Abstract
Crosslinked poly(vinyl alcohol) (PVA) composite membranes were synthesized by casting selective crosslinked PVA films on the polyacrylonitrile (PAN) porous substrates. The PVA films were prepared by in-situ crosslinking technique using four different crosslinking agents, such as glutaraldehyde, fumaric acid, maleic acid and malic acid. The separation performance in terms of permeation flux and separation factor of prepared membranes were evaluated for pervaporation dehydration of ethanol/water mixture of 80/20 wt% at 60 oC. The prepared membranes were also characterized by FTIR, SEM, swelling and sessile drop contact angle measurements. It was found that the chemical structure of the PVA membrane was changed via crosslinking reaction. The physicochemical properties (hydrophilicity and swelling degree) and separation performance of the prepared membranes were affected by the chemical structures of the crosslinking agents. Furthermore, there was a trade-off between permeation flux and selectivity of the resulting membranes. When the flux increased, the separation factor decreased. The results of this study contributed to enrich the data of the crosslinking reaction of PVA membranes, and expected to help researcher in suitable choosing crosslinking agent for producing pervaporation PVA membrane for dehydration of ethanol solutions.
Highlights
Nowadays, pervaporation has been gaining much attention as an effective membrane technique for separating heat sensitive; close boiling and azeotropic mixtures due to its low energy consumption, benign operating conditions, no emission to the environment, no involvement of additional species into the feed stream and simplicity of the process [1,3]
Four crosslinkers including GA, fumaric acid, maleic acid and malic acid with different chemical structures were investigated for modifying poly(vinyl alcohol) (PVA) composite membrane
The FTIR spectra of virgin PVA and crosslinked PVA composite membranes were shown in Figure 3 showed the contact angle and swelling degree of the prepared membranes
Summary
Pervaporation has been gaining much attention as an effective membrane technique for separating heat sensitive; close boiling and azeotropic mixtures due to its low energy consumption, benign operating conditions, no emission to the environment, no involvement of additional species into the feed stream and simplicity of the process [1,3]. The commercialized pervaporation membrane employed in ethanol/water separation is PERVAP membrane, which is formed by Sulzer (Germany) It is a composite membrane with a PVA active layer coated on a polyacrylonitrile (PAN) porous support membrane. To our knowledge, the effect of different chemical structures of crosslinking agent on the physicochemical properties and separation performance of modified membrane was not concerned sufficiently. In-situ crosslinking technique was employed to prepared crosslinked PVA selective layer using four different crosslinking agents such as glutaraldehyde (GA), fumaric acid, maleic acid and malic acid in the presence of HCl as catalyst. The. separation performance of the prepared membrane in terms of flux and separation factor was evaluated for pervaporation dehydration of the ethanol/water mixture of 80/20 (wt%) at 60 oC
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