| With the increasing shortage of water resources and water pollution,surface water quality has attracted much attention as an important source of drinking water.Humic acid is the major natural organic matter,which commonly exist in surface water.It is the main source of chroma,odor and the precursor of disinfection by-products and would affect the water quality seriously.Membrane separation technology is widely used in humic acid treatment in water for its excellent separation and low consumption performance.With stable physicochemical properties,PVDF compounds is a kind of excellent membrane material.However,the strong hydrophobic of membrane surface would lead to serious membrane fouling,and the treatment effect drop greatly.Modification with hydrophlicity and photocatalysis of PVDF membrane could improve the anti-fouling performance and the removal rate of humic acid by photocatalytic degrade and membrane separation.In this research,ZnS/GO was blended with PVDF to fabricate composite membrane with photocatalysis and enhanced anti-fouling performance.The treatment properties of humic acid of composite membranes have been studied.To take the advantages of grapheme oxide(GO)such as high hydrophlicity and superior electron transfer behavior and the photocatalysis of zinc sulfide(ZnS)in the modification of membrane,GO,ZnS nanoparticles and ZnS/GO composites were prepared by modified Hummer method and hydrothermal synthesis method,respectively.The structure performance of modified additives was characterized.The results showed that the particle size of ZnS nanoparticles was among 100-200 nm,and it wasb-cubic crystal structure.GO nanosheets possess various hydrophlic functional groups such as-OH、C=O and C-O-C groups.ZnS nanoparticles were distributed evenly on GO nanasheets surface in the strcture of ZnS/GO composites.Compared with ZnS,the photocatalytic property of ZnS/GO composites has been enhanced notably.The reason is that GO reduced the agglomeration and the electron-hole recomibination rate of ZnS nanoparticles with high efficiency electron transfer characteristics.The remove rate of MB by ZnS/GO was up to 93%after degrading 120 min.What’s more,with the introduction of various oxygen-containing functional groups and the change of membrane pore size and structure,the hydrophlicity,permeation and anti-fouling properties of composite membranes was increased simultaneously.The rejection of PVDF/ZnS/GO-3 membrane was highest,and the flux recovery rate was promoted from 57.2%to 79.3%with the strongest anti-fouling property.The PVDF/ZnS/GO-3 membrane also exhibits high hydrophlicity and photocatalysis.The ZnS/GO/PVDF-5 membrane with the highest water flux,which increased from 222.9L/(m~2h)of neat PVDF membrane to 431.9 L/(m~2h).The ZnS/GO/PVDF-5 membrane possessed the strongest photocatalytic effect.The remove rate of MB was up to 98.8%after degrading 90 min.The best antifouling and rejection properties was obtained by PVDF/ZnS/GO-3 membrane,and the strongest photocatalysis and permeation performance was received by ZnS/GO/PVDF-5 membrane.The filtration of humic acid with or without UV irradiation by composite membranes has been studied.The humic acid rejection property of PVDF/ZnS/GO-3membrnae was best in the filtration process without UV irradiation.The removal of humic acid by PVDF/ZnS/GO-3 membrane in photocatalysis-membrnae separation process was highest,which up to 91.2%.Besides,the antifouling performance of PVDF/ZnS/GO-3 membrane was promoted 20.3%and the membrane resistance was decreased 12%.The influence of factors during photocatalysis-membrnae separation process has been investigated.When the concentration of humic acid was lower and under neutral condition,and the ion concentration was 0 and the pressure was 0.02 MPa,the treatment ablity and removal efficiency was both reach to optimum.PVDF/ZnS/GO-3 membrne could run long-term continuously under regular cleaning.Which suggest that in the removal of humic acid in water,PVDF/ZnS/GO-3 membrne has a certain application value. |
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