The Study Of Biochar Used As An Adsorbent And Support For Photocatalyst To Remove Of Typical Antibiotics In Aqueous

Antibiotics can effectively inhibit the growth and reproduction of pathogenic bacteria,and they are widely used to treat and prevent diseases of human and animals.However,the abuse of antibiotics in recent years leads to these drug residues being frequently detected in surface water,groundwater and sediments.Additionally,many drug-resistant genes have been found throughout the world,which may threaten the safety of human health and ecosystem.In this paper,biochar was used as adsorbent and support for photocatalyst to study the adsorption and photocatalytic degradation of typical antibiotics in aqueous.In order to explore and prepare a new-type and environment-friendly material that could effectively remove antibiotics in aqueous,the conventional characterization methods and the influence of external environmental factors on the photocatalyst were studied.(1)Reed straw biochar(RSBC)and municipal sewage sludge biochar(SSBC)were prepared as adsorbents,and removal of norfloxacin(NOR),chloramphenicol(CAP)in water was studied.The experimental results showed that the adsorption kinetics of NOR,CAP on RSBC and SSBC followed the pseudo second order kinetic model,and adsorption isotherm was fitted well with the Sips model.The adsorption of the antibiotics on RSBC and SSBC were easier under acidic conditions.All adsorption processes were endothermic reaction.Due to its high specific surface area,RSBC had better ability to adsorb NOR,CAP than SSBC.(2)A biochar-supported Ti O2(TiO2/pBC)was prepared by sol-gel method..The photocatalytic activities of TiO2/pBC at different calcinations temperatures(300 °C,400 °C and 500 °C)were compared.The photocatalytic removal rate of sulfamethoxazole(SMX)on TiO2(TiO2/pBC)under ultraviolet light(UV)was 91.27% after 3 hours photocatalysis,which was 1.56 times as much as that on pure TiO2 powder.Under acidic conditions,the photocatalytic activity of TiO2/pBC was better than that under alkaline condition.TiO2/pBC was shown stable photocatalytic activity after five sequential photocatalytic degradation cycles and high photocatalytic removal efficiency for SMX.The valence band hole on the surface of photocatalyst generated hydroxyl radical(·OH)with H2 O,·OH could oxidate SMX and its intermediates.(3)Zn ion was doped in the reed straw biochar-supported TiO2(Zn-TiO2/pBC),it could effectively inhibit the agglomeration of TiO2,and impede the recombination of photo-generated electrons and valence band hole,which made Zn-TiO2/pBC had photocatalytic activity under visible light.The concentration of Zn influenced the removal efficiency of SMX on Zn-TiO2/pBC.The removal efficiency of SMX under visible light onto Zn-Ti O2/pBC was 81.21% after 3 hours photocatalysis,which was 1.37 times as much as that of TiO2/pBC under the same conditions.Besides,the COD removal rate of SMX on Zn-TiO2/pBC was 56.13%.In the Yellow River samples,the photocatalytic activity of Zn-TiO2/pBC was inhibited by SO42-,Cl-and NO3-.Zn-TiO2/pBC had stable photocatalytic activity,and could be reused in photocatalytic degradation processe of SMX.In the photocatalytic process,seven intermediates were identified and four parallel degradation pathways were proposed.