Extending the working pH of nitrobenzene degradation using ultrasonic/heterogeneous Fenton to the alkaline range via amino acid modification

Oxides of iron, alpha-Fe2O3 (I), and copper, CuO (II) prepared by usual precipitation method without surfactant were used at room temperature in the process of nitrobenzene (10 mg L-1) degradation at different pH values with ultrasonic at 20 kHz. The degradation was complete in 20 and 30 mm for (I) and (H), respectively in the pH range 2-7 using1.0 g L-1 of solids and 10 mM of H2O2. A remarkable decrease in degradation efficiency was recorded on increasing the pH to values higher than the neutral range. This loss in efficiency was cancelled to a great extent through modifying the used oxides with amino acids. Arginine showed higher improving effect to (II) (1:1 weight ration) than glycine or glutamic acid. Modification of both oxides with increasing amounts of arginine increased the degradation efficiency of (I) in a more regular way than in case of (II). However, the extent of improvement due to amino acid modification was higher in case of (II) because of its originally low degradation efficiency in strongly alkaline media. (C) 2014 Elsevier Ltd. All rights reserved.