Facile polyamide microstructure adjustment of the composite reverse osmosis membrane assisted by PF127/SDS mixed micelles for improving seawater desalination performance

Abstract

The integrity and uniformity of polyamide (PA) layer have a great influence on the separation performance of thin-film composite (TFC) polyamide reverse osmosis (RO) membrane. In this work, three kinds of micelles including the neutral macromolecule Pluronic F127 (PF127), anionic surfactant sodium dodecyl sulfate (SDS) and the PF127/SDS mixed micelles (PSMM), were proposed to be introduced in the aqueous phase to regulate the interfacial polymerization (IP) process with the purpose of constructing a more integrated and uniform PA separation layer of the RO membrane for seawater desalination. Compared to the single PF127 and SDS, the PSMM-1 (0.05 wt% PF127/0.05 wt% SDS) in the aqueous solution exhibited special advantages including unique three-dimensional (3D) spherical structure, lower solution viscosity and water-Isopar G interface tension (IFT), which sped up m-phenylenediamine (MPD) to homogeneously diffuse to the water-Isopar G interface and further regulated the interfacial polymerization reaction between MPD and trimesoyl chloride (TMC). Ultimately, the regulated RO membrane via PSMM-1 had more uniform PA layer and thus exhibited better comprehensive separation performances including higher salt rejection (more than 99.5%) and ideal water flux (about 35 L·m−2·h−1). This study provides a facile method of PA microstructure adjustment via micelles to fabricate higher-performance TFC RO membrane for seawater desalination.