Preparation and Photocatalytic Degradation Performance of C@Cd_xMn_1-xS to Tetracycline Hydrochloride

Cd_xMn_1-xS solid solutions were synthesized by incorporating Mn²⁺ into CdS and the optimal ratio of Mn²⁺ to Cd²⁺ was explored via photocatalytic degradation performance for tetracycline (TC). Subsequently, the composite catalyst C@Cd_xMn_1-xS was prepared by loading Cd_xMn_1-xS onto the biomass gasification carbon residue (C) by hydrothermal method and characterized by various characterization tests. The optimal TC photodegradation condition and degradation mechanism catalyzed by C@Cd_xMn_1-xS was investigated. The results showed Cd_0.6Mn_0.4S had the optimal photocatalytic degradation efficiency, which is about 1.3 times that of CdS. The TC photodegradation efficiency by C@Cd_0.6Mn_0.4S prepared at the mass ratio of C to Cd_0.6Mn_0.4S of 1:2 was the best, which was 1.24 times that of Cd_0.6Mn_0.4S and 1.61 times that of CdS. Under the optimal conditions (visible light irradiation for 60 min, C@Cd_0.6Mn_0.4S of 20 mg, 40 mL TC solution of 40 mg/L), the TC degradation efficiency was 90.35%. The degradation efficiencies of 20 mg/L levofloxacin, ciprofloxacin, and 40 mg/L oxytetracycline catalyzed by C@Cd_0.6Mn_0.4S range from 89.88% to 98.69%. In the photocatalytic reaction system, •O₂^- and h⁺ are the dominant active species, which directly participate in the photocatalytic degradation reaction of TC, and •OH contributes little. The work provides a strategy to improve the photocatalytic performance of CdS for photocatalytic degradation antibiotics, and opens an interesting insight to deal with solid waste from biomass gasification.