Study on the mechanisms for the influence of nanomaterials on the separation performance of nanocomposite membrane from a modeling perspective

Abstract

An understanding of how nanomaterials, serving as “nanofillers” in nanocomposite membranes, affect membrane performance is limited. This study investigates the mechanisms by which nanomaterials affect membrane performance from a paired modeling and experimental perspective using the Donnan-steric pore model with dielectric exclusion (DSPM-DE). Specifically, the membrane parameters of the nanocomposite membrane containing carboxyl-functionalized cellulose nanocrystals (CNC-COOHs) and the pristine membrane are fitted and compared, based on the experimental results combined with the model. We quantify and compare the effect of CNC-COOHs on the separation mechanism by calculating the contribution ratio of each of these mechanisms in two types of membranes toward the cations and anions in brackish water. Changes in membrane dielectric constant and membrane charge induced by CNC-COOHs increased the contribution of dielectric exclusion at the feed/membrane interface and Donna equilibrium at the permeate/membrane interface by 9–14% and 12–16%, respectively. This study is meaningful for the development of nanocomposite membrane toward a given application for water treatment, which builds up a good basis for further in-depth exploration.