Pore size and surface chemistry effects on the transport of hydrophobic and hydrophilic solvents through mesoporous γ-alumina and silica MCM-48

Chowdhury, Sankhanilay Roy

doi:10.1016/j.memsci.2003.07.018

Cited by 72 publications

(34 citation statements)

References 33 publications

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“…If Darcy's law is followed, the relationship ηJ CO 2 versus − P for a given membrane is expected to be independent of solvent type and solely dependent upon k m . Deviations from Darcy's law have been attributed to multiple transport mechanisms and solvent-membrane interactions [2,3]. For liquid carbon dioxide, mass transfer resistance in the ␣-alumina support is negligible (data not shown).…”

Section: Theorymentioning

confidence: 98%

“…In submicron pores, these interactions yield a disjoining pressure, which is dominated by van der Waals and structural surface forces [1,2]. Physical and chemical solvent sorption may further influence the effective pore radius, porosity, and surface chemistry [3,4]. Results have shown that the ultimate effect of solvent-membrane interactions is low permeability and deviation from Darcy's law (viscous flow), which states that liquid flux through a given membrane is dependent on viscosity and the transmembrane pressure [2,3,5,6].…”

Section: Introductionmentioning

confidence: 99%

“…Physical and chemical solvent sorption may further influence the effective pore radius, porosity, and surface chemistry [3,4]. Results have shown that the ultimate effect of solvent-membrane interactions is low permeability and deviation from Darcy's law (viscous flow), which states that liquid flux through a given membrane is dependent on viscosity and the transmembrane pressure [2,3,5,6]. Given the complex solvent permeation behavior, a number of investigations have focused on elucidating membrane transport mechanisms and the effects of solvent-membrane interactions for alcohols [2,3,5], apolar organics [2,3,6,7], and supercritical carbon dioxide (T c = 304.2 K; P c = 73.8 bar) [8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

“…Recent investigations have focused on hexane [2,3,6,7], heptane [2], and toluene [2,3,7] permeability in mesoporous (2-50 nm pore diameter) and microporous (<2 nm) ceramic membranes. For instance, Chowdhury et al [3] observed 40 and 73% reductions in toluene and hexane permeability (relative to water) through 4.5-7.4 nm ␥-alumina, respectively, despite normalizing against solvent viscosity. It was shown in a subsequent study [7] that initial threshold pressures observed for hexane and toluene were due to trace amounts of water in the solvent phases.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Sorption and hydration effects on liquid carbon dioxide transport through mesoporous γ-alumina and titania membranes

Bothun

Ilias

Nelson

2006

Journal of Membrane Science

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Section: Theorymentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Sorption and hydration effects on liquid carbon dioxide transport through mesoporous γ-alumina and titania membranes

Bothun

Ilias

Nelson

2006

Journal of Membrane Science

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“…In addition, water molecules are also known to interact with the alumina surface. 23 These interactions are competitive. Therefore, when the water concentration increases, the interaction between solutes and the alumina surface is reduced by not only solvation of solutes but also interactions between alumina and water molecules.…”

mentioning

confidence: 99%

Utilization of Nanometre-order Diameter Columns inside Porous Anodic Alumina for Chromatography Chip System

Yamashita¹,

Kodama²,

Ohto³

et al. 2007

Chemistry Letters

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Porous anodic alumina (PAA) membranes were used as a nanometre-order diameter column for chromatography chip with acetonitrile-water mobile phase using gradient elution. In a chromatogram, 9-anthracenemethanol (AM), 9-anthracenecarboxylic acid (AC), and dansyl-glycine (DG) showed different retention times, indicating that PAA membranes are applicable to stationary phase for chromatography chip.Porous anodic alumina (PAA) membranes, 1-5 which consist of a self-assembled honeycomb array of uniformly sized parallel channels, have attracted considerable interest in various areas such as electronics, chemistry, and biomedical science because of their ordered structure, superior resistance to organic solvents, and potentially low cost. The diameter of PAA channels can range from about ten to several hundred nanometers, and membrane thickness is 10 to 100 mm. When solutes permeate through the PAA membrane, the interior of the columnar channels interacts with the solutes molecules. The elution of solutes from the channels depends on the strength of the interaction with the interior.6 Alumina is widely used for chromatographic matrix in liquid chromatography, and its chromatographic properties have been studied in detail. [7][8][9] However, few studies have been carried out on the utilization of PAA in liquid chromatography.A PAA membrane is very thin, which is favorable for reducing the sizes of analysis systems. In this study, we used PAA membranes (Anodisk, 100-nm-diameter pores, 60-mm thick, Whatman) as stationary phase in the chromatography chip and tested whether PAA membranes can function as chromatographic columns in chip system. The chromatography chip, which has been intensively studied, 10-21 is a small tool that can function as chromatographic system. Figure 1 shows a schematic illustration of the experimental setup for chromatographic measurements and a picture of a chip. Five PAA membranes were set in the chip as stationary phase.24 Glycol-modified polyethylene terephthalate (PETG, Mitsubishi Rayon Co., Ltd.) was used for the chip substrate. As solute molecules, 9-anthracenemethanol (AM), 9-anthracenecarboxylic acid (AC), and dansyl-glycine (DG) were selected. The chromatograms of each solute were presented in Figure 2. The retention times of each solute were different, indicating that PAA membranes can function as chromatographic columns with acetonitrile-water mobile phase.The retention time reflects the strength of the interaction between solutes and interior of the nanochannels. The strength of the interaction was measured by putting a solution of the solutes to be tested in two bottles, one with one without a PAA mem-

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A Microporous Titania Membrane for Nanofiltration and Pervaporation

Sekulic

Elshof²,

Blank

2004

Advanced Materials

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Ceramic microporous membranes with pore sizes < 2 nm are known for their relatively high chemical, mechanical, and thermal stability, and they offer potential applications in gas purification and separation, pervaporation, and nanofiltration processes. However, very few microporous ceramic materials with a pore size < 1 nm (therefore suitable for membrane applications) are available. Amorphous silica membranes with pore sizes of between 0.3±0.5 nm have been studied extensively over the past decade.[1] However, ceramic sol±gel membranes with a narrow pore size distribution and pore sizes in the range of 0.6±1.3 nm are scarce.[2] Although microporous silica is a very selective membrane material for hydrogen separation [3] and pervaporation of water from liquid mixtures, [4] its chemical stability in alkaline media and strong electrolyte solutions is limited. [5] The amorphous phase of titania, which is known to be microporous, is expected to be more stable under these conditions. We prepared defect-free microporous titania membranes of between 50±150 nm thickness with a maximum pore size of~0.9 nm. These membranes demonstrated ideal hydrogen/hydrocarbon permselectivities above the theoretical limit for Knudsen diffusion and have also been shown to be selective in the pervaporation of water from water/1,4-dioxane and water/glycol binary liquids. Moreover, nanofiltration experiments have showed that these membranes have a molecular weight cut-off below 400, indicating their potential for water purification applications. Attempts in the 1990s to prepare microporous titania membranes already showed some promising results, but the average pore sizes obtained in those studies were~1.5 nm, and the Knudsen diffusion limit was not exceeded.[6] More recently, microporous titania membranes attracted attention as nanofiltration membranes [7] and molecular weight cut-offs ranging between 500±600 were reported. We studied the relationship between sol±gel processing conditions and the titania microstructure. Polymeric titania sols in ethanol were prepared by mixing titanium alkoxide solutions with water and nitric acid. Unlike silica, which does not crystallize, amorphous titania easily converts into crystalline anatase during synthesis. Low molecular weight polymeric sols were obtained only when the hydrolysis conditions were strictly controlled. The rate of hydrolysis of titanium alkoxides by water is extremely high [8] and any local excess of water at any moment had to be avoided. For a given titanium concentration, the hydrolysis-condensation reactions were governed by two parameters, the initial hydrolysis ratio . The hydrolysis of titanium tetraethoxide in the presence of different amounts of acid and water led to sols, turbid or clear gels, or precipitates, depending on r w and r a , as shown in Figure 1a.The main determining parameter for the final particle size was found to be r w , which had to be kept at values below 2 in order to prevent fast gelation of the sol. A pH > 3 solution was required to form polymeric so...

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Pore size and surface chemistry effects on the transport of hydrophobic and hydrophilic solvents through mesoporous γ-alumina and silica MCM-48

Cited by 72 publications

References 33 publications

Sorption and hydration effects on liquid carbon dioxide transport through mesoporous γ-alumina and titania membranes

Sorption and hydration effects on liquid carbon dioxide transport through mesoporous γ-alumina and titania membranes

Utilization of Nanometre-order Diameter Columns inside Porous Anodic Alumina for Chromatography Chip System

A Microporous Titania Membrane for Nanofiltration and Pervaporation

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