Catalytic ozonation of dye industry effluent using mesoporous bimetallic Ru-Cu/SBA-15 catalyst

Abstract

Abstract Catalytic ozonation was employed for the degradation of aqueous solution containing reactive orange 4 (RO4) azo dye and textile dye industry effluent using mesoporous bimetallic Ru-Cu/SBA-15 catalyst. The catalyst was synthesized and characterized using BET, SEM, TEM and EDX techniques. The effect of operational parameters like initial solution pH and ozone dose on the degradation of RO4 azo dye was studied. The degradation pathway of the dye solution was investigated using radical scavenger t-butanol. The optimum values of initial solution pH and ozone dose were found to be 9 and 5 g/m3 respectively. A colour removal efficiency of 100% and COD removal efficiency of 70.4% of RO4 dye aqueous solution were obtained at the optimum conditions after 21 min and 60 min of catalytic ozonation respectively. The colour and COD removal pathways were governed by direct ozone molecular and hydroxyl radical mechanism respectively. The bicarbonate ions present in the textile dye industry effluent were found to act as radical scavengers, thereby, lowering the COD removal efficiency significantly. The removal of bicarbonate ions from the effluent prior to its ozonation enhanced the COD removal efficiency from 30.2% to 90% after 4 h of catalytic ozonation.