The study on the reduction process of Vat dye on cotton fabric using ferrous sulphate and its effect on effluent load

In textile chemical processing industries vat dye is one of the important dyes for coloration of cotton, when high fastness properties are required. But, vat dye has the problem of insolubility in water .Hence, the process of vatting is needed to reduce and solubilize the dye in water. Vat dye is normally dissolved in water using sodium hydrosulphite (hydrose) as reducing agent and sodium hydroxide as solubilising agent suitable for dyeing. In this work, an attempt is made to reduce the vat dye using ferrous sulphate (2% owm) and its combination with hydrose as ferrous sulphate (1.5% owm) +hydrose (0.5% owm) and ferrous sulphate (1%owm) + hydrose (1%owm).The effect of ferrous sulphate as reducing agent and its combination with hydrose is compared with the conventional reducing agent (hydrose).The effluent load is analysed for all samples and can be compared among themselves. The other test parameters like the strength of the fabric, rubbing fastness, washing fastness, and light fastness, were also studied and compared.