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

Magnetic porous copper ferrite (CuFe₂O₄) showed a notable catalytic activity to peroxymonosulfate (PMS). More than 98% of atrazine was degraded within 15min at 1mM PMS and 0.1g/L CuFe₂O₄. In contrast, CuFe₂O₄ exhibited no obvious catalytic activity to peroxodisulfate or H₂O₂. Several factors affecting the catalytic performance of PMS/CuFe₂O₄ were investigated. Results showed that the catalytic degradation efficiency of atrazine increased with PMS and CuFe₂O₄ 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/CuFe₂O₄ at low concentrations but inhibited the degradation at high concentrations. Furthermore, the reactive species for atrazine degradation in PMS/CuFe₂O₄ system were identified as hydroxyl radical (HO) and sulfate radical (SO4·-) 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 CuFe₂O₄ were a critical part in radical generation and the copper on CuFe₂O₄ surface was an active site to catalyze PMS. The catalytic degradation of atrazine by PMS/CuFe₂O₄ was also effective under the background of actual waters.