Study On Fe₃O₄/SiO₂/TiO₂ Composite Catalyst For Enhanced Degradation Of SMX By UV-H₂O₂ System

Sulfonamide antibiotics are a class of antibiotics that are easy to detect and have high concentrations in the water environment,and sulfamethoxazole（SMX）is the most used antibiotic among sulfonamides.SMX is extremely biologically active,and as long as it exists in the body,it will cause a series of abnormal reactions,even in trace concentrations,it will have adverse effects on organisms.UV-H₂O₂system is widely used in the removal of refractory substances in water due to its strong oxidizing ability.In this study,a composite catalyst with a"core-shell"structure was selected based on the shortcomings of titanium dioxide（TiO₂）,such as good photocatalytic activity but uneven dispersion,easy agglomeration,and difficulty in recycling,to enhance the removal effect of UV-H₂O₂ system on SMX,and By investigating the influencing factors and exploring the reaction mechanism,it provides theoretical reference and practical basis for the treatment of antibiotic wastewater.The main research contents are as follows:1.To explore the removal effect of UV-H₂O₂ system on SMX through influencing factors.The study found that the optimal removal rate of 20mg/L SMX by UV-H₂O₂ system at p H=5reached 67.51%,while the removal rate of SMX at p H=7 was only 47.93%.From the perspective of practical application,the degradation process of SMX in the UV-H₂O₂ system at p H=7 was strengthened by composite catalysts,and it was found that all three catalysts had strengthening effects,among which Fe₃O₄/Si O₂/Ti O₂ had a strengthening effect on the UV-H₂O₂ system.Optimum,the removal rate of SMX can reach 80.12%.2.Under the Fe₃O₄/SiO₂/TiO₂ enhanced UV-H₂O₂ system,the influencing factors of SMX initial concentration,H₂O₂ concentration,catalyst dosage and other factors were explored and kinetically analyzed.It is found that the system conforms to the first-order reaction kinetics.Through the experiment of influencing factors,it was found that the adsorption effect of the catalyst on SMX was small.With the increase of the initial concentration of SMX,the removal rate decreased;with the increase of H₂O₂ concentration and catalyst dosage,the removal first increased and then decreased,and the best catalyst was obtained.The dosage is 0.30g/L,and the optimum concentration of H₂O₂ is 20mmol/L;after the catalyst is recovered several times,the iron ion leaching of the system is low,the catalyst still has strong stability,and the system maintains a high removal rate.3.Use active species and synergistic effect to analyze the reaction mechanism of the system,and analyze the possible degradation pathways.It was found that in the UV-H₂O₂-Fe₃O₄/Si O₂/Ti O₂ system·OH played the main oxidation role,and·O₂^-and h⁺played the auxiliary role.Further exploring the effect of·OH,it was found that in this system,the removal rate of SMX was negatively correlated with the concentration of tert-butanol,and·OH had a great influence on the removal rate of the system.Through the synergy calculation,it is proved that there is a synergistic effect in the system,which further proves the feasibility of the system.