Reduction of E-factor in Production of Vinyl Sulphone

Abstract

Dyes can be defined as soluble colored substances which can be applied mainly to textile materials from solution in water. Whereas pigments are insoluble compounds integrated by a dispersion process into products such as paints, printing inks and plastics. Dyes are soluble substances used to pass color to the substrate and find applications primarily in textiles and leather. The raw material may be natural or synthetic using products of the chemical industry. Green chemistry eliminates waste at source, i.e. it is primary pollution prevention rather than waste remediation (end-of-pipe solutions). Useful measures of the potential environmental acceptability of chemical processes are the E factor, defined as the mass ratio of waste to desired product. E Factor concept has played a major role in focusing the attention of the chemical industry world-wide. The concept of pollution prevention and reduction in E-factor have been proven to reduce costs, improve efficiency, reduce risk and reduce liability in vinyl sulphone industry. Vinyl sulphone production includes mainly 4 unit processes which are Chlorosulphonation, Reduction, Condensation, and Esterification. Vinyl sulphone is the highest export dye intermediate. Vinyl sulphone industry in India received a set back in the late nineties due to world competition and insistence on environmental regulations by the controlling authorities. Excess of chlorosulphonic acid is used in chlorosulphonation, Which is hazardous and it is used in excess as large quantity of chlorosulphonic acid is reacted with water as a liquid effluent generated is toxic having high BOD, COD & TDS, which is difficult to biodegrade, and solid waste generated is hazardous. This thesis describes to minimize the quantity of chlorosulphonic acid. The production of vinyl sulphone based dyes in India grew rapidly as the demand increased in indigenous as well as world market. In the manufacturing process of vinyl sulphone cholorosulphonic acid is obtained as a waste that is identified. To overcome this problem ethylene dichloride is used as solvent which act as medium instead of chlorosulphonic acid and in the second step of chlorosulphonation thionyl chloride is used .As a result qualntity of chlorosulphonic acid is reduced, yield of the company increased upto 95.6% using Ethylene dichloride and Thionyl chloride and E-factor is also reduced