Visible light driven mesoporous Ag/Ag2CrO4/g-C3N4 degrades multiple organic pollutants efficiently: synthesis, mechanism, and degradation pathway

With the development of economy, overuse of antibiotics has been seen as a huge threat to human health. Photocatalytic degradation is an effective method for resolving this problem at present. The method of combining plasmon resonance effect and Z-scheme heterojunction can effectively improve the separation efficiency of photogenerated carrier, which is of great significance for the treatment of antibiotic wastewater. Herein, the Ag/Ag2CrO4/g-C3N4 catalyst was prepared by in-situ loading and photo-reduction method for the degradation of antibiotic wastewater containing tetracycline and quinolone antibiotics. The research results showed that mesoporous graphitized carbon nitride (denoted as g-C3N4) provided good support for Ag and Ag2CrO4 nanoparticles, and mesoporous composite Ag/Ag2CrO4/g-C3N4 (denoted as ACO/CN) provided more reaction sites for organic pollutants degradation. Under visible light irradiation, 5%ACO/CN catalyst showed the best degradation activity and stability for tetracycline (TC), levofloxacin (LVFX), oxytetracycline hydrochloride (OTC) and norfloxacin (NFLX), and their degradation rate constants were respectively 5.66, 8.26, 11.72 and 15.97 times of Ag2CrO4 which indicated it had good potential application value in the treatment of wastewater containing various organic pollutants. This benefits from the plasmon resonance effect of silver effectively improves the utilization efficiency of visible light and the Z-scheme heterojunction between Ag2CrO4 and g-C3N4 promotes the rapid transmission of photogenerated carriers. Based on the experimental results, the possible TC degradation pathway and photocatalytic mechanism were proposed. This study provides a simple way for the successful design and preparation of plasmon resonance effect synergistic Z-scheme heterojunction with promising applications in the treatment of antibiotic wastewater.