Studies On Preparation And Application Of Forward Osmosis Membrane

Clean water shortage is one of the biggest global crises,and thus clean water production and regeneration have become the main concerns.Among a variety of technologies,forward osmosis?FO?has been gaining increasing attentions in many applications including desalination,water purification,wastewater reuse and sustainable power generation due to its low hydraulic pressure requirement,reduced fouling tendency and environmental friendliness.However,internal concentration polarization?ICP?,as a mainly responsible for water flux decline.The ideal forward osmosis membrane should have high water flux and low reverse salt flux,good mechanical strength to ensure long-term stability operation.Therefore,in this study,two types of forward osmosis membranes were developed via using different support layers.Through optimizing the preparation process of forward osmosis membranes,under the premise of ensuring high salt rejection and water flux to enhance the strength of forward osmosis membrane.Thus,were prepared.As we all know,electrospun nanofibers exhibits an intrinsically high porosity and low tortuosity,which make nanofiber membrane promising candidates for TFC-FO membrane supports.However,there are still some problems such as the poor mechanical properties of electrospun nanofiber membranes.This has seriously affected the application prospect of electrospun membrane.Therefore,polyethylene terephthalate?PET?nanofiber FO membrane with strength was prepared via interfacial polymerization method using m-phenylene diamine?MPD?and trimesoyl chloride?TMC?as monomers on composite support electrospun membrane.Under the optimum conditions,the surface water contact angle and tensile strength of the obtained nanofibers support membrane were 121 o and 11.4 MPa,respectively.Furthermore,the separation performances such as water flux and reverse salt flux of the prepared FO membrane were tested and the result showed that the water flux was up to 27.8 LMH with 1 mol/L Na Cl solution and deionized water as draw solution and feed solution,respectively,and the corresponding reverse salt flux was 4.5 gMH.In the phase conversion process,Polysulfone?PSF?was used as material to prepare TFC-FO membrane.The influence of the concentration polysulfone and the interfacial polymerization conditionswere investigated.The structure and properties of the forward osmosis membrane is used by scanning electron microscopy?SEM?,surface contact angle and XPS test.The best performance of forward osmosis membrane was producted by optimizing the experimental conditions.In PRO mode,the water flux was up to 42.3 LMH with 1 mol/L NaCl solution and deionized water as draw solution and feed solution.The result shows that the flux is much higher than HTI FO membrane.It provides the basis for the study of the forward osmosis membrane preparation.Finally,the acrylamide solution concentrating using the optimized polysulfone TFC-FO membrane was studied.NaCl and MgCl₂ solution were used as the draw solution.The effects of different concentration solution,cross flow velocity and different orientation of acive layer were investigated.It was found that the MgCl₂ as draw solution showed the higher water and lower reverse salt diffusion.When the5 mol/L MgCl₂ was used as the draw solution,the concentration of acrylamide could be increased from20 % to 40 % after the experiment was run for 20 h,which could meet the requirements of industrial production.Because forward osmosis has the characteristics of low energy consumption and low membrane fouling.It shows great advantages in the field of industrial applications.Therefore,this study is a great significance for development and optimization of acrylamide concentrating in the future.