Indirect electrochemical reduction of vat dye

This paper presented the findings of an investigation into the use of indirect electrochemical technique in the reduction of vat dye. The area studied included the feasibility of this technique, its environmental impact, the fastness and the colour yield of the dyed material. The results were compared with conventional method which required the addition of excess non-reusable chemicals. It was found that this new reduction method was feasible. The washing and rubbing fastness of the materials dyed by this new technique were comparable to that of the conventional method, but the colour yield was not satisfactory. The cost of dyeing between using the new technique and the conventional method was compared. The Chemical Oxygen Demand (COD) value of the dye liquor collected from the dyebath using the new reduction method was much higher than that of using the traditional method. Since the mediator of the new reduction method can be re-used for many times, the indirect electrochemical reduction technique is still more environmentally friendly than the traditional one. The possible reasons for the experimental results were also discussed.Institute of Textiles and ClothingRefereed conference pape