Efficient degradation of atrazine by magnetic porous copper ferrite catalyzed peroxymonosulfate oxidation via the formation of hydroxyl and sulfate radicals

摘要

Magnetic porous copper ferrite (CuFe_2O_4) showed a notable catalytic activity to peroxymonosulfate (PMS). More than 98% of atrazine was degraded within 15 min at 1 mM PMS and 0.1 g/L CuFe_2O_4. In contrast, CuFe_2O_4 exhibited no obvious catalytic activity to per-oxodisulfate or H_2O_2. Several factors affecting the catalytic performance of PMS/CuFe_2O_4 were investigated. Results showed that the catalytic degradation efficiency of atrazine increased with PMS and CuFe_2O_4 doses, but decreased with the increase of natural organic matters concentration. The catalytic oxidation also showed a dependence on initial pH. The presence of bicarbonate stimulated atrazine degradation by PMS/CuFe_2O_4 at low concentrations but inhibited the degradation at high concentrations. Furthermore, the reactive species for atrazine degradation in PMS/CuFe_2O_4 system were identified as hydroxyl radical (HO) and sulfate radical (SO_4~-) through competition reactions of atrazine and nitrobenzene, instead of commonly used alcohol scavenging, which was not a reliable method in metal oxide catalyzed oxidation. Surface hydroxyl groups of CuFe_2O_4 were a critical part in radical generation and the copper on CuFe_2O_4 surface was an active site to catalyze PMS. The catalytic degradation of atrazine by PMS/CuFe_2O_4 was also effective under the background of actual waters.