The Study Of Distribution Characteristics Of Sulfonamides In Water By H₃PW₁₂O₄₀-TiO₂ Composite Catalyst

Along with the development of industry and constant improvement of the human living quality,more and more persistent organic pollution into water body,this kind of material in the water environment has many characteristics,such as persistence,degradation-resistant,high toxicity,they cause serious harm to human health and the environment by accumulation through the food chain.Antibiotic is a typically refractory and persistent organic pollutant,which is continuously detected in water environment.At present,advanced oxidation technology is an effective technology to degrade persistent organic pollutants in water and has been widely studied in the field of antibiotic drug degradation.In this paper,a modified efficient composite photocatalyst H₃PW₁₂O₄₀/TiO₂(PW₁₂/TiO₂ for short)was prepared,at the same time,two sulfonamide antibiotics-sulfamethoxydiazine and sulfadiazine-which are existing widely in the water environment were chosen as the research object of study,used the photocatalytic oxidation technology to study the degradation of sulfonamide antibiotics,analyzed the impact factors and mechanism of action of this catalyst during the degradation process of sulfonamide antibiotics,discussed the mechanism of degradation process,and provided the theoretical basis and technical reference for a broader range of applications of the catalyst in the POPs efficient control in water environment.The following conclusion were drawn in this study:1.During the preparation of composite catalyst,mass ratio of PW₁₂ to TiO₂ is 0.35,calcination temperature is 500 ℃,roasting time is 2 h,synthetic composite catalyst is typical anatase type TiO₂,average pore size is 4.737 nm,specific surface area is 104.875 m2/g,and it has good conductivity and stability with good photocatalytic activity under a 125 W high pressure mercury lamp,to degrade effectively the sulfonamide antibiotics.2.Degradation characteristics study of SMM and SM2 was conducted by using the photocatalytic system,the optical degradation conditions are:dosing quantity of catalyst is 1.0 g/L,pH is neutral,initial concentration is less than 10 mg/L,the reaction time is 1 h,all degradation rate of sulfonamide antibiotics are more than 99%under these conditions,and the degradation process is consistent with first order kinetics equation.3.The common ion pair in water body have an influence on the degradation of SMM and SM2,of which the existence of SO42-and NO3-had no obvious effect on the system,the inhibition will appear when the contents of HCO3-、Cl-、Fe3+、Cu2+ and Mn2+ is beyond a certain range,humus had obvious inhibitory effect.4.During the photocatalytic degradation of sulfonamide antibiotics,hydroxyl radicals（·OH）and superoxide radicals（·O₂-）are active substances,and ·O₂-is in a dominant position.When the photocatalytic reaction takes more than 3h,the removal rate of TOC in the target degradation solution increased significantly,and the toxicity to algae and escherichia coli was greatly reduced.