Synthesis of CuS/NiS heterostructural photocatalyst and its performance in the degradation of metronidazole and diclofenac drugs: optimization of operating conditions

In this research, nanoparticles of copper sulfide (CuS), nickel sulfide (NiS), and CuS/NiS were synthesized and characterized by XRD, DRS, BET, EDS, FE–SEM, FT-IR, BET/BJH, and PZC. The photocatalytic efficiency of the synthesized nanoparticles on the degradation of diclofenac and metronidazole was measured and compared via UV–Vis spectroscopy. In addition, the effective parameters on the degradation process including pH, diclofenac and metronidazole concentrations (mg/L), CuS/NiS photocatalyst mass (g), and irradiation time (min) were investigated using the response surface methodology (RSM) with Box–Behnken design (BBD). Based on the results, diclofenac had a higher removal efficiency than metronidazole. Under optimal conditions with 0.2 g of CuS/NiS photocatalyst, with concentrations of 131.115 mg/L of diclofenac and 150 mg/L of metronidazole at pH 10 for 120 min, they had efficiencies of 68.45% and 23.31%, respectively.