Efficiency Of Mn(?) Pre-oxidation Enhancing Gravity Driven Membrane To Remove Atrazine In Water

Atrazine,an emerging pollutant in water,is widely used as a herbicide in cropland,forests,etc..However,its solubility in water makes it easy to transport to the surface and groundwater,which causes water pollution.The refractory and structurally stable Atrazine will continue to exist once it is introduced into the water environment,and threaten biological reproduction and human health.How to effectively remove micro-pollutants in water environment is an important issue.Advanced oxidation process has a significant effect on the removal of the micropollutant like atrazine in water,such as the persulfate radical system and the Mn(?)system.However,NOM and anions in natural waters may inhibit the degradation efficiency of the oxidation system.Therefore,this study combines advanced oxidation process with gravity-driven filtration system(GDM)to further improve the removal efficiency of atrazine.GDM system has the advantages of low energy consumption,low membrane fouling,stable performance and relatively simple maintenance.Furthermore,it has better rejection of humic acid under lower head.This study focuses on the efficacy of system coupling Mn(?)-PES pre-oxidation and GDM to remove atrazine in water,and uses PMS-Co(II)oxidation system as a control.For a given humic acid(HA)concentration,the removal of atrazine by the coupling system was superior to other single processes.The data illustrated that the removal rate of atrazine by Mn(?)pre-oxidation which was improved was much stronger than PMS pre-oxidation.Finally,manganese dioxide nanoparticles deposited on raw membrane could effectively enhance the atrazine retention of coupling system.By analyzing the influence of Mn(?)pre-oxidation on characteristics like functional group of humic acid substances and the foulant layer formed on the membrane,the mechanism of strengthening the efficiency of atrazine removal by the coupling process was obtained.After Mn(?)pre-oxidation treatment,the intensity of function groups such as hydroxyl group and carboxyl group of the modified HA was increased,and hydrogen bonding was more likely to occur.Hence,the adsorption between the solute-solute was lifted.The modified HA molecules aggregate on the membrane to form pores,and the fouling layer was loose and rough so that the atrazine molecules possibly could be adsorbed and trapped into fouling layer.Focusing on the efficiency in removing Atrazine by coupling process,it can provide new ideas for efficient removal of micropollutants in water environment.The characteristics of pre-oxidized humic acid substances and its membrane fouling behavior on polysulfone membrane were studied,which provide theoretical support for the application of the coupling process.