Atomic scale manipulation of sublayer with functional TiO2 nanofilm toward high-performance reverse osmosis membrane

Abstract

Recently, engineering the sublayer of polyamide thin film composite (PA-TFC) membrane by functional nanomaterials at nanoscale has been developed as an effective strategy to control interfacial polymerization reaction to fabricate high-performance reverse osmosis (RO) membrane. However, a reliable and practical manipulation technique is still needed to overcome the limitation of conventional sublayers. In this work, an approach of using atomic layer deposited (ALD) monomer-affinitive titanium dioxide (TiO2) nanofilm to modify the sublayer of TFC was proposed to form a thin, smooth, and highly cross-linked PA selective top layer. The functional TiO2 nanofilm increases the affinity between modified sublayer and amine monomer in favor of the efficient and subtle tuning of the adsorption and diffusion of amine monomer during the interfacial polymerization process. The obtained TFC membrane with optimal ALD TiO2 coverage demonstrates well-improved RO performance in terms of high permeance of 1.8 L.m−2.h−1.bar−1 and high salt rejection rate of 96.1% in a dead-end process. This work reveals that coating functional nanomaterials by ALD is a practical manipulation technique toward the controllable fabrication of promising TFC membrane and the optimization of sublayer materials.