Oxalate enhanced mechanism of hydroxyl-Fe-pillared bentonite during the degradation of Orange II by UV-Fenton process.

An enhanced method of hydroxyl-Fe-pillared bentonite (H-Fe-P-B) during the degradation of Orange II was studied to provide novel insight to interactions of degradation intermediates with heterogeneous catalyst in UV-Fenton system. Based on the degradation mechanism of Orange II, oxalate enhanced mechanism of H-Fe-P-B in heterogeneous UV-Fenton system was developed. The results showed that additional oxalate could increase the Fe leaching of H-Fe-P-B during heterogeneous UV-Fenton process, which led to higher mineralization efficiency of Orange II and lower energy consumption of treatment. When the concentrations of additional sodium oxalate increased up to 0.1 mmol L(-1), 0.2 mmol L(-1) and 0.4 mmol L(-1), the rate of Orange II degradation could increase 30%, 46% and 63%, respectively. The iron ions leached from catalyst could be adsorbed back to the catalyst again after the organic intermediates were mineralized completely. Then the catalyst of H-Fe-P-B could be reused and additional pollution caused by iron ions could be avoided.