Eco-friendly indigo reduction using bokbunja (Rubus coreanus Miq.) sludge

Abstract

The utilization of Bokbunja (Rubus coreanus) sludge as a source of reductant was investigated to develop an eco-friendly indigo dyeing process. Total sugar contents were 18.94 and 50.87% for ethanol and water extracts, respectively. The extract was effective to reduce indigo dye. Reduction of indigo was occured rapidly in the solution containing the extract and indigo dye in alkaline condition and it reached to the maximum color yield in one or two day. The reduction potential of the extract was stabilized between -550 mV and -600 mV depending on concentration of the extract. At higher concentration of the extract, reduction power was maintained stably for longer time and stronger color yield. It was confirmed that the Bokbunja sludge extract can be an eco-friendly and safe alternative to sodium dithionite as a reducing agent in indigo dyeing processes.