Cationization of cotton fabrics and dyeing them with Reactive dyes.

Raheem Umer

05-NTU-43

Textile Chemistry

A thesis based for requirement of B.Sc Textile Engineering (Textile Chemistry)

Department of Textile ChemistryNational Textile University,

Faisalabad(2004-2008)

Dedication

Those who live in our heart,

throughout the whole span of our life,

whose devotion and prayers make us

able and nearest,

dearest and deepest to us.

To our beloved parents.

Acknowledgement

I feel great pleasure in acknowledging our indebtedness to all those who have been of substantial help and support to us during the preparation of this manuscript.The work presented in this manuscript was accomplished under the inspiring guidance and enlightened supervision of Dr. Tanveer Hussain, Head of department of textile chemistry, National Textile University, Faisalabad. His efforts towards the inculcation of the sprit of constant work and maintenance of professional integrity besides other valuable words of advice encouraged us to keep on fighting against all over whelming odds till success was ensured. We avail this opportunity to express our deepest sense of gratitude and thankfulness to him.I deem it utmost pleasure to express our heartiest gratitude and deep sense of obligation to Sir Ali Raza Ali and Sir Hammad Cheema for their guidance, co-opeeration, encouragement and invaluable suggestions throughout the course of the project in Nishat Dyeing and Finishing, Lahore. I thank all the staff of the textile chemistry lab for their cooperation and assistance during the performance of our experimental work.The completion of this project is a long term task and needs an ideal atmosphere for its completion. We pay tribute to all our well wishers and class fellows for their cooperation and sincere help.

Abstract

Cationization is emerging an effective tool that solves the environmental problems associated with dyeing of cotton with anionic dyes, in this research work, the dyeing properties of cationized cotton that had been pretreated with cationic fixing agents were examined. Fixation, color yield and fastness properties were evaluated for number of reactive dyes with cationized cotton fabrics.

The cotton fabric was treated with cationic fixing agents i.e. FIXANOL PN and MATEXIL FCER by varying the concentration of fixing agents. The concentrations of fixing agents were 10 g/L, 20g/L and 30g/L.the cationized cotton samples were then dyed with different reactive dyes i.e. Leavafix, Cibacrone, and Remazol containing different reactive groups. After dyeing, the properties which were treated are as follows:

1. Washing Fastness2. Rubbing Fastness(Dry and Wet)3. Color depth

The results showed that wash and rubbing fastness of cationized cotton, dyed with different reactive dyes were improved. The results showed higher increase in light shades and lesser increase in dark shades. Also the Cationization of cotton was found to be very effective in increasing the color yield.

Introduction:

The fiber reactive dyes are known as the best for cotton for its wide range of applications and best fastness properties. However all the reactive dyeing systems require huge amount of electrolyte and alkali to exhaust and fix the dye respectively.

These electrolytes are neither exhausted nor destroyed and hence remain in the dye bath after dyeing. All the above only 60 to 65% dye utilization is attainable even with the use of salt in the normal dyeing systems.

When alkalinity is introduced in the bath in order to facilitate the formation of covalent bond between the fiber and functional groups of reactive dyes. The abundance of hydroxyl ions causes significant hydrolysis of reactive dyes. Those hydrolyzed dye are called ‘’Dead Dyes’’ As they have no affinity towards cotton and hence remain in the dye bath, deposition of same on the fiber significantly lower the fastness properties that calls on severe wash-off.

Reactive dye thus pollutes the environment by discharging highly colored reactive dye baths and higher electrolyte concentration. Higher electrolyte concentration effluents cause worse effects such as:

1. Impairing the delicate bio chemistry of aquatic organisms.

2. Destructive attack on concrete pipes is sodium sulphate is used as electrolyte due to the

formation of alumino-sulphato complexes which swell and crack concrete with considerable alumina content.

3. Evolution of hydrogen sulphide gas under anaerobic conditions when sodium sulphate is used as electrolyte.

4. Dissolution of such sulphide and subsequent bacterial oxidation to harmful sulphuric acid.

OPTIONS FOR REDUCTION OF SALTS

1. Shifting from exhaust to pad-batch dyeing.2. Shifting from higher liquor ratio to lower

liquor ratio machines.3. Recycling the salt contaminated dye bath after

eliminating the hydrolyzed dye.4. Molecular engineering of reactive dyes to have

good affinity and good wash-off properties.5. Molecular modification of fiber to have greater

affinity and attraction towards anionic dyes.

The last option totally eliminates the salt and reduces alkali considerably that leads to:

1. Reduction of colorant in the effluent.2. Lower COD (chemical oxygen demand), BOD

(Biological oxygen demand), TDS (Total dissolved solvents) and no AOX (absorbable organic halogens) in the effluents.

3. Reduced no of wash –offs and elimination of neutralization.

4. Reduced effluent volume5. Increased productivity due to reduced dyeing

time.6. Increased dye utilization.7. Reduced cost of dyeing and cost of effluent

treatment.

Numerous processes have been proposed to improve the substantivity of anionic dyes for cellulose by introducing cationic sites in the fiber. In this research work an attempt has been made to optimize the process condition to cationize the cotton with FIXANOL PN and MATEXIL FCER cationizing agent and to critically analyze the influence of process variables on cationizing efficiency.