Abstract
Conventional dyeing process of cotton fabric with reactive dyes requires the use of large amount of electrolyte as exhausting agent. Thus the discharged wastewater from dye house creates unavoidable environmental threats due to very high salt concentration. This paper presents the possibility of salt free dyeing of cotton fabric with reactive dye by treating the fabric with chitosan. Exhaustion of dye by the fabrics was increased by treating them with chitosan prior to dyeing. It has been noticed that absorption of dye has significantly increased with the increment of chitosan concentration. The K/S value, i.e. dye absorption of chitosan treated fabrics was found as 1.6, 1.7, 2.2 and 2.9 respectively for 1%, 2%, 3% and 4% chitosan concentration whereas the K/S value of untreated fabric was 1.9. Fastness of the dyed samples had also been investigated through color fastness to washing, perspiration and rubbing. No fastness deterioration had been experienced for the dyed fabric treated with chitosan. However in case of chitosan treatment at high concentration, the wet rubbing fastness was found slightly inferior to untreated dyed samples which can be explained as the consequence of higher depth of shade due to high absorption of dyestuff by the fabric.
Highlights
The current paper investigated the dyeability and color performance of chitosan treated cotton fabric treated with chitosan dyed without salt and compared the results with the fabric dyed with salt
The above figure shows that the dye absorption, i.e the K/S value increases with the increasing of chitosan concentration in the fiber
The increased K/S value in the chitosan treated fabric indicates the presence of higher amount of the dye absorbed in the chitosan treated fabric
Summary
The polymer chain of cotton consists of several hundreds to more than thousand β (1 - 4) D-glucose units [1] linked to each other. It builds up negative charges on its surface when immersed in water, resulting an inverse effect on exhaustion of anionic dyes such as reactive dye. Reactive dye is the worldwide acceptable dye for the coloration of cotton goods due to their ease of applicability, cost, brilliancy of color and high wet fastness properties [2]. High wash fastness property of reactive dye with cellulose is due to the formation of covalent bond with fiber polymer [3]. The reactive system of this dye enables it to react with the hydroxyl groups in cellulose by nucleophilic addition or substitution reaction
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