Modification Of Ultrafiltration Membrane With GO And Its Property For Water Purification

Ultrafiltration (UF) membrane technology has been widely applied in the process of water treatment, but the membrane fouling problem seriously restrains its more widespread application. In this study, graphene oxide (GO), hydrophilic GO blended Polyvinyl chloride(GO/PVC) membranes and GO blended Polyvinylidene fluoride (GO/PVDF) membranes were prepared in order to solve the poor hydrophilicity problem of conventional UF membranes. Then, the performance characteristics of the blend membranes were analyzed in this paper. Further, Ag-GO nanocomposites and antibacterial Ag-GO/PVDF blend membranes were prepared to improve the antibacterial performance of pure PVDF membrane.GO was prepared via a modified Hummers approach. Then, it was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and transmission electron microscope (TEM). Preliminary results showed that GO has a layer structure with a lot of hydrophilic functional groups like hydroxyl (-OH) and carboxyl(-COOH) groups. Through the analysis of the characterizations, it was found that adding small amount (0-0.20%) of GO into the PVC or PVDF membranes significantly improved the hydrophilic, mechanical, anti-fouling properties, and the permeation performance of the membranes. After the comparison, it was proved that the optimal contents of GO in GO/PVC and GO/PVDF blended membranes were 0.10% and 0.15%, respectively. Meanwhile, the GO/PVDF membrane casting solutions were proved to form the solid membranes more easily,and the GO/PVDF blend membranes showed a better appearance than GO/PVC membranes.Therefore, the 0.15%GO/PVDF blend membranes were used to do the water purification research. By adding GO, the removal rate of CODCr and BOD5 increased by 51.9% and 42.8%.Ag-GO was prepared via a solution intercalation method, and the TEM and FITR results showed that the silver ions and a large number of ester groups were loaded on the layer surface of GO successfully. The analysis of EDS and ICP-MS proved that the silver ions wereloaded into the Ag-GO/PVDF blend membranes. The water contact angle and antifouling testsshowed that after loading silver ions, GO still kept the similiar modification effects on PVDFultrafiltration membrane. The antibacterial tests confirmed that the Ag-GO/PVDF blend membranes showed an effective antibacterial performance. Meanwhile, the loss of silver element under the hydraulic impact was much less compared to the nano silver-blended PVDF membranes, which proved that GO can help decrease the loss of silver ions.