Interfacial Interaction Analysis And Advanced Oxidation Pretreatment Of NOM Ultrafiltration Membrane Fouling

Ultrafiltration technology plays an important role in drinking water treatment,but membrane fouling can not be ignored.Although many membrane fouling control technologies have been put forward,the mechanism of membrane fouling is still unclear.In this study,polyether sulfone(PES)flat membrane was used as the research object,and the mechanism of membrane fouling was studied from microscopic interaction.The removal of organic matter and the control of membra ne fouling by ultraviolet activated potassium two sulfate(UV/PDS),ultraviolet activated hydrogen peroxide(UV/H2O2)and ultraviolet activated potassium bisulfate(UV/PMS)were investigated.The control effect of UV/PMS on the membrane pollution of different molecular weight organic compounds was investigated,so as to deepen the understanding of membrane fouling and to be preformed before the advanced oxide film.The application of technology is provided for reference.Atomic Force Microscopy(AFM)and Dissipative Quartz Crystal Microbalance(QCM-D)were used to investigate the relationship between adhesion,adsorption and membrane fouling between natural organic matter(NOM)and ultrafiltration membrane.By analyzing organic content and fluorescence char acteristics,SEM,contact angle,FTIR and XPS were used to analyze pollutants by DOC,UV 254,EEM and so on.Morphology,roughness and functional groups were used to investigate the effects of molecular weight and cations of organic compounds on membrane fouling.The effects of UV/PDS,UV/H2O2 and UV/PMS on the removal of organic compounds,the leading free radicals and the control ability of membrane fouling were investigated,and the effect of UV/PMS on the pollution control of NOM membrane with different molecular weights was investigated.Membrane fouling is related to adhesion and adsorption properties of NOM-PES membrane,and the adhesion and adsorption properties are affected by the number of cationic charges and NOM molecular weight.The higher the nu mber of cation charges,the smaller the electrostatic repulsion between NOM-PES films,the larger the molecular weight,the greater the Edward force among the NOM molecules,the increase of the adhesion and adsorption properties,the density of the mud cake layer and the aggravation of the pollution.The Songhua River mainly contains three kinds of fluorescent components: microbial source humic acid(C1),tryptophan protein(C2)and terrestrial humic acid(C3),in which C2 has the greatest impact on the total membrane and irreversible pollution,and increases with the increase of molecular weight.The existence of Na+ has an effect on C3,making it the main pollutant,and the rejection rate of reversible and irreversible pollution increases;the existence of Ca2+ has an effect on the C2,making it a major pollutant,partial reversible pollution is converted to irreversible pollution,the reversibly interception rate increases but the reversible interception rate decreases,and the unsaturated organic matter intercepted.The rate of retention is increasing.In the three UV oxidation technologies,UV/PMS has the best control effect on NOM removal and membrane pollution.The leading free radicals are and.The effect of UV/PDS and UV/H2O2 is slightly poor,and the leading free radicals are and UV/PMS can significantly reduce the small molecular weight(<5k Da,5~30k Da)NOM membrane pollution,but the large molecular weight(30~100k Da,100 k Da~0.45um)NOM membrane pollution control effect is limited.UV/PMS can not only oxidize organic matter,but also enhance the biodegradability of organic matter,and it has greater effect on humic acids or polysaccharides than protein.In addition,UV/PMS can also reduce the content of fluorophore related to the formation of membrane fouling in water and reduce membrane pollution.The removal efficiency is C2,C1 and C3.Therefore,the cation band charge and NOM molecular weight mainly affect the membrane fouling degree by changing the adhesion and adsorption prop erties between NOM-PES films.UV/PMS can reduce organic matter content and improve biodegradability through and interactions,thereby slowing down membrane fouling,and the effect is related to molecular weight.