Enhancing reverse osmosis membrane performance via interfacial diffusion control using porous graphene oxide

The development of polyamide (PA) thin-film composite (TFC) membranes with enhanced water permeance and salt rejection is essential for energy-efficient desalination. This study introduces a reverse osmosis (RO) membrane that achieves rapid water transport and high salt rejection through precise control of interfacial polymerization (IP), enabled by porous graphene oxide (PGO) with optimally sized nanopores. These nanopores act as diffusion pathways for m-phenylenediamine (MPD) during IP in a confined space, reducing residual unreacted MPD and creating additional water transport channels. This process facilitates the formation of a highly crosslinked and permeable PA selective layer. The thin-film nanocomposite (TFN) membrane incorporating PGO etched for 3 h exhibited outstanding water permeance of 3.57 L m⁻² h⁻¹ bar⁻¹ and NaCl rejection of 98.7 %, surpassing state-of-the-art GO-modified RO membranes. Additionally, the membrane demonstrated superior antifouling performance and long-term operational stability. Structural and performance comparisons with TFN membranes incorporating PGO with varying nanopore sizes, controlled via etching time, elucidated the transport mechanism across the membrane. This work highlights a robust strategy for manufacturing high-performance TFC membranes by modulating interfacial diffusion during IP.