Study On Degradation Of Chlortetracycline By Heterogeneous Ultraviolet Fenton Ceramic Membrane Coupling System

With the rapid development of industry and agriculture and the increasing living standards of the people,micro-polluting of water has become a worldwide environmental problem.As a representative water micro-pollutant,chlortetracycline has high detection frequency and content in sewage,and traditional sewage treatment technology can not effectively remove it.The UV-Fenton-membrane separation coupling technology retains the original advantages of UV-Fenton technology and membrane separation technology.It is non-selective for contaminants,highly efficient and thorough,and the strong oxidant hydroxyl radical generated by the photo-Fenton reaction can also degrade the organic contaminants on the surface of the membrane,thereby reducing membrane fouling and increasing membrane life.In this paper,chlortetracycline was used as the research object,and ?-FeOOH photocatalyst was synthesized by precipitation method.The photocatalytic ceramic membrane was synthesized by covalent bonding method.The removal efficiency and kinetic behavior of chlortetracycline in the two systems were investigated.The research mechanism of chlortetracycline was explored.Through the research on the anti-fouling performance of ceramic membrane,the superiority of heterogeneous ultraviolet Fenton-membrane separation coupling technology is clarified.The main research contents and results are as follows:1.The ?-FeOOH catalyst was synthesized by precipitation method,and the photocatalytic ceramic membrane was prepared by covalent bonding method.The catalyst and photocatalytic ceramic membrane were characterized by SEM,XRD,EDS,UV-Vis and FTIR.The synthesized catalyst is in the form of needles or spindles.The structure is uniform,the length is 500-550 nm,the width is 25-50 nm,and the crystal form is consistent with the JCPDS standard card of ?-FeOOH.The catalyst is significantly responsive to ultraviolet light.The surface of the ceramic membrane was coated with photocatalyst ?-FeOOH;the presence of Fe,Al and O elements was detected on the surface;the XRD image contained both the diffraction peak of photocatalyst ?-FeOOH and the diffraction peak of ?-Al2O3 and TiO2;The vibrations appeared at 3152 cm'1,890 cm-1 and 793 cm-1 in the FTIR spectrum,indicating that the photocatalytic ceramic membrane loaded with the catalyst ?-FeOOH was successfully synthesized.2.The superiority of heterogeneous ultraviolet Fenton technology was determined by analyzing the removal effect of chlortetracycline under different conditions.The effects of initial concentration of chlortetracycline,concentration of H2O2,UV intensity and catalyst dosage on the removal of contaminants during the degradation process were investigated to determine the optimal conditions for chlortetracycline degradation in the two systems.The degradation of chlortetracycline under the optimal conditions of the two systems accords with the first-order reaction kinetics.The apparent rate constant of chlortetracycline degradation in the Fentonton ceramic membrane coupling system is 0.25005,and the apparent rate constant of chlortetracycline degradation in the photocatalyst system is 0.13069.The former is about twice as large as the latter,indicating that the combination of heterogeneous ultraviolet Fenton technology and membrane separation technology will have a coupling effect and increase the degradation rate of chlortetracycline.3.Degradation experiments of chlortetracycline under optimal conditions using two systems(photocatalyst system,photo-Fenton ceramic membrane coupling system),analysis of UV-visible spectrum,NH4+-N concentration and the change in TOC removal rate further validates the coupling effect of heterogeneous UV Fenton technology and membrane separation technology.4.Filtration experiments of chlortetracycline at a constant flow rate showed that membrane separation technology coupled with heterogeneous ultraviolet Fenton reaction can slow the fouling of the membrane.After ten cycles of recycling,the degradation performance,permeation flux and surface morphology of the photocatalytic ceramic membrane did not change substantially,demonstrating the stability and reusability of the photocatalytic ceramic membrane.The degradation effect of chlortetracycline in simulated livestock and poultry wastewater is good.