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 FePO 4 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 FePO 4 . The resultant catalysts possessed large surface area to provide substantial active sites for the activation of PMS. The Co-doped FePO 4 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 Co 3 O 4 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 FePO 4 and the fast electron transfer of Co 2+ /Co 3+ 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 SO 4 − was primarily responsible for the degradation of atrazine.