Modification of tetraethylorthosilicate crosslinked poly(vinyl alcohol) membrane using chitosan and its application to the pervaporation separation of water–isopropanol mixtures

Abstract

ABSTRACT:Tetraethylorthosilicate crosslinked poly(vinyl alcohol) membrane was modified by varying the amounts of chitosan. The resulting membranes were characterized by Fourier transform infrared spectroscopy and differential scanning calorimetry. The effects of chitosan content and feed composition on the pervaporation performance of the membranes were analyzed. The modified membranes exhibit simultaneous increase of both flux and selectivity. The membrane containing 15 mass % of chitosan shows the highest separation selectivity of 2991, with a flux of 2.39 ϫ 10 Ϫ2 kg/(m 2 h) at 30°C for 10 mass % of water in the feed. The total flux and flux of water are almost overlapping each other, manifesting that the membranes could be used effectively to break the azeotropic point of waterisopropanol mixture, so as to remove water from the isopropanol. From the temperature dependent diffusion and 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 membranes developed here have higher separation ability for water-isopropanol system. In addition, difference was negligibly small between the activation energy values of total permeation (E p ) and water permeation (E pw ), indicating that coupled transport is minimal because of a higher selective nature of membranes. The E p and E D values ranged between 40.92 and 52.60, and 39.58 and 52.47 kJ/mol, respectively. The positive heat of sorption (⌬H s ) values observed in all the membranes suggests that Henry's mode of sorption is predominant.

Synthesis and characterization of GTMAC grafted chitosan membranes for the dehydration of low water content isopropanol by pervaporation

“…In PV process, the overall selectivity of a membrane is generally explained on the basis of interaction between the membrane and permeating molecules, molecular size of the permeating species, and the free-volume in the membrane [35]. Fig.…”

Development of novel membranes for PV separation of water–isopropanol mixtures using poly(vinyl alcohol) and gelatin

“…In PV process, mass transport of binary liquid mixtures through a non-porous polymer membrane is generally described by the solution-diffusion mechanism, which occurs in three steps: sorption, diffusion and evaporation [33]. Thus, permeation rate and selectivity are governed by the solubility and diffusivity of each component of the feed mixture to be separated.…”

Development of novel grafted hybrid PVA membranes using glycidyltrimethylammonium chloride for pervaporation separation of water–isopropanol mixtures

“…To enhance the flux of this membrane, we have modified the hybrid membrane by judiciously interposing hydrophilic chitosan [27] and NaY zeolite [28], and subjected for the dehydration of isopropanol. The trade-off phenomenon exists between permeability and selectivity was successfully solved using these hybrid membranes.…”