Enhanced reverse osmosis performance via amphiphilic polyMOF embedded thin-film nanocomposite membranes

Abstract

Achieving optimal dispersibility of metal–organic framework (MOF) particles in organic solvents such as n-hexane is crucial for enhancing the performance of thin-film nanocomposite (TFN) membranes. However, improving MOF dispersibility without compromising their hydrophilicity and porosity remains challenging. In this study, we introduce polyUiO-66 (pU-66), a novel filler synthesized by incorporating an amphiphilic microporous polymer ligand (cPIM-1) into conventional UiO-66 (U-66) nanoparticles. The cPIM-1 ligand promotes effective dispersion of pU-66 particles in the organic phase while preserving the particles' hydrophilicity and porosity, which are critical for desalination. Additionally, the cPIM-1 ligand reduces particle size, improving their integration into the polyamide (PA) layer. pU-66 also enhances the diffusion of m-phenylenediamine (MPD) into the organic phase, resulting in a denser PA layer with increased backside surface porosity. The optimized pU-66-loaded TFN membrane demonstrated a high NaCl rejection of 98.5% and an exceptionally high water permeance of 4.3 Lm−2 h−1 bar−1. Moreover, the pU-66-embedded membranes showed superior resistance to organic fouling, attributed to increased surface hydrophilicity and a more negatively charged surface.