Thin film composite membrane with improved permeance for reverse osmosis and organic solvent reverse osmosis

Abstract

Reverse osmosis (RO) is a widely used pressure-driven membrane process for desalination. Advancements in membrane materials have driven RO technologies' development and widespread application. Thin-film composite (TFC) membranes of a thin polyamide (PA) layer, porous substrate, and nonwoven fabric support are considered the gold standard in desalination technology. These membranes exhibited excellent separation performance and mechanical strength. Recently, TFC membranes with PA layers have been successfully employed in organic solvent reverse osmosis (OSRO) to differentiate organic liquids molecularly. Developing TFC membranes with improved solvent resistance and permeance is required to expand the applications of TFC membranes beyond solvent-solute systems. This study explored polyketone (PK) membranes as porous substrates in TFC membranes for general reverse osmosis processes. PK membranes offer excellent solvent resistance and are easier to prepare than other membranes. Furthermore, a surface modification approach was proposed to enhance the interfacial polymerization (IP) of the polyamide layer on both PK and polysulfone (PSf) substrates, resulting in improved TFC membranes with enhanced water permeance for RO and increased organic liquid permeance for OSRO while maintaining permselectivity. These findings highlight surface chemistry's significance in controlling crumpled PA layers' formation, ultimately improving the filtration efficiency for general RO applications. This study provides an example of the design of composite structures of TFC membranes for broader RO applications.