Degradation of p-nitrophenol using CuO/Al2O3 as a Fenton-like catalyst under microwave irradiation

Abstract

CuO/Al₂O₃ was synthesized successfully by the impregnation-deposition method and used as a heterogeneous catalyst in a microwave assisted Fenton-like process (MW/FL). The morphology and physico-chemical properties of the CuO/Al₂O₃ catalyst were characterized using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and Brunauer–Emmett–Teller (BET) analysis. The degradation of p-nitrophenol (PNP) was investigated by different processes, including microwave irradiation (MW) alone, hydrogen peroxide (H₂O₂) oxidation under microwave irradiation without the catalyst (MW/H₂O₂), a Fenton-like (FL) process, a MW/FL process and a thermally-assisted Fenton-like (TH/FL) process. The results showed that the CuO/Al₂O₃ catalyzed MW/FL could generate more hydroxyl radicals (˙OH) and remove PNP more effectively compared to other processes. The effects of initial pH, dosage of H₂O₂ and catalyst, microwave power and radiation time, and PNP concentration on the removal efficiency were also studied. The results showed that 93% removal efficiency of PNP was obtained within 6 min under optimized conditions. Moreover, the catalyst had a good stability and reusability, thus expanding the scope of non-iron based catalysts in the Fenton-like reactions.