Preparation Of ZnO/Biochar Composite Photocatalytic Materials And Study On Degradation Of Antibiotic Wastewater

At present,the pollution of pharmaceutical wastewater caused by antibiotics poses a threat to human health and the ecological environment of earth.Photocatalytic oxidation technology is considered as a promising antibiotic degradation strategy.Zinc oxide is nontoxic and has strong redox ability and controllable morphology,which is widely used in the field of photocatalysis.However,the specific surface area of ZnO is small and the carrier transport capacity is poor,resulting in low photocatalytic activity.In order to solve the above problems,this study attempts to use biochar materials and graphene oxide materials combined with zinc oxide to improve the photocatalytic performance.Firstly,three different biochar materials were prepared from pomelo peel.The material structure was characterized,and the results showed that the prepared three biochars were amorphous carbon structure.The biochar obtained by carbonization at 800°C has more oxygen-containing functional groups,more atomic lattice defects,and better surface micropore structure.Its specific surface area reaches 321.17 m²g^-1,and the micropore volume reaches 0.110 cm³g^-1.Secondly,ZnO and three kinds of ZB composites with different structures were prepared by hydrothermal method.The structure of the material was characterized,and the light response ability and photocatalytic degradation of tetracycline were tested.The results showed that ZnO was well combined with biochar.The optical response range of ZB composite is wider than that of ZnO material,and the band gap energy is 2.89 e V.TCH removal rate of ZB composite reached 91.04%after 135 min;the optimal reaction conditions were as follows:material dosage 0.3 g/L,initial concentration 20 mg/L,and initial p H=9.After five cycles,the removal rate of TCH was 77.84%;ZB composites mainly rely on photogenerated holes（h⁺）to degrade TCH.Thirdly,four ZBG composites with different structures were prepared by hydrothermal method.The material structure was characterized and its light response ability and photocatalytic degradation effect of tetracycline were tested.The results showed that the ZBG material was successfully composited and the structure was good;the number of active sites of ZBG increases,and it has better electron conductivity and optical response,and the band gap energy is 2.73 e V lower than that of ZB.TCH removal rate of ZBG composite reached99.24%after 90 min;the optimal reaction conditions for photocatalytic removal of TCH by ZBG material were as follows:material dosage 0.3 g/L,initial concentration of solution 10mg/L,and initial p H=7.After five cycles,the removal rate of TCH was still 88.46%;ZBG composites mainly rely on·OH to degrade TCH.Finally,the photocatalytic Fenton-like system was constructed using ZB₁₀G₁₀material and PDS,and its catalytic degradation ability of TCH was tested.The results showed that the removal rate of tetracycline in the photocatalytic Fenton-like system was 99.25%in 40 min.The optimal reaction conditions of TCH removal by photocatalytic Fenton-like system were as follows:material dosage 0.4 g/L,PDS dosage 0.04 g/L,initial solution concentration 10mg/L,initial solution p H=5.After five cycles,the removal rate of TCH was still90.09%;·OH is the main active substance for TCH degradation in photocatalytic Fenton-like system.