Catalytic Properties Of Copper-based Catalysts In Advanced Oxidation Processes For The Degradation Of Typical Organic Pollutants And Their Mechanisms Investigation

With the development of the industry and the growing population,the industrial pollution has become more and more serious.A large amount of organic pollutants wastewater from the production of dyes,drugs,rubber and pesticides is mostly discharged without further treatment,which severely has damaged to the environment.Therefore,it is imperative to find some efficient methods for the disposal of organic pollutants wastewater.In recent years,advanced oxidation processes（AOPs）have been widely concerned by scientists in the field of organic pollutants degradation.Among these methods,molecular oxygen,peroxymonosulfate（PMS）and peroxydisulfate（PDS）activation technologies have attracted extensive attention.In this study,some typical organic pollutants（aniline,p-nitrophenol,2,4-Dichlorophenoxyacetic acid and phenacetin）were selected as the model pollutants to evaluate the catalytic performance of the copper-based catalysts for activating dissolved oxygen,PMS and PDS.This study aims to provide theoretical guidance in AOPs for wastewater treatment.The main research contents are as follows:1.Micro-scale zinc-copper（mZn/Cu）bimetallic particles were synthesized via precipitating Cu on the surface of Zn and applied in aniline removal.The results showed that the degradation efficiency of aniline was greatly related to theoretical Cu mass loading and initial pH.The optimal Cu loading and initial pH for the destruction of aniline were determined to be 60.45 wt%and 3,respectively.To further assess the catalytic reactivity of mZn/Cu,the removal of aniline and total organic carbon（TOC）was investigated in the different systems.The degradation of aniline by mZn,mCu,and mZn+mCu was negligible within 75 min.However,97%of aniline（10 mg/L）was decomposed and 47%of TOC was removed by mZn/Cu.When N2 was bubbled into the reaction system to remove the dissolved oxygen and the scavengers such as tert-butyl alcohol（TBA）and benzoquinone（BQ）were introduced,the degradation of aniline was also greatly inhibited.This also proved that under acidic and aerobic conditions,the dissolved oxygen could accepted electrons from the surface of mZn/Cu to produce ·OH and O2·-radicals responsible for the rapid removal of aniline.Furthermore,based on the analyses of the intermediates via HPLC-TOF-MS2,possible degradation pathways of aniline were proposed.Our findings suggest that mZn/Cu is a potential approach for aniline removal,which is different from other bimetallic systems reported in previous literature mainly as the reductive degradation.2.Micro-scale zinc-copper（mZn/Cu）bimetallic particles were synthesized via the above-mentioned method and applied in the degradation of p-nitrophenol（PNP）.Three control parameters including reciprocating speed,mZn/Cu dosage,and PNP concentration were investigated by the response surface methodology（RSM）to determine the optimal reaction conditions.The maximum mineralizing of PNP was realized in the system of mZn/Cu/PNP,suggesting that PNP mainly underwent oxidative degradation.However,these results also indicated that PNP was basically reduced in the presence of mZn and mFe.As compared with single metals,the formation of microbatteries on mZn/Cu significantly improved its ability to provide electrons and its chemical activity,resulting in the more efficient degradation of PNP.Thus,this study not only provides a low-cost and high-efficiency technology for the degradation of organic contaminants in aqueous solution but also puts insight into the mechanism of the reaction.3.CuO-Co3O4@CeO2 nanoparticles used as a heterogeneous catalyst were prepared through a sol-gel method and utilized for the catalytic degradation of 2,4-dichlorophenoxyacetic acid（2,4-D）.For comparison,monometallic oxides（CuO,Co3O4,CeO2）and bimetallic oxides（CuO@CeO2,Co3O4@CeO2,CuO@Co3O4）were also prepared by the same processes.The results indicated that CuO-Co3O4@CeO2 exhibited the highest catalytic performance among the catalysts.Moreover,recycling experiments confirmed that CuO-Co3O4@CeO2 was very stable,and the 2,4-D degradation efficiencies ranged from 100%to 97.5%,decreasing by only 2.5%after the fifth run.Electron paramagnetic resonance（EPR）and radical scavenger experiments confirmed the production of SO4·-and ·OH radicals in the CuO-Co3O4@CeO2/PMS system,which were responsible for efficient decomposition of 2,4-D.With mechanism analysis,the synergy of cerium,cobalt,and copper ions maintained the high concentrations of Co（Ⅱ）and Ce（Ⅲ）ions in the catalyst,which efficiently activated PMS to generate free radicals.Cyclic voltammograms（CV）and electrochemical impedance spectroscopy（EIS）investigations revealed that CuO-Co3O4@CeO2 has the higher electrical conductibility and more electron transfer.Based on these results,the possible degradation pathways of 2,4-D were proposed.4.In this study,rice straw biochar modified by copper oxide（RSBC-CuO）was successfully fabricated via a hydrothermal method and was characterized by scanning electron microscope（SEM）,transmission electron microscope（TEM）,high resolution transmission electron microscope（HRTEM）,X-ray diffraction（XRD）,Brunauer-Emmett-Teller（BET）,and X-ray photoelectron spectroscopy（XPS）to observe surface morphology and determine its composition.It was found that RSBC-CuO-activated PDS exhibited an excellent performance than CuO and RSBC on the degradation of phenacetin（PNT）.The effect of catalyst dosage,PDS concentration,solution pH,co-existing ions and humic acid was investigated to find the optimal reaction condition.It was observed that the PNT degradation increased with the higher catalyst dosage and PDS concentration.In the wide range of 3-10,PNT could be degraded efficiently.The result of EPR confirmed that the reactive oxygen species（ROS）included SO4·-,·OH,O2·-radicals and singlet oxygen（1O2）,which were mainly responsible for the efficient destruction of PNT.Scavenger experiments further conformed that 1O2 and O2·-played the crucial role in the PNT removal.According to the result of the experiments,RSBC-CuO exhibited excellent stability and reusability,respectively.The main intermediates in the degradation of PNT by the RSBC-CuO/PDS system were determined by HPLC-TOF-MS2,and the possible degradation pathways of the PNT were further proposed.Therefore,the removal of typical organic pollutants and TOC were efficient by the copper-based catalysts prepared in our study.It means that the copper-based catalysts in Advanced Oxidation Processes are a potential approach to degrade organic pollutants in the environment.