Silylated Mesoporous Silica Membranes on Polymeric Hollow Fiber Supports: Synthesis and Permeation Properties

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• 作者：Hyung-Ju Kim ; Nicholas A. Brunelli ; Andrew J. Brown ; Kwang-Suk Jang ; Wun-gwi Kim ; Fereshteh Rashidi ; Justin R. Johnson ; William J. Koros ; Christopher W. Jones ; Sankar Nair
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2014
• 出版时间：October 22, 2014
• 年：2014
• 卷：6
• 期：20
• 页码：17877-17886
• 全文大小：599K
• ISSN：1944-8252

文摘

We report the synthesis and organic/water separation properties of mesoporous silica membranes, supported on low-cost and scalable polymeric (polyamide-imide) hollow fibers, and modified by trimethylsilylation with hexamethyldisilazane. Thin (鈭? 渭m) defect-free membranes are prepared, with high room-temperature gas permeances (e.g., 20鈥?00 GPU for N₂). The membrane morphology is characterized by multiple techniques, including SEM, TEM, XRD, and FT-ATR spectroscopy. Silylation leads to capping of the surface silanol groups in the mesopores with trimethylsilyl groups, and does not affect the integrity of the mesoporous silica structure and the underlying hollow fiber. The silylated membranes are evaluated for pervaporative separation of ethanol (EtOH), methylethyl ketone (MEK), ethyl acetate (EA), iso-butanol (i-BuOH), and n-butanol (n-BuOH) from their dilute (5 wt %) aqueous solutions. The membranes show separation factors in the range of 4鈥?0 and high organic fluxes in the range of 0.18鈥?.15 kg m^鈥? h^鈥? at 303 K. The intrinsic selectivities (organic/water permeability ratios) of the silylated membranes at 303 K are 0.33 (EtOH/water), 0.5 (MEK/water), 0.25 (EA/water), 1.25 (i-BuOH/water), and 1.67 (n-BuOH/water) respectively, in comparison to 0.05, 0.015, 0.005, 0.08, and 0.14 for the unmodified membranes. The silylated membranes allow upgradation of water/organics feeds to permeate streams with considerably higher organics content. The selective and high-flux separation is attributed to both the organophilic nature of the modified mesopores and the large effective pore size. Comparison with other organics/water separation membranes reveals that the present membranes show promise due to high flux, use of scalable and low-cost supports, and good separation factors that can be further enhanced by tailoring the mesopore silylation chemistry.

Keywords:

mesoporous silica; membrane; hollow fiber; silylation; organics/water separation