Efficient degradation of atrazine with porous sulfurized Fe2O3 as catalyst for peroxymonosulfate activation

In this study, magnetic porous sulfurized Fe2O3 (PS-Fe2O3) composites were prepared through the co-precipitation method and were applied to activate peroxymonosulfate (PMS) for the degradation of emerging contaminants. Characterization results indicated that PS-Fe2O3 catalyst with uniform elemental distribution possessed a large number of micro- and meso- pores. When the molar ratio of FeSO4:S2O32− was 2:1 during the synthesis process, the PS-Fe2O3-2 exhibited the best performance on PMS activation for atrazine (ATZ) removal. The catalytic activity of PS-Fe2O3 catalysts was enhanced with increased sulfurization extent. The effects of catalyst dosage, PMS concentration, pH, and water impurities (i.e. Cl−, HCO3−, NO3− and humic acid) on ATZ degradation were investigated. Both sulfate radicals and hydroxyl radicals were detected in the PS-Fe2O3-2/PMS system, and sulfate radicals played the predominant role for the degradation of ATZ. The cycle of Fe(II)/Fe(III) and surface-bonded hydroxyl group both contributed to the PMS activation, and the reduction of Fe3+ to Fe2+ was significantly accelerated by the low-valent sulfur species (such as sulfite) on the catalyst surface. The transformation products of ATZ in PS-Fe2O3-2/PMS system were monitored on LC/MS, which were probably generated through lateral chain oxidation and dechlorination-hydroxylation. Overall, PS-Fe2O3 has potential to be a feasible catalyst for the removal of organic pollutants from water.