| Much of oily wastewater is produced in metallurg,chemical industry and machining process.If oily wastewater wasn't treated and was directly discharged,the inflow of oily wastewater into water body such as oceans and lakes would imperil human health and growth of animals and plants.Emulsified Oily Wastewater that is directly generated in the process of cold rolling,metal extraction and petroleum production,is one of the most difficult to deal with in oily wastewater and electrical double layer systems in the surface of oil droplets cause the stabilized property of oil droplets.Compared with traditional chemical demulsification method,ultrafiltration membrane separation technology possesses high separation efficiency,simple operation and recyclable utilization of oil.However,membrane pollution that is caused by the adsorption and deposition of oil droplet on membrane surface and pore seriously restricts practical applications of ultrafiltration membrane in the treatment of oily wastewater.Graphene oxide(GO)is widely used for membrane material modification to improve the antifouling performance of membrane because of its high specific surface area and abundant hydrophilic functional groups,but easy aggregation of GO in the membrane matrix restricts the complete exertion of its excellent property and has an unfavourable influence on membrane structure and performance.Initially,L-tyrosine(Tyr),N-(trimethoxysilylpropyl)ethylenediaminetriacetic acid sodium(EDTS)and Chitosan(CS),which are hydrophilic material,were reacted with GO in the suitable condition to prepare three different functionalized graphene oxide(F-GO)and the chemical composition,morphology and structure and dispersibility before and after GO was functionalized were analyzed.The results indicate after GO was functionalized by Tyr,EDTS and CS the regular lamellae accumulation structure was destructed and the unordered construction consisting of various orientated GO lamellae was formed,which weakens the ?-? interaction between GO lamellae and improving its dispersibility.Moreover,Tyr-GO,EDTS-GO and CS-GOmodified polyvinylidene fluoride(PVDF)ultrafiltration membranes were prepared by the blending method and the effects of the three F-GO addition contenton the structure andperformance of PVDF ultrafiltration membrane were systematacially investigated.The results show the hydrophilicity,porosity and water permeation of PVDF ultrafiltration membrane initially increase and then decrease with the F-GO content.The optimizedaddition content of Tyr-GO is 1.5%,at this condition,the pure water flux reaches 684.49 L/m2·h,the oil rejection reaches 94.63%;the optimized addition content of EDTS-GO is 0.5%,at this condition,the pure water flux reaches 711.23 L/m2·h,the oil rejection reaches 93.87%;the optimizedaddition content of CS-GO is 0.6%,at this condition,the pure water flux reaches 737.18 L/m2·h,the oil rejection reaches 91.67%.Finally,the performances of treatment of emulsified oily wastewater with F-GO modified PVDF ultrafiltration membrane,GO modified PVDF ultrafiltration membrane and unmodified PVDF ultrafiltration membrane wereinvestigated.The results indicate during treatment of emulsified oily wastewater,the addition of Tyr-GO makes the permeation of PVDF membrane improve 84.47%,the permeation of GO/PVDF membrane improve 38.46%;the addition of EDTS-GO makes the permeation of PVDF membrane improve 78.96%,the permeation of GO/PVDF membrane improve 47.83%;the addition of CS-GO makes the permeation of PVDF membrane improve 80.00%,the permeation of GO/PVDF membrane improve 45.16%.Moreover,the flux recovery ratio and the reversible flux attenuation ratio of Tyr-GO,EDTS-GOand CS-GO modified PVDF ultrafiltration membrane are obviously higher than PVDF ultrafiltration membrane and GO modified PVDF ultrafiltration membrane,which indicates GO functionalized by Tyr,EDTS,and CS modified PVDF membranes possessstronger the performance of treatment of emulsified oily wastewater than unfunctionalized GO modified PVDF membrane. |
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