Preparation Of ZIFs Materials And Its Efficiency Research For Catalytic Ozonation

The advanced oxidation technology can effectively remove pollutants from water,among which the exploration of catalyst is the core.ZIFs materials and their derivatives have catalytic advantages in many aspects.It is of great significance to study their catalytic performance in water treatment for ozone removal of refractory pollutants.In this study,ZIF-8,ZIF-9,ZIF-67 and their respective derived materials calcined at 800℃were prepared to screen the effect of catalytic ozone degradation of SMX in the early stage.The screened ZIF-67-C materials were prepared with other three different molar ratios.The four materials were characterized by XRD,SEM,FTIR,BET,XPS,Raman and TG-DSC before and after the derivatization of different molar ratios.It was found that different molar ratios would affect the pore structure and specific surface area of the derived materials,the surface functional groups,the existing states and proportions of the elements contained,and the internal defects of carbon materials.With the increase of ligands,the ZIF-67-C burst agglomeration phenomenon is obvious,the ratio of oxidized Co²⁺/Co³⁺increases obviously,the defect degree decreases,the graphitization degree increases,the thermal stability decreases,and the weight loss decreases.After calcination,the ZIF-67 material changes from microporous material to mesoporous material,and hydroxyl groups and oxygen vacancies appear on the surface.The results showed that ZIF-67-C had a better catalytic effect on SMX removal and mineralization than the ozonation system alone,and a higher degradation effect could be achieved at a lower concentration of ozone.Compared with the other three molar ratios,ZIF-67（1:8）-C had the best catalytic effect.The removal rate of SMX was positively correlated with the dosage of ozone,the p H of solution and the temperature of solution,negatively correlated with the concentration of SMX,and was firstly increased and then decreased with the dosage of catalyst.The degradation kinetics fitting results show that the oxidation catalysis systems belong to pseudo first order kinetics,and the reaction rate constant is basically consistent with the law of removal effect.ZIF-67-C catalyst can improve the utilization rate and transfer rate of ozone and the efficiency of mass transfer of gaseous ozone to liquid phase.The catalytic system can produce more free radicals,and the degradation mechanism of the catalytic system includes free radicals,and is accompanied by the direct attack of ozone molecules and the partial action of electron transfer.