Analysis of the permeation behavior of ethanol/water mixtures through a polydimethylsiloxane (PDMS) membrane in pervaporation and vapor permeation conditions

In this study the interactions between ethanol and water penetrating in a supported polydimethylsiloxane membrane were investigated both using experimental and mathematical modelling work. To reach comprehensive analysis of the membrane performance and the penetrant interactions, the experimental work included a wide range of pervaporation and vapor permeation experiments with pure and binary ethanol-water mixtures. A Maxwell-Stefan model was used to further analyze the membrane performance with a Flory-Huggins formulation to describe the sorption behavior. According to the formed model, both water and ethanol permeation are slowed down from the permeation rates observed with pure feeds and in binary permeation especially the experimental ethanol flux is lower than the flux expected by the model. This suggests that the interactions between the penetrants in PDMS are high resulting to decreased diffusion rate of both ethanol and water.