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The nickel-doped bis [3-(trimethoxysilyl) propyl] amine (BTPA) derived membrane has a microporous coordinated network that has high potential to be an ideal separation barrier for methanol-toluene azeotropic mixtures via the pervaporation process. Ni-BTPA membranes were modified by employing a nickel dopant over amine groups in mole ratios (mol/mol) that ranged from 0.125 to 0.50. The incorporation of different amounts of nickel dopant into flexible amine-rich organosilica precursors of BTPA increased the rigidity and resulted in a porous structure with a large specific surface area (increased from 2.36 up to 282 m2 g-1) and a high pore volume (from 0.024 up to 0.184 cm3 g-1). Methanol-toluene separation performance by the nickel-doped BTPA (Ni-BTPA) membranes was increased with increases in the nickel concentration. Ni-BTPA 0.50 showed separation performance that was superior to other types of membranes, along with a high-level of flux at 2.8 kg m-2 h-1 and a separation factor higher than 900 in a 10 wt % methanol feed solution at 50 °C. These results suggest that the balance between the microporosity induced by amine-nickel coordination and an excessive amount of nickel-ion facilitates high levels of flux and separation of methanol.

Starting from room temperature (27 °C), graphene oxide (GO) was annealed stepwise at 100 °C, 200 °C and 300 °C and detailed structural characterizations like FTIR (Fourier transform infrared spectroscopy), XPS (X-ray photoelectron spectroscopy), XRD (X-ray powder diffraction) and Raman spectroscopy revealed that with increase in temperature, transformation from GO to rGO (reduced graphene oxide) took place and complete conversion was achieved at 300 °C. With increase in temperature, the functional groups like epoxy, ether, carbonyl and carboxyl were gradually reduced and at 300 °C, only the hydroxyl group became dominant. The gas sensing study was carried out using NH3 and alcohols in the concentration range of 125 ppb-700 ppm. It was observed that for lower ppm (5-50 ppm) the GO based sensors offered better selectivity towards NH3, while rGO exhibited better NH3 selectivity at higher concentrations (200-700 ppm). Possibly, presence of hydroxyl group is favorable for NH3 adsorption and therefore NH3 selectivity is better in rGO particularly at high concentrations. On the other hand, at low NH3 concentrations, presence of various types of functional groups in GO gives a resultant selectivity which is better compared to that of rGO.

In this study an easy template was devised for the fabrication and microstructural control of ligand-chelated, silica–zirconia-based composite membranes with a thickness of less than 400 nm. Hybrid materials with crosslinking between the organic moieties were successfully fabricated via the sol–gel co-condensation of 3-(trimethoxysilyl)propyl methacrylate and zirconium(IV) butoxide chelated via acetylacetone and allyl acetoacetate ligands using an azobisisobutyronitrile radical initiator as a crosslinking agent. Characterization of the films and gels via FTIR, XRD and thermogravimetry indicated that both the polymerization and hybridization of the networks was achieved. Gas permeation experiments showed that the organic crosslink-derived membranes possess molecular sieving properties (H2 permeance: ≈10−7 mol m−2 s−1 Pa−1; H2/N2 selectivity: ≈20–30) that are superior to those of non-crosslink-derived membranes (H2 permeance: ≈10−7 mol m−2 s−1 Pa−1; H2/N2 selectivity: ≈7–11). Quantitative analysis of the microstructures of the membranes based on the permeation behaviors of H2 and N2 revealed that organic crosslinking led to significant control of the microstructural characteristics of the membranes.

Inorganic microporous materials have shown promise for the fabrication of membranes with chemical stability and resistance to high temperatures. Silicon-carbide (SiC) has been widely studied due to its outstanding mechanical stability under high temperatures and its resistance to corrosion and oxidation. This study is the first to prepare mesoporous SiC membranes for use in sulphuric acid decomposition to achieve thermochemical water splitting in the iodine–sulfur process. Single-gas permeation was carried out to confirm the stability of this mesoporous membrane under exposure to steam and H2SO4 vapor. Benefiting from the excellent chemical stability of the α-Al2O3 membrane support and the SiC particle layer, the SiC membrane exhibited stable gas permeance without significant degradation under H2SO4 vapor treatment at 600 °C. Additionally, with extraction, the membrane reactor exhibited an increased conversion from 25 to 41% for H2SO4 decomposition at 600 °C. The high performance combined with outstanding stability under acidic conditions suggests the developed SiC membrane is a promising candidate for H2SO4 decomposition in a catalytic membrane reactor.

A 34-year-old man was transported by ambulance to our hospital after experiencing generalized convulsions. He had been of short stature since birth, and had been diagnosed with growth hormone deficiency, which was treated with growth hormone therapy from 10 to 14 years of age. He experienced convulsions two times at 32 and 33 years of age, respectively, with spontaneous recovery. He had no specific family history. On arrival, he had clear consciousness and sinus tachycardia. A physical examination revealed short stature. A biochemical analysis of venous blood revealed hypocalcemia and a low level of parathyroid hormone. Head computed tomography (CT) revealed diffuse hyperostosis of the cranial vault and truncal CT revealed cartwheel apperance in the thoracic vertebral bodies from Th9 to Th12. He was treated with levetiracetam, alfacalcidol and calcium agents. Next-generation sequencing suggested heterozygous large deletion of T-box transcription factor (TBX1) gene. This is the first report of hypoparathyroidism with cartwheel-like change in the thoracic vertebral body. The further accumulation of cases is necessary to determine whether this change is specific to hypoparathyroidism.

Polyhedral oligomeric silsesquioxane (POSS) is a promising nanofiller with a cubic inorganic framework and optional organic functional groups. In this work, organosilica–POSS mixed matrix membranes...

Sol-gel-derived organosilica membranes with different linking groups consisting of 2 carbon atoms (ethane, ethylene, and acetylene) were fabricated using bis(triethoxysilyl)ethane (BTESE), bis(triethoxysilyl)ethylene (BTESEthy), and bis(triethoxysilyl)acetylene (BTESA). No research group has ever proposed tailoring the microstructure and permeation properties of bridged organosilica membranes as a way to control the bond angles. In this study, however, we found that increases in the Si–O–Si and Si–C–C bond angles contributed to the formation of a loose and uniform structure, which was suggested by the blue shift of Si–O–Si and Si–C–C bonds in the FT-IR spectra. BTESA membranes featured a more open and accessible pore structure, which was suitable for the separation of C3H6/C3H8. The present study provides a novel way to design the microstructure and permeation properties of organosilica membranes via controlling the bond angles in the network structure.

The hydrothermal stability of TiO2-ZrO2 nanofiltration (NF) membranes fired at 200, 400, and 550 °C was examined at 90 °C for 4–100 h, followed by an evaluation of the NF performance at 25 °C. After hot-water treatment, the water permeability (Lp) of a membrane fired at 200 °C had slightly increased, while that of membranes fired at 400 and 550 °C had drastically decreased. Meanwhile, the values for molecular weight cut-off (MWCO) were decreased for all membranes. The Lp and MWCO changed during the initial 20 h and remained constant for as long as 100 h, confirming the stability in an aqueous solution at 90 °C. The permeation properties of water and neutral solutes were evaluated for temperatures that ranged from 25 to 85 °C. The water permeability and permeate flux increased with an increase in temperature, while the rejection of solutes decreased. Based on analysis using the Spiegler-Kedem equations, the reflection coefficient was constant irrespective of permeation temperature, while both water and solute permeability were increased with an increase in the permeation temperature, which revealed that the permeation mechanism of water and neutral solutes is an activated process. In addition, the activation energies of solute permeability were found to be higher than those of water permeability.

Network size control was evaluated for microporous membranes derived from triethoxysilane (TRIES) that contains highly reactive Si–H groups. It was possible to control the concentration of the Si–H...

Experimentation and numeric calculation were focused on n-butyl acetate (BA) production from Methyl acetate (MA) and n-butanol (BuOH) via Membrane reactor to extract methanol (MeOH) through 1,2-bis(triethoxysilyl)acetylene(BTESA)-derived organosilica membranes. A batch reactor (BR) model was formulated using Damkohler number (Da) and Permeation number (θ) similarly to plug flow reactor. Simulation on the effect of Da, θ, permeance ratio of MeOH (αi) and MA/BuOH feed molar ratio (δ) showed that a α > 20 and a θ > 10 are required to achieve a high BA yield. BTESA membranes showed high performance for MeOH removal from the mixtures with various types of organic solvents such as various esters, alcohols, Toluene, and ketone. Two types of BTESA membranes: high-flux (M−1) and high-selectivity (M−2), which showed MeOH flux of 4.2 kg/(m2 h) and 2.6 kg/(m2 h), and separation factor of 3100 and 9200, respectively, for MeOH/BA mixtures (MeOH 10 wt%, 50°C), were used for the transesterification membrane reactor. Batch-type membrane reactor performances were evaluated experimentally using M−1 and M−2 membranes. At MA/BuOH feed molar ratio, δ , of 2, extraction of MeOH increased the BA yield reached as high as 95.4%, which was higher than that of equilibrium (60%). Experimental results agreed with numeric calculations without fitting parameters.

Long-chain organosilica bis(triethoxysilyl)propane (BTESP) membranes typically have a flexible non-porous structure. Fluorine was used to tune the network pore structure of BTESP membranes in an effort to improve the gas permeation properties. The network pore size was enlarged and the effect of calcination temperature on the network structure was evaluated based on gel and membrane characterizations. Fluorine-doped BTESP membranes calcined at 350 °C and 650 °C have shown H2 permeance on the orders of 1.2 × 10−6 mol m−2 s−1 Pa−1 and 1.5 × 10−6 mol m−2 s−1 Pa−1 with H2/N2 selectivities of 8 and 6, respectively, which indicates similar pore sizes with lower condensation effect at high temperature of 650 °C, that was suppressed due to the presence of Si–F and C–F bonds. Undoped BTESP membranes, on the other hand, showed H2/N2 selectivity that was significantly lower—from 24 to 11 at 650 °C. FT-IR and N2 adsorption isotherms clearly indicated that fluorine significantly decreased the Si–OH density and increased the surface area and micropore volume. Further water adsorption analysis revealed that fluorine significantly increased the hydrophobicity of the BTESP network structure. Overall, the results of this study endorse the effectiveness of fluorine to control the network pore structure in both wet and dry molecular separation systems.

This work reports the preparation of a carbonized SiO2–ZrO2 composite membrane with enhanced H2 permselectivity via a sol-gel process. The sol-gel synthesis of the precursor SiO2–ZrO2-acetylacetonate composite was optimized by studying the effect that the water/alkoxide molar ratio exerted on the final properties of carbon-SiO2-ZrO2. Characterization by thermogravimetry, XRD, and N2 adsorption revealed that utilizing a water/alkoxide molar ratio of 60 was optimal for the retention of carbon and for promoting the qualities of amorphousness and microporosity. Furthermore, using a Si/Zr ratio of 9/1 in a carbon-SiO2-ZrO2 membrane resulted in a high level of H2 permselectivity. This membrane showed H2 permeance of 16 x 10−7 mol m−2 s−1 Pa−1 and H2/N2 and H2/CH4 ideal selectivities of 75 and 148, respectively. More importantly, the H2 permselectivity of the carbon-SiO2-ZrO2 membrane exceeded that of a similarly pore-distributed unmodified SiO2–ZrO2 membrane with an H2 permeance of 3 x 10−7 mol m−2 s−1 Pa−1. This enhanced H2 permselectivity was attributed to the increase in pore volume contributed by ultra-micropore-bearing carbon nanoparticles.

Hybrid organosilica membranes of silver-doped bis [3-(trimethoxysilyl) propyl] amine (BTPA) were prepared via sol-gel processing followed by coordination reactions to improve the permeability and separation performance. The evolution of silver in two phases as silver ions and as nanoparticles was observed during modification of the aminosilica networks; the silver ions coordinated with amine moieties while the silver nanoparticles developed following reduction on the aminosilica surface. The silver/amine mole ratio was evaluated against the formation of coordinated and particulate species during modification in the range of 0.1–0.5 mol mol−1. The formation of microporosity was successfully developed from 2.36 to 115 m2 g−1 by increasing the silver mole ratio. Furthermore, silver-modified aminosilica membranes showed a hydrogen (H2) permeance of 1.46 × 10−6 mol m−2 s−1 Pa−1, which was 65-fold higher than pure BTPA with excellent selectivity for H2/propane (C3H8) separation of 1500. It is evident that the proposed modification method via the two-phase structural evolution of silver coordination and nanoparticles reorganized the organosilica framework and improved the separation in the dehydrogenation of propane.

Organosilica membranes were developed and showed excellent stability in aqueous solutions, which raised expectation for applications to pervaporation dehydration. In order to investigate the properties of pervaporation through organosilica membranes, 1,2-(bistriethoxysilyl)ethane (BTESE)-derived membranes with different pore sizes (0.44 nm and 0.54 nm) were prepared by tuning the acid molar ratio in the sols, then applying the resultant membranes to the gas permeation of various single gases (He, H2, CO2, N2, CH4, CF4, and SF6) as well as to the pervaporation dehydration of aqueous solutions (methanol, ethanol, n-propanol, iso-propanol, n-butanol, tert-butanol, acetone, and n-methyl-2-pyrrolidone). Both membranes showed high levels of both water permeance (>10−6 mol/(m2 s Pa)) and separation factors for water/iso-propanol (500–6000). Both the permeances in pervaporation and in gas permeation tended to decrease with an increase in the molecular size and a decrease in the pore size, which confirmed the contribution of the molecular sieving effect. Pervaporation performance was correlated with gas permeation performance.

A SiOC membrane with high oxidative stability for gas separation was tailored by utilizing vinyltrimethoxysilane, triethoxysilane, and 1,1,3,3-tetramethyldisiloxane as Si precursors. Amorphous SiOC networks were formed via the condensation of Si–OH groups, the hydrosilylation of Si–H and Si–CH=CH2 groups, and a crosslinking reaction of Si–CH3 groups, respectively. The crosslinking of Si–CH3 groups at temperatures ranging from 600 to 700 °C under a N2 atmosphere was quite effective in constructing a Si–CH2–Si unit without the formation of mesopores, which was confirmed by the results of N2 adsorption and by the gas permeation properties. The network pore size of the SiOC membrane calcined at 700 °C under N2 showed high oxidative stability at 500 °C and was appropriate for the separation of large molecules (H2/CF4 selectivity: 640, H2/SF6: 2900, N2/CF4: 98). A SiOC membrane calcined at 800 °C showed H2/N2 selectivity of 62, which was approximately 10 times higher than that calcined at 700 °C because the SiOC networks were densified by the cleavage and redistribution reactions of Si–C and Si–O groups.

This study investigated the effect of acid post-treatment on the filtration performance of organosilica membranes. The membranes were prepared from 1,2-bis(triethoxysilyl)ethane (BTESE) via sol-gel processing with different H2O/BTESE molar ratios. Fourier-transform infrared spectra significant residual ethoxy groups within membranes derived from sols with low H2O/BTESE ratios, after firing at 300 °C in N2. The ethoxy groups within the membranes were hydrolyzed to hydroxide groups by immersing the membranes in hydrochloric acid (HCl). This rendered the membranes more hydrophilic. The hydroxyl groups may have promoted the formation of hydrophilic pores, which would in turn promote water permeation. The HCl-treated membranes showed higher water permeability than the original BTESE-derived membrane. The effect of HCl treatment was more pronounced for the membrane prepared with the lowest H2O/BTESE ratio of 1, resulting in approximately three times higher water permeability than the original membrane. Membranes prepared from sols with low H2O/BTESE ratios showed improved solute rejection and increased water permeability, upon HCl treatment. This was attributed to cross-linking in the organosilica matrix via the condensation of newly-formed hydroxyl groups, that caused the narrowing or blocking of large pores.

Based on their high performance in gas and liquid-phase separations, 1,2-bis(triethoxysilyl)ethane (BTESE)-derived organosilica membranes have attracted much attention. To improve performance, we focused on the acid molar ratio (AR) in sol preparation and its effect on the pore formation mechanism during sol-gel processing. BTESE-derived sols with AR = 10−4–100 were prepared, and the effect of the AR on the gel structure was evaluated in detail via FT-IR, nuclear magnetic resonance (NMR), N2 adsorption, and positron annihilation lifetime (PAL) measurements. The chemical structure of the gels was confirmed by FT-IR and NMR and showed that sols with the largest number of silanol groups (AR = 10−2) experienced a significant increase in condensation during the firing process. The porous structures of fired gels characterized by N2 adsorption and PAL measurement showed that the AR = 10−2 fired gel consisted of a larger number of small pores that had formed during the firing process. Single-gas permeation experiments showed high H2 permeance (5–9 × 10−7 mol/(m2 Pa s)) and H2/CF4 selectivity (700–20,000). The gas permselectivity (He/H2, H2/N2, and H2/CF4) was highest for the intermediate AR (=10−2), which corresponded to the greatest amount of silanol groups in unfired gels and confirmed that small pores had formed from the condensation of silanol groups during firing.

The use of inexpensive porous polymers instead of conventional ceramics to support silica-based membranes can potentially minimize the cost of membrane synthesis. To develop polymer-supported silica-based membranes, lowering the high synthesis temperature of the silica-based top layer is essential. In this study, we explore the application of atmospheric-pressure plasma-enhanced chemical vapor deposition (AP-PECVD) for synthesizing polymer-supported silica-based membranes. The deposition of a continuous silica-based layer on an asymmetric polysulfone ultrafiltration membrane using hexamethyldisiloxane as an organosilicon precursor was achieved at ambient temperature and pressure via AP-PECVD. The gas permeation properties of the AP-PECVD-derived polymer-supported membranes strongly depended on the deposition duration, as prolonged deposition could reduce the remaining defects by covering the entire surface of the support with the plasma-deposited layer. The membranes showed increased selectivities for H2/N2 and H2/SF6 from 2.9 to 9.5, and from 4.5 to 184, respectively, exhibiting gas permeation dominated by molecular sieving. The present study demonstrates that AP-PECVD is a promising strategy for the fabrication of polymer-supported silica-based membranes for gas separation.

Triethoxyfluorosilane (TEFS), which is a pendant-type alkoxysilane with a Si–F bond, was utilized for the development of a molecular sieving membrane. The effect that a source of fluorine and calcination temperature exerted on gas permeation properties and network pore size was evaluated via single-gas permeation properties across a wide range of temperatures. A TEFS membrane calcined at 350 °C showed high H2 permeance (2.0 × 10–6 mol m–2 s–1 Pa–1) and high selectivity for H2 over larger molecules (H2/CF4: >300; H2/SF6: >18 000), indicating that this network pore size would be suitable for a H2 permselective membrane that could promote the process of methylcyclohexane (MCH) dehydrogenation to produce toluene (TOL). Based on the gas permeation properties and the results of XPS and FTIR, network pore size depended on the fluorine concentration incorporated in SiO2 that existed as Si–F bonds, irrespective of the fluorine source. A TEFS membrane showed approximately the same pore size distribution and level o...

Organosilica membranes were fabricated using bridged organoalkoxysilanes (bis(triethoxysilyl)methane (BTESM), bis(triethoxysilyl)ethane (BTESE), bis(triethoxysilyl)propane (BTESP), bis(trimethoxysilyl)hexane (BTMSH), bis(triethoxysilyl)benzene (BTESB), and bis(triethoxysilyl)octane (BTESO)) to produce highly permeable molecular sieving membranes. The effect of the organoalkoxysilanes on network pore size and microporous structure was evaluated by examining the molecular size and temperature dependence of gas permeance across a wide range of temperatures. Organosilica membranes showed H2/N2 and H2/CH4 permeance ratios that ranged from 10 to 150, corresponding to network pore size, and both H2 selectivity decreased with an increase in the carbon number between 2 Si atoms. Organosilica membranes showed activated diffusion for He and H2, and a slope of temperature dependence that increased approximate to the increase in the carbon number between 2 Si atoms. The relationship between activation energy and He/H2 permeance ratio for SiO2 and organosilica membranes suggested that the molecular sieving can dominate He and H2 permeation properties via the rigid microporous structure, which was constructed by BTESM and BTESE. With increased in the carbon concentration in silica, polymer chain vibration in organic bridges, which is a kind of solution/diffusion mechanism, can dominate the permeation properties. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4491–4498, 2017

A novel pyrimidine-bridged organoalkoxysilane precursor, 4,6-bis(3-triethoxysilyl-1-propoxy)-1,3-pyrimidine (BTPP), was synthesized via a platinum-catalyzed reaction and subsequently a BTPP membrane was developed via a sol-gel process. This new membrane exhibits great potential for improved CO 2 separation compared with common amine-functionalized organosilica membranes. Possible CO 2 transport mechanisms across amine-functionalized organosilica membranes were explored by comparing the CO 2 sorption behaviors of organoalkoxysilane materials with both strong and mild affinities. The results showed that a membrane with strong affinity to CO 2 does not lead to a superior CO 2 separation capability. Hence, the concept of a “mild-affinity membrane” was proposed, which describes membranes with intermediate-to-low CO 2 binding energy that exhibits an improved level of CO 2 transport efficiency. The concept of a mild-affinity membrane offers the development of technological innovation leading to the realization of highly efficient CO 2 separation membranes.

Triethoxysilane (TRIES), which consists of three ethoxy groups and a Si-H bond as a pendant-type alkoxysilane, was utilized as a Si precursor for the fabrication of a gas separation membrane. The effect of membrane fabrication parameters such as sol preparation conditions and calcination temperatures on Si-H groups and network structures was evaluated. The degree of dehydrogenation of Si-H groups in aqueous solution was independent of the H 2 O/Si molar ratio in the sol, but the degree of hydrolysis and polymerization of ethoxy groups (-OEt) depended on the H 2 O molar ratio. TRIES membranes calcined at 550 °C under N 2 showed a decrease in network size with an increase in the H 2 O/Si molar ratio in the sol. The TRIES-derived network pore size also depended on the calcination temperature, and the network size was decreased under lower calcination temperatures. For example, a TRIES membrane calcined at 550 °C showed high selectivity for He/N 2 and H 2 /N 2 at approximately 1000 and 600, respectively, however, in the case of calcination at 300 °C, Knudsen diffusion dominated for small molecules (H 2 /N 2 selectivity: 4.3) and molecular sieving favored large molecules (H 2 /CF 4 : >100, H 2 /SF 6 : >400). When a TRIES membrane was fabricated by calcination at 300 °C, most Si-H groups were still present in the networks, the estimated network pore size for the TRIES membrane was 0.577 nm, which was larger than that of a tetraethoxysilane (TEOS) membrane calcined at 350 °C (0.426 nm). On the other hand, when TEOS and TRIES membranes were fabricated at 550 °C, both membranes showed approximately the same network pore size (TEOS: 0.385 nm, TRIES: 0.382 nm), due to the dehydrogenation of Si-H groups in the formation of Si-OH groups as well as for the forming of a Si–O–Si bond.

Microporous silica membranes with high permselectivity are fabricated by atmospheric-pressure plasma-enhanced chemical vapor deposition (AP-PECVD) using hexamethyldisiloxane as the precursor in plasma working gases of pure argon, and mixture of argon with oxygen or nitrogen. A silica membrane grown using plasma composed of a mixture of argon and nitrogen displays highly efficient gas separation, with selectivities for He/N 2 and He/SF 6 of 196 and 820, respectively, and He permeance of 1.1×10 −7 mol m −2 s −1 Pa −1 at 50 °C. Characterization of the membranes by FTIR and X-ray photoelectron spectroscopies reveals a relatively high concentration of carbon remains in the membrane grown using a mixture of argon and nitrogen. Annealing at elevated temperature after plasma deposition improves the permselectivity of the membranes. After annealing at 300 °C, the permeance of He at 50 °C increased to 4.0×10 -7 mol m -2 s -1 Pa -1 with no marked decrease of selectivity (He/N 2 =98, He/SF 6 =770). The annealed membrane also exhibits remarkable permselectivity for CO 2 , showing selectivities for CO 2 /N 2 and CO 2 /CH 4 of 46 and 166, respectively, with CO 2 permeance of 1.9×10 -7 mol m -2 s -1 Pa -1 at 50 °C. AP-PECVD shows great promise to fabricate microporous silica membranes highly permselective for gas separation.

A novel approach to the preparation of polymer-supported silsesquioxane membranes is developed via photo-induced sol–gel processing. An organically bridged silsesquioxane thin layer by coating a silsesquioxane sol with a photo-acid generator onto a polymeric SPES/PSF composite nanofiltration membrane followed by irradiation with UV at room temperature. This polymer-supported silsesquioxane membrane derived from 1,2-bis(trimethoxysilyl)ethane displays selective water permeation with a water permeance of 3.0 × 10−6 mol m−2 s−1 Pa−1, and shows a separation factor of 99 in the pervaporation of a 90 wt% isopropanol aqueous solution.

Objective: This study aimed to retrospectively determine which laboratory data on arrival for patients with mamushi bites was useful to predict the severity of mamushi bites. Materials and Methods: The subjects were divided into the following two groups: the mild group included subjects with mamushi bites Grades I and II, while the severe group included subjects with mamushi bites Grades III, IV, and V. The subjects' variables were compared between the two groups. Results: There were no significant differences between the two groups regarding the levels of hematocrit, total protein, alanine aminotransferase, aspartate aminotransferase, creatinine phosphokinase, blood urea nitrogen, creatinine, and international normalized ratio of prothrombin time on arrival. Moreover, white blood cell count and platelet count on arrival in the mild group were significantly lower than those in the severe group. Furthermore, activated partial thromboplastin time on arrival was significantly higher in the mild group than in the severe group. Multivariate analysis using white blood cell count and platelet count and level of activated partial thromboplastin time revealed the following significant prognostic indicators of severity of mamushi bites: white blood cell count (Log Worth, 2.1; p

SiOC membranes were fabricated by a sol-gel method using three types of silica precursors: vinyltrimethoxysilane (VTMS), triethoxysilane (TRIES), and 1,1,3,3-tetramethyldisiloxane (TMDSO). The timing of the addition of TMDSO was evaluated via single-gas permeation for its effect on formation of the SiOC structure and on membrane performance. The effect that VTMS compounding exerted on membrane performance and on oxidation stability was also evaluated. The network size of SiOC membranes was precisely tailored by controlling the timing of the addition of TMDSO during the sol preparation process. There was no significant change in the network pore size either before or after thermally induced hydrosilylation (Si–C=C + Si–H → Si–CH2–CH2–Si) and the cross-linking of Si–CH3 groups (Si–CH3 + Si–CH3 → Si–CH2–Si + CH4). These SiOC membranes were highly selective of H2 over larger molecules such as CF4 and SF6. The effect of VTMS compounding on network pore size was small, but the oxidation stability of the SiOC structure at 500 °C was dramatically enhanced.

F-BTESM membranes were fabricated by doping a fluorine source into bis(triethoxysilyl)methane (BTESM), which is an organosilica precursor composed of Si–CH2–Si bonds. Pore size controllability and C3–C4 hydrocarbon permeation properties for F-BTESM membranes with different concentrations of fluorine were evaluated using single-gas permeation and N2/C3–C4 hydrocarbon binary separation. The pore size of an organosilica membrane can be precisely controlled via doping with the correct concentration of fluorine. The molecular sieving properties for C3/C4 hydrocarbon separation such as that for C3H6/iso-C4H8 was dramatically enhanced with the addition of a fluorine concentration of F/Si = 0.05, and this membrane showed a C3H6/iso-C4H8 permeance ratio of 388 at 50 °C. The permeance of hydrocarbon gases was increased with an expansion of the pore size, and F-BTESM (F/Si = 0.15) showed a high level of C3H6 permeance (>5.0 × 10−7 mol m−2 s−1 Pa−1). The results of hydrocarbon adsorption and single permeation properties showed that the carbon number of the hydrocarbons and the presence of unsaturated bonds enhanced the adsorption affinity to silica-derived materials. In the binary separation of N2/C3–C4 hydrocarbons, N2 permeance was remarkably decreased by comparison with single-gas permeation, which was due to a blocking effect by the hydrocarbons adsorbed inside the pores. Hydrocarbon gases with a stronger affinity tended to inhibit the permeation of N2.

The development of robust membranes able to withstand harsh environments such as oxidative conditions would improve the sustainability of several separation processes. Therefore, organosilica and ceramic non-commercial membranes were characterized and their performances were compared before and after contact with hydrogen peroxide. The organosilica membrane showed a high level of solute rejection coefficients (0.928 for NaCl and 0.969 for MgCl 2 ), but low permeability (5.04·10 –13 m 3 /m 2 s Pa, equivalent to 0.181 L/m 2 h bar). The ceramic membrane, however, showed low solute rejection (0.187 for NaCl and 0.649 for MgSO 4 ), but high membrane permeability (7.05·10 –12 m 3 /m 2 s Pa, equivalent to 2.538 L/m 2 h bar). While the organosilica membrane was quite sensitive to the presence of hydrogen peroxide, the chemical stability of the ceramic membrane in 30% hydrogen peroxide solution was very satisfactory. A Kedem-Katchalsky membrane transport model and a logistic decay model were applied to successfully test the performance of the membranes and to characterize the evolution of the organosilica membrane, respectively.

Membrane-based separation technologies are considered an effective process for the capture of CO2 due to advantages such as high levels of energy efficiency with inexpensive levels of investment. It remains challenging, however, to develop a membrane with high levels of both permeance and selectivity with the ability to capture CO2 in a highly efficient manner. Herein, we report amino-decorated organosilica membranes that are based on a facile and effective co-polymerization strategy that uses bis(triethoxysilyl)acetylene (BTESA) and (3-aminopropyl) triethoxysilane (APTES) precursors. This co-polymerization strategy simultaneously endows the resultant membranes with a controlled pore size and enhanced CO2-philic properties that have significantly improved CO2 separation performance. These composite membranes display CO2 permeance that ranges from 2550–3230 GPU and a range for CO2/N2 selectivity of 31–42 in the separation of CO2/N2 mixtures, which outperforms most state-of-the-art membranes and exceeds the target for post-combustion CO2 capture operations. A satisfying performance was achieved with a CO2 permeance of 8 ✕ 10−7 mol m−2 s−1 Pa−1 (2390 GPU) and CO2/CH4 selectivity of 70. The present study highlights an elegant decoration strategy for the production of membranes with ultrahigh CO2 capture capacities, which can also be extended to other organosilica precursors for target-oriented separations by varying the bridged or side-chain groups.

Membrane-based separation of organic/organic mixtures is of great importance in the chemical and petrochemical industries, but remains very challenging owing to the harsh working conditions. Herein, ultrathin and chemically stable Bis(triethoxysilyl)acetylene (BTESA)-derived organosilica membranes were reproducibly prepared, and for the first time they were utilized in the pervaporation separation of methanol/organic azeotropes. The as-prepared BTESA membranes exhibited exceptional pervaporation performance in a 10 wt%/90 wt% methanol/dimethyl carbonate (DMC) mixture, and showed a high separation factor of approximately 120 with a permeation flux of 2–4 kg m-2 h-1 at 50 °C. This impressive performance was primarily the result of the preferential sorption of methanol and the efficient size sieving of DMC. In addition, the effects of feed concentration and temperature on methanol/DMC pervaporation performance were thoroughly investigated. Importantly, a generalized solution-diffusion model successfully described the pervaporation performance of BTESA membranes, and the usefulness of this model was further confirmed via the pervaporation of methanol/methyl acetate and methanol/methyl tert-butyl ether (MTBE) mixtures. This work demonstrates the great potential of organosilica membranes for high-performance organic/organic pervaporation.

Bis(triethoxysilyl)propane (BTESP) is a bridged-type organoalkoxysilane with a Si-C3H6-Si bond. It was utilized for membrane fabrication via a sol-gel method to achieve high permselectivity for large molecules. Membrane fabrication parameters such as the acid molar ratio (AR) in the sol and calcination temperature were evaluated for their effect on the network pore size and on gas permeation properties, as evaluated by the molecular size dependence (0.26–0.55 nm) and temperature dependence (50–200 °C) of gas permeance. BTESP membranes with different ARs (10−1, 100, and 10) showed H2/N2 and H2/CF4 selectivities of 20–30 and 640–32,000, respectively. As AR was increased, each gas permeance also increased, but H2 selectivity that corresponds to network pore size was decreased. FT-IR analysis indicated that the density of the Si-OH groups (Si-OH/Si-O-Si) of unfired gels was decreased with a higher AR, so that condensation of the Si-OH groups during the calcination process formed a dense network structure in the case of BTESP membranes with a low AR (10−1). Calcination temperature also affected the network structure of BTESP membranes. BTESP membranes calcined at different temperatures (350, 450, and 600 °C) showed H2/N2 and H2/CF4 selectivities of 10–30 and 410–32,000, respectively. A BTESP membrane calcined at high temperature (600 °C) showed loose networks since the linking units derived from BTESP were decomposed at temperatures above 500 °C, which resulted in the formation of methyl groups. In conclusion, the AR in a sol is suitable for tuning small pore sizes, while calcination temperature as a membrane fabrication parameter offers the advantage of controllability for loose network structures.

Membrane-based separation techniques are responsible for great advances in the separation of propylene/propane mixtures. In this study, bis(triethoxysilyl)acetylene (BTESA) was selected as the precursor in the fabrication of organosilica membranes for use in propylene/propane separation. We proposed an effective strategy to finely engineer the pore subnano-environment of BTESA membranes for highly selective propylene/propane separation via controlling the calcination temperatures. Measurement of the surface energy, the 29Si-NMR spectra, and the gas sorption isotherms clearly indicated that low-temperature calcined BTESA materials with a greater number of silanol groups showed an enhanced affinity to propylene molecules. BTESA membranes calcined at 150 °C featured a promisingly high C3H6/C3H8 selectivity of 52 and a C3H6 permeance of 1.7 ✕ 10−8 mol m−2 s−1 Pa−1 at 50 °C. These values were approximate to those reported for ZIF-8 membranes and higher than the standards for commercialization. The high level of C3H6/C3H8 separation performance was believed to be accounted by the synergetic effects of both controlled pore size and enhanced affinity to propylene molecules. Moreover, compared with traditional organosilica membranes that were calcined at ~350 °C, low-temperature calcination (150 °C) for BTESA membranes efficiently reduced the energy consumption and fabrication cost.

We developed a procedure that saves significant amounts of energy during the separation of organic liquids via organic solvent reverse osmosis (OSRO). The proof-of-concept was confirmed using theoretical calculation to demonstrate energy-consumption at less than 1/100th and 1/10th that of conventional distillation and pervaporation (PV), respectively. Bis(triethoxysilyl)acetylene (BTESA)-derived organosilica membranes consisting of a SiO2–ZrO2 intermediate layer and an α-Al2O3 support were evaluated by challenging a series of azeotropic mixtures of methanol/toluene, methanol/methyl acetate, methanol/dimethyl carbonate (DMC), and methanol/methyl tert-butyl ether (MTBE). BTESA membranes showed excellent size- and/or shape-sieving properties and remarkable levels of organic-tolerance with an ultrahigh methanol flux that outperforms state-of-the-art polymeric membranes. In particular, the robust ceramic support and rigid organosilica networks endowed the resultant membranes with the ability to withstand transmembrane pressures as high as 18 MPa.

The separation of azeotropic mixtures such as methyl acetate and methanol via a membrane is an interesting and challenging issue, since the membrane must be able to withstand these harsh solvents and provide good flux and selectivity. SiC-based membranes have attracted a great deal of interest due to their high mechanical strength, structural stability, and corrosion resistance at elevated temperatures. Herein, we describe the first use of polytitanocarbosilane (TiPCS), which is known as a precursor of continuous Si–Ti–C–O fibers (Tyranno), in the preparation of Ti-incorporated SiC-based membranes for the pervaporation (PV) removal of water or methanol, and describe the evaluation of hydrothermal stability. For this study, the physical and chemical properties of TiPCS-derived materials during pyrolysis were characterized via TG-MS, ATR-FTIR, XPS, XRD, and N2 adsorption-desorption isotherms. The pore characteristics and surface areas of TiPCS-derived ceramic powders revealed that the titanium components in TiPCS inhibit and/or reduce the densification of the network structures at elevated temperatures. The network structure of TiPCS-derived, SiC-based membranes showed trends similar to those of TiPCS-derived ceramic powders. The membrane prepared at 750 °C featured reproducibility and attractive selectivities for the PV removal of water or methanol from liquid mixtures.

The aim of this work was to study the fouling and cleaning behavior of bis(triethoxysilyl)ethane (BTESE)-derived organosilica membranes, which is a new class of RO membranes that feature chlorine tolerance and thermal stability. The foulants used in this study included bovine serum albumin (BSA) and sodium alginate (SA), which are typical examples of effluent organic matter (EOM). Sodium dodecyl sulfate (SDS) and dodecyltrimethyl ammonium bromide (DTAB) surfactants served as typical industrial waste. With the EOM foulants, BSA fouling occurred at a pH that approximated its iso-electric point (IEP), and the fouling became more severe with the addition of electrolytes into the SA solution. In both cases, however, the fouled BTESE membrane was recovered with the use of deionized water (DIW). The fouling was more pronounced in the presence of DTAB by comparison with SDS surfactants. Surprisingly, in all tests, within 30 min and without the need of chemical agents, the integrity of the fouled BTESE membranes was recovered by applying water at a temperature of at least 80 °C.

Ceramic microfiltration membranes with superior chemical and mechanical stability for sustainable operation under harsh conditions have demonstrated great potential for industrial wastewater treatment. In this study, low-cost ceramic microsheet membranes with a thickness of sub-0.5 mm that possess superhydrophilic and underwater superoleophobic properties were fabricated from an Al2O3-rich Al2O3/polysulfone composite slurry via a phase inversion/sintering strategy. The cross-sectional morphologies of these phase inversion-induced composite films appear as ceramic green bodies that can be precisely controlled by tuning the operation parameters during the classic phase-inversion process of a polymer, which allows the morphology to withstand a subsequent high-temperature (1250 °C) sintering process. The thinner nature ( 99% and a much higher emulsion permeability of ~3,000 L/(m2 h bar), which is 2 orders of magnitude higher than most commercially available microfiltration membranes that are capable of similar levels of separation performance. This process resulted in a favorable membrane that combines robustness under complex chemical environments with low cost for both materials and processing approaches, which should facilitate its practical application in the industrial treatment of oily wastewater.

Ceramic membranes were newly developed with hydrophobic intermediate layers to achieve high gas permeance in the presence of water vapor. Me-SiO 2 sols, which were prepared by co-precursors of tetraethoxysilane (TEOS) and methyltrimethoxysilane (MTMS) were coated as intermediate layers. Two types of organosilica sols prepared with bis(triethoxysilyl)ethane (BTESE) and bis(triethoxysilyl)octane (BTESO) were used for the top layers. By characterization of nanopermporometry using hexane and water as condensable vapors, Me-SiO 2 layers showed pore diameter of approximately 1.5 nm and exhibited hydrophobic properties and that SiO 2 –ZrO 2 layers were hydrophilic. BTESE- and BTESO-derived sols were coated on hydrophobic Me-SiO 2 layers, referred to as BTESE/Me-SiO 2 and BTESO/Me-SiO 2 , and on hydrophilic SiO 2 –ZrO 2 layers, which are referred to as BTESE/SiO 2 –ZrO 2 and BTESO/SiO 2 –ZrO 2 . Gas permeation was examined for four types of membranes under a dry and a wet atmosphere. Under dry conditions, BTESO/Me-SiO 2 showed a gas permeation trend that was similar to that of BTESO/SiO 2 –ZrO 2 . The selectivity of H 2 /SF 6 for BTESE/Me–SiO 2 (334) was much lower than that of BTESE/SiO 2 -ZrO 2 (>20,000) due to the inhomogeneous coatings of BTESE on the Me-SiO 2 layers. Under humidified conditions, BTESE/Me–SiO 2 and BTESO/Me-SiO 2 with hydrophobic intermediate layers, exhibited less of a decrease in CO 2 permeance compared with either BTESE/SiO 2 -ZrO 2 or BTESO/SiO 2 –ZrO 2 , both of which had hydrophilic intermediate layers. The water vapor resulted in a negligible effect on gas permeance for totally hydrophobic BTESO/Me-SiO 2 , while a little larger decrease was observed for hydrophilic top layers of BTESE/Me–SiO 2 , showing that membranes with hydrophobic surface chemistry can effectively resist water vapor condensation or adsorption during gas permeation.

Organosilica membranes were fabricated under controlled sol-preparation conditions such as the ratio of triethoxysilane (TRIES) and vinyltrimethoxysilane (VTMS) and the hydrosilylation temperature. The single-gas permeation properties and hydrothermal stability of organosilica membranes were evaluated to clarify the relationship between hydrothermal stability and organosilica structure. Pt-catalyzed and thermally cured hydrosilylation was applied to evaluate the effect that hydrosilylation temperature exerts on the properties of membranes. Organosilica membranes (Pt-catalyzed hydrosilylation at 40 °C) showed H 2 permeance of approximately 10 −6 mol m −2 s −1 Pa −1 with H 2 selectivity (H 2 /CH 4 :15, H 2 /CF 4 :950) at 500 °C, and were stable under an oxidative atmosphere at 500 °C. The organosilica network size derived by thermal curing at 500 °C was smaller than that by Pt-catalyzed hydrosilylation, even though the units (Si–C–C–Si, Si–O–Si) were the same. Hydrosilylation reactivity derived by thermal curing (500 °C, N 2 ) strongly depended on the TRIES/VTMS (= H / V ) ratio in the SQ sol, and an H / V ratio of 1.25 showed a higher level of hydrosilylation reactivity. Its hydrothermal stability was better than that of amorphous silica membranes, due to the incorporation of Si–(CH 2 ) 2 –Si units in the networks via hydrosilylation, based on the decreased ratio of He and H 2 permeance, the He/H 2 permeance ratio, and the activation energy before/after steam treatment.

A pore network of bis(triethoxysilyl)ethane (BTESE) organosilica membranes was controlled by adjusting the molar ratios of BTESE/H2O/acid=1/x/0.2 (x=3 and 240). The mechanisms for solute transport in the BTESE RO membrane were investigated using three different aqueous solutions of sodium chloride (NaCl), ethanol (EtOH) and isopropanol (IPA). The pressure and temperature were varied from 0.4 to 1 MPa and from 25 to 80 °C, respectively. Water flux and rejection increased for both alcohols and electrolyte with an increase in the applied pressure. It was noteworthy that the rejection of alcohols decreased with an increase in the RO operating temperature, while the electrolyte rejection remained almost constant. The BTESE membranes exhibited high thermal robustness under the long-term testing conditions, delivering salt rejections >98% until the end of the testing period (50 h). The BTESE membranes could also be regenerated after use in the gas and RO experiments, thus demonstrating robust properties.

Organosilica membranes for gas separation were prepared by plasma-enhanced chemical vapor deposition (PECVD) using three different types of silicon precursors: hexamethyldisiloxane (HMDSO), trimethylmethoxysilane (TMMOS), and methyltrimethoxysilane (MTMOS). Based on gas permeation measurement, the MTMOS-derived membrane showed the highest He/N2 selectivity, followed by the TMMOS-derived and HMDSO-derived membranes. FT-IR characterization indicated that the HMDSO-derived membrane had the highest content of methyl group and the lowest Si O Si, while the methyl group content for the MTMOS-derived membrane was the lowest and Si O Si was the highest. These results suggest that the pore size of organosilica membranes could be tuned by changing the chemical structure of the silicon precursor. The MTMOS-derived membrane was further heat-treated to determine the effect of thermal annealing on gas-permeation properties. The gas permeances were drastically improved by the thermal annealing. After heat-treatment at 500 °C, the membrane showed a high H2 permeance of 6.5×10−7 mol/(m2 s Pa) with a H2/SF6 selectivity of 410 at 200 °C, and 5.6×10−7 mol/(m2 s Pa) with a H2/SF6 selectivity of 360 at 50 °C.

Uniform and defect-free silica films were prepared by spin-coating silica sols on plasma-treated hydrophobic sub-layers. Three kinds of silica films were prepared using tetraethoxysilane (TEOS), bis(triethoxysilyl)ethane (BTESE) and bis(triethoxysily)octane (BTESO) via sol–gel method. First, hydrophobic sub-layers were pre-coated on silicon wafers with Me-SiO 2 sols prepared from mixtures of methyltrimethoxysilane (MTMS) and TEOS. After firing at 400 °C, the films showed water contact angles of 120°. Then TEOS- and BTESE-derived sols were directly spin-coated on the Me-SiO 2 films, resulting in separated and scattered coatings. A H 2 O/N 2 plasma modification method was used to change the properties of the Me-SiO 2 films from hydrophobicity to hydrophilicity without damaging either the surface morphology or the bulk chemistry. After the treatment, the TEOS- and BTESE-derived sols formed homogenous films. On the other hand, the Me-SiO 2 films were fully coated with BTESO either with or without plasma treatment. This was probably due to both the polar (–OH) and non-polar (long –CH 2 ) portions of the BTESO-derived sols. For gas separation applications, the corresponding BTESE membranes showed great improvement in gas selectivity after the plasma treatment of hydrophobic Me-SiO 2 layers.

The effect of the operation conditions on the recovery of acid–alkali pairs by electrodialysis was studied to improve the efficiency of the newly developed mineral carbonation process for carbon dioxide fixation. Sodium nitrate (NaOH + HNO3), sodium chloride (NaOH + HCl), and potassium chloride (KOH + HCl) showed almost equal performance in the recovery process for the two fixed membrane configurations. For the same salt, the configuration of anion-exchange membrane bipolar membrane (AEM–BPM) showed higher recovery rate and lower power consumption than the cation-exchange membrane bipolar membrane (CEM–BPM) configuration. Significantly higher recovery rates were observed when potassium acetate was used for the CEM–BPM configuration. A higher recovery rate was observed for a lower initial concentration, but the power consumption was lower for higher initial concentrations. Calcium in waste cement powder can be rapidly leached with acetic acid. The results showed that the process performance would be signif...

The dehydrogenation of methylcyclohexane (MCH) to toluene (TOL) for hydrogen production was theoretically and experimentally investigated in a bimodal catalytic membrane reactor (CMR), that combined Pt/Al2O3 catalysts with a hydrogen-selective organosilica membrane prepared via sol-gel processing using bis(triethoxysilyl) ethane (BTESE). Effects of operating conditions on the membrane reactor performance were systematically investigated, and the experimental results were in good agreement with those calculated by a simulation model with a fitted catalyst loading. With H2 extraction from the reaction stream to the permeate stream, MCH conversion at 250°C was significantly increased beyond the equilibrium conversion of 0.44–0.86. Because of the high H2 selectivity and permeance of BTESE-derived membranes, a H2 flow with purity higher than 99.8% was obtained in the permeate stream, and the H2 recovery ratio reached 0.99 in a pressurized reactor. A system that combined the CMR with a fixed-bed prereactor was proposed for MCH dehydrogenation. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1628–1638, 2015

Silsesquioxane (SQ) membranes derived from 3-methacryloxypropyltrimethoxysilane and bis(trimethoxysilyl)ethane were successfully fabricated at low temperature via photo-induced sol-gel processing. Radical and cationic polymerization of SQ membranes showed high degrees of separation factor and permeance for water/isopropanol separation in pervaporation.

In this study a new type of layered hybrid membrane was fabricated. This new membrane consisted of a thin organically bridged silica separation layer deposited onto the surface of a flexible polymeric membrane, NTR-7450 (Nitto Denko, Japan), and was comprised of a sulfonated polyethersulfone top layer and a porous polysulfone support. Using 1,2-bis(triethoxysilyl)ethane (BTESE) as a precursor, a continuous and defect-free BTESE separation layer was deposited onto the surface of a polymeric nanofiltration membrane via a facile, reproducible and scalable sol–gel spin-coating and low-temperature curing process. First, the optimal preparation conditions were established, which included the curing temperature and the spin-coating cycles. The membranes were then used for the vapor permeation dehydration of isopropanol-water solutions, and showed a stable water flux of 2.3 kg/(m2 h) and an improved separation factor of about 2500, which was an increase of approximately 5-fold compared with that of a polymeric nanofiltration membrane. In addition, single-gas permeance through this membrane was also discussed and a modest H2/N2 selectivity of 26 was obtained, which approximated the performance of ceramic-supported BTESE-derived silica membranes.

The sol–gel method was applied to the fabrication of Al-doped bis (triethoxysilyl) methane (BTESM)-derived membranes. The single-gas permeation properties for Al-doped BTESM-derived membranes were examined to evaluate the effect of aluminum concentration on amorphous silica network sizes. Each permeance was decreased with an increase in the Al concentration, and the H 2 /CH 4 and H 2 /C 3 H 8 permeance ratios increased with an increase in Al concentration. For example, an Al-doped BTESM (Si/Al=8/2) membrane fabricated at 200 °C showed a H 2 permeance of 4.4×10 −7 mol m −2 s −1 Pa −1 , which was approximately 1/10th that of a BTESM membrane fabricated at 200 °C. The H 2 /CH 4 and H 2 /C 3 H 8 permeance ratios were 60 and 2700 with Al doping, but 30 and 1000 without Al-doping, respectively. The activation energy of He, H 2 , N 2 , and CH 4 permeation was increased with an increase in the Al concentration, indicating that the pore size of BTESM-derived networks was decreased with an increase in Al concentration. The decrease in BTESM-derived network sizes that resulted from an increase in the Al concentration can be ascribed to the absolute amount of Al incorporated into BTESM-derived networks and/or coordinated with Si-OH groups, as suggested by 27 Al MAS NMR. High C 3 H 6 /C 3 H 8 permeance ratios of approximately 40 for Al-doped BTESM (Si/Al=9/1) membranes fabricated at 200 °C were achieved through the precise control of the silica network size via a spacer method using Si–C–Si units as well as the incorporation of Al in BTESM-derived networks.

A modified gas-translation (GT) model was applied for the theoretical analysis of gas permeation through microporous organosilica membranes derived from bis(triethoxysilyl)ethane (BTESE) via a sol–gel method using different water/alkoxide molar ratios. The pore sizes of BTESE-derived membranes were quantitatively determined by normalized Knudsen-based permeance analysis, which was based on a modified-GT model, using experimentally obtained permeances of He, H2, N2, C3H8, and SF6. The pore sizes of BTESE-derived membranes were successfully controlled from 0.65 to 0.46 nm by increasing the H2O/BTESE ratio from 6 to 240. Furthermore, theoretical correlations of all possible pairs of permeance ratios were calculated based on the modified-GT model. The experimental data were in good agreement with the theoretical correlation curves, indicating that the modified-GT model can clearly explain gas permeation mechanisms through microporous membranes, and, thus, can be used to predict the gas permeation properties for these membranes. © 2014 American Institute of Chemical Engineers AIChE J 60: 4199–4210, 2014