Modelling of mass transfer during pervaporation of ethanol/water mixture using polydimethylsiloxane membrane

Abstract

The application of pervaporation (PV) as a membrane-based separation process for the recovery of dilute organic solutes has become a promising alternative to conventional distillation due to its easy scaleup, energy-saving, process continuity. The present study aims at the modelling of mass transfer during the pervaporation process for ethanol recovery from ethanol/water mixture using a solution-diffusion model at different concentrations (5–20%), and different temperatures (30–60 °C). The results revealed that the estimated values of ethanol reference permeance and water reference permeance were respectively Q0eth = 11.77 ± 0.10 g/m2 h kPa and Q0water = 13.31 ± 0.16 g/m2 h kPa. It was also found that the estimated value of ethanol activation energy (Ea(eth)) was 60.40 ± 6.40 kJ/mol whereas the estimated value of water activation energy (Ea(w)) was 56.09 ± 5.05 kJ/mol. The validation of the suggested solution-diffusion model was assessed in terms of mean absolute percentage error (MAPE) using fermentation broth where it showed high accuracy with a low value of MAPE for the ethanol flux (MAPE = 2.8%), water flux (MAPE = 2%), total flux (MAPE = 3.2%). These findings suggest the solution-diffusion model as an efficient tool for optimizing and controlling the pervaporation process when it is coupled with continuous alcoholic fermentation for bioethanol production.