Characterization And Antifouling Performance Of Functionalized Graphene Oxide/Cellulose Triacetate Forward Osmosis Membranes

As a new separation technology, forward osmosis(FO) has been studied widely and applied in some fields. In this study, graphene oxide(GO) and amino functionalized GO(AminoGO) were prepared and mixed into cellulose triacetate(CTA) casting solution to modify the CTA FO membranes, aiming at improving the water permeability and antifouling ability. Phase inversion was used to prepare the CTA membranes while GO and AminoGO were blent with CTA to prepare the modified membranes. Water flux and reverse solute flux were measured by cross-flow RO and FO device to compare the performance of membranes with and without modification.(1) Characterization of membranes. The contact angle(CA), fourier transform infrared spectroscopy(ATR-FTIR), transmission electron microscopy(TEM), X-ray photoelectron spectroscopy(XPS) and X-ray diffraction pattern(XRD) were used to characterize CTA membrane, CTA/GO membrane and CTA/AminoGO membrane. These methods were also used to anlyze the GO and AminoGO. It was confirmed by the results that GO and amino functional GO with the-NH2 group had also been grafted onto GO nanosheets had been prepared successfully. The GO and AminoGO could be uniformly dispersed inside membrane layer and optimize the structure of the FO membrane which were verified by the results of FTIR、FESEM and XPS characterization. The values of CA showed that addition of GO and AminoGO increased the membrane hydrophilicity. CTA/0.2%GO membrane(20.56°) and CTA/AminoGO membrane(16.95°) were lower than CTA membranes(63.01°).(2) Transport property of FO membranes. In this paper, membranes of 150μm in thickness were produced by phase inversion method. The water flux, reverse salt flux and structure coefficient(S) of CTA membrane, CTA/GO membrane and CTA/AminoGO were tested and analyzed. Experimental results showed that the water permeability coefficient(A), salt permeability coefficient(B) and S of CTA membrane were 1.39, 11.87 and 0.87 respectively. These parameters changed when membranes were blended with GO. The water flux of FO membrane increased with the increasing addition of GO. When the addition of GO reached 0.2%, the average water flux of CTA/GO membrane increased to 17.04 LMH which was 54.31% higher than that of CTA membrane as well as for CTA/AminoGO Membrane. Moreover, the water flux of CTA/AminoGO was increased by 5.7% compared to CTA/GO membrane. With the increasing of the GO content in membrane, the salt flux of FO membrane also increased.(3) Antifouling performance. The BSA, SA and emulsion oil were used as simulating foulant solution to investigate the antifouling performance of the modified membranes. Compared with the CTA membrane, CTA/GO membrane and CTA/AminoGO increased about 45% and 52% in flux during simulating foulant solution, respectively. Experiments showed that the both of two modified membranes had better antifouling performance with higher GO nanoparticle contentIn conclusion, the antifouling performance of modified FO membrane was improved due to the special structure of GO, especially CTA/AminoGO membrane. Simultaneously, the structure of FO membrane was optimized with blending GO and AminoGO into CTA polymer matrix as well as the hydrophilicity and mechanical tensile properties were enhanced. Obviously, GO and its functionalized derivates have significant affects on membrane modification and provide a new way to improve the water flux and antifouling performance of FO membranes.