Estimation of Mass Transfer Rates through Hydrophobic Pervaporation Membranes

Abstract

In pervaporation of dilute solutions (acids, esters, and ketones) through hydrophobic membranes, mass transfer coefficients increased with temperature in an Arrhenius-like manner. Activation energies and pre-exponential factors were estimated through empirical correlations, allowing estimation of mass transfer coefficients. The activation energy was a function of the heat of sorption and the elastic modulus of the membrane. For low molecular weight compounds, the heat of sorption was the more important of these two factors, whereas the membrane thickness (which influenced the elastic modulus) became more important for larger compounds. The compensation effect allowed pre-exponential factors to be estimated from the activation energies.

Keywords:

• Activation energy
• compensation effect
• heat of sorption
• pervaporation
• pre-exponential factor

ACKNOWLEDGEMENTS

This work was funded by Fonterra Co-operative Group Ltd and the Foundation for Research, Science and Technology, New Zealand (contract number FCGL0403). The membranes were kindly supplied by GKSS-Forschungszentrum.

Notes

^a All flavor compounds were supplied by Sigma-Aldrich Co. (St Louis, MO, USA), and had purities of greater than 98%.