| As a common source of pollution,oily wastewater has a great impact on the environment and the health of humans.Therefore it is very important to separate oil and water from it.Compared with other traditional methods of oil-water separation,membrane separation technology has the advantages of low energy consumption,strong environmental adaptability and high efficiency.Although membrane separation technology has now been widely used in human daily production and life,common separation membranes often suffer from poor anti-fouling performance.Therefore,this work aims to prepare an oil-water separation membrane with special wettability by combining the two modification methods of blending and surface grafting.First of all,the blending system of PVDF and high molecular weight SMA is calculated as a partially compatible system through the mixed enthalpy change theory.Then,using PVDF and SMA as the blending materials,Li Cl as the pore-forming additive and DMAc as the solvent,PVDF/SMA blended membranes with different SMA contents were prepared by the Nonsolvent Induce Phase Separation(NIPS)method.The results showed that with the increase of SMA content,the pure water flux of the blend membrane increased simultaneously with the average pore size and porosity of the membrane,while the BSA rejection and water contact angle gradually decreased.When the SMA content is 6.0wt%,the average pore size of the PVDF/SMA blend membrane is 47.58 nm,the porosity is 66.34%,the pure water flux is 369.75 L·m-2·h-1,the BSA rejection rate is 91.3%and the water contact angle is 97°.Secondly,the maleic anhydride ring of SMA on the blend membrane surface can undergo an esterification reaction with substances containing hydroxyl groups under a certain condition.Using this principle,the Pluronic F127(F127)can be grafted onto the surface of the PVDF/SMA blend membrane.The characterization results of FT-IR,XPS,AFM and SEM proved that the PVDF/SMA-g-F127 membrane was successfully prepared.On this basis,the effects of different reaction conditions on the grafting rate of F127,the wettability of the membrane,the permeability and the anti-fouling performance were investigated.The results show that when the reaction time is 9 h,the concentration of F127 is 4.0 g/L,the concentration of PTSA is 1.0 g/L and the reaction temperature is 80?,the PVDF/SMA-g-F127 membrane showed highly hydrophilic and nearly underwater superoleophobic.At this time,the grafting rate of F127 is 476.2mg·g-1,the water contact angle is 31°,the underwater oil contact angle is 148°,the pure water flux is 191.30 L·m-2·h-1 and the BSA rejection is over 99%.After the three cycle filtration experiments of BSA solution,the flux recovery rate of pure water can still maintain 96.82%.Finally,PVDF/SMA-g-F127 membrane was used to carry out oil-water separation experiments on different O/W emulsions.The results show that the membrane has a certain separation efficiency for petroleum ether-water,1,2-dichloroethane-water,toluene-water and pump oil-water emulsions.In the ten cycle filtration experiments of petroleum ether-water emulsion,the pure water flux of the membrane was seriously reduced,indicating that its recyclability was poor. |
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