Durable activation of peroxymonosulfate mediated by Co-doped mesoporous FePO4 via charge redistribution for atrazine degradation

Cobalt-mediated activation of peroxymonosulfate (PMS) is an attractive option for degradation of organic pollutants in water. How to develop durable Co-based catalysts (i.e., low Co leaching) of high activity is still a challenging task. In this study, Co-doped mesoporous FePO4 was synthesized via a facile sol-gel method followed by calcination. Multiple characterizations indicated that the Co species were uniformly distributed within the crystal structure of FePO4. The resultant catalysts possessed large surface area to provide substantial active sites for the activation of PMS. The Co-doped FePO4 with an optimized Co/Fe molar ratio of 0.1 (CoFeP-0.1) was highly effective and robust for degradation of atrazine at pH = 7 in PMS system with trivial Co leaching (52 μg/L or lower). The pseudo first-order kinetic constant of atrazine degradation was 0.225 min−1, about 2.7 times and 23 times higher than that of Co3O4 and CoFe-0.1, respectively. Both experimental study and density functional theory (DFT) calculation suggested that the excellent catalytic performance of CoFeP-0.1 was ascribed to the well dispersion of Co species in the mesoporous FePO4 and the fast electron transfer of Co2+/Co3+ redox via the charge redistribution between Fe atom and Co atom. A reasonable mechanism of CoFeP-0.1/PMS system-based catalysis was proposed where SO4− was primarily responsible for the degradation of atrazine.