The Preparation Of Magnetic Rare-Earth Catalyst And Its Catalytic Activity For The Degradation Of Pharmaceutical Wasterwater

In recent years, advanced oxidation technology is get more and more attention in the field of water treatment, and ozone catalytic oxidation technology is an important branch of it. In the catalytic ozonation technology, catalyst plays a key role. In this paper, core-shell model of magnetic Gd2O3and magnetic CeO2catalysts were successfully prepared by hydrolysis-precipitation method. The catalytic efficiency of these two kinds of catalysts for degradation the common medical wastewater composition (L-DOPA and SA) was mainly researched. In the experiment, the catalytic activity was studied by adding catalyst into the single ozone oxidation system. And the reaction factors on the catalytic ozonation system effects, comparison of the mineralization efficiency, reaction mechanism, kinetics of degradation path and catalytic synergy effect are discussed, in order to provide reference for practical application.The first study was focus on the single ozone oxidation degradation of one common drug (L-DOPA). The influence factors of pH, initial concentration, ozone dosage of ozone degradation of L-DOPA were studied; magnetic Gd2O3catalyst was prepared, and the effect of the catalytic degradation of L-DOPA was studied, results showed that COD removal rate was improved by adding (1.0g/L) gadolinia magnetic nanoparticle into the single ozone system, promoting the mineralization rate from24.5%to31.0%. The crystal structure, elemental composition and functional groups on the surface energy of the prepared magnetic Gd2O3catalyst were characterized to provide reference for the follow-up study.Secondly, the magnetic CeO2oxide catalyst was prepared and its effect of catalytic ozonation degradation of salicylic acid (SA) was studied. The effects of pH, initial concentration, ozone dosage, catalyst types and dosage of catalyst and other factors on the ozone degradation of SA were researched by the pseudo first order kinetic analysis; the crystal structure, elemental composition and functional groups on the surface energy of the prepared magnetic CeO2catalyst were characterized; the possible degradation pathway of catalytic ozone degradation of salicylic was discussed. The results showed that, after reacting60min, compared to the single ozone system, the TOC removal rate is increased from28.9%to34.4%, improving the biodegradability of wastewater.Finally, the dynamic model of gas-liquid reaction was studied to provide theoretical reference for ozone degradation of wastewater. Gas-liquid reaction rate was mainly controlled by two aspects:physical absorption and chemical absorption affects,in different rates of gas-liquid reaction kinetic model, their contribution to the overall reaction rate are also different. The catalytic ozonation degradation of salicylic acid by magnetic CeO2catalyst was proved as a slow dynamic system through the calculation of Ha constant (Hatta number). The equation of the reaction rate constant ki in the initial stages of oxidative degradation of salicylic acid reaction (slow reaction) catalyzed by magnetic CeO2catalytic has been established. Compared with the apparent rate constant ksp, the affecting degree by experimental factors of the rate constant ki was discussed in order to provide data and reference for the study of process optimization and ozone catalytic degradation kinetics.