Development of Novel NH4Y Zeolite‐Filled Chitosan Membranes for the Dehydration of Water‐Isopropanol Mixture Using Pervaporation

Abstract

NH₄Y zeolite‐filled chitosan membranes were developed for the separation of water‐isopropanol mixture using pervaporation process. The NH₄Y zeolite‐filled chitosan membranes were prepared using a solution technique with the variation of NH₄Y zeolite loading (0, 0.1, 0.2, 0.3, 0.4, 0.5 wt.%). The membranes morphologies were studied using Scanning Electron Microscopy (SEM) and the membranes mechanical strength were tested using the parameter of tensile strength and percent strain at maximum. The effects of NH₄Y zeolite loading on the liquid sorption characteristics and pervaporation performance were also evaluated. The diffusion coefficient of water and isopropanol for the chitosan membranes at different NH₄Y zeolite loading is estimated. The presence of NH₄Y zeolite in the chitosan membranes caused non‐homogeneous dispersion of NH₄Y zeolite crystals and membrane swelling due to its hydrophilic properties. However, the presence of NH₄Y zeolite was able to improve both tensile strength and percent strain at maximum of chitosan membranes. The presence of NH₄Y zeolite also increased the total permeation flux and separation factor simultaneously. The Pervaporation Separation Index shows that 0.2 wt.% of NH₄Y zeolite‐filled membrane gave the optimum performance in the pervaporation process. The diffusion coefficient estimated proves that the membranes were highly water selective.     

Preparation and characterization of HY zeolite‐filled chitosan membranes for pervaporation separation

A novel zeolite (HY)‐filled polymeric chitosan membrane was prepared. The membrane was characterized by wide‐angle X‐ray diffraction and a swelling test. The pervaporation (PV) experiments were also performed for an ethanol–water system. The results showed that the crystalline structure of chitosan was damaged with increase in the zeolite content, indicating a strong interaction between the HY zeolite and chitosan. The separation factor of the ethanol–water mixture by PV was improved by the filling zeolite. When the HY zeolite content in the membrane was 20 mass %, the separation factor reached the maximum and remained constant during the PV process. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1144–1149, 2001     

Separation of alcohol–water mixture by pervaporation through a novel natural polymer blend membrane–chitosan/silk fibroin blend membrane

A novel natural polymer blend membrane, namely chitosan/silk fibroin blend membrane, was prepared. The selective solubility and the pervaporation properties of alcohol–water mixture were studied. The results showed that the membrane was water selective and the separation factor of ethanol–water mixture could be improved compared to pure chitosan membrane, when silk fibroin content in blend membrane was no more than 40 wt %. The blend membrane exhibited a best performance, (i.e., the water in permeate was large than 99 wt % when silk content was 20 wt % and the crosslinking agent–glutaraldehyde content was 0.5 mol %). The mechanism of improvement on pervaporation properties was explained by reducing the free volume and freeing hydrophilic groups of chitosan because of the strong intermolecular hydrogen bond forming between chitosan and silk fibroin in blend membrane. In addition, the influence of operation temperature and feed concentration as well as the pervaporation properties of isopropanol–water mixture were also studied. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 975–980, 1999     

Preparation of novel ZSM‐5 zeolite‐filled chitosan membranes for pervaporation separation of dimethyl carbonate/methanol mixtures

Novel mixed matrix membranes were prepared by incorporating ZSM‐5 zeolite into chitosan polymer for the pervaporative separation of dimethyl carbonate (DMC) from methanol. These membranes were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X‐ray diffraction (XRD) to assess their morphology, intermolecular interactions, and crystallinity. Sorption studies indicated that the degree of swelling for zeolite‐filled membranes increased with zeolite content in the membrane increasing and the separation selectivity of DMC/methanol was dominated by solubility selectivity rather than diffusivity selectivity. The characteristics of these membranes for separating DMC/methanol mixtures were investigated by varying zeolite content, feed composition, and operating temperature. The pervaporation separation index (PSI) showed that 5 wt % of ZSM‐5 zeolite‐filled membrane gave the optimum performance in the PV process. From the temperature‐dependent permeation values, the Arrhenius activation parameters were estimated. The resulting lower activation energy values obtained for zeolite‐filled membranes contribute to the framework of the zeolite. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Dehydration of THF‐water mixtures using zeolite‐incorporated polymeric membranes

Using a solution technique, polymeric composite membranes were prepared by the incorporation of NaY zeolite into chitosan. The resulting membranes were tested for pervaporation separation of water–tetrahydrofuran mixtures in a temperature range of 30–50°C. The effect of membrane swelling on the separation performance was studied by varying the water composition in the feed from 5 to 30 mass %. Pervaporation data demonstrated that both flux and selectivity increased simultaneously with increasing zeolite content in the membrane. This was explained on the basis of enhancement of hydrophilicity, selective adsorption, and establishment of molecular sieving action. It was found that both total flux and flux of water are close to each other, suggesting that the developed membranes are highly selective toward water. The membrane containing the highest loading of zeolite exhibited the highest separation selectivity of 2140 with a substantial water flux of 16.88 × 10^?2 kg/(m² h) at 30°C for 5 mass % of water in the feed. From the temperature dependency of diffusion and permeation data, the Arrhenius activation parameters were estimated. A significant difference was noticed between E_pw and E_pTHF, E_Dw and E_DTHF values, signifying that membranes developed with higher loading of zeolite exhibited remarkable separation selectivity toward water. The E_p and E_D values ranged between 11.69 and 21.23, and 11.21 and 20.72 kJ/mol, respectively. All the membranes exhibited positive ΔH_s values, suggesting that the heat of sorption is still dominated by Henry's mode of sorption. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Comparison of the pervaporation separation of a water–acetonitrile mixture with zeolite‐filled sodium alginate and poly(vinyl alcohol)–polyaniline semi‐interpenetrating polymer network membranes

The pervaporation (PV) separation performance of ZSM‐5‐ and Na‐Y‐type zeolite‐filled sodium alginate (NaAlg) membranes were compared with those of pure NaAlg and semi‐interpenetrating polymer network (semi‐IPN) membranes of poly(vinyl alcohol) (PVA) with polyaniline (PANI) for the dehydration of acetonitrile. The PV separation characteristics of the zeolite‐filled membranes showed a dependence on the nature of the zeolites. The variation of the acidity function of the ZSM‐5 zeolite had an influence on the flux and selectivity of the membranes when compared to unfilled membranes. The crosslinked membranes were characterized by differential scanning calorimetry, X‐ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. Increasing the PANI content of the semi‐IPN network increased the separation selectivity. Among the NaAlg membranes, the plain NaAlg membrane showed the highest selectivity of 414 at 30 mass % water in the feed mixture, whereas the Na‐Y‐ and ZSM‐5 (40)‐filled NaAlg membranes exhibited much lower values of selectivity, that is, 7.3 and 4.3, respectively for 30 mass % water in the feed. When the flux and selectivity data of ZSM‐5 (250)‐filled NaAlg membranes were compared with that of Na‐Y‐ or ZSM‐5 (40)‐filled NaAlg membranes, a noticeable increase in the selectivity for the ZSM‐5 (250)‐filled NaAlg membrane was observed, but a somewhat comparable flux was observed compared to the plain NaAlg membrane. For the first time, PANI was polymerized with PVA to yield a semi‐IPN. The total flux and water flux increased systematically, whereas the selectivity decreased greatly from 251.87 to 5.95 with increasing amounts of water in the feed. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1968–1978, 2005     

Pervaporation separation of water–acetic acid mixtures through NaY zeolite‐incorporated sodium alginate membranes

The pervaporation (PV) separation and swelling behavior of water–acetic acid mixtures were investigated at 30, 40, and 50°C using pure sodium alginate and its zeolite‐incorporated membranes. The effects of zeolite loading and feed composition on the pervaporation performance of the membranes were analyzed. Both the permeation flux and selectivity increased simultaneously with increasing zeolite content in the polymer matrix. This was discussed on the basis of a significant enhancement of hydrophilicity, selective adsorption, and molecular sieving action, including a reduction of pore size of the membrane matrix. The membrane containing 30 mass % of zeolite showed the highest separation selectivity of 42.29 with a flux of 3.80 × 10^?2 kg m^?2 h^?1 at 30°C for 5 mass % of water in the feed. From the temperature dependency of diffusion and permeation data, the Arrhenius activation parameters were estimated. The E_p and E_D values ranged between 72.28 and 78.16, and 70.95 and 77.38 kJ/mol, respectively. The almost equal magnitude obtained in E_p and E_D values signified that both permeation and diffusion contribute equally to the PV process. All the membranes exhibited positive ΔH_s values, suggesting that the heat of sorption is dominated by Henry's mode of sorption. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2101–2109, 2004     

Pervaporation separation of IPA‐water mixtures through 4A zeolite‐filled sodium alginate membranes

Incorporation of zeolites into natural polymers has been shown experimentally to enhance both the flux and selectivity in pervaporative dehydration separation of organic compounds. Pervaporation is a promising membrane technique for separation of volatile organic compounds (VOCs)/water mixtures. In this study, hydrophilic sodium alginate (SA) mixed membranes were prepared using solution casting technique by incorporating zeolites into the polymer matrix. The prepared membranes were characterized by ATR‐Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), scanning electron microscopy (SEM), Thermal Gravimetric Analysis (TGA), and differential scanning calorimetry (DSC) were tested in a laboratory scale pervaporation experimental set‐up. The effect of experimental parameters such as the type and composition of zeolites on permeation flux and selectivity was investigated. When tested on IPA‐water mixtures, the zeolite‐filled membrane was found to give much higher selectivity. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Separation properties of alcohol–water mixture through silicalite-I-filled silicone rubber membranes by pervaporation

The structure and the adsorption–desorption properties of zeolite silicalite-I by different treatments after synthesis were studied. The pervaporation properties of the alcohol–water mixture through silicone rubber filled with zeolite silicalite-I by different treatments were also investigated. Treating silicalite-I by acid or/and under steam was found to eliminate the metallic impurities in the zeolite and to perfect the crystalline structure of the zeolite. After treatment, silicalite-I is more selective to alcohol and the desorption of the alcohol from the zeolite is also easier. The silicone rubber membrane filled with treated silicalite-I shows a high performance for alcohol extraction from the dilute aqueous solution by pervaporation. The separation factor of the poly(dimethyl siloxane) (PDMS) membrane filled with silicalite-I treated successively by acid and steam is about 30 when the ethanol content in the feed is 5 wt % at 50°C. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 629–636, 1998     

Water–alcohol separation by pervaporation through zeolite‐modified poly(amidesulfonamide)

Pervaporation membranes were fabricated by blending different amount of zeolite NaA or NaX with three types of poly(amidesulfonamide) (PASA). The zeolite‐filled membranes were characterized by IR spectroscopy, SEM, sorption measurements, and wide‐angle X‐ray diffraction. By adding the proper amount of NaA into the polymer casting solutions, the resultant zeolite‐filled membranes exhibited improvement in both selectivity and permeability in the separation of 10% aqueous solutions of ethanol and propan‐1‐ol, as compared with the zeolite free membrane. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1323–1329, 2001     

Pervaporation separation of water‐isopropanol mixtures using polymeric membranes: Modeling and simulation aspects

Pervaporation technique was used to separate water + isopropanol azeotropic mixtures at 30°C using pure sodium alginate, pure poly(vinyl alcohol), and blend membranes of sodium alginate containing 10 and 20 mass % of poly(vinyl alcohol). The membrane performance was studied by calculating flux, selectivity, pervaporation separation index, and enrichment factor. Pure sodium alginate membrane gave the highest pervaporation separation index for all compositions of water. Pervaporation experiments were carried out for 10 mass % containing water + isopropanol mixture at 30, 40, and 50°C. The Arrhenius activation parameters were computed. The PV results have been analyzed by considering complete mixing and plug flow models. Design parameters, like membrane area, permeate concentrations, flux, stage cut, separation selectivity, etc., have been calculated for different feed compositions of water in the mixture. Results are explained in terms of sorption‐diffusion principles. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1143–1153, 2005     

Mixed matrix membranes of H‐ZSM5‐loaded poly(vinyl alcohol) used in pervaporation dehydration of alcohols: Influence of silica/alumina ratio

Mixed matrix membranes of poly(vinyl alcohol) loaded with zeolite particles having different silica alumina ratio were prepared and used in the pervaporation dehydration of ethanol and isopropanol (IPA) from their aqueous mixtures. The membranes were characterized by physicochemical techniques that revealed higher interaction between polymer and zeolite particles having higher alumina than those with lower alumina in the zeolite framework. Both, membrane selectivity to water and flux were increased as the alumina content in the zeolite increases. Separation factors of zeolite with lower alumina incorporated membranes were, respectively, 236 and 334 for the feed mixture compositions of 4 wt% water in ethanol and 10 wt% water in IPA at 30°C. On the other hand, membranes containing zeolites with higher alumina content showed slightly higher separation factors of 349 and 568, respectively, for the same feed mixtures at 30°C. Such an incremental improvement in membrane performance with increase in alumina content in the zeolite framework is attributed to favorable interaction between zeolite particles and the polymer matrix. POLYM. ENG. SCI., 54:1774–1782, 2014. © 2013 Society of Plastics Engineers     

Effect of operation conditions in the pervaporation of ethanol–water mixtures with poly(1‐trimethylsilyl‐1‐propyne) membranes

Poly(1‐trimethylsilyl‐1‐propyne) (PTMSP) is known to show preferential permeation of ethanol in the pervaporation of ethanol–water mixture. Although this polymer presents good characteristics for the separation of organic–water solutions, operation conditions and membrane characteristics, such as thickness, affect its pervaporation performance. The effect of temperature and feed concentration on pervaporation was studied. During pervaporation of 10 wt % ethanol–water solution, the separation factor (α_H2O^EtOH) remains almost constant, whereas the permeation flux (F) increases exponentially with operation temperature. On the other hand, the separation factor decreases, whereas the permeation flux increases with ethanol content in the feed mixture. The membrane thickness also affects the performance of PTMSP polymer films: selectivity increases sharply with membrane thickness up to 50 μm, whereas it remains constant for thicker membranes. The permeation flux decreases with membrane thickness in the whole range studied. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94:1395–1403, 2004     

Characterization of sodium alginate and poly(vinyl alcohol) blend membranes in pervaporation separation

By blending a rigid polymer, sodium alginate (SA), and a flexible polymer, poly(vinyl alcohol) (PVA), SA/PVA blend membranes were prepared for the pervaporation separation of ethanol–water mixtures. The rigid SA membrane showed a serious decline in flux and a increase in separation factor due to the relaxation of polymeric chains, whereas the flexible PVA membrane kept consistent membrane performance during pervaporation. Compared with the nascent SA membrane, all of the blend membranes prepared could have an enhanced membrane mobility by which the relaxation during pervaporation operation could be reduced. From the pervaporation separation of the ethanol–water mixtures along with the temperature range of 50–80°C, the effects of operating temperature and PVA content in membrane were investigated on membrane performance, as well as the extent of the relaxation. The morphology of the blend membrane was observed with PVA content by a scanning electron microscopy. The relaxational phenomena during pervaporation were also elucidated through an analysis on experimental data of membrane performance measured by repeating the operation in the given temperature range. SA/PVA blend membrane with 10 wt % of PVA content was crosslinked with glutaraldehyde to enhance membrane stability in water, and the result of pervaporation separation of an ethanol–water mixture through the membrane was discussed. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:949–959, 1998     

Blend membranes of chitosan and poly(vinyl alcohol) in pervaporation dehydration of isopropanol and tetrahydrofuran

Blend membranes of a natural polymer, chitosan, with a synthetic polymer, poly(vinyl alcohol) (PVA), were prepared by solution casting and crosslinked with a urea formaldehyde/sulfuric acid (UFS) mixture. Chitosan was used as the base component in the blend system, whereas PVA concentration was varied from 20 to 60 wt %. Blend compatibility was studied by differential scanning calorimetry, and Fourier transform infrared spectroscopy was used to study membrane crosslinking. Membranes were tested for pervaporation dehydration of isopropanol and tetrahydrofuran (THF) at 30°C in close proximity to their azeotropic compositions. Membrane performance was assessed by calculating flux and selectivity. Swelling experiments performed in water + organic mixtures at 30°C were used to explain the pervaporation results. The blend membrane containing 20 wt % PVA when tested for 5 and 10 wt % water–containing THF and isopropanol feeds exhibited selectivity of 4203 and 17,991, respectively. Flux increased with increasing concentration of water in the feed. Selectivity was highest for the 20 wt % PVA‐containing blend membrane. The results of this study are unique in the sense that the crosslinking agent used—the UFS mixture—was novel. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1918–1926, 2007     

Mixed matrix membranes of Matrimid 5218 loaded with zeolite 4A for pervaporation separation of water–isopropanol mixtures

Mixed matrix membranes were prepared by incorporating zeolite 4A into polyimide of Matrimid 5218 using solution-casting technique. The fabricated membranes were characterized by scanning electron microscopy (SEM), differential scanning calorimeter (DSC) and thermo gravimetric analysis (TGA). It was found that the higher annealing temperature of 250 °C is more favorable to improve adhesion between zeolite and polymer phases. Effects of different parameters such as temperature (30–60 °C), water content in feed (10–40 wt.%), zeolite loading (0–15 wt.%) and polymer content (10 and 15 wt.%) on pervaporation dehydration of isopropanol were studied. Sorption studies were carried out to evaluate degree of swelling of the membranes in feed mixtures of water and isopropanol. The experimental results showed that both pervaporation flux and selectivity increase simultaneously with increasing the zeolite content in the membranes. The membrane containing Matrimid 5218 (10 wt.%)–zeolite 4A (15 wt.%) exhibits the highest separation factor (α) of 29,991 with a substantial permeation flux (J) of 0.021 kg/m² h at 30 °C for 10 wt.% of water in the feed. The PV performance was also studied in term of pervaporation separation index (PSI). Permeation flux was found to follow the Arrhenius trend over the investigated temperature range.     

Study on polybenzoxazinone membrane in pervaporation processes

Poly(benz‐3,1‐oxazinone‐4) was prepared by thermal cyclization of its hydrolytically stable precursor polyamic acid. Both polymer and its precursor were investigated as membrane materials. Thermogravimetric analysis and contact angle measurements were carried out for characterization of peculiarity of membrane compositions and analysis of membrane surface. Pervaporation of water–isopropanol mixture was studied in the wide range of feed composition. To interpret the pervaporation transport properties of the membranes, swelling experiments were performed, kinetic curves of sorption and desorption were plotted, and basic sorption and diffusion parameters were analyzed. It was established that poly(benz‐3,1‐oxazinone‐4) membrane is extremely effective in dehydration of water–isopropanol mixture and shows high separation factor. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4024–4031, 2013     

Pervaporation separation of water/isopropanol mixtures through crosslinked carboxymethyl chitosan/polysulfone hollow‐fiber composite membranes

Carboxymethyl chitosan (CMCS)/polysulfone (PS) hollow‐fiber composite membranes were prepared through glutaraldehyde (GA) as the crosslinking agent and PS hollow‐fiber ultrafiltration membrane as the support. The permeation and separation characteristics for dehydration of isopropanol were investigated by the pervaporation method. Pure chitosan, carboxymethyl chitosan, and crosslinked carboxymethyl chitosan membranes were characterized by Fourier transform infrared (FT‐IR) spectroscopy and X‐ray diffraction (XRD) to study the crosslinking reaction mechanism and degree of crystallinity, respectively. The effects of feed composition, crosslinking agent, membrane thickness, and feed temperature on membrane performance were investigated. The results show that the crosslinked CMCS/PS hollow‐fiber composite membranes possess high selectivity and promising permeability. The permeation flux and separation factor for isopropanol/water is 38.6 g/m²h and 3238.5, using 87.5 wt % isopropanol concentration at 45°C, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1959–1965, 2007     

Preparation and characterization of 4A zeolite‐filled mixed matrix membranes for pervaporation dehydration of isopropyl alcohol

Sodium carboxymethylcellulose/poly (vinyl alcohol) mixed matrix membranes filled with different amounts 4A zeolite (0, 5, 10, 15, and 20 wt %) were prepared by solution casting method. Prepared membranes were crosslinked with GA and used for pervaporation dehydration of isopropyl alcohol of different feed mixtures at 35°C. On increment in zeolite content in the membrane it was found the improvement in the performance of the membrane, due to its hydrophilic nature and molecular sieving effect in addition to its favorable interaction with hydrophilic sodium carboxymethylcellulose and polyvinyl alcohol. The structure and chemical constituents of the MMM's were investigated by attenuated total reflectance Fourier transform infrared spectroscopy. Thermal stability of the membranes was assessed by DSC and TGA techniques. Crystallinity of the membranes was assessed using X‐ray diffraction, and the morphological properties were assessed by scanning electron microscopy. Mechanical properties were also carried out to determine the tensile strength and % of elongation at break using universal testing machine. It was found that the mechanical strength increases with increase in the zeolite content upto 15 wt % of zeolite with an optimum tensile strength of 113.31 N/mm². Pervaporation was carried out to asses the membrane performance, the highest flux and selectivity obtained is 0.584 kg/m²/h and 6945 for NaCMCA20 and NaCMCA15, respectively, for a feed composition containing 17.5 and 10 wt % of water in the feed and further swelling studies also supporting the pervaporation results. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Zeolite filled P84 co-polyimide membranes for dehydration of isopropanol through pervaporation process

We have developed zeolite 5A and 13X embedded P84 co-polyimide membranes with enhanced permeability and selectivity for the pervaporation dehydration of isopropanol (IPA). It is found that a higher annealing temperature, i.e., is more favorable to improve adhesion between zeolite and polymer phase, and to enhance charge transfer complexes (CTCs) formation. FESEM, DSC and gas permeation results show that zeolite 13X has better compatibility with the matrix polymer than zeolite 5A because of stronger interactions between Na cations in zeolite 13X framework and electron acceptor groups of P84 polyimide. The addition of zeolite into the P84 dense membrane improves water sorption capacity and pervaporation separation performance significantly. Owing to the bigger pore size, larger pore volume, higher sorption capacity and better adhesion, the zeolite 13X incorporated P84 membranes has a much higher permeability than zeolite 5A filled membranes. Interestingly, both have comparably high selectivity possibly because of the effects of chain rigidification and partial pore blockage. The addition of zeolite 13X reduces activation energy for water permeation through the membrane but increases that for IPA permeation. However, the addition of zeolite 5A increases activation energy for both water and IPA permeation. Pervaporation permeability increases with zeolite 13X loading, while the selectivity achieves the maximum at 30 wt% zeolite 13X loading. When the zeolite 13X loading approaches 40 wt%, the adhesion between zeolite and polymer becomes poor and the membrane selectivity declines. A comparison between pervaporation and gas separation results reveals that pervaporation membranes can tolerate a higher degree of interstitial defects than gas separation membranes because of stronger molecular interactions between the feed and the polymer, and the larger molecular size difference between penetrants in the former.