Efficiency And Mechanism Of Removal Of 2,4 Dichlorophenol By Peroxymonosulfate Activated With Modifed Biochar

With the rapid development of human industry,more and more synthetic organics are widely used.Among them,2,4-dichlorophenol（2,4-DCP）is widely used in medicine and pesticide production,but it has strong toxicity,difficult degradation,very stable chemical properties and long half-life.Therefore,when it enters the natural environment,it will have a serious dangerous impact on human health and ecosystem,This has aroused widespread concern.Therefore,it is urgent to develop an efficient and environment-friendly 2,4-DCP processing technology.In this paper,modifed biochar catalyst was prepared by the combination of ball milling and anaerobic pyrolysis.It was used as Peroxymonosulfate（PMS）activator for the adsorption and degradation of 2,4-DCP.The surface morphology,structural parameters and physicochemical properties of biochar catalysts were studied by a series of characterization methods.Through the adsorption and degradation effect of 2,4-DCP,the adsorption performance of modifed biochar and the activation performance of PMS were evaluated.Through the study of the internal relationship between the structural parameters,maximum adsorption capacity（Q_m）and reaction rate(k_obs)of biochar catalyst,the influencing factors of catalytic performance were revealed.In addition,the degradation mechanism and pathway of 2,4-DCP in NSBC8-50/PMS system were revealed by EPR free radical identification and intermediate product identification.The main research results of this paper are as follows:（1）In this paper,modifed biochar:BC8,NSBC7-50,NSBC8-30,NSBC8-50,NSBC8-100 and NSBC9-50 were prepared by ball milling and anaerobic pyrolysis.The successful preparation of carbon based materials was proved by XRD and Raman spectroscopy;XPS,FTIR and EDX analysis showed that nitrogen and sulfur were successfully mixed into biochar catalyst;The results of SEM and TEM show that biochar catalyst has rich pore structure and surface folds;The N₂ adsorption analysis shows that the biochar catalyst has a high specific surface area,up to 1714.336m~2/g,and is a typical mesoporous structure;Raman spectrum test shows that heteroatom doping can make carbon based materials have higher structural defects.（2）In this paper,the adsorption and catalytic properties of biochar materials were studied by adsorption removal of 2,4-DCP and activated PMS degradation of 2,4-DCP.Under the same conditions,NSBC8-50 had the best adsorption performance for 2,4-DCP（76.00%）;In NSBC8-50/PMS system,the highest degradation efficiency of 2,4-DCP is99.97%within 5 minutes.Through the analysis of the internal relationship between the structural parameters of the catalyst,the maximum adsorption capacity（Q_m）and the reaction rate(k_obs),it can be seen that the structural defects are the main factors affecting the performance of the catalyst;In NSBC8-50/PMS reaction system,common anions have no obvious inhibitory effect on the degradation of pollutants and have a wide p H application range.The TOC removal rate of 2,4-DCP can reach 89.89%in 5 min,and the intermediate products are analyzed.The above results show that NSBC8-50 is an environment-friendly catalyst with good adsorption and catalytic properties.（3）In this paper,the catalytic mechanism of NSBC8-50/PMS system was studied by EPR test and quenching experiment.The results show that in the reaction system,there are main pathways guided by·O₂^-and ~1O2,as well as auxiliary pathways guided by·OH,SO₄^·-.