Li Yuan, Yang Yu, Li Chen, Hou Li-An
State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University No. 19, Xinjiekouwai Street, Haidian District Beijing China
Xi'an High-Tech Institute No. 2, Tongxin Road, Baqiao District Xi-An Shanxi Province China.
RSC Adv. 2019 Feb 25;9(12):6502-6509. doi: 10.1039/c8ra08838a. eCollection 2019 Feb 22.
In this study, the influence mechanisms of graphene oxide (GO) on the membrane substrate/active layer for improving the water flux and anti-biofouling ability of thin-film composite (TFC) membranes in forward osmosis (FO) were systematically investigated. We fabricated a pristine TFC membrane, a TFC membrane in which the substrate or polyamide active layer was modified by GO (TFN-S membrane or TFN-A membrane), and a TFC membrane in which both the substrate and active layer were functionalized by GO (TFN-S + A membrane). Our results showed that the TFN-S membrane possesses a higher water flux (∼27.2%) than the TFN-A because the substrate that contained GO could improve the porous structure and porosity, while the TFN-A membrane exhibited a lower reverse salt flux and higher salt rejection than the TFN-S membrane, indicating that the surface properties played a more important role than the substrate for the salt rejection. Regarding the biofouling experiment, the TFN-A and TFN-S + A membranes facilitated a higher antifouling performance than the TFN-S and TFC membranes after 72 h of operation because of the greater hydrophilicity, lower roughness and facilitated higher bactericidal activity on the GO-modified surface. In addition, the biovolume and biofilm thickness of the TFN-A and TFN-S + A membranes were found to follow the same trend as flux decline performance. In conclusion, the substrate modified by GO could greatly improve the water flux, whereas the GO-functionalized active layer is favorable for salt rejection and biofouling mitigation. The advantage of TFN-A in biofouling mitigation suggests that the antibacterial effect of GO has a stronger influence on biofouling control than the changes of hydrophilicity and roughness.
在本研究中，系统地研究了氧化石墨烯（GO）对膜基材/活性层的影响机制，以提高其在正向渗透（FO）中薄膜复合（TFC）膜的水通量和抗生物污染能力。我们制备了原始TFC膜、基材或聚酰胺活性层用GO改性的TFC膜（TFN-S膜或TFN-A膜）以及基材和活性层均用GO功能化的TFC膜（TFN-S+A膜）。我们的结果表明，TFN-S膜比TFN-A膜具有更高的水通量（约27.2%），因为含有GO的基材可以改善多孔结构和孔隙率，而TFN-A膜比TFN-S膜表现出更低的反向盐通量和更高的脱盐率，这表明表面性质对脱盐的作用比基材更重要。关于生物污染实验，由于GO改性表面具有更高的亲水性、更低的粗糙度和更强的杀菌活性，在运行72小时后，TFN-A和TFN-S+A膜比TFN-S和TFC膜表现出更高的抗污染性能。此外，发现TFN-A和TFN-S+A膜的生物体积和生物膜厚度与通量下降性能遵循相同的趋势。总之，用GO改性的基材可以大大提高水通量，而用GO功能化的活性层有利于脱盐和减轻生物污染。TFN-A在减轻生物污染方面的优势表明，GO的抗菌作用对生物污染控制的影响比亲水性和粗糙度的变化更强。
