Understanding water and solute transport in thin film nanocomposite membranes by resistance-in-series theory combined with Monte Carlo simulation

Abstract

The lack of mechanistic insights into the water and solute transport in the thin film nanocomposite (TFN) membrane active layer posed a major challenge in the fundamental understandings and performance optimization of such membranes in water treatment. In this work, we develop a novel water and solute transport model to qualitatively and quantitatively study the influence of intrinsic permeabilities and geometric parameters of the NPs and the NPs-polymer intermediate layer on the widely observed flux enhancement of TFN membranes based on the resistance-in-series theory and Monte Carlo simulation. The simulation results demonstrate a small amount of porous or even non-porous NPs addition would result in a significant flux increase due to either high NP permeability, high intermediate layer permeability, or the combined effects of the abovementioned factors. Besides, we find that an optimized combination of NPs mass loading and NPs size, thicker intermediate layer and TFN membrane with minimized NPs aggregation are preferred to achieve high permeate flux. This simulation can be used to predict TFN membrane performance and provide guidance on engineering the next-generation TFN membranes with high flux as well as improved rejections, to tackle with the widely acknowledged problem of flux and rejection trade-off.