Copper sulfide as an excellent co-catalyst with K₂S₂O₈ for dye decomposition in advanced oxidation process

Copper sulfide (CuS) nanoparticles were prepared at 140 degrees C by a simple hydrothermal method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Brunauer, Emmett, Teller (BET) specific surface area method. Orange II (60 mg/L) was used as the target pollutant to investigate the degradation performance of CuS and K2S2O8 under visible light irradiation. The degradation efficiency reached 98.88% in CuS/K2S2O8/visible light system within 120 min, which showed very strong activity. Moreover, the catalyst also showed good stability and recycling performance for degrading Orange II. After three consecutive degradation cycles, the degradation efficiency of Orange II was found to be not less than 98%. The dye degradation mechanism was proposed as follows: Cu2+/Cu+ cycling catalyzed K2S2O8 to produce free radicals (SO4 center dot-), which significantly improved the oxidation ability of CuS/K2S2O8/visible light system.