Preparation Of Composite Metal Silicate And Its Catalytic Oxidation Of Wastewater Containing Ciprofloxacin By Ozonation

With the development and progress of science and technology,the use of antibiotics in medical treatment,animal husbandry and agriculture can be seen everywhere.Ciprofloxacin（Ciprofloxacin,CIP）is one of the widely used antibiotics with high antibacterial activity and can inhibit the activity of activated sludge in conventional water treatment.Therefore,there is an urgent need to find a water treatment technology which can effectively remove CIP in water.In this study,Zn-Cu-Ni,Zn-Mn-Ni,Fe-Cu-Ni and Fe-Mn-Ni composite metal silicates prepared in our laboratory were used as catalysts for catalytic ozonation,and their physical structures and surface properties were characterized respectively.By comparing the catalytic activity of four kinds of catalysts for CIP ozonation under the same experimental conditions in static experiments,the catalysts with the highest catalytic activity were selected.The effects of ozone dosage,catalyst dosage,initial concentration of CIP and common anions and cations in water on the catalytic ozonation of CIP in water were studied,and the reaction mechanism of CIP catalytic ozonation was studied.According to the characterization results of the catalysts,the appearance of the four catalysts are basically the same,the crystallinity is poor,all of them are amorphous,and the four catalysts all have a wide pore size distribution.the H3 hysteresis loop can be observed in the adsorption-desorption isotherms,and lattice oxygen and adsorbed oxygen exist on the surface of the catalyst.In the static experiment,by adding ozone at one time,the four catalysts have good catalytic removal effect on CIP at the reaction temperature of 20℃,and the catalytic activity of Zn-Cu-Ni catalyst is the highest.When the initial ozone dosage is 1.5mg,the initial concentration is 3.0 mg/L,the initial p H=8,dosage is 500 mg/L,the CIP removal rate is about84%,and the TOC removal rate is 40%.After repeated use of the catalyst,the removal rate of CIP in water by catalytic ozonation decreased slightly,but still maintained at about 80%,with good stability.The common anions and cations(Na⁺,K⁺,Mg²⁺,Ca²⁺,Cl^-,SO₄^2-and NO₃^-)in water will adversely affect the removal of CIP in water by catalytic ozonation to some extent.Among them,K⁺and Cl^-have great influence on the removal of CIP in water by catalytic ozonation.When the dosage of K⁺was 0.5 m M/L,the removal rates of CIP and TOC decreased by 19.21%and 9.58%,respectively,and when the speculative amount of Cl^-was 0.5 m M/L,the removal rates of CIP and TOC decreased by 32.19%and 11.80%,respectively.When free radical inhibitors such as carbonate/bicarbonate and tert-butanol were added in the process of catalytic ozonation,the degradation efficiency of CIP decreased obviously.When the concentration of HCO₃^-was 1.0 m M/L,the removal rate of CIP decreased by 19.15%.When the concentration of CO₃^2-was 1.0 m M/L,the removal rate of CIP decreased by 15.36%.When the concentration of tert-butanol was 0.6 m M/L,the removal rate of CIP decreased by30.5%.There is obvious inhibition,so it can be seen that hydroxyl radical（·OH）is produced in the process of ozonation of Zn-Cu-Ni composite metal silicate,which plays a leading role in the degradation of CIP.