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Tuning the functional groups of a graphene oxide membrane by ·OH contributes to the nearly complete prevention of membrane fouling

Han, Jing-Long, Zhang, Depeng, Jiang, Wanrun, Tao, Yu, Liu, Mei-Jun, Haider, Muhammad Rizwan, Ren, Rui-Yun, Wang, Hong-cheng, Jiang, Wen-Li, Ding, Yang-Cheng, Hou, Ya-Nan, Zhang, Bo, Cheng, Hao-Yi, Xia, Xue, Wang, Zhigang, Wang, Ai-Jie
Journal of membrane science 2019 v.576 pp. 190-197
X-ray photoelectron spectroscopy, adhesion, alginates, artificial membranes, energy, fouling, graphene oxide, hydrogen bonding, hydroxyl radicals, microparticles, moieties, oxidation, purification methods, quantum mechanics, water purification
Graphene oxide(GO) membrane has the potential to become the next generation of water purification membrane, which could help to ease water crisis in many counties. However, organic membrane fouling is still difficult to avoid. In this study, we used a trace of ·OH to mitigate fouling by tuning surface functional groups of GO membrane and altering fouling layer. X-ray photoelectron spectroscopy (XPS) analysis indicated that ·OH changed the epoxide-dominated GO surface to a hydroxyl-dominated surface. The adhesion force between the GO membrane and organic microspheres decreased from 0.37 ± 0.16 mN/m to 0.08 ± 0.14 mN/m after functionalization by ·OH. Quantum mechanical simulations showed that the interaction energy of the hydroxyl-dominated GO surface with a modified alginic acid monomer was 4.07 eV, which was lower than that (5.68 eV) between the epoxide-dominated GO surface and the modified alginic acid monomer. A thicker water molecule layer formed on the hydroxyl-dominated GO surface than on the epoxide-dominated GO surface through hydrogen bonding, thus repelling organic foulants. Combined with the oxidative effect of ·OH, the current method achieved the nearly complete prevention of membrane fouling. This result could provide us a new perspective for the fouling-free membrane-based water purification process.