Photocatalytic persulfate activation by silica microsphere-supported g-C3N4 for efficient carbamazepine degradation

A silica-loaded g-C 3 N 4 composite photocatalyst (M-SiO 2 /g-C 3 N 4 ) was prepared by grinding amorphous SiO 2 microspheres (M − SiO 2 ) with melamine and calcining the resulting grinding products. This composite was used for photocatalytic persulfate (PMS) activation to degrade carbamazepine (CBZ). The results showed that the degradation efficiencies of CBZ by M-SiO 2 /g-C 3 N 4 -2.5 (39.16 % of g-C 3 N 4 )-activated PMS were 78.92 % and 100 % after simulated sunlight irradiation for 60 and 120 min, respectively. These values were significantly greater than those of the system with pure g-C 3 N 4 (29.15 % and 42.4 %). In particular, the degradation efficiency of CBZ with M-SiO 2 /g-C 3 N 4 -2.5 decreased by only 9.47 % after 4 cycles of recycling. In the catalytic process, h + , SO 4 •− and O 2 •− were the main reactive species contributing to CBZ degradation. Compared with g-C 3 N 4 , loading g-C 3 N 4 on the surface of M − SiO 2 resulted in a decrease in g-C 3 N 4 lamellar stacking, which increased the number of active surface sites and improved the separation and migration of photogenerated carriers, improving the degradation performance.