Plasma‐modified poly(vinyl alcohol) membranes for the dehydrationof ethanol

Abstract

Non‐porous poly(vinyl alcohol) (PVA) membranes prepared by a cast‐evaporating technique were covered with an allyl alcohol or acrylic acid plasma‐polymerized layer. The wettability and the surface energy, as well as the chemical nature of the deposit, were assigned by X‐ray photoelectron spectroscopy (XPS) and Fourier‐transform infrared spectroscopy (FTIR). The ability of the modified membranes for dehydrating the water/ethanol azeotropic mixture by pervaporation was studied at 25, 40 and 60 °C. The best selectivity (α H 2O = 250 at 25 °C) was obtained in the case of the allyl alcohol plasma treatment. The results obtained are discussed on the basis of the hydrophilicity as well as in terms of the weakly crosslinked superficial layer that favoured the membrane swelling. Copyright © 2003 Society of Chemical Industry

Time-dependence of pervaporation performance for the separation of ethanol/water mixtures through poly(vinyl alcohol) membrane

“…However, some investigations have revealed that the separation performance of the membrane had significant time dependence [8,[11][12][13][14][15]. For example, H 2 O wt% in the permeation through poly(vinyl alcohol) (PVA) membrane treated with allyl alcohol plasma first increased, and finally attained equilibrium as the pervaporation process proceeded [8].…”

“…For example, H 2 O wt% in the permeation through poly(vinyl alcohol) (PVA) membrane treated with allyl alcohol plasma first increased, and finally attained equilibrium as the pervaporation process proceeded [8]. When the poly(ether imide) (PEI) membrane deposed an allylamineplasma-polymerized layer employed to dehydrate the water/ethanol azeotropic mixture, its selectivity toward water increased from 2000 to 10,850, while the total flux decreased from 3 to 2.6 g/m 2 h after about 30 h of operation [12].…”

“…Generally, membrane surfaces play an important role in their pervaporation performance, and thus many researchers have focused their attention on membrane surface modification to improve separation performance [7][8][9][10]. For example, the hydrophobically surfacemodified membrane consisting of poly(dimethylsiloxane) and poly(methyl methacrylate) exhibited excellent benzene selectivity from a dilute aqueous solution of benzene due to the preferential sorption of benzene into the hydrophobic surfaces [7].…”

Investigation on surface molecular conformations and pervaporation performance of the poly(vinyl alcohol) (PVA) membrane

“…The organic selectivity of a membrane can be improved by enhancing the hydrophobicity of the membrane [1][2][3], whereas increasing the hydrophilicity of the membrane raises the selectivity of water toward organic aqueous solution [4][5][6][7].…”

Preparation and characterization of CMCS/PVA blend membranes and its sorption and pervaporation performance (I)

“…In this study, the PAN membrane was treated by introducing PAN flat membrane into 5 wt % aqueous NaOH solution at 40 C for 3 h. Then, the NaOH-hydrolyzed PAN flat membrane was washed using deionized water. A 8 wt % of PVA solution was prepared in deionized water at 100 C. A 4 wt % solution of CMCS was prepared and the solution was filtered to remove any undissolved suspend matters.…”