Highly-efficient degradation of triclosan attributed to peroxymonosulfate activation by heterogeneous catalyst g-C3N4/MnFe2O4

Abstract

• g-C 3 N 4 /MnFe 2 O 4 was prepared via sol-gel method. • TCS was degraded effectively by g-C 3 N 4 /MnFe 2 O 4 (1:1) activation PMS. • Heavy metal leaching decreased after MnFe 2 O 4 combined with g-C 3 N 4 . • SO 4 · − , ·OH, ·O 2 − and 1 O 2 were contributed to the TCS degradation. • The main degradation pathway of TCS was preliminarily proposed. The g-C 3 N 4 /MnFe 2 O 4 as recyclable catalyst was synthesized via auto-combustion sol-gel method. Peroxymonosulfate (PMS) activation by the catalyst for triclosan (TCS) degradation was investigated considering the activation performance, reaction parameters and activation mechanism. The catalyst prepared with 1:1 of g-C 3 N 4 and MnFe 2 O 4 molar ratio performed the best catalytic activity in the TCS degradation and with lest metal leaching. The concentration of Cl − showed a dual effect on the TCS degradation, while HCO 3 − and SO 4 2− performed inhibitory effect. Sulfate radicals, hydroxyl radicals, superoxide and non-radical single oxygen contributed to the degradation of TCS. Compared with MnFe 2 O 4 /PMS system, few heavy metals were leached from g-C 3 N 4 /MnFe 2 O 4 (1:1)-PMS after each reuse ( Fig. S6 b), suggesting that g-C 3 N 4 was conducive to the stability of g-C 3 N 4 /MnFe 2 O 4 (1:1) catalyst. Dichlorination, hydroxylation, cyclization and other bond breaking reaction were inferred as the TCS degradation pathways. These results demonstrated that g-C 3 N 4 /MnFe 2 O 4 (1:1) was a highly effective and stable catalyst for PMS activation to treat toxic organic pollutants in water.