Modelling of the separation performance and electrokinetic properties of nanofiltration membranes

Nanofiltration (NF) has been developed and commercialised over the past decades as a promising liquid separation technology. Recent insights in separation and purification mechanisms related to NF underlined its potential applications for liquid mixtures. During the last years, substantial progress has been made in mathematical modelling of NF, which resulted from a better understanding of separation mechanisms and physico-chemical interactions. The NF separation mechanism is known to be largely related to steric and electrostatic partitioning effects. This combination of effects requires an in-depth analysis of interactions to predict the separation and electrokinetic performance of NF membranes. The mathematical models used to describe the NF process include the following: the nonequilibrium thermodynamic model, structure models and semi-empirical models. This article reviews the origins and general ideas of the above models, as well as their applications to the prediction of separation performance and description of the electrokinetic properties for NF membranes.