Liquid Flow through Defective Layered Membranes: A Phenomenological Description

TL;DR

This paper develops a phenomenological model for liquid flow through defective layered membranes, accounting for slip flow and defect types, and explains high water permeability in graphene oxide membranes quantitatively.

Contribution

It introduces a formalism that extends conventional laminar flow models to include slip flow and defect effects, providing a quantitative explanation for high permeability.

Findings

Flow remains laminar in defective multilayer graphene oxide membranes.

High water permeability is explained by in-layer pores reducing diffusion paths.

Flow rate is highly sensitive to the radius of vacancy defects, entering the flux expression to the fourth power.

Abstract

We present a realistic phenomenological description of liquid transport through defective, layered membranes. We derive general expressions based on conventional models of laminar flow and extend the formalism to accommodate slip flow. We consider different types of defects including in-layer vacancies that provide an activation-free tortuous path through the membrane. Of the many factors that affect flow, the most important is the radius of in-layer vacancy defects, which enters in the fourth power in expressions for the flux density. We apply our formalism to water transport through defective multilayer graphene oxide membranes and find that the flow remains in the laminar regime. Our results show that observed high water permeability in this system can be explained quantitatively by a sufficient density of in-layer pores that shorten the effective diffusion path.