Ultrasonic assisted-Fenton-like degradation of nitrobenzene at neutral pH using nanosized oxides of Fe and Cu

Ultrasonic-assisted heterogeneous Fenton reaction was used for degradation of nitrobenzene (NB) at neutral pH conditions. Nano-sized oxides of alpha-Fe2O3 and CuO were prepared, characterized and tested in degradation of NB (10 mg L-1) under sonication of 20 kHz at 25 degrees C. Complete degradation of NB was effected at pH 7 in presence of 10 mM H2O2 after 10 min of sonication in presence of alpha-Fe2O3 (1.0 g L-1), (k = 0.58 min(-1)) and after 25 min in case of CuO (k = 0.126 min(-1)). alpha-Fe2O3 showed also effective degradation under the conditions of 0.1 g L-1 oxide and 5.0 mM of H2O2, even though with a lower rate constant (0.346 min(-1)). Sonication plays a major role in enhancing the production of hydroxyl radicals in presence of solid oxides. Hydroxyl radicals-degradation pathway is suggested and adopted to explain the differences noted in rate constants recorded on using different oxides. (C) 2013 Elsevier B.V. All rights reserved.