Preparation And Experimental Characteristics Of Graphene Oxide Composite Forward Osmosis Membranes

The forward osmosis(FO)membrane technology has its own advantages of low energy consumption and low membrane pollution,so it is widely used in sewage treatment.The composite FO membrane prepared by combining the new carbon nanotechnology material graphene oxide(GO),it not only has a good concentration of high-concentration brine,but also improves the flux of the FO membrane.This study use improved Hummers method to prepare GO,and its characterization and analysis were performed.The methylene blue dye was used as the target pollutant to verify the separation performance of GO.combined by vacuum filtration and in-situ polymerization to prepare graphene oxide/cellulose triacetate composite FO membrane(CTA/GO)and graphene oxide/polyethersulfone composite forward osmosis Membrane(PES/GO),and apply CTA/GO,PES/GO and original CTA and PES to the experimental bench of the forward osmosis module,and use the change of membrane flux,osmotic pressure and solubility of the FO membrane separation process The change in total solids(TDS)illustrates the influence of GO on the process of FO membranes.The research conclusions are as follows:(1)In this study,GO was prepared by the improved Hummers method,and used scanning electron microscope(SEM),transmission electron microscope(TEM),Fourier transform infrared spectroscopy(FT-IR),X-ray diffractometer(XRD),Raman spectrometer(Raman),thermogravimetric analyzer(TG)and other characterization methods to analyze graphene oxide,the results show that the surface of graphene oxide has obvious wrinkles,which can reduce its surface energy and make it exist stably;The functional groups on the surface of graphene oxide samples include hydroxyl,carboxyl and carbonyl groups.These oxygen-containing functional groups enhance the hydrophilicity of graphene oxide;calculations show that the carbon-to-oxygen ratio of graphene oxide prepared in the experiment is about 2.04;XRD results show that graphite oxide The interlayer spacing of olefin is about 1.26nm;Raman spectrum results show that the R value of graphene oxide is about 1.18,which indicates that graphene oxide has a higher degree of oxidation;TG results can clearly show that it is divided into two stages of weight loss,And it has the maximum degradation rate at 255.79℃.The methylene blue dye separation experiment verified that the rejection rate of the organic dye molecules by the graphene oxide film can reach more than 80%.(2)This study,prepared PES/GO and CTA/GO by in-situ polymerization,based on the grafting effect of polydopamine,using trimesic acid chloride and m-phenylenediamine.The polymerization reaction stabilizes the GO on the surface of the base film.SEM and EDS results show that GO is tightly integrated with the base membrane,and the carbon-to-oxygen ratio on the surface of PES/GO and CTA/GO composite forward osmosis membranes is slightly greater than that of GO materials,which are 3.07 and 2.74,respectively;FT-IR results show that the functional groups on the surface of the two composite FO membranes are same as those of graphene oxide;the test results of the thermogravimetric analyzer show that the weight loss of PES/GO and CTA/GO is divided into three stages.The weight loss in each stage is caused by the free water combined with the functional groups on the surface,the uns Tab.functional groups in the GO;and the s Tab.functional groups in the membrane material and GO.(3)In this study,a self-made FO experiment component was used to verify the performance of the graphene oxide composite forward osmosis membrane.Four FO membranes were tested after 8 hours,under the same concentration of the draw solution,the membrane flux decreased with the increase of time.The membrane flux of GO/CTA and GO/PES at the end of the experiment was higher than that of CTA and PES,indicating that graphite oxide was added.After olefin,a FO membrane with high water flux is obtained.When the concentration of the draw solution is 1.0mol/L,CTA/GO and PES/GO show the same membrane flux,both of 9.367kg/(h·m~2);when the concentration of the draw solution is 1.5mol/L,PES/GO has The highest membrane flux is 14.050kg/(h·m~2);when the concentration of the draw solution is 2.0mol/L,CTA/GO and PES/GO show the same membrane flux,which is 16.392 kg/(h·m~2));When the concentration of the draw solution is different,the membrane flux increases with the increase of the concentration.(4)The four FO membranes all show that under the condition of higher draw solution concentration,the two sides of the forward osmosis membrane have a higher osmotic pressure difference.After the experiment is run,the PES/GO membrane is better than the other three forward osmosis membranes.The osmotic pressure difference is higher,the range is:PES/GO>CTA/GO>PES>CTA.During the experiment,the TDS on the feed solution side of the forward osmosis membrane showed a continuous upward trend.The concentration ratio of the feed solution showed an upward trend as the concentration of the draw solution increased;the FO membrane with graphene oxide added was higher than the original membrane.The concentration ratio of PES/GO is higher;the concentration effect of PES/GO is lower than that of CTA/GO forward osmosis membrane.