Pervaporation Flux Research Articles

Comparative study on dehydration of isopropanol and acetonitrile by pervaporation using PEBA/PANI/zeolite mixed matrix membranes

ABSTRACT Isopropanol (IPA) and Acetonitrile (ACN) solvents form azeotrope with water and separation by conventional processes is energy intensive. So, Pervaporation (PV) process became quite prominent and an alternative technique for dehydration of azeotropic mixtures. The selection of membrane places a crucial role in pervaporative separation and Mixed Matrix Membranes (MMMs) were widely employed. In this context, MMMs designated as PEBA-PANI and PEBA-PANI-4A were prepared by embedding PANI, zeolite 4A fillers in PEBA matrix. The synthesised zeolite particles, pristine PEBA and MMMs were characterised by XRD, FTIR, as well as contact angle measurements. Further, surface morphology and average particle size of zeolite particles are observed using SEM. Sorption studies with varying composition of isopropanol, and acetonitrile aqueous mixtures were correlated with their PV performances. The PEBA-PANI-4A MMMs showed higher % sorption of 11.34 and 8.57 for IPA–Water and ACN–Water systems respectively. Similarly greater pervaporation flux and selectivity of 0.28 kg/m2h and 720 were obtained for IPA–Water and 0.068 kg/m2h and 564 for ACN–Water systems at 10 wt. % water concentration. The PV results revealed that the MMMs exhibited better performance than pristine PEBA. All three membranes showed greater sorption, flux and selectivity for IPA-Water system than ACN-Water system.

High-flux recovery of aromatic compounds from tobacco extract using an MCM-41/PDMS hybrid membrane

Recovery of valuable aromatic compounds from tobacco waste is important, and efficient separation methods remain highly demanding. This work proposed a hybrid PDMS membrane for high flux aromatic compounds recovery. MCM-41, a silicone-based molecular sieve, was selected to fabricate the membrane to improve the pervaporation performance. The prepared MCM-41/PDMS membrane was investigated in model aqueous solution at different concentrations and temperatures. The optimal pervaporation fluxes of the MCM-41/PDMS membrane achieved 0.95 g/(m2·h), 0.51 g/(m2·h), and 0.26 g/(m2·h) for 2-phenylethanol, β-ionone, and dihydroactinidiolide, respectively, exhibiting superior performance to the PDMS membrane. Moreover, the long-term stability of the hybrid membrane was examined with practical tobacco extract. The average fluxes were 41.20 mg/(m2·h), 20.57 mg/(m2·h), and 9.73 mg/(m2·h), respectively. The hybrid PDMS membrane in this study, with high permeate flux and selectivity, is promising for recovery of aromatic compounds particularly from tobacco waste.

Poly(vinyl alcohol)/ZSM-5 zeolite mixed matrix membranes for pervaporation dehydration of ethanol and n-propanol.

In this study, mixed matrix membranes (MMMs) composed of poly(vinyl alcohol) (PVA) and porous ZSM-5 zeolite are thoroughly investigated for concentrating alcohols of ethanol and n-propanol via dewatering pervaporation. The effects of the zeolite content (10-30 wt.%), feed composition (5-30 wt.% water), and feed temperature (50-90 °C) on the pervaporation flux/separation factor and component permeance/selectivity of these MMMs are examined in detail. These MMMs achieve higher separation efficiency and pervaporation flux than their pure PVA counterparts as expected, even if the dehydration results strongly depend on the pervaporation conditions. The disparity in pervaporation performances acquired for different alcohol solutions may be understood in terms of polarity and molecular size, which differ among these alcohol molecules. The PVA/zeolite MMM of 20 wt.% ZSM-5 zeolite content performs substantially stably at 60 °C for the feed with 80 wt.% alcohol while maintaining separation factors of 660 or 820 and total fluxes of 970 or 825 g/m2h for dewatering water/ethanol and water/n-propanol, respectively. Thus, our membranes appear to be technically feasible for practical alcohol dehydration uses.

High flux and ultra‐thin poly‐dimethyldiethoxysilane/poly(vinylidene fluoride) composite membrane for alcohols recovery from aqueous solution by pervaporation

AbstractPervaporation (PV) of membrane separation technology has become an efficient approach to separate alcohols from aqueous solution. In this study, focusing on increasing the total flux and breaking the trade‐off in PV, an ultra‐thin and high flux poly‐dimethyldiethoxysilane (PDMDES)/poly(vinylidene fluoride) (PVDF) composite membrane was prepared. By employing various means, the characterizations of PDMDES/PVDF composite membrane were extensively investigated and the promising results indicated the high hydrophobicity and good affinity to alcohols. To be specific, PDMDES selective layer with different thicknesses, the thinnest of which was approximately 265 nm, were fabricated, and better PV performance can be achieved in a thickness range of 1.10 ~ 1.69 μm. The optimal PV performance of PDMDES/PVDF composite membrane was obtained in separating methanol from 5 wt% methanol/water solution at 40°C, resulting in a total high permeation flux of 5.38 kg m−2 h−1 and a higher pervaporation separation index (PSI) of 18.63 kg m−2 h−1.Highlights The ultra‐thin and high flux composite membranes for alcohols recovery via pervaporation (PV) are prepared by using monomer in membrane preparation through a simple fabrication method. The trade‐off is broken in the ultra‐thin composite membrane compared with traditional composite membrane. The influence between membrane thickness and PV performance is investigated through experimental tests, and the results show that the ultra‐thin composite membrane has a total high permeation flux of 5.38 kg m−2 h−1.

High-flux corrugated PDMS composite membrane fabricated by using nanofiber substrate

Polydimethylsiloxane (PDMS) is a benchmarked membrane material for pervaporation, gas separation, and nanofiltration, remaining challenges in achieving high-flux membrane. Herein, we proposed a high-flux PDMS membrane with corrugated morphology realized by simply coating PDMS solution on nanofiber substrate. It was demonstrated that the electrospun nanofiber substrate with highly interconnected and porous structures could generate a corrugated PDMS membrane layer with highly increased surface area and meanwhile remarkably reduce transport resistance of the membrane. By optimizing the pore structure of nanofiber substrate and reducing the membrane thickness to sub-micrometer, the corrugated PDMS membrane exhibited up to one order of magnitude higher permeation flux compared with state-of-the-arts PDMS membranes for pervaporation separation of ethanol/water mixtures. Specifically, using a 5 wt% ethanol/water mixture as feed at 60 °C, a total flux of 8.7 kg m −2 h −1 and a separation factor of 7.2 were obtained. This work provides a facile approach to develop nanostructured membranes with highly enhanced transport properties. ➢ Corrugated membrane surface is created by coating PDMS on nanofiber substrate ➢ Highly porous and interconnected nanofiber substrate reduce transport resistance ➢ Corrugated PDMS/nanofiber membrane show significantly enhanced pervaporation flux

TiO2-decorated NaA zeolite membranes with improved separation stability for pervaporation dehydration of N, N-Dimethylacetamide

It is a great challenge for conventional NaA zeolite membrane to maintain stable water flux in pervaporation (PV) dehydration of polar aprotic solvents because the aggressive adsorption of these solvents on membrane surface restrain water adsorption and thereby reduce water flux gradually. To address this issue, a facile surface modification method was adopted to decorate the surface of NaA zeolite membrane with sol-gel derived TiO2 nanoparticles for PV dehydration of N, N-Dimethylacetamide (DMAc). Effect of TiO2 precursor composition on properties and separation performance of TiO2/NaA zeolite composite membranes was investigated extensively in terms of SEM, XRD, XPS, solvent adsorption and water contact angle. The results showed that the porous TiO2 layer on top of zeolite membrane not only hindered the electrostatic interaction between DMAc molecules and sodium cations from zeolite membrane but also allowed water permeation without large loss in flux. The minimum loss in water flux of TiO2/NaA zeolite membrane was about 17% after continuous PV dehydration of 10 wt% water/DMAc mixture for 24 h at 363 K while that of bare NaA zeolite membrane was over 95% within 15 h, indicating the effective improvement on separation stability of NaA zeolite membrane for PV dehydration of DMAc.

MFI-Type Zeolite Membranes for Pervaporation Separation of Dichlorobenzene Isomers.

MFI-type zeolitic membranes were prepared on the porous α-A2O3 support to investigate the separation properties of dichlorobenzene isomers. The pervaporation tests were performed with unary and binary isomer mixtures at 333 K. The results indicate that the silicalite membranes, irrespective of being synthesized by the templated or template-free method, are permeable for all dichlorobenzene isomers. The pervaporation fluxes of the pure dichlorobenzene isomers decrease in the order p-DCB > o-DCB > m-DCB. For the binary pervaporation system, the dichlorobenzene fluxes are all less than those with a single component due to the binary interactions between DCB isomers and between the DCB isomer and the zeolite membrane. Comparatively, the template-free MFI-type zeolite exhibits higher selectivity for dichlorobenzene isomers due to less inter-crystalline gaps. The separation factors for p-/o-DCB and p-/m-DCB can reach 16.7 and 22.0, respectively.

Synthesis of chitosan grafted polymethyl methacrylate nanopolymers and its effect on polyvinyl chloride membrane for acetone recovery by pervaporation

In comparison to conventional nanoparticles biopolymer like chitosan based nanoparticles will be of much lower cost, non-toxic and more compatible with polymer membranes. As a cationic polymer surfactant chitosan is able to generate polymer nanoparticles during emulsion polymerization of methyl methacrylate. Accordingly, the organophilicity of polyvinyl chloride (PVC) membrane was significantly improved by incorporating chitosan grafted polymethyl methacrylate (PMMA) nanopolymers(NPs) prepared by emulsion polymerization. The NPs and the PVC-NP blend membranes were characterized. The chitosan: MMA wt. ratio and the wt.% of NP in PVC were optimized by a 5-level factorial design. The membranes prepared from i) PVC, PVC blended with 6.5 wt.% each of ii) chitosan, iii) PMMA and iv) NP showed a pervaporative flux (kg/m2h)/acetone selectivity of 0.439/24.31, 0.477/21.56, 0.461/23.41 and 0.502/27.96, respectively for 5.6 wt.% acetone in feed. The sorption and pervaporation data showed close fitting to ENSIC and six-parameter solution-diffusion model, respectively.

Влияние модификации изотактического полипропилена на его транспортные свойства

Модификацией промышленных полимеров можно создать материалы с определенным набором эксплуатационных свойств. В данной работе проведена модификация структуры пленок изотактического полипропилена марки 01030 (ПП) путем обработки их жидкими алканами с увеличивающимся числом атомов углерода (гексан, гептан, н-нонан), которая приводит к увеличению сорбции и проницаемости воды в процессе первапорации. Эксперименты проводили по четырем маршрутам, как при изучении набухания ПП, так и при первапорации. Показано, что при проведении эксперимента по маршруту № 1 с увеличением числа атомов углерода в молекуле алкана степень набухания ПП растет, а величина плотности первапорационного потока падает. При модификации пленок ПП алканами по маршрутам №№ 3-4 происходит рост подвижности сегментов макромолекулярных цепей и увеличение расстояний между ними. При десорбции алканов образовавшаяся структура, по-видимому, сохраняется. После полного удаления ранее растворенного вещества (гексан и гептан) остаются «пустоты», через которые проникает вода (маршрут № 3) и наблюдается рост равновесной степени набухания ПП, а н-нонан полностью не удаляется, поэтому вода не может проникнуть в ПП. Аналогичное поведение наблюдается и при первапорации воды по маршруту №3. В случае маршрута № 4, когда десорбцию алканов не проводили, вода выталкивает алканы из полимера и проникает вслед за ними в пленку по образовавшимся каналам. С повышением температуры в изучаемом интервале плотность потока алканов возрастает (для гексана в 5 раз). Увеличение плотности потока воды после модификации происходит для всех изучаемых алканов, но она уменьшается при переходе от гексана к н-нонану. Показано, что в маршруте № 2 происходит поверхностная модификация пленки, в маршрутах № 3 и № 4 − объемная модификация. Таким образом, модификация полимерных пленок с использованием гидрофобных веществ приводит к увеличению сорбции и проницаемости гидрофильных веществ (воды).

Surface-modified polyvinyl alcohol (PVA) membranes for pervaporation dehydration of epichlorohydrin (ECH), isopropanol (IPA), and water ternary feed mixtures

Conventional distillation failed to separate a ternary azeotropic mixture of ECH, IPA and water (50/30/20w/w, %) exist in the epoxy resin manufacturing process. Thus, we prepared a PVA-tetraethyl orthosilicate organic–inorganic hybrid membrane and modified the membrane by layer-by-layer deposition of a PVAm/silicotungstic acid polyelectrolyte for the pervaporation (PV) dehydration of ECH/IPA/water mixtures. In PV experiments at 30°C, the flux decreased from 0.14 to 0.05kg m−2h−1 and separation factor increased from and 2099 to 13,320 with TEOS addition in the PVA membrane was observed. And for the layer by layer deposition on PVA-TEOS (4) membranes flux increased and separation factor decreased from 0.14 to 0.28kgm−2h−1 and 2099 to 416 with the number of layer of deposition were observed respectively. On varying the feed water content from 20 to 10wt. %, the pervaporation flux at 30°C decreased from 0.22 to 0.0066kgm−2h−1 and the separation factor increased from 1061 to 9094 was observed. By applying the Arrhenius equation, permeation activation energies of ECH and IPA (97.42 and 111.96kJmol-1, respectively) are higher than that of water (40.88kJmol−1) were reported for the layer by layer membrane.

Acetic acid Separation as a Function of Temperature Using Commercial Pervaporation Membrane

Acetic acid was separated from a dilute mixture using a commercial polyvinyl alcohol (PVA) membrane. Intrinsic separation characteristics of the membrane were studied as a function of temperature. The degree of membrane swelling decreased marginally with increase in feed temperature. At 25oC the maximum degree of swelling was found out to be 46.3%, which reduced to 39.5% at 65oC. Although the pervaporation flux increased with increasing temperature of the liquid feed mixture, the separation factor decreased. From the temperature dependence of diffusion and permeation values, the Arrhenius apparent activation parameters for water permeation were estimated. Diffusion and partition coefficient for water and acid were found to increase with temperature, but the diffusion coefficient of water was substantially higher than that of acetic acid at a constant feed concentration. The membrane used in the present study could tolerate highly concentrated corrosive acetic acid, thus may be useful for dehydration of other organics.

Beer dealcoholization using pervaporation

This work was aimed at laboratory testing of beer (and model solution) dealcoholization using pervaporation. Four commercially available membranes from the Sulzer company were tested. The modes of performed pervaporation tests were into the vacuum and into the stripping gas (N2). Pervaporation into the vacuum was observed to result in the precipitation of resin-like matter on the membrane permeate side. The performances of individual membranes are discussed in terms of selectivity and pervaporation fluxes.

PVA/H-β zeolite mixed matrix membranes for pervaporation dehydration of isopropanol-water mixtures

Mixed matrix membranes (MMMs) of poly (vinyl alcohol) (PVA) containing certain amounts of H-beta zeolite for pervaporation were manufactured by using a solution casting protocol. These zeolite-embedded membranes were then characterized with scanning electron microscope (SEM), X-ray diffraction (XRD) and swelling tests. The membrane separation performance has been examined by means of isopropanol (IPA) dewatering from its highly concentrated aqueous solutions via response surface methodology (RSM). The results have demonstrated that the influences of feed IPA composition (85-95 wt.%), feed temperature (50-70 Celcius degree), zeolite loading (15-25 wt.%) and their interactive influences are all statistically significant on both pervaporation flux (398-1228 g/m2.h) and water/isopropanol separation factor (617-2001). The quadratic models based on the RSM analysis have performed excellently to correlate experimental data with very high determination coefficients and very low relative standard deviations. The optimal pervaporation predictions given by using the RSM models demonstrate a total flux of 953 g/m2.h and separation factor of 1458, and are excellently verified by experimental results. As reflected by these results, PVA MMMs embedded with hydrophilic H-beta zeolite entities have performed considerably better than its pure counterpart and indicated great potential for isopropanol dehydration applications.

Pervaporation and vapour permeation of methanol – dimethyl carbonate mixtures through PIM-1 membranes

The separation of dimethyl carbonate (DMC) from its mixtures with methanol was studied using pervaporation (PV) and vapour permeation (VP) through thick (∼0.5 mm) PIM-1 membranes; PV characteristics of PDMS and PTMSP membranes are provided for comparison. DMC is a “green” chemical with numerous applications in chemistry, but its production is energy- and cost-intensive. As their azeotrope contains 82 mol.% of methanol at 40 °C, DMC-selective rather than common methanol-selective membranes can allow for energy efficient separation and thus production of this “green chemical”. PV of the azeotropic mixture through the PIM-1 membrane showed a separation factor of 2.3, which is comparable to that observed for PV through the PDMS membrane; the PTMSP membrane showed practically no separation. The total PV fluxes followed the order: PTMSP ≫ PIM-1 > PDMS. When the PIM-1 membrane was operated in the VP mode, a separation factor of up to 5.1 was reached for the vapours having the azeotropic composition, while total fluxes dropped ca 50-times compared to PV. The highest observed separation factor of 6.5 was found for VP of DMC-rich vapour mixtures highly diluted with inert gas. To our knowledge, VP through PIM-1 membranes enables to date the most selective membrane-based removal of DMC from its azeotrope with methanol.

Poly(vinyl alcohol)/ZSM-5 zeolite mixed matrix membranes for pervaporation dehydration of isopropanol/water solution through response surface methodology

Mixed matrix membranes (MMMs) of poly(vinyl alcohol) (PVA) containing certain amounts of ZSM-5 zeolite were evaluated for pervaporation dehydration of highly concentrated isopropanol aqueous solution. The effects of zeolite content, feed composition and feed temperature on the membrane separation performance are in detail examined by using a preliminarily one-factor-each time method and a systematically response surface methodology (RSM). Preliminarily results show the dehydration separation factor/selectivity have been greatly boosted but without the cost of pervaporation flux/permeance after adding zeolite ZSM-5, and it is consistent very well with the Arrhenius activation energy estimations where water molecules require much less energy whereas ethanol molecules need much more energy to transport through the membrane, probably because of the favorable hydrophilic and porous features of zeolite ZSM-5 as revealed by swelling and water contact angle results. High feed isopropanol concentration and low feed temperature are both observed to lead to very low pervaporation flux/permeance but very relatively high separation factor/selectivity. The RSM results suggest that zeolite content, feed composition and feed temperature all have highly significant impacts on total pervaporation flux and separation factor. The interaction effect of zeolite content and feed temperature on separation factor is for the first time found to be also significant. The polynomial models established according to the RSM analysis can fit very well against the experimental data with a very high coefficient of determination and the predictions given for optimized conditions have been experimentally confirmed by the validation results with a deviation of less than 2.0%.

PIM-1/PDMS hybrid pervaporation membrane for high-efficiency separation of n-butanol-water mixture under low concentration

Mixed matrix membranes (MMMs) prepared by blending nanocomposites and organic polymers are attractive for producing new materials with improved characteristics such as good hydrophobicity, excellent permeate flux and high separation factor in pervaporation (PV). In order to overcome the aggregation of inorganic nanofillers in membrane and the leakage of inorganic nanoparticles from hybrid membrane in separation process, the polymers of intrinsic microporosity (PIMs) materials with unique properties were successfully synthesized and employed as organic microporous fillers owning good affinity with polymer matrix. The PIM-1/polydimethylsiloxane (PDMS) hybrid pervaporation membranes were then fabricated by mutual combination of the rigidity of PIM-1 and the flexibility of PDMS. The organophilic PIM materials were discovered to provide definite improvements in enhancing the interfacial compatibility and solvent resistance ability to achieve defect-free membrane. Various techniques including FTIR, SEM, EDS, NMR, GPC, contact angle goniometry, N2 absorption/desorption, pervaporation measurements and swelling tests were used to characterize and evaluate the properties of PIMs and membranes. Compared with the pristine PDMS membrane, the prepared PIM-1/PDMS pervaporation membrane exhibited superior permeate flux of 1425.3 g m−2 h−1 and competitive separation factor of 30.7 in the separation of n-butanol–water system under a very low concentration of 1.0 wt%. Moreover, the membrane displayed excellent stability and integrity even over 240 hour’s long-term continuous operation, which showed great potential for industrial application.

Synthesis, Characterization and Application of Disodium Tetraborate Cross-Linked Polyvinyl Alcohol Membranes for Pervaporation Dehydration of Ethylene Glycol

Dehydration of ethylene glycol-water mixture was carried out in a laboratory pervaporation unit using a flat sheet membrane test cell. Polyvinyl alcohol-polyether sulfone (PVA-PES) composite membranes were synthesized and cross linked with two different concentrations, viz 0.2 and 0.5% of disodium tetraborate (borax). The derived membranes were extensively characterized for their morphology, intermolecular interactions, thermo-mechanical stability, and physicochemical properties using field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and water uptake studies. The membrane performance was evaluated in terms of pervaporation flux, separation factor, selectivity, permeability and solute diffusion coefficients of EG-water mixture at varying feed flow rate. Both in terms of flux and separation factor PVA-PES-0.2% borax composite membrane was found superior to PVA-PES-0.5% borax crosslinked and its uncrosslinked counterpart. Cross-linking the composite with borax produced a membrane with lower crystallinity and a smaller swelling degree, but having improved thermostability and mechanical properties.

Selective Recovery of n-Butanol from Aqueous Solutions with Functionalized Poly(epoxide ionic liquid)-Based Polyurethane Membranes by Pervaporation

In this study, hydroxyl-terminated polybutadiene–poly(epoxide ionic liquid)–poly(urethane urea) (HTPB-PEIL-PU) membranes, HTPB-PEIL1-PU and HTPB-PEIL2-PU, were prepared by the reaction of functionalized PEIL, poly(1-methylimidazole-3-methyl-ethyloxy)hexafluorophosphate or poly(1-methylimidazole-3-methyl-ethyloxy)bistrifluoromethanesulfonimidate, respectively, with HTPB using 4,4′-diphenylmethane diisocyanate (MDI) as the chain extender. The HTPB-PEIL-PU and HTPB membranes were investigated for the selective recovery of n-butanol from aqueous solutions by pervaporation. PEIL was confirmed to be successfully embedded in the PU membranes by 1H NMR, Fourier transform infrared, and differential scanning calorimetry measurements. According to our mechanical measurements, the HTPB-PEIL-PU membranes retain the mechanical properties of the original PU membrane. PEIL was shown to enhance the diffusion rate of n-butanol significantly based on swelling behavior tests. The pervaporation flux through the HTPB-PEIL1-PU membrane increased with increasing feed temperature and feed concentration. In contrast, the separation factor of the HTPB-PEIL1-PU membrane increased with increasing feed temperature but decreased with increasing feed concentration. In addition, the HTPB-PEIL2-PU membrane exhibited an optimal separation factor of up to 29.2 at a feed concentration of 3% and a feed temperature of 70 °C, which is superior to that (22.7) through pure HTPB membranes. Furthermore, the HTPB-PEIL1-PU and HTPB-PEIL2-PU membranes show better long-term stability than other supported ionic liquid membranes.

Adjustable pervaporation performance of Zr‐MOF/poly(vinyl alcohol) mixed matrix membranes

AbstractBACKGROUNDPolymer membranes often display trade‐off effects between permeation flux and separation factor in pervaporation, and exploring the strategies for breaking the effects is crucial. In this study, by altering the organic linkers (1,4‐benzenedicarboxylate acid, 2‐hydroxyterephthalic acid, 2,5‐dihydroxyterephthalic acid and biphenyl‐4,4‐dicarboxylate), UiO‐66, UiO‐66‐OH, UiO‐66‐(OH)2 and UiO‐67 were prepared and incorporated in poly(vinyl alcohol) (PVA) membranes for pervaporation of 90 wt% ethanol solution for the first time.RESULTSThe membrane properties and pervaporation performances were tuned, and anti‐trade‐off effects were demonstrated for UiO‐66/PVA, UiO‐66‐OH/PVA and UiO‐66‐(OH)2/PVA mixed matrix membranes (MMMs). For the UiO‐66‐(OH)2/PVA MMM with 1.0 wt% loading, the permeation flux, separation factor and pervaporation separation index (PSI) were increased by 16, 14 and 32% respectively and the water permeance and selectivity were increased by 24 and 10% respectively, while the swelling degree in 90 wt% ethanol declined by 28% in comparison with that of pristine PVA membrane.CONCLUSIONThe pervaporation performance of the UiO‐66‐(OH)2/PVA MMM demonstrated good potential in alcohol dehydration. © 2018 Society of Chemical Industry

Ionic liquid modified multiwalled carbon nanotube embedded styrene butadiene rubber membranes for the selective removal of toluene from toluene/methanol mixture via pervaporation

Abstract Present work reports the fabrication of elastomeric membrane based on ionic liquid functionalized multiwalled carbon nanotubes (f-MWCNT) incorporated Styrene butadiene rubber (SBR) for the separation of azeotropic composition of toluene and methanol. The fabricated membranes were characterized by morphological analysis using transmission electron microscopy and glass transition temperature and heat capacity measurements by differential scanning calorimetry. Composite membranes demonstrate impressive separation performance with preferential selectivity towards toluene and 5 phr f-MWCNT loaded membranes was found to show the best result with respect to toluene flux and selectivity. Optimal separation performance with the permeation flux 225% of SBR control membrane and separation factor of 128 (1.6 times of SBR control membrane) is obtained for this membrane. The concurrent optimization of the physical and chemical structures of toluene permeation path on f-MWCNT surface provides the membrane with high-efficiency toluene permeation. Ionic liquid on MWCNT surface confer aromatic pi-pi interaction with toluene molecules leading to greater toluene affinity and higher repellency against methanol. Pervaporation characteristics of the membranes were also strongly influenced by the feed mixture composition. The study confirmed that increasing toluene concentration improved the toluene flux but reduced the separation factor. The experimental pervaporation fluxes were compared with the calculations based on modified Maxwell–Stefan equation. The model allows a good quantitative prediction of experimental flux values.