Recycling of exhausted reactive dyebaths

Abstract

The recycling of exhausted dyebaths offers the potential of reduced dyeing costs by lowering the consumption of water, chemicals and energy as well as by reducing waste treatment costs. If the residual dye in the exhausted dyebath is to be reused by reconstitution of the dyebath with fresh dye, the dyeing behaviour of the residual dye should, ideally, be identical to that of the fresh dye. In the case of the reactive dyeing of cotton, the exhausted dyebath was found to contain both hydrolysed and reactive dye; the dyeing behaviour of the residual dye in the exhausted reactive differed from that of the fresh reactive dye.