UCL Discovery
UCL home » Library Services » Electronic resources » UCL Discovery

The role of hydrogen bonding in the dehydration of bioalcohols in hydrophobic pervaporation membranes

Madero-Castro, RM; Calero, S; Yazaydin, AO; (2021) The role of hydrogen bonding in the dehydration of bioalcohols in hydrophobic pervaporation membranes. Journal of Molecular Liquids , 340 , Article 117297. 10.1016/j.molliq.2021.117297.

[thumbnail of the-role-of-hydrogen-bonding-in-the-dehydration-of-bioalcohols-in-hydrophobic-pervaporation-membranes.pdf] Text
the-role-of-hydrogen-bonding-in-the-dehydration-of-bioalcohols-in-hydrophobic-pervaporation-membranes.pdf - Accepted version
Access restricted to UCL open access staff until 20 August 2022.

Download (671kB)

Abstract

The dehydration of bioalcohols is considered one of the major factors contributing to the cost of biofuel production. In this study, liquid phase separation of water from methanol and ethanol in a siliceous MFI pervaporation membrane was studied by performing concentration gradient driven molecular dynamic (CGD-MD) simulations. CGD-MD simulations work by imposing a higher concentration in the feed side and a lower concentration in the permeate side of the membrane. This creates a concentration gradient across the membrane that facilitates the diffusion of molecules from the feed to the permeate side, mimicking the experimental pervaporation membrane set up. Fluxes of methanol, ethanol and water were calculated in single component permeation simulations and in equimolar methanol–water and ethanol–water mixture separation simulations. It was found that water formed hydrogen bonds with the silanol (Si-OH) groups on the external surface of the MFI and did not enter the membrane in the single component permeation simulation. While this may suggest that MFI can be used to effectively dehydrate bioalcohols, our simulations showed that water permeated through the MFI membrane when it was in a mixture with either methanol or ethanol. Furthermore, in the alcohol-water mixture simulations, the fluxes of methanol and ethanol were significantly lower than that of expected based on their single component fluxes. A detailed analysis of hydrogen bonding in the alcohol-water mixture separation simulations revealed that water preferred making hydrogen bonds with methanol and ethanol rather than with the silanol groups. This resulted in drifting of water molecules along with permeating alcohol molecules in to the MFI membrane in mixture simulations, while slowing the permeation of methanol and ethanol fluxes. The hydrogen bonding between water and alcohol molecules indicates that it may not be possible to achieve complete alcohol selectivity even if defect-free membranes were manufactured; however, our findings also hint at the possibility of functionalizing membrane surfaces with chemical groups that will overcome water-alcohol hydrogen bonding and retain water molecules in order to approach complete selectivity.

Type: Article
Title: The role of hydrogen bonding in the dehydration of bioalcohols in hydrophobic pervaporation membranes
DOI: 10.1016/j.molliq.2021.117297
Publisher version: https://doi.org/10.1016/j.molliq.2021.117297
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Dehydration, bioalcohol, water, hydrogen bonds, separation
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Chemical Engineering
URI: https://discovery.ucl.ac.uk/id/eprint/10134273
Downloads since deposit
1Download
Download activity - last month
Download activity - last 12 months
Downloads by country - last 12 months

Archive Staff Only

View Item View Item