Study On The Degradation Of Organic Pollutants In Water By Activating Persulfate With Iron-rich Enteromorpha Based Iron Single Atom Catalysts

Single-atom catalysts(SACs)have become the research frontier and hotspot in the field of advanced oxidation processes(AOPs)because of their unique electron and coordination structure and excellent performance in AOPs.However,it is still an urgent problem to be solved how to prepare SACs on a large scale via green synthesis routes and apply them in the AOPs for refractory pollutants elimination.In this study,through the in-situ coordination of organic iron in iron-rich Marine algae(Enteromorpha),Enteromorpha based iron single-atom catalyst with high content of Fe-Nx active center was prepared and used to activate peroxymonosulfate(PMS)to achieve efficient degradation of organic pollutants.The main contents of this dissertation are summarized as follows:1.Construction and characterization of Enteromorpha based iron single-atom catalysts.In this paper,in situ coordination of Fe in iron-rich Enteromorpha was carried out.Enteromorpha based iron single-atom catalysts with different coordination structures were prepared by adjusting the addition amount of urea without adding any mental.Besides,the number of Fe and N coordination atoms,the spacing between Fe and adjacent atoms,the disorder degree,and the valence state of Fe atoms were determined by X-ray absorption spectroscopy(XAFS).Furthermore,the relationship between nitrogen gradient and Fe-Nx coordination structure of Enteromorpha based iron single-atom catalysts was analyzed.2.The structure-activity relationship between the coordination structure of monatomic catalysts and the mechanism of activating PMS to degrade pollutants.Using naproxen as the target pollutant,the catalytic degradation performance of Enteromorpha based iron single-atom catalysts with different coordination structures was investigated.The dynamic changes of free radicals(SO4-·,·OH),non-free radicals(1O2),electron transfer,and high valence iron were analyzed by PMSO transformation experiment,free radical quenching experiments(ethanol,tert-butanol,furfuryl alcohol,and methyl phenylsulfoxide),electrochemical,and in-situ characterization methods.3.Synergistic catalytic mechanism of Fe monatomic central sites and other active sites.The biomass catalyst without metal was compared with Enteromorpha based iron monatomic catalyst.On the one hand,the biomass catalyst without metal was compared with Enteromorpha based iron monatomic catalyst.On the other hand,metal masking agents were added to mask the catalytic activity of iron single atoms.By the above means,the transformation process of free radical/non-free radical and the variation trend of pollutant degradation rate in PMS catalytic system were analyzed.Besides,we clarified the role and contribution of single atom and other non-metal active sites in the catalytic system.In addition,the synergistic catalytic mechanism of Fe single atom central site and other active sites was revealed.