Molecular transport across the dense pervaporation membrane is usually governed by solution-diffusion mechanism. Nonporous membranes or asymmetric membranes with dense active layers are preferentially utilized in pervaporation process. Membrane pervaporation can provide profitable benefits: simple process design, straightforward operation, easy maintenance, compact space, low energy consumption, high product quality, and low pollution, leading to widespread applications, such as solvent dehydration, azeotropic solvent purification, removal of volatile organic compounds (VOCs) from aqueous streams, separation of liquid hydrocarbons, dehydration to intensify esterification reaction, and so on. Its driving force is the chemical potential difference between membrane upstream and downstream. The principle of pervaporation, combining permeation and evaporation, is the separation of liquid solvents by partial vaporization through a nonporous or porous membrane, whereafter the vapor permeating through the membrane is removed by vacuum or sweeping inert gas in the permeate side. Amid various membrane applications, pervaporation is a popular membrane approach commonly employed as an alternative to conventional separation processes, such as distillation, extraction, adsorption, etc. Membrane separation has been a persuasive technology utilized broadly in industrial separation processes. Furthermore, these two biodegradable membranes were applied in the pervaporation of simulated ABE (acetone-butanol-ethanol) fermentation solution, and the results were comparable with those reported in the literature. In spite of their biodegradability, the stability of both PGS and APS membranes was not deteriorated on ethanol/water pervaporation for one month. In particular, a positive relationship between the separation factor and the swelling ratio of organic solvent to water (DS o/DS w) was noticed. In the pervaporation process for five organic solvent/water systems at 37 ☌, both biodegradable membranes exhibited higher separation factors for ethanol/water and acetic acid/water separations, while the PDMS membrane attained better effectiveness in the other three systems. The prepared membranes were characterized by FE-SEM, AFM, ATR-FTIR, TGA, DSC, water contact angle, and degree of swelling, in comparison with the PDMS (polydimethylpolysiloxane) membrane. In this study, two dense membranes were made from biodegradable PGS (poly(glycerol sebacate)) and APS (poly(1,3-diamino-2-hydroxypropane-co-polyol sebacate)), respectively. Biodegradable polymers are a green alternative to apply as the base membrane materials in versatile processes.
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