Pressure-assisted self-assembly technique for fabricating composite membranes consisting of highly ordered selective laminate layers of amphiphilic graphene oxide |
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| Affiliation: | 1. R&D Center for Membrane Technology and Department of Chemical Engineering, Chung Yuan University, 200 Chung Pei Rd., Chung Li 32023, Taiwan, ROC;2. MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science & Engineering, Zhejiang University, Hangzhou, 310027, China;3. Chemical and Materials Engineering, National Ilan University, 1 Sec. 1 Shen-Lung Rd., I-Lan 26047, Taiwan;1. Department of Physics, Ocean University of China, Qingdao 266100, China;2. College of Mathematics and Physics, Qingdao University of Science and Technology, Qingdao 266061, China;1. Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China;2. Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, China;1. School of Biotechnology, Dublin City University, Dublin 9, Ireland;2. School of Mechanical and Chemical Engineering, Cork Institute of Technology, Ireland;1. Department of Chemical & Biomolecular Engineering, National University of Singapore, Singapore 117585, Singapore;2. NUS Graduate School for Integrative Science and Engineering, National University of Singapore, Singapore 117456, Singapore;1. NUS Graduate School for Integrative Science and Engineering, National University of Singapore, 28 Medical Drive, 117456, Singapore;2. Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117585, Singapore |
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| Abstract: | We prepare highly ordered flexible layers of graphene oxide (GO) on modified polyacrylonitrile substrates by the pressure-assisted self-assembly technique. This composite membrane shows excellent performance during the pervaporation separation of a 70 wt.% isopropyl alcohol (IPA)/water mixture: 99.5 wt% water in permeate and 2047 g m−2 h−1 permeation flux. Despite the specific GO deposition increase from 4.3 to 43.3 × 10−5 g cm−2 (ninefold layer thickness growth), its effect on the permeation flux is not significant, as manifested by only a little decrease in the flux. At 70 °C feed temperature, the permeate water concentration remains 99.5 wt% and the permeation flux reaches 4137 g m−2 h−1. The high selectivity may be due to the dense GO film consisting of highly ordered and packed laminates, allowing water but inhibiting IPA molecules to pass through. GO is demonstrated to be amphiphilic: water molecules adsorb first at the hydrophilic edge (hydroxides) and then rapidly diffuse through the hydrophobic core (mainly carbon), forming a water passage channel that promotes high permeation flux. When water molecules permeate through the GO layers, they accumulate and form a monolayer structure that pushes the successive layers away from each other, leading to widening of the d-spacing. |
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