Degradation of tetracycline using persulfate activated by Mn, Ce co-doped g-C3N4 composites under visible light

The construction of efficient composite photocatalysts is significant for degrading antibiotic contaminants. Herein, a novel MnCe bimetallic-modified g-C3N4-based photocatalyst was synthesized using an impregnation calcination method and applied in persulfate (PS) activation under visible light (ViS). Characterization indicated that the doping of Mn and Ce bimetals promoted electron transfer and separation on the g-C3N4 surface. It broadened the visible light absorption range. Owing to the synergistic effect of visible light and PS, 1 wt% Mn-Ce/g-C3N4 had the highest removal rate of tetracycline (TC), reaching 89.1 % within 120 min of the reaction, and its kinetic constant was 3.2 times that of pure g-C3N4. Through quenching experiments, superoxide radicals (O2·−) and sulfate radicals (SO4·−) were found to be dominant in activating PS to accelerate the degradation of TC by reactive radicals. Moreover, the TC removal rate remained at 81.1 % after five cycles of degradation, indicating the satisfactory stability and reusability of the synthesized composite catalyst. Therefore, Mn-Ce/g-C3N4/PS/ViS system will be an effective option for antibiotic-containing wastewater treatment.