AIC-NIFTTEA Incubation Centre for Textiles and Apparels will join hands with ICAR-Central Institute for Research on Cotton Technology (CIRCOT) to promote ‘Salt-free dyeing technology’, which would not use salts for setting dyes on fabric or yarn resulting in reduced virility of effluents. The eco-friendly method, already successfully tested in woven fabric, was developed by the Mumbai-based CIRCOT, and the institute wanted to take it to the knitwear industry now.
Since cotton gets negatively charged once soaked in water, negative-charged reactive dye would not get transferred on it. To convert cotton into positive charge, common salts are utilised. But in the technology developed by CIRCOT, cotton would be pre-processed to positive charge by cationisation. So fabric or yarn can absorb dye without using salt as catalyst.
For one kg fabric or yarn, 0.5 to 0.6 kg salt is used in the current technology. It would result in formation of effluents which would even carry TDS up to 80,000ppm, and after the treatment of effluents, it will be reduced to 16,000 ppm.
With the salt-free technology, TDS of the effluents would be reduced to 1,600ppm from 16,000ppm, below the CPCB permissible level — 2,100ppm. This technology will save cost of the dyeing process as the units have no need to buy salts or spend more in the effluent treatment process.