Highly conductive Ti3C2 MXene reinforced g-C3N4 heterojunction photocatalytic for the degradation of ciprofloxacin: Mechanism insight

The extensive use of ciprofloxacin (CIP) poses a great threat to aquatic ecosystem, due to its potentially serious inhibitory effect on the microbial activity and low natural degradation rate. Photocatalytic degradation has emerged as a feasible method for treating CIP pollution. In this study, Ti3C2 reinforced g-C3N4 heterojunction material (MX/CN) was prepared using solvent drying method. The heterojunction composite accelerated the electron transfer rate, and the resulting MX/CN exhibited superior photocatalytic activity against CIP under visible light driving. The MX/CN sample achieved higher CIP photocatalytic removal rate of 97.8 %, 1.23 times higher than CN. Moreover, 6 %-MX/CN showed the best photocatalytic activity at pH = 7 when the initial concentration of CIP was 10 mg/L. Under neutral condition, the presence of Cl−, NO3−, and HCO3− reduced the degradation of CIP, where the addition of HCO3– caused a competed redox reaction with •OH in the system, resulting in a reduction of the CIP degradation efficiency to 30.9 %. The photocatalytic mechanism involving MX/CN was proposed according to the trapping experiments of active species, which confirmed that •O2− was the primary active component in photocatalytic degradation of CIP and h+ and •OH also played significant roles. Finally, cycling experiments using MX/CN showed that the CIP degradation efficiency maintained more than 90 % after five cycles.