CrPO4 as a recycled material supported Co3O4 as an efficient peroxymonosulfate catalyst for phenacetin elimination from aqueous solution

In this study, CrPO 4 -supported Co 3 O 4 (CrPO 4 @Co 3 O 4 ) as an efficient peroxymonosulfate (PMS) catalyst was obtained for the first time and used to eliminate phenacetin (PNT) from aqueous solution efficiently. CrPO 4 @Co 3 O 4 composite exhibited a superb catalytic performance, and over 98% PNT was degraded by PMS (0.5 mM) within 15 min, which is much more efficient than in the systems of CrPO 4 /PMS and Co 3 O 4 /PMS. The excellent catalytic performance of CrPO 4 @Co 3 O 4 was attributed to its higher BET surface area. On the other hand, the presence of PO 4 3- in the catalyst might improve the conversion of Co(III) to Co(II). The latter served as the main active site for the PMS activation. CrPO 4 @Co 3 O 4 also possessed superior stability and reusability, and the removal rates of PNT remained over 91% through 4 cycle tests. Solution pH significantly impacted the PNT decomposition, and the optimal catalytic degradation of PNT was achieved in an initial range of 5 to 7. Humic acid, HCO 3 − , and Cl − inhibited PNT degradation. Radical scavenging experiments and EPR technology revealed that SO 4 •− free radicals were the main reactive oxygen species (ROS) responsible for PNT degradation. While O 2 •− mainly acted as the intermediate to form SO 4 •− and 1 O 2 . To assess the practical application of the CrPO 4 @Co 3 O 4 /PMS system, the PNT degradation was investigated in real lake water. Based on HPLC-TOF-MS 2 analysis, 14 intermediates were identified, and the degradation pathways were further inferred. Therefore, this study provides a feasible strategy for the valuable use of CrPO 4 as recycled material and a practical solution for the efficient degradation of organic contaminants.