Antibacterial And Degradation Properties Of Bi₄O₅I₂/AgI And CdIn₂S₄/W₁₈O₄₉photocatalysts

Recently,with the abuse of antibiotics,water pollution has become more serious,and more and more bacteria become resistant.Therefore,it is urgent to develop new wastewater treatment technology that can degrade organic pollutants as well inactivate pathogenic microorganisms.As a green and environmental friendly technology,semiconductor photocatalysis provides new ideas for modern wastewater treatment.In this paper,the somposite photocatalysts based on Bi₄O₅I₂ and CdIn₂S₄ materials were synthesized.The crystal,morphology,element composition and optical properties of prepared catalysts were analyzed via a variety of characterization methods.The photocatalytic activity of the prepared catalysts was evaluated through antibacterial experiments and degradation experiments.Finally,combine the characterization results with free radical quenching experiments to further explore the photocatalytic reaction mechanism.The main contents and results are as follows:1.A series of visible light driven（VLD）Bi₄O₅I₂/AgI composite photocatalysts with different AgI contents were synthesized.The effects of different AgI loadings on photocatalytic performance were explored by Escherichia coli（E.coli）inactivation and tetracycline（TC）degradation experiments under visible light irradiation.The results showed,compared with the original AgI and Bi₄O₅I₂,BOA-3 with optimal AgI contents exhibited the best photocatalytic activity in E.coli inactivation and TC degradation experiments,which was able to degrade 82%of TC and inactivate 3x10⁷ CFU/m L of E.coli within 30 min.Electrochemical tests showed that the enhanced separation efficiency of electrons and holes is the main reason for the improved photocatalytic activity.Ag⁺releasing experiments of catalysts,free radical trapping experiments reveal that h⁺and·O₂^-are the main active speciecs in photocatalytic process.Besides,the stability of catalysts was also investigated.Finally,combined with the energy band structure,the photocatalytic mechanism of Bi₄O₅I₂/AgI nanomaterials was discussed in detail.2.A full-spectrum light driven CdIn₂S₄/W₁₈O₄₉ photocatalyst with a dual-channel charge carrier transfer path was synthesized by alcohol thermal method.The morphology structure,element composition and optical properties of synthesized materials were systematically characterized.The photocatalytic performance of E.coli inactivation and TC degradation was investigated under full-spectrum light and near-infrared light irradiation,respectively.The experimental results showed that CdIn₂S₄/W₁₈O₄₉ composite exhibits higher photocatalytic activity than that of CdIn₂S₄ and W₁₈O₄₉.The enhanced photocatalytic performance can be attributed to the synergistic effect of the Z-scheme heterojunction and the LSPR effect,which significantly improves the interface charge transfer efficiency and light absorption capacity.Besides,the LSPR effect can effectively activate molecular oxygen to generate reactive oxygen species（ROS）to achieve E.coli inactivation and TC degradation.Nitrogen blue tetrazole（NBT）and terephthalic acid（TA）conversion experiments further confirmed the enhanced molecular oxygen activation capability.Finally,based on density functional theory（DFT）calculations,band theory and experimental results,a possible photocatalytic reaction mechanism was proposed.