Modeling phase behavior for quantifying micro-pervaporation experiments

TL;DR

This paper introduces a theoretical model for understanding the concentration evolution in micro-pervaporation devices, linking experimental observations to thermodynamic and dynamic properties of binary mixtures.

Contribution

It provides a simplified one-dimensional model that connects measurable experimental data with underlying chemical potentials and coefficients.

Findings

Model accurately predicts concentration profiles

Links experimental data to thermodynamic parameters

Applicable to dilute and dense mixtures

Abstract

We present a theoretical model for the evolution of mixture concentrations in a micro-pervaporation device, similar to those recently presented experimentally. The described device makes use of the pervaporation of water through a thin PDMS membrane to build up a solute concentration profile inside a long microfluidic channel. We simplify the evolution of this profile in binary mixtures to a one-dimensional model which comprises two concentration-dependent coefficients. The model then provides a link between directly accessible experimental observations, such as the widths of dense phases or their growth velocity, and the underlying chemical potentials and phenomenological coefficients. It shall thus be useful for quantifying the thermodynamic and dynamic properties of dilute and dense binary mixtures.