Highly Efficient Removal Of C Iprofloxacin By Persulfate Activated With Oxygen-functionalized Mesoporous Carbon

The discharge of pharmaceutical wastewater inevitably generates a large amount of wastewater containing antibiotics,which will cause serious environmental pollution problems if discharged into the external environment without strict control,so it is urgent to study green and efficient technological means to eliminate antibiotics from water bodies.Mesoporous carbon is a new type of catalyst,and mesoporous carbon activated peroxynitrite catalytic degradation system is an efficient,low pollution and green process technology.Therefore,in order to efficiently remove antibiotics from water,this paper investigates the environmental and process parameters of mesoporous carbon activated persulfate degradation of ciprofloxacin based on sulfate advanced oxidation technology with mesoporous carbon as the catalyst,and also investigates the oxidation mechanism and degradation pathway of ciprofloxacin by analyzing the characterization results of the material.(1)In this study,ordered mesoporous carbon(CMK-3)was firstly prepared and then oxidatively modified by wet oxidation,and oxygen-functionalized mesoporous carbon(OCMK-3)was successfully prepared and used for the removal of ciprofloxacin.Among the optimal oxidation conditions,0.1 g of dried CMK-3 powder was treated with 5 mL of 4 mol/L nitric acid solution for 45 min at 80℃ under reflux conditions.(2)The effects of environmental and process parameters on the removal rate of ciprofloxacin were investigated,and the optimal reaction conditions were obtained by optimization of the parameters.In addition,comparative experiments on the catalytic degradation performance of CMK-3 and OCMK-3 were carried out.Compared with CMK-3,OCMK-3 showed a 32%improvement in the removal efficiency of ciprofloxacin under the optimal conditions.This increase in activity was attributed to the abundant oxygen-containing functional groups on the surface of OCMK-3,the large porosity and high specific surface area,and the modification of oxygen elements improved the structural defects and electron transfer efficiency of the catalyst material.(3)The catalyst showed good reusability and practical application prospects,and the ciprofloxacin removal rate decreased slightly after four cycles of cycling experiments on OCMK-3.In addition,when the OCMK-3/PS system was used for the treatment of actual pharmaceutical wastewater,it could efficiently remove various hardto-degrade organic pollutants from water,which could greatly improve the biodegradability of water,and had a strong mineralization ability,and could remove about 75%of TOC after 3 hours of reaction.(4)Based on the analysis of free radical burst experiments and electron paramagnetic resonance spectroscopy characterization results,SO4--,·OH and O2·reactive radicals were generated in the reaction system,and the oxidation mechanism of free radicals and non-free radicals acting together was found.(5)The degradation pathway of ciprofloxacin mainly contains defluorination,fluorine substitution,hydroxylation of quinolone and decomposition reaction of piperazine ring.Based on the results of liquid chromatography-mass spectrometry,three rational pathways for the degradation of ciprofloxacin were analyzed.This study provides an efficient method for the removal of ciprofloxacin from water bodies,an in-depth oxidation mechanism for the degradation of organic pollutants based on sulfate advanced oxidation technology,and theoretical support and technical guidance for the in situ remediation of antibiotic contamination in actual pharmaceutical wastewater.