Modeling of polyphenol filtration by polyethersulfone ultrafiltration membrane : A classical molecular dynamics study

Polyphenols are abundant in plants and their antioxidant and anti-inflammatory properties have numerous therapeutic applications. Ultrafiltration membrane processes represent an ecological and economical alternative for the extraction of polyphenols from biomass juices. However, one of the main limitations is the fouling of the membranes, the mechanism of which remains unclear. Therefore, it is essential to determine and understand the interactions in the vicinity of the membrane to improve operating conditions.

We studied the interactions between tannic acids (TA) and a polyethersulfone (PES) ultrafiltration membrane, using classical molecular dynamics (MD) simulations. Initially equilibrium MD simulations were performed to determine the interactions responsible for TA self-aggregation or TA adsorption on the PES.

In addition, we developed a methodology aimed at creating a water flow through non-equilibrium MD simulations, intending to study the interactions as close as possible to the experimental conditions. The process was modeled by applying forces onto the water molecules. We highlight that simply defining a force perpendicular to the membrane leads to artifacts. Thus, the characterization of the applied forces was improved by adding randomly defined components.