Degradation of Acid Orange II at neutral pH using Fe 2(MoO 4) 3 as a heterogeneous Fenton-like catalyst

Abstract

Iron molybdate, Fe 2(MoO 4) 3, has been successfully prepared by a simple wet chemical process. Degradation of Acid Orange II (AOII) was studied in detail using Fe 2(MoO 4) 3 as a heterogeneous Fenton-like catalyst. The results show that this new catalyst is highly effective for the degradation of AOII at neutral pH. For 100 mg l −1 of the initial concentration with an initial pH of 6.7, the degradation efficiency of AOII reaches 94.1% within 60 min. Moreover, the catalytic activity is slightly affected by the solution pH in a wide range of 3.0–9.0. This indicates that the use of Fe 2(MoO 4) 3 overcomes the low efficiency of Fenton-like reaction at neutral and even alkaline pH. Fe 2(MoO 4) 3 exhibits low iron leaching, good structural stability and no loss of performance after five recycle times. A mechanism proposed herein suggests that the high catalytic activity can be attributed to the formation of an acidic microenvironment near the surface of the solid acid Fe 2(MoO 4) 3 particles where catalysis occurs, as well as the synergistic effect of Fe 3+ and MoO 4 2−.