Practical realisation of ozone clearing after disperse dyeing of polyester

In this study, a novel system utilising ozone in jet dyeing machines is introduced, and the results of ozone‐clearing treatments of disperse dyed polyester on the prototype modified machine are reported. A Venturi injector was mounted on the liquor circulation pipe of the jet dyeing machine to feed ozone gas into the machine. Ozone was generated via an ozone generator by feeding conditioned air into the generator. The ozone gas entering the pipe partly dissolved in the treatment liquor; the dissolved portion and the gaseous ozone interacted via the fabric in the pipe, especially in the nozzle and also at the bottom of the autoclave (machine body). Disperse dyed polyester fabrics of textile‐company mass production were ozone cleared in this prototype. Ozone clearing was achieved in cold water (room temperature), and no other chemicals were used. The colour of the samples, wet fastness properties, and the chemical oxygen demand of the effluent were investigated, and costs were compared with those of conventional reduction clearing of ozone. Results were outstanding: an 83% cost reduction, 67% timesaving, and an 88% COD reduction were achieved.