Mixed matrix membranes for pervaporative separation of isopropanol/water mixtures (original) (raw)
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Composite Interfaces, 2006
ZSM-5 zeolite-incorporated poly(dimethyl siloxane) membranes were prepared and molecular dispersion of zeolite in the membrane matrix was confirmed by scanning electron microscopy. After studying the behaviour of membrane swelling at 30°C, the membranes were subjected to pervaporation separation of isopropanol-water mixtures at 30, 40 and 50°C. The effects of zeolite loading and feed composition on the pervaporation performances of the membranes were analyzed. Both permeation flux and selectivity increased simultaneously with increasing zeolite content in the membrane matrix. This was discussed on the basis of enhancement of hydrophobicity, selective adsorption and establishing molecular sieving action. The membrane containing the highest zeolite loading (30 •s mass %) exhibits the highest separation selectivity of 80.84 and flux of 6.78 x 10' kg/m h at 30 C for 5 mass % of isopropanol in the feed. From the temperature dependency of diffusion and permeation values, the Arrhenius activation parameters were estimated. A pure membrane (M) exhibits higher Ep and ED values compared to zeolite-incorporated membranes, signifying that permeation and diffusion require more energy for transport through a pure membrane, owing to its dense nature. Obviously, zeolite-incorporated membranes require less
Journal of Membrane Science, 2004
Using solution technique, NaY zeolite-incorporated sodium alginate (SA) membranes were prepared and were subjected for the pervaporation separation of water-isopropanol mixtures. The resulting membranes were characterized by Fourier transform infrared spectroscopy, wide-angle X-ray diffraction and differential scanning calorimetry. The effects of zeolite loading and feed composition on the pervaporation performance of the membranes were analyzed. Both flux and selectivity increased simultaneously with an increase of zeolite content in the polymer matrix. This was explained on the basis of enhancement of hydrophilicity, selective adsorption and molecular sieving action including creation of pores in the membrane matrix. The membrane containing 30 mass % of zeolite shows the highest separation selectivity of 614 with a flux of 14.59 x 10'2 kg/m2h for 5 mass % of water in the feed mixture at 30°C. The total flux and flux of water are found to be almost close to each other throughout the investigated range, suggesting that the membranes developed here are highly water selective. From the temperature dependent diffusion and permeation values, the Arrhenius activation parameters have been estimated. The resulting low activation energy Chapter-Ill
2015
Novel polymeric membranes were prepared by incorporating different amounts of 13X Zeolite into Sodium alginate/Wheat protein isolate (SA/WPI) blend matrix. The resulting composite membranes were characterized by Fourier transform infrared spectroscopy and the results were used to analyze the possible chemical reaction between SA/WPI and glutaraldehyde. X-ray diffraction, Scanning electron microscopy, and Differential scanning calorimeter were used to analyze the crystallinity, surface morphology and thermal stability of the membranes, respectively. The membranes were tested for pervaporation studies for water /IPA mixtures at different feed water compositions at 30 º C. The experimental results showed that both flux and selectivity increased with increase in zeolite content. Membrane containing 20 wt% of zeolite shows the highest separation selectivity of 4991 with a substantial flux of 0.120 Kg/m 2 /h at 30 º C containing 10 wt% of water in the feed, suggesting that the membranes c...
RSC Advances, 2018
Ag-exchanged NaY zeolite (Ag-NaZ) particles were prepared by ion exchange and introduced to a polyvinyl alcohol (PVA) membrane cross-linked with polyacrylic acid (PAA) for the pervaporation dehydration of an isopropanol (IPA) aqueous mixture. The Ag-exchanged NaY zeolite particles were characterized by FE-SEM, EDS, BET, and XRD studies. The prepared Ag-NaZ-loaded PVA/PAA composite membrane was characterized by FE-SEM, XRD, a swelling study, and contact angle measurements. Pervaporation characteristics were investigated in terms of Ag-NaZ concentrations within PVA/PAA membranes using diverse feed solution conditions. The preferential sorption of IPA/water mixtures for Ag-NaZ-introduced membranes were also determined by calculating the apparent activation energies of IPA and water permeation, respectively. As a result, flux and selectivity increased with the Ag-NaZ concentration to 5 wt% in the membrane. Optimum pervaporation performance was observed in a 5 wt% Ag-NaZincorporated membrane with a flux equal to 0.084 kg m À2 h À1 and a separation factor of 2717.9 at 40 C from an 80 wt% IPA aqueous feed solution.
Journal of Applied Polymer Science, 2004
Hybnd membranes were prepared using poly(vmyl alcohol) (PVA) and tetraethylorthosilicate (TEOS) via hydrolysis followed by conden sation The obtained membranes were characterized by Founer transform infrared spectroscopy, wide-angle X-ray diffraction and differential scanning calorimetry The remarkable decrease m degree of swelling was observed with increasing TEOS content in membranes and is at tributed to the formation of hydrogen and covalent bonds in the membrane matrix. The pervaporation performance of these membranes for the separation of water-acetic acid mixtures was mvestigated in terms of feed concentration and the content of TEOS used as crosslinkmg agent The membrane can taming 1 2 mass ratio of PVA and TEOS gave the highest separation selectivity of 1116 with a flux of3 33 x 10"2 kg/m2 h at 30 °C for 10 mass% of water in the feed Except for membrane M-l, the observed values of water flux are close to the values of total flux in the mvestigated composition range, signifying that the developed membranes are highly water selective From the temperature dependence of diffusion and permeation values, the Arrhenius apparent activation parameters have been estimated The resulting activation energy values, obtained for water permeation being lower than those of acetic acid permeation values, suggest that the membranes have higher separation efficiency The activation energy values calculated for total permeation and water permeation are close to each other for all the membranes except membrane M-l, signifying that coupled-transport is minimal as due to higher selective nature of membranes Further, the activation energy values for permeation of water and diffusion of water are almost equivalent, suggesting that both diflusion and permeation contribute almost equally to the pervaporation process The negative heat of sorption values (A Hs) for water m all the membranes suggests the Langmuir's mode of sorption
Journal of Chemical & Engineering Data, 2010
Using a sol-gel technique, organic-inorganic hybrid membranes were prepared using chitosan and mixed silica precursors such as tetraethoxysilane and γ-glycidoxypropyltrimethoxysilane. The γ-glycidoxypropyltrimethoxysilane acted as a coupling agent to enhance the compatibility between the organic (chitosan) and the inorganic (tetraethoxysilane) phase. Different techniques such as Fourier transform infrared spectroscopy (FTIR), wide-angle X-ray diffraction (WAXD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) were employed to study the physicochemical changes in the resulting membranes. These membranes were tested for their ability to separate water + isopropanol mixtures by pervaporation in the temperature range of (303 to 323) K. The experimental data demonstrated that both flux and selectivity were increased simultaneously with increasing the amount of γ-glycidoxypropyltrimethoxysilane. However, this trend no longer remained when the content of γ-glycidoxypropyltrimethoxysilane was increased beyond 0.25 mass fraction. The membrane containing 0.25 mass fraction of γ-glycidoxypropyltrimethoxysilane (M-2) exhibited the highest separation selectivity of 18 981 with a thickness-normalized flux of 7.45 • 10-7 kg • m-1 • h-1 at 303 K. The total flux and flux of water were found to be overlapping with up to 0.25 mass fraction of γ-glycidoxypropyltrimethoxysilane, suggesting that these membranes could be used effectively to break the azeotropic point of water-isopropanol mixtures. From the temperature-dependent permeation values, the Arrhenius activation parameters were estimated. The activation energy values obtained for water permeation (E pw) are significantly lower than those of isopropanol permeation (E pIPA), suggesting that the developed membranes have demonstrated an excellent separation performance for water-isopropanol systems.
Journal of Applied Polymer Science, 2007
A solution technique was employed to prepare ZSM-5 zeolite incorporated poly(vinyl alcohol) (PVA) membranes for the pervaporation separation of water-isopropanol mixtures. The membranes were characterized by Fourier transform infrared spectroscopy and differential scanning calorimeter. Glass transition temperatures of the membranes varied from 102 to 110°C, with increasing zeolite content of the membrane. The effect of zeolite loading and feed composition on pervaporation performance of the membranes was analyzed. The membrane containing 6 mass % of zeolite gave the highest separation selectivity of 216 for 10 mass % of water containing feed mixture at 30°C. Increase in water selectivity of the membrane was explained as due to a reduction in free volume by increasing zeolite content of the membrane. Separation selectivity and permeation flux data are dependent on water composition of the feed mixture, but are comparatively less dependent on temperature. The hindrance of water permeation at higher composition of water in the feed mixture was explained as due to the formation of clusters of water molecules. The overall activation energy and preexponential factors were calculated using Arrhenius equation. Pervaporation data have also been explained on the basis of thermodynamic parameters calculated by using Arrhenius equation as well as relationship proposed by Ping et al.
PERVAPORATION OF ISOPROPANOL-WATER MIXTURE USING POLY(VINYL) ALCOHOL-ZSM-5 MEMBRANES
The pervaporation separation of isopropanol-water mixture was carried out using poly(vinyl) alcohol (PVA) membrane incorporated with 0.2 wt% ZSM-5 zeolite. The manipulated variables were feed temperature and feed concentration. Initially, 5 wt% of PVA powder was dissolved in distilled water at 98 °C. The solution was stirred using magnetic stirrer for 1 hour to produce a homogenous solution. It was then cooled to room temperature before added with the zeolite. The PVA-zeolite solution was stirred for 24 hours at room temperature before it was casted on a porous support. The support layers were produced through phase inversion using casting solution of 12 wt% polysulphone, 11 wt% cellusolve and 77 wt% N,N-dimetil formamide (DMF). Finally, the modified composite membranes were produced by casting the PVA- zeolite solution on the porous polysulphone support layers. Pervaporation tests were conducted using SOLTEQ Pervaporation Bench Test Unit (Model: TR 12). The results showed the incre...
Journal of Applied Polymer Science, 2011
Mixed matrix membranes of poly(vinyl alcohol) and poly(vinyl pyrrilidone) blends were prepared by loading with phosphomolybdic acid (PMA) and their pervaporation (PV) properties were investigated for the PV separation of isopropanol. Membrane performance shown a dependence on the extent of PMA loading. The 4 wt % PMA-loaded blend membrane had the highest separation factor of 29991, which declined considerably at higher loading. The flux of 4 wt % PMA-loaded membrane was lower than that of nascent blend membrane. Feed water composition and temperature influenced the PV performance. Solubility selectivity was higher than diffusion selectivity. Degree of swelling was smaller after PMA loading exhibiting better separation ability. The PV results were analyzed using the Flory-Huggins theory and sorption was dominated by Langmuir's mode.
SN Applied Sciences, 2020
Pervaporation (PV) separation of water-isopropanol has been attempted using the blend membranes of poly (vinyl alcohol) (PVA) with poly (styrene-co-acrylonitrile) (PSA), and poly (vinyl alcohol) (PVA) with poly (styrene-co-methyl methacrylate) (PSM). Here, we described the fabrication of Hydrophilic-hydrophobic blend polymer membranes of PVA/PSM and PVA/PSA by solution casting method and cross-linked with glutaraldehyde (GA) in the presence of aqueous hydrochloric acid (HCl). These membranes were analyzed by Fourier transform (FTIR) infrared analysis, Field emission scanning electron microscopy (FESEM) analysis, Differential scanning calorimetry (DSC) and Thermo gravimetric analysis (TGA). Pervaporation experiments were conducted at 30 °C for 10, 12.5, and 15 wt.% of aqueous isopropanol feed mixtures and membrane performance was evaluated by calculating flux, selectivity and pervaporation separation index (PSI). Highest selectivity of 281 with flux of 0.076 kg/m 2 h has been observed PVA/PSM blend membrane when compared to pristine PVA membrane to dehydrate 12.5 wt.% water in feed mixture. Flux values were decreased from 0.112 to 0.076 kg/m 2 h to dehydrate 12.5 wt.% water in feed mixture for PVA/PSM blend membrane and plain PVA membrane. The developed blend membrane selectivity was improved dramatically whereas flux was decreased compared to the plain PVA membrane.