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Open AccessArticle

Permeation Properties of Ions through Inorganic Silica-Based Membranes

1
Department of Applied Chemistry, Shibaura Institute of Technology, 3-7-5 Toyosu, Koto-ku, Tokyo 135-8548, Japan
2
National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan
*
Author to whom correspondence should be addressed.
Membranes 2020, 10(2), 27; https://doi.org/10.3390/membranes10020027
Received: 28 December 2019 / Revised: 3 February 2020 / Accepted: 5 February 2020 / Published: 8 February 2020
(This article belongs to the Special Issue Membranes for Energy, Optics, and Electronics)
The development of inorganic membranes has mainly found applicability in liquid separation technologies. However, only a few reports cite the permeation and separation of liquids through inorganic nanofiltration membranes compared with the more popular microfiltration membranes. Herein, we prepared silica membranes using 3,3,3-trifluoropropyltrimethoxysilane (TFPrTMOS) to investigate its liquid permeance performance using four different ion solutions (i.e., NaCl, Na2SO4, MgCl2, and MgSO4). The TFPrTMOS-derived membranes were deposited above a temperature of 175 °C, where the deposition behavior of TFPrTMOS was dependent on the organic functional groups decomposition temperature. The highest membrane rejection was from NaCl at 91.0% when deposited at 200 °C. For anions, the SO42− rejections were the greatest. It was also possible to separate monovalent and divalent anions, as the negatively charged groups on the membrane surfaces retained pore sizes >1.48 nm. Ions were also easily separated by molecular sieving below a pore size of 0.50 nm. For the TFPrTMOS-derived membrane deposited at 175 °C, glucose showed 67% rejection, which was higher than that achieved through the propyltrimethoxysilane membrane. We infer that charge exclusion might be due to the dissociation of hydroxyl groups resulting from decomposition of organic groups. Pore size and organic functional group decomposition were found to be important for ion permeation. View Full-Text
Keywords: silica membrane; counter diffusion CVD method; chemical vapor deposition; reverse osmosis; nanofiltration; ion separation; fluorine silica precursor silica membrane; counter diffusion CVD method; chemical vapor deposition; reverse osmosis; nanofiltration; ion separation; fluorine silica precursor
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Yoshiura, J.; Ishii, K.; Saito, Y.; Nagataki, T.; Nagataki, Y.; Ikeda, A.; Nomura, M. Permeation Properties of Ions through Inorganic Silica-Based Membranes. Membranes 2020, 10, 27.

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