Study on the application of environmentally suitable reduction and solubilisation process for vat dyeing of cotton fabric

Abstract

Cotton is one of the widely used textile fiber substrates in the world, particularly in India, due to its comfort, aesthetic value, strength, affinity towards various chemicals and dyestuffs, and customer - friendly endues products. Cotton is dyed by various dyestuffs including natural dyes, the prominent among which are direct dye, reactive dye, sulphur dye, pigment dye and vat dye. Vat dye is insoluble in water; hence, powerful reducing agent like sodium hydrosulphite in the presence of strong alkali is required for its solubilisation. Therefore, the aim of this research work is to reduce the problem of vat dyeing due to the commercial reducing agent and to revive the use of vat dyes for cotton dyeing within the effluent parameters set for industries. With respect to solving this problem, the methodology was fixed after many literature surveys and dyeing trials in the laboratory and in an industry using various techniques and reducing agents. Against this background, a vat dye (Jade green XBN) was selected in this research work, for dyeing on cotton fabric. For the reduction of vat dye, reducing agents such as hydrose, zinc and ferrous sulphate and their combinations in different proportions were selected. Different reducing agents for vat dyeing on cotton fabric were applied. Then effect of reducing agents on vat dyeing of cotton fabric was studied. Using different reducing agents Vat dyed cotton fabric was analysed for fabric strength, fastness properties, colour strength, SEM study and FTIR study. This dyeing effect on vat dyed cotton fabric was also confirmed by FTIR analysis, as given for original vat dye and for the vat dyed cotton fabric using different reducing agents especially FeSO41.0% owm + Hydrose 1.0% owm. In general the results are convincing for the textile material, as there is no considerable change in the tensile strength of the cotton fabric after vat dyeing using various reducing agents, and the fastness properties are also very good relevant to the textile materials. newline