Investigation of membrane fouling phenomenon using molecular dynamics simulations: A review

Abstract

Membrane fouling remains a tremendous obstacle in the implementation of membrane technology, which has motivated the use of a wide range of experimental techniques to study and understand fouling behavior in the past decades. However, molecular-level insights, which underlie the macroscopic phenomena observable experimentally-, remain incomplete. With the rapid advancement of computational power, molecular dynamics (MD) simulation has become increasingly popular to explore the interaction occurring at the ternary interface (i.e., foulant, membrane and solvent) by using explicit atom representations. MD studies have quantified interfacial physical properties and generated MD trajectories for direct visualization of the adsorption process. This review focuses on reported MD studies on membrane fouling and related foulantadsorption processes. The fundamentals of MD and procedures for constructing an MD system for fouling investigation are overviewed first. Subsequently, representative parameters and related insights generated from unbiased simulation are discussed. Then, biased simulations with enhanced sampling algorithms, which addresses some shortcomings of unbiased simulations and allows for quantification of the free energy landscape, are outlined. Additionally, the unique characteristics of representative foulants revealed by MD are summarized. Finally, future perspectives are proposed to enhance the value of MD as a tool for understanding and predicting membrane fouling.