Catalytic Ozonation Of Recalcitrant Organic Chemicals In Water Using Loaded γ-Al₂O₃

The composition of petrochemical wastewater is complex,among which the refractory organics are difficult to be degraded.Catalytic Ozonation Processes（COPs）is one of the technologies for the removal of low-concentration refractory organic pollutants,and is considered to have the most promising industrial prospects.This research uses the volume impregnation method such as Cu,Fe,Mg,Mn,Ce load ofγ-Al₂O₃catalyst,selection simulated wastewater of nitrobenzene,benzoic acid and nitro phenol as the treatment object,uses the single factor variable method to investigate the catalytic activity of catalysts,and to explore the Cu load and the influence of calcination temperature on catalytic activity,as well as the role of Cu/γ-Al₂O₃in COP system mechanism.The results showed that the Cu₃-550 catalyst prepared at 3.0 wt%Cu load and 550℃roasting temperature had the highest catalytic activity.The surface structure,element composition and specific surface area of the catalyst were analyzed by means of XRD,XRF,SEM-EDX,BET,XPS and other characterization analysis.The prepared catalyst had large specific surface area,uniform load and abundant mesoporous structure,which were conducive to improving the reaction rate of catalytic ozonation.Compared with commercial catalysts,the prepared catalysts have better activity.The TOC removal rates of the three pollutants can reach 60.16%,82.94%and73.28%,respectively,after the addition of 0.4 g/L of catalyst and 4 mg/L of ozone flux for 60min,which are 32%,53%and 41%higher than those of the single ozone-oxidation system.Catalyst adsorption and stripping contributed little to TOC removal.The results showed that the catalytic activity of the catalyst was inhibited in the strong acid environment,and the catalytic activity was good in the range of neutral and above（p H value was 7～10）.Through the experiment of adding free radical inhibitor,it was indirectly proved that the catalytic ozone-oxidation of 3 simulated sewage by Cu/γ-Al₂O₃followed the mechanism of hydroxyl radical and the reaction process met the quasi-first-order kinetic equation,and the reaction rate constants of the three pollutants reached 0.0179 s^-1、0.0313 s^-1、0.0222 s^-1,respectively.