Permeation Properties of Ions through Inorganic Silica-Based Membranes.

Junko Yoshiura,Yuta Saito,Katsunori Ishii,Ayumi Ikeda,Mikihiro Nomura,Takaya Nagataki,Yuhei Nagataki

doi:10.3390/membranes10020027

Abstract

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.

Highlights

The technique of liquid separation using inorganic membranes has been one of the most compelling developments in recent decades, as they have the potential for highly selective separations through manipulation of their thermal and chemical properties [1,2]
In this paper, the ion permeation behavior of silica membranes prepared by the counter were investigated, tracking the effects of some unique hydrophobic membranes prepared from 3,3,3-trifluoropropyltrimethoxysilane (TFPrTMOS)
We found the decomposition of CF3 –C2 H4 to occur around 120–230 ◦ C and compared◦ with C3H

Summary

Introduction

The technique of liquid separation using inorganic membranes has been one of the most compelling developments in recent decades, as they have the potential for highly selective separations through manipulation of their thermal and chemical properties [1,2]. Sintered inorganic microfiltration (MF) membranes have had ample interest, especially for industrial applications. For NF membranes, their permeation properties can be described through molecular sieving and charge effects. Compared with RO, modern NF membranes have been used successfully for the production of ultrapure water in semiconductor production facilities due to the higher fluxes they administer. Commercial NF membranes such as aromatic polyamides, polypiperazine amides, and sulfonated polyethersulfones, have all been favorably applied for water treatment. Yuan et al [3] reported the ion permeation behavior of the polyamide membrane where the ion rejections

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Results

Conclusion