Vacuum Pervaporation Research Articles

Trifluoroethylacrylate-Substituted Polymethylsiloxane—Promising Membrane Material for Separating an Abe Fermentation Mixture

This work is aimed at obtaining a membrane material that is resistant to the formation of a precipitate on the surface upon contact with an ABE fermentation mixture and has a good separating ability during the pervaporation isolation of n-butanol from a water–alcohol mixture. In this regard, in this work, for the first time, the creation of pervaporation membranes based on polymethyltrifluoroethylacrylatesiloxane (F3-Acr), as well as a copolymer of polydecylmethylsiloxane and polymethyltrifluoroethylacrylatesiloxane (C10-F3-Acr) is proposed. In comparison with polydecylmethylsiloxane (C10), the structure and sorption properties of the developed membrane materials for n-butanol, ethanol and acetone were studied. It should be noted that the highest sorption of n-butanol is characteristic of C10-F3-Acr (0.46 g/g). Changes in surface properties were assessed by the contact angle and elemental composition of the surface before and after exposure for 1 month in a fermentation medium. The transport and separating properties of the synthesized membrane materials were studied in the vacuum pervaporation mode during the separation of a model ABE fermentation mixture. It was shown that the introduction of a fluorine-containing substituent into the side chain of polysiloxane made it possible to increase the hydrophilicity of the polymer: the water flow for F3-Acr was 0.7 × 10–6 kg m m–2 h–1, which is almost 3 times higher than for C10. It is worth noting the positive effect of the combination of C10 and F3-Acr groups in polysiloxane. Thus, with an increase in the total flow by 60% compared to the C10 membrane, the values of the separation factor for n-butanol, acetone, and ethanol were 40.5, 32.7, and 4.3 and increased by 6, 15, and 12%, respectively, compared to the C10 membrane. For the C10-F3-Acr membrane, the pervaporation separation index for n-butanol, acetone, and ethanol was 136, 109, and 11. Therefore, this membrane is twice as efficient as C10. Taking into account the absence of detectable contamination of the surface of the membrane material with fermentation products, one can note the high potential of the C10-F3-Acr membrane for the task of isolating alcohols from the ABE fermentation mixture.

Fouling of Polyalkylmethylsiloxane Composite Membranes during Pervaporation Separation of ABE-Fermentation Mixtures

Production of bio-alcohols is one of the approaches used in the development of alternative energy. Pervaporation is a promising option for the separation of bio-alcohols from the fermentation mixture. A serious problem in the process of continuous extraction of biobutanol from the fermentation broth is the contamination of the membrane, which leads to a decrease in its permeability over time. In this work, the transport properties of composite membranes based on polyheptylmethylsiloxane (PHeptMS), polydecylmethylsiloxane (PDecMS), and a commercial membrane MDK-3 were studied during separation of a real ABE-fermentation broth in vacuum pervaporation mode. The study was performed before and after continuous contact of the membranes with the fermentation broth for one month. Visually and by scanning electron spectroscopy, the presence of membrane surface residue and its effect on the wettability of the membrane selective layer by the components of the ABE broth were determined. The sediment composition was evaluated by energy dispersive analysis and infrared spectroscopy. According to the pervaporation separation of the ABE-broth using PHeptMS, PDecMS, and MDK-3 membranes, the butanol flux was 0.029, 0.012, and 0.054 kg/(m2·h), respectively. The butanol-water partition factor was 41, 22, and 13 for PHeptMS, PDecMS, and MDK-3, respectively. After one month of incubation of the membranes in ABE-fermentation broth during the separation of the model mixture, a decrease of 10 and 5% in permeate flux and separation factor, respectively, was observed for all membranes. Temperature dependences (30–60 °C) of permeate flux, permeability, and selectivity were obtained for the membranes after clogging. The most promising in terms of minimal negative changes as a result of fouling was demonstrated by the PHeptMS membrane. For it, the clogging dynamics during separation of the real fermentation broth for 216 h were investigated. Two characteristic steps of decrease in transport and separation properties were observed, after 28 and 150 h of the experiment. After 216 h of experiment, a 1.28-fold decrease in total flux through the membrane, a 9% decrease in butanol permeability, and a 10% decrease in n-butanol selectivity were found for PHeptMS.

High Efficiency Membranes Based on PTMSP and Hyper-Crosslinked Polystyrene for Toxic Volatile Compounds Removal from Wastewater.

For the first time, membranes based on poly(1-trimethylsilyl-1-propyne) (PTMSP) with 5–50 wt% loading of hyper-crosslinked polystyrene sorbent particles (HCPS) were obtained; the membranes were investigated for the problem of effective removal of volatile organic compounds from aqueous solutions using vacuum pervaporation. The industrial HCPS sorbent Purolite Macronet™ MN200 was chosen due to its high sorption capacity for organic solvents. It has been found that the membranes are asymmetric when HCPS content is higher than 30 wt%; scanning electron microscopy of the cross-sections the membranes demonstrate that they have a clearly defined thin layer, consisting mainly of PTMSP, and a thick porous layer, consisting mainly of HCPS. The transport and separation characteristics of PTMSP membranes with different HCPS loading were studied during the pervaporation separation of binary and multicomponent mixtures of water with benzene, toluene and xylene. It was shown that the addition of HCPS up to 30 wt% not only increases the permeate fluxes by 4–7 times, but at the same time leads to 1.5–2 fold increase in the separation factor. It was possible to obtain separation factors exceeding 1000 for all studied mixtures at high permeate fluxes (0.5–1 kg/m2∙h) in pervaporation separation of binary solutions.

Butanol-1 Dehydration via Pervaporation Using Membranes Based on Thermally Rearranged Polymer

The process of dehydration of n-butanol as one of the most used solvents and a biofuel base has been studied by a membrane separation method with the use of vacuum pervaporation. Nonporous diffusion membranes based on a thermally rearranged polymer and its hydrolytically stable prepolymer have been selected as the objects of the research. The main physicochemical parameters of the membranes, such as contact angles, surface tension, membrane density, and the results of sorption tests, are reported. Transport properties of the membranes have been studied for separation the water–n-butanol mixture with the water content in the mixture varied from 10 to 75 wt %. It has been shown that thermal rearrangement of the polymers leads to structure compacting and to more selective penetration of water molecules through the polymer matrix, thereby facilitating effective removal of water impurities from n-butanol.

Olefin-polymethylsiloxane membrane composition for oxygenates removal from wastewater by pervaporation

To separate oxygenates from aqueous effluents by pervaporation first obtained and studied composite membrane material based on 1-hexene and polymethylsiloxane (C6). Synthesis of the composite membrane material was performed by hydrosilylation reaction between polymethylhydrosiloxane, 1-hexene and 1,7 octadiene. The synthesized composite membrane material characterized by FTIR spectroscopy and studied its sorption properties in relation to the alcohols: ethanol, n-propanol and n-butanol. It was found that affinity of the composite membrane materials to alcohols is increasing with an increase in their molecular weight. First studied pervaporation properties of the composition C6 and compares its separation characteristics of the commercial high-permeability membrane polymer polydimethylsiloxane (PDMS) and compositions based polymethylsiloxane and 1-octene (polyoctylmethylsiloxane) for the task allocation of n-butanol, n-propanol and ethanol from dilute aqueous solutions by vacuum pervaporation. It is shown that a C6-based membrane is most effective in the separation of oxygenate-water mixtures by vacuum pervaporation. When compared to the PDMS flow of butanol, the membrane based on composition C6 exhibits a high separation factor of butanol-water 78.

Polyheptylmethylsiloxane—A Novel Material for Removal of Oxygenates from Water by Pervaporation

A new membrane for the removal of oxygenates from wastewater by pervaporation has been prepared on the basis of polymethylsiloxane bearing 1-heptene as a substituent on the side chain. The synthesized membrane material has been characterized using Fourier-transform IR spectroscopy, and its sorption properties with respect to C2–C4 alcohols have been examined. It has been found that polyheptylmethylsiloxane (PHepMS) has a greater affinity for the C3 and C4 alcohols to be separated than its closest analogue known from the literature (polyoctylmethylsiloxane (POMS)), which makes the PHepMS membrane promising for the pervaporative separation of aqueous solutions of these alcohols. The pervaporation properties of PHepMS have been studied for the first time, and its separation characteristics have been compared with those of the commercial highly permeable membrane polymer polydimethylsiloxane (PDMS) and POMS in relation to the problem of recovery of n-butanol, n-propanol, and ethanol from dilute aqueous solutions by vacuum pervaporation. It has been shown that PDMS has the highest separation efficiency for n-propanol–water mixture and PHepMS is the most promising membrane material for the pervaporative separation of water–butanol mixtures. Having a butanol flux comparable to that through PDMS, the PHepMS membrane demonstrates a record-breaking value of butanol/water separation factor of 97.

Concentration of natural aroma compounds from fruit juice hydrolates by pervaporation in laboratory and semi-technical scale. Part 1. Base study

The first article of a two-article series presents pervaporation (PV) of volatile aroma compounds from fruit juice hydrolates (plum, apple, blackcurrant and cherry). The purpose of this research was to evaluate the effectiveness of fruit juice hydrolates separation on a laboratory scale (inert gas flow pervaporation system) and semi-technical (vacuum pervaporation system) by means of pervaporation. To create precise matrices for hydrolates before and after pervaporation for each of the separated systems, solid phase microextraction (SPME) technique and the gas chromatography-mass spectrometry (GC-MS) was applied. Sensory analysis confirmed improvement of aroma note of concentrated permeates as compared to feed hydrolates solutions. The results indicated that pervaporation may be applied in condensing aromatic water or fruit juice hydrolate, which may significantly enhance product quality and lengthen shelf life.

New experimental setup for continuous mass flux measurement in pervaporation

Pervaporation is a separation process of liquid mixtures through a thin non-porous membrane. In vacuum pervaporation, the global mass flux is classically estimated by weighing the mass of permeate collected in cold traps. In this work, we propose a new experimental setup that allows a continuous measurement of the mass flux. The new mass flux method measurement was validated for single component permeation (ethanol and water) by comparing mass of permeate collected in cold traps with the level decrease of feed liquid measured with a pressure sensor. This new setup can be useful for laboratory studies dealing with the evolution of mass flux according to different parameters of the process as, for example, the permeate side pressure level or temperature of liquid feed.

Iono-molecular Separation with Composite Membranes IV. Mono-nitrophenol s pervaporation through polysulfone composite membranes

In this paper, were study the pervaporation of mono-nitrophenols in a laboratory installation of the Membrane, Materials, and Membrane Processes Group of the Polytechnic University of Bucharest, from aqueous synthetic solutions, to composite membranes with polysulfone matrix (PSf) and nanometric inclusions: Polyaniline (PANI), carbon nanotubes (CNT), magnetic nanoparticles (MNP) and sulfonated polyetheretherketone (PEEK-S). Tests carried out over 144 h at a pressure of 100 mm Hg or 5 L / min air flow at 25oC and pH 7 of the feed solution show that vacuum pervaporation is better than vacuum. The more advanced composite membranes are those with sulfonated polyether-ether cellulose (PSf-PEEK-S) and polyaniline (PSf-PANI) ionizers. The results of airborne pervaporation show that composite membranes (PSf-PEEK-S and PSf-PANI) present a marked difference in flux for the mono-mono-nitrophenol isomers, which could also be found in a technically exploitable selectivity. Thus, in the case of the PSf-PEEK-S composite membrane, the mono-nitro-phenol streams decrease in the order: m-C6H5NO3] o-C6H5NO3] p-C6H5NO3, while for the PSf-PANI composite membrane the order is o-C6H5NO3] m-C6H5NO3] p-C6H5NO3. At the same time, it is noted that the PSf-PEEK-S composite membrane performance is superior during operation, but shows the opposite of the more pronounced drop.

Pervaporative performance of PEBA and PDMS based commercial membranes in thiophene removal from its binary mixtures with hydrocarbons

This work describes vacuum pervaporation tests which were performed to identify the influence of five hydrocarbons typically presented in gasoline, i.e. n-hexane, n-heptane, n-octane, isooctane (2,2,4-trimethylpentane), and 1-octene on thiophene removal efficiency from hydrocarbon/thiophene binary mixtures. Commercial hydrophobic PEBA-based and PDMS-based composite membranes were applied. The impact of process parameters such as feed temperature and feed composition was examined. Experiments performed with various hydrocarbon confirmed, that the membrane performance and overall separation efficiency is influenced by the physiochemical properties of the mixture components (solute and solvent) and the differences in the affinities towards a given membrane. Permeate fluxes and corresponding separation factors presented typical trade-off regardless the type of membrane and solvent. The separation factors were higher in the case of the PEBA membrane which corresponded with the Hansen's Solubility Parameters Theory. The batch pervaporation removal of thiophene from isooctane was also modeled, proving that the PEBA membrane is more effective than the PDMS one. Solvents fluxes were 3 orders of magnitude higher than solute ones, therefore Pervaporation Separation Index (PSI) should be used only as a preliminary assessment of the membrane performance.

Continuous separation, with microfluidics, of the components of a ternary mixture: from vacuum to purge gas pervaporation

The general objective of this paper is to investigate the separation, with microfluidics, of the components of a ternary mixture, when using vacuum or purge gas pervaporation. The ternary mixture considered is a mixture of methanol (MeOH), water (H2O) and hydrogen peroxide (H2O2). In a previous work (Ziemecka in Lab Chip 15:504–511, 2015), we presented the proof of concept of a microfluidic device, which was able to partially separate MeOH from the other components of such a mixture, by using vacuum pervaporation. Here, our goal is to optimize the operation of this device, by considering vacuum pervaporation, but also purge gas pervaporation. First, we provide a mathematical model of the device. This model is used to discuss the influence of the operating parameters on the device operation. To apply this model to the considered mixture, we determined the MeOH and H2O permeability coefficients of PDMS membranes prepared from different concentrations of the curing agent. The model is then successfully compared to experimental data. The model and the experiments show that high efficiencies can be reached for both vacuum and purge gas pervaporation, provided a fine-tuning of the operating parameters. For instance, a good efficiency of the vacuum pervaporation is reached at high temperature and low pressure. For purge gas pervaporation, it is reached for low temperature and high pressure.

Pervaporative butanol removal from PBE fermentation broths for the bioconversion of glycerol by Clostridium pasteurianum

Batch-wise butanol removal using vacuum pervaporation (VPV) was investigated to assess its technical feasibility for future integration with a continuous PBE (1,3-propanediol-butanol-ethanol) fermentation process using glycerol as feedstock. Two commercial polydimethylsiloxane (PDMS) membrane configurations were characterized using binary model solutions and authentic fermentation broths, while varying feed temperature, butanol concentration and flow rate. The Sulzer Chemtech flat sheet membrane (Pervap 4060) showed superior selective removal of butanol, presumably due to the thinner membrane and the turbulent flow regime which minimizes concentration polarization. Most important, butanol had the highest removal rate of all fermentation products and intermediates measured, while glycerol (substrate), acetic acid and 1,3-propanediol (1,3-PDO) did not cross the membrane in measurable quantities. Great improvements can be made by operating pervaporation at higher temperature (50 versus 35°C) and higher feed butanol concentration. The performances using fermentation broths mimicked that of binary model solutions in repeated trials, indicating little interference from media components. Under the best operating conditions, 8.8gh−1 (517.3gm−2h −1) butanol was removed when the feed concentration of butanol was 11gL−1 (1.1% w/w). The potential of using pervaporation for in-situ butanol removal in PBE fermentation was successfully demonstrated.

Application of commercial PEBA-based membranes in separation of sulfur compounds from gasoline by vacuum pervaporation

Application of commercial PEBA-based membranes in separation of sulfur compounds from gasoline by vacuum pervaporation

Dewatering of 2,2,3,3-tetrafluoropropan-1-ol by hydrophilic pervaporation with poly(vinyl alcohol) based Pervap™ membranes

Pervap™ 2200, 2201, 2216, 2255, and 2510 hydrophilic, PVA membranes were investigated in pervaporation of water-tetrafluoropropanol mixtures. Physicochemical properties of membranes were characterized by determining the contact angle (CA) of water and glycerol and the surface free energy (SFE). The separation and transport properties of membranes were determined during vacuum pervaporation in contact with water-TFP mixtures containing up to 22 wt.% water. It was found that all membranes were hydrophilic (CA < 90°) and the polar component of SFE was much higher than the dispersive one. The apparent activation energy for water transport was very high (Eapp = 81.3 kJ/mol), indicated that water transport is activated thermally. Pervap™ membranes were very selective during the dehydration process of TFP. In contact with the Pervap™ 2200, 2201, and 2216 permeate contained practically pure water, regardless the feed composition. The process separation index (PSI) for Pervap™ 2200 and 2216 was close to 5000 kg m−2 h−1, suggesting that both membranes can be efficiently applied in the batch pervaporation process for TFP dehydration.

Pervaporative removal of organosulfur compounds (OSCs) from gasoline using PEBA and PDMS based commercial hydrophobic membranes

Vacuum pervaporation experiments were conducted to recognize the efficiency of organosulfur compounds (OSCs) separation from gasoline using commercial hydrophobic membranes. Three of typically presented in gasoline sulfur species, i.e. thiophene, 2-methylthiophene and 2,5-dimethylthiophene, were selected to investigate the different sulfur compounds removal efficiency from n-octane/sulfur species used as a model gasoline. The influence of process parameters such as feed temperature, feed concentration on OSCs removal from model n-octane/sulfur compound mixtures was also examined. During the test, the commercial hydrophobic PEBA-based and PDMS-based composite membranes were applied. Conducted experiments with chosen sulfur species confirmed that the structure of a component and the resulting differences in the affinity toward tested membrane and physico-chemical properties can influence the membrane performance and led to different separation efficiency. Total fluxes for n-octane/thiophene, n-octane/2-methylthiophene and octane/2,5-dimethylhiophene mixtures at 30°C were equal to be 1.33, 1.42 and 1.29kg/m2h in case of PEBA membrane and 7.21, 7.48 and 7.34kg/m2h for PDMS-base membrane, with the corresponding separation factor β values of 7.04, 3.95 and 1.25 for PEBA and 2.95, 1.56 and 1.01 for PDMS, respectively. The intrinsic selectivity for tiophene/n-octane mixture (αT/O) also indicated that PEBA membrane (αT/O≈18) is much more selective than PDMS one (αT/O≈7.5).

Preparation, characterization and performance of sulfonated poly(styrene-ethylene/butylene-styrene) block copolymer membranes for water desalination by pervaporation

Sulfonated poly(styrene-ethylene/butylene-styrene) (S-SEBS) polymer was synthesized by grafting sulfonic groups onto SEBS triblock copolymer with acetyl sulfate as the sulfonating reagent. Effects of sulfonation reaction time, temperature, and the amount of sulfonating reagent on sulfonation degree were investigated. S-SEBS membranes with different sulfonation degrees were prepared and characterized by various techniques including FTIR, SEM, EDS, TG and DSC. Tensile strength, water sorption measurement and contact angle goniometry were also applied to investigate the mechanical property and hydrophilicity of S-SEBS membrane. Membrane performance for water desalination by vacuum pervaporation was investigated as a function of sulfonation degree, feed concentration, temperature, and feed flow rate. Results indicated that the hydrophilicity, water permeate flux and anti-fouling property of the membrane increased remarkably with the sulfonation degree. The majority of rejection to various salts was over 99% and all were above 98.4% irrespective of sulfonation degree of S-SEBS. The membrane with 54.1% sulfonation degree showed a high water flux of 22.87kg/m2·h at 63°C and 6kPa permeate pressure for a 1wt% NaCl feed solution. The membrane exhibited good restorability of water flux after acid cleaning.

Nonequilibrium Dissolution-diffusion Model for PDMS Membrane Pervaporation of ABE Water Binary System

Previous models of equilibrium dissolution-diffusion, pore flow and virtual phase change cannot describe the mass transfer process of pervaporation precisely. The fact that dissolution process on the surface of the membrane does not reach equilibrium is seldom emphasized in the literature. The aim of the present work is to develop the nonequilibrium dissolution-diffusion model (nonequilibrium model) for membrane pervaporation process. In this research, the steps of dissolution and desorption were treated as the pseudo surface reaction processes on the surface based on the hypothesis of nonequilibrium dissolution at the interface of the feed liquid and membrane. The semi-experimental model was set based on steady state mass transfer, ignoring the concentration polarization and adsorption at the permeation side. Through linear fitting of the flux with different thickness of the membrane, the diffusion coefficients and adsorption kinetic rate constants of the model were achieved with equilibrium partition coefficient estimated by UNIFAC-ZM model. The calculated values of the model were well in consistent with experimental flux in the vacuum pervaporation of acetone, butanol and ethanol with polydimethylsiloxane membrane. The nonequilibrium model and its parameters will be further applied for prediction of separation performance and selection of operation conditions.

Pervaporative desulfurization of gasoline—separation of hydrocarbon/thiophene mixtures using polydimethylsiloxane (PDMS)-based membranes

A series of vacuum pervaporation tests were carried out to investigate the performance of the commercial composite membrane with an active layer made of polydimethylsiloxane (PDMS). The effects of feed temperature, the sulfur content in the mixture, and feed composition on membrane performance were investigated. Toluene/thiophene and n-heptane/thiophene binary organic mixtures (thiophene concentration 0.8–1.6% by mass) simulating gasoline were separated at 30–50°C, at laboratory scale. Studies have shown that the concentration of thiophene in the mixture and the temperature of the feed have a significant impact on the yield and selectivity of the desulfurization process. Experimental results indicated that higher feed temperature yielded higher total and partial fluxes and a lower sulfur enrichment factor. The total and partial fluxes increased as the sulfur content in the feed increased. The sulfur enrichment factor decreased with the amount of thiophene added in the gasoline. The experiments also showed that commercial PDMS membrane was more selective to thiophene in the case of n-haptane/thiophene mixture and it may be mainly due to higher affinity of toluene toward PDMS. The total fluxes for n-heptane/thiophene mixture and toluene/thiophene mixture were measured to be 7.4 and 9.4 kg/m2 h at 40°C, with the corresponding enrichment factor values of 1.7 and 1.4, respectively.

Removal of hazardous volatile organic compounds from water by vacuum pervaporation with hydrophobic ceramic membranes

Hydrophobic alumina and titania micro and mesoporous ceramic membranes were prepared by grafting of C6F13C2H4Si(OEt)3 (C6) molecules and subsequently applied in a pervaporation (PV) process to the removal of hazardous organic solvents (MTBE, EtAc and BuOH) from binary aqueous solutions. The transport and separation properties of investigated membranes were discussed. Additionally it was found that membrane material and grafting time have an important impact of the pervaporative properties. All tested membranes were selective toward organics. Titania membrane was the most efficient and was characterized by the highest value of PSI and the highest value of permeate flux of organic compounds in water–EtAc (JEtAc=1.1kgh−1m−2; PSIEtAc=140kgh−1m−2) and water–MTBE (JMTBE=1.0kgh−1m−2; PSIMTBE=194kgh−1m−2) systems. This behavior of titania membrane was also discussed based on the Hansen solubility parameters. In presented work the evaluation of MTBE removal degree with titania modified membrane from water binary mixture in the pervaporation process was discussed.

Novel PTMSP-based membranes containing elastomeric fillers: Enhanced 1-butanol/water pervaporation selectivity and permeability

To improve organic solvent preferential permeation of poly[1-(trimethylsilyl)-1-propyne] (PTMSP) and to provide efficient separation of dilute 1-butanol/water mixtures, the membranes were modified by the addition of minor amounts of a soft elastomeric filler, poly(dimethylsilmethylene) (PDMSM), to the host polymeric matrix. As compared with virgin PTMSP membranes, the modified membranes demonstrate better 1-butanol/water pervaporation selectivity and permeability. This unique coupled phenomenon is observed at low concentrations of the elastomeric filler (~1–3wt%) in the host matrix and for the feed aqueous mixtures containing 0.6–3.6wt% of butanol. For vacuum pervaporation of butanol solutions, introduction of only 1.2wt% of PDMSM into the PTMSP matrix makes it possible to increase the permeate flux up to 75% and the separation factor up to 67%. When studying pervaporation of the feed solution containing 2wt% of butanol, the dependences of the permeate flux and separation factor on the elastomeric filler content in the host matrix show the well-pronounced maxima at 1.2–3wt% (MW of the elastomer is 83–1000kg/mol). In this case, the attained permeate flux is 1.5–1.8 times higher than that of the virgin PTMSP, and the separation factor increases by a factor of 1.4–1.7. The corresponding values of thickness-corrected flux and separation factor for the PTMSP/PDMSM membranes are 3.5–4.0kgm/(m2h) and 112–136, respectively. More specifically, the 30µm thick PTMSP/PDMSM (98/2) membrane exhibited permeate flux 0.12kg/(m2h) and separation factor 128 upon pervaporation of 2wt% aqueous butanol solution at 25°C. The experiments on the equilibrium sorption of butanol solutions on the PTMSP membranes modified by the elastomeric filler revealed similar dependences with their well-pronounced maxima in the same region of the PDMSM content. The highest value of membrane selectivity αmem for PTMSP/PDMSM is 8.9 as compared with 5.3 for the virgin PTMSP membranes. Qualitative explanation of the enhanced pervaporation selectivity coupled with the improved permeate flux for the PTMSP/PDMSM membranes was advanced.