing was discussed.
In chapter three, to understand the dyeing mechanism,
the equilibrium dyeings were carried out at 400C from I F-
TCE mixtures. The adsorption isotherms were constructed
and interpreted in terms of distribution of dye between the
dye bath and the solvent closely associated with the fibre
followed by Langmuir adsorption on cotton. Using Iangmuir
equation affinity values were calculated. It was observed
that the dye affinity increased with the increase in
aulphonic acid groups in dye molecule and also with the
increase of TCE content in the solvent mixture.
The study of equilibrium adsorption of the dyes on
oxidized cotton from DMF-TCE mixtures as reported in
chapter four revealed that at any IMF-TOE ratio the dye
uptake expressed in terms of percent exhaustion was decreased
with increase in carboxyl content. However, with the Increase
in TOE content in the solvent mixture the dye uptake was
increased. Although there was increase in dye uptake with
the increase in TCE content in the solvent mixture, for any
iv
particular dye, the repulsive effect of carboxyl groups,
as determined from the extent of reduction in dye uptake
was found to be almost same. This fact revealed that the
internal liquid closely associated with the fibre was
essentially DMF, from which dyeing takes place. The
reduction in dye uptake due to repulsive effect of carboxyl
groups varied with the number of suiphonic acid groups in
the dye niolee ule. It was noticed that the presence of
carboxyl groups changed the isotherm from Iangmuir to Sigmoid shape.
In chapter five some of the basic principles of solu-
bility parameter concept and its effect on dyeing behaviour
have been discussed. The solubility parameters of the dyes
were theoretically calculated by Van Krevelen's method.
The solubility parameters of cotton, DMF and TOE were taken
from literature. The solubility parameter of solvent
mixtures were calculated using standard equation. The solu-
bilities of dyes in DMF and DMF-WE mixtures and dyeing
behaviour of cotton from DMF-LE mixtures were related to
solubility parameter values. However, in order to explain
all the dyeing observations it was thought to be essential
to divide the total solubility parameter of cellulose ,dyes
and solvent mixtures into solubility parameter due to
v
association forces (CcA) and solubility parameter due to
dispersion forces (9d). The cd.-values were calculated
from refractive indices. The refractive indices of the
dyes were theoretically determined with the help of model
compounds using Lorentz and Lorenz equation. For solvent
mixtures the refractive indices were experimentally deter-
mined and the refractive index of cotton was taken from
literature. £-values were calculated using a standard
equation. The total picture on the dyeing behaviour of
cotton from solvent mixtures emerged from the above concept
revealed that the dye adsorption was mainly governed by dis-
persion forces. This fact was experimentally verified by
studying the effect of temperature on dye uptake. It was
observed that the temperature had no effect on dye uptake
which suggested that the adsorption process was mainly
governed by the weak attractive forces like dispersion
forces.
The sixth chapter deals with the aggregation behaviour
of the dyes in DMF-TOE solvent mixtures. For this purpose,
a new technique, namely, quasi-elastic light scattering (QI5)
was employed. It was observed that the aggregation tendency
vi
0
of the dyes in DMF- TE mixtures was dependent on the TOE
content and on the number of sulphonie acid groups and
their position in the dye molecule.
The salient features of the dyeing systems are
swnmarised in the concluding chapter.
vii
Page CONTENTS No.
ABSTRACT
SYNOPSIS
CHAPTER 1 GENERAL INTRODUCTION
1.1 Solvent Dyeing of Cotton
1.2 Solvent Exchange Technique and its Application. 9
CHAPTER 2 EI,ECTROKINETIC STUDY
2.1 Introduction 13
2.1.1 Electrokinetic phenomena 13
2.1.2 Electrokinetic studies on cotton 16
2.2 Materials 18
2.3 Experimental Methods 19
2.3.1 Streaming Potential Measurements 19
2.3.2 Viscosity and Density 21
2.3.3 Dyeing 21
2.4 Results and Discussion 21
CHAPTER 3 THERMO DYNAMICS OF DYEING
3.1 Introduction 25
3.1.1 Adsorption Isotherms 25
3.1.2 Thermodynamic treatment of adsorption isotherms. 25
3.1.3 Mechanism of dyeing of cellulosic fibres with anionic dyes in aqueous 30 system.
Page No.
3.2 Materials 37
3.3 Experimental Ii[ethods 37
.3.3.1 Preparation of Naphthalene Red EA 37
3.3.2 Purification of dyestuffs 38
3.3.3 Determination of dye purity 39
3.3.4 Dye solubility 40
3.3.5 Dyeing 41
3.3.6 Estimation of dye 42
3.4 Results and Discussion 42
3.4.1 Effect of solubility on dye uptake 42
3.4.2 Rate of dyeing 45
3.4.3 Analysis of adsorption isotherms 46
CHAPTER 4 DYEING OF OXIDIZED COTTON
4.1 Introduction 53
4.2 Experimental Methods 56
4.2.1 Preparation of oxidized cotton 56
4.2.2 Estimation of carboxyl groups 57
4.2.3 Dyeing 59
4.3 Results and Discussion 59
4.3.1 Effect of DMF-TCE ratio on dye uptake. 59
4.3.2 Effect of sulphonic acid groups on dye uptake 61
4.3.3 Adsorption Isotherms. 61
Page No.
CHAPTER 5 SOLUBIISTY 21)11L'IUMP,
5.1 Introduction 63
51.1 Solubility parameter 63
5.1.2 Determination of solubility parameter 63
5.1.2.1 Solvents 63
5,1,2,2 Solvent mixtures 67 5.1.2.3 Polymers 67
5.1,3 Three dimensional solubility parameter 71
5.1,3.1 Determination of individual components. 72
5.1.4 Application of solubility para- meter concept 75
5.1.4.1 Pigment dis-persion 75
5.1.4,2 Polymer and plasticizer compati- bility 76
5.1.4.3 Wettability of polymers 76
5.1.4.4 Gas-liquid solubility 77
5.1.4.5 Tensile strength 78
5.1.4.6 Dyeing 79 5.1.5 Limitation of solubility parameter
concept in dyeing 82
5.2 Experimental Methods : Determination of Solubility Parameter and its Components 83
5.2.1 Dyes 83
5.2.1.1 Total solubility parameter 83
5.2.1.2 Solubility parameter due to dispersion and association forces 83
Page No.
5.2.2 D14F, TOE and their mixtures 87
5.2.3 Cotton 87
5.3 Results and Discussion 88
5.3.1 Dye solubility in DMF and DMF-1E mixtures 88
5.3.2 Dye uptake from DMF-TCE mixtures 89
CHAPTER 6 AGGREGATION OF DYES IN SOLUTION
6.1 Introduction 93
6:.1.1 Determination of aggregation number 93
6.1.1.1 Conductivity measurements 93
6.1.1.2 Radiation induced processes 94
6.1.1.3 Diffusion measurements 97
6.1.1.4 Other methods 101
6.1.2 Reasons for aggregation 101
6.1.3 Aggregation behaviour of anionic dyes 10~
6.2 Experimental methods 107
6.2.1 Quas ie lastic light scattering study 107
6.2.2 Theory 108 6.2.3 Determination of the radius of
the aggregate and aggregation number 109
6.2.4 Instrumentation and experimental procedure 111
6.3 Results and Discussion 113
Page No.
CHAPTER 7 HOARY 118
REFERENCES
APPENDIX I
APPENDIX II
APPENDIX III
List of Research Publications and
Review Articles written.
i to xi