| As one of osmosis-driven membrane technologies developed in recent years, forwardosmosis (FO) membrane process has many advantages, such as low membrane fouling, lowenergy consumption and so on. It has good application prospect in many fields, such asdesalination, wastewater treatment, food processing, pharmaceutical production and powergeneration. This paper is based on the preparation of high performance forward osmosismembrane. The effect of the different conditions on membrane structure and performancewere studied; the effect of different kinds of draw solutions and different concentration ofdraw solution on the FO process were also studied. Graphene oxide and acidified carbonnanotubes were prepared, and used as hydrophilic additives in preparation of FOmembranes. Prepared high-performance silica-stainless steel wire mesh composite FOmembrane with the prepared conditions were as follows:500stainless steel wire mesh assupporter, the average particle size of2.5nm of silica sol as coating solution.The effects of polymer content in polymer solution, kinds of solvents, the temperatureof coagulate bath and annealing, time of coagulate bath and annealing, kinds ofpore-forming agent on the membrane performance (the water flux and the rejection forNaCl) were investigated. The best membrane prepared process conditions were as follows:polymer mass fraction was3.57%, solvent was the mixed solvent of acetone and1,4–dioxane, heat treatment temperature was60℃, heat treatment time was20min,pore-forming agent were the polyethylene glycol (PEG) whose molecular weight less than1000, zinc chloride and lactic acid. The maximum water flux of commercialized FOmembrane was3.248L/(m2.h) and the NaCl rejection rate was above99.99%while Themaximum water flux of homemade FO membrane was14L/(m2.h) and the NaCl rejectionrate was also above99.99%when the test conditions were as follows: deionized water asfeed solution, the mass fraction of3.5%salt water as draw solution. The water flux ofNa2SO4was the largest,1.874L/(m2.h) and the water flux of MgSO4was the smallest,0.207L/(m2.h) when the draw solution were sodium sulfate, magnesium sulfate andmagnesium chloride, respectively with concentration of1mol/L. Bigger concentration of glucose had bigger water flux when the feed solution was deionized water and drawsolution was different concentrations of glucose solution.The results show that, the graphene oxide and acidified carbon nanotubes preparedthrough the method of modified Hummers can significantly increase the membrane waterflux when they were put in the casting membrane solution as the hydrophilic additives andthe effect of graphene oxide were better than the acidified carbon nanotubes. The membranewater flux of graphene oxide and acidified carbon nanotubes were18.7L/(m2.h) and17.9L/(m2.h) respectively and the NaCl rejection rate were both above99.97%.The results show that, the membrane water flux can be2times higher and the NaClrejection rate was lower when using the hydrophilic inorganic porous carrier to replacingthe organic polyether sulfone. The prepared conditions were as follows:500stainless steelwire mesh as supporter, the average particle size of2.5nm of silica sol as coating solution.The maximum water flux of the composite FO membrane was27.3L/(m2.h) and the NaClrejection rate was99.75%when the deionized water was feed solution and the mass fractionof3.5%salt water was draw solution.The results show that, the membrane water flux of SiO2-stainless steel metal meshcomposite FO membrane was increased significantly and the NaCl rejection rate wasreduced, the membrane water flux of the modified FO membrane with additives of acidifiedcarbon nanotubes and graphene oxide was increased slightly on the basis of the NaClrejection rate kept essentially unchanged when compared with the commercialized FOmembrane. |
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