Catalytic Oxidation of Dyeing Wastewater by Copper Oxide Activating Persulfate: Performance, Mechanism and Application

The effective treatment of dyeing wastewater has been considered as one of the challenges. The sulfate radical (SO4•−)-based technology exhibited great potential in the field of organic wastewater treatment. In this study, copper oxide was synthesized and used to activate persulfate (PS) for removing methylene blue (MB) from aqueous solution. The effects of reaction parameters and coexisting substances on this process were studied. Under the optimal conditions ([CuO] = 0.2 g/L, [PS] = 2 g/L, pH = 7.0–9.0), more than 90% of MB was degraded. Cl− had little effect on MB removal, while SO42− and HCO3− showed inhibitory effect. The activation energy of the reaction was 137.8 kJ/mol at 25 ℃ with an initial MB concentration of 10 mg/L. The mechanisms of PS activated by CuO was elucidated by radical scavenger and electron spin resonance trapping studies. The results found that sulfate radical (SO4·−) and singlet oxygen (1O2) were the primary reactive oxygen species in the CuO/PS system. The recycling experiments showed that MB removal efficiency remained more than 70% after five cycles, which exhibited good stability and high efficiency of the catalyst. The favorable degradation performance of simulated textile wastewater indicated the potential application of CuO/PS for dyeing wastewater treatment.