High Performance Thin-film Composite Membranes with Mesh-Reinforced Hydrophilic Sulfonated Polyphenylenesulfone (sPPSU) Substrates for Osmotically Driven Processes

Abstract

We have for the first time combined the strength of hydrophilic sulfonated material and thin woven open-mesh via a continuous casting process to fabricate mesh-reinforced ultrafiltration (UF) membrane substrates with desirable structure and morphology for the development of high-performance thin-film composite (TFC) osmosis membranes. A new sulfonated polyphenylenesulfone (sPPSU) polymer with super-hydrophilic nature is used as the substrate material, while a hydrophilic polyester (PET) open-mesh with a small thickness of 45 μm and an open area of 44.5% is employed as the reinforcing fabric during membrane casting. The newly developed sPPSU-TFC membranes not only exhibit a fully sponge-like cross-section morphology, but also possess excellent water permeability (A=3.4–3.7 L m−2 h−1 bar−1) and selectivity toward NaCl (B=0.10–0.23 L m−2 h−1). Due to the hydrophilic nature and low membrane thickness of 53–67 μm, the PET-woven reinforced sPPSU substrates have remarkably small structural parameters (S) of less than 300 μm. The sPPSU-TFC membranes thereby display impressive water fluxes (Jw) of 69.3–76.5 L m−2 h−1 and 38.7–47.0 L m−2 h−1 against a deionized water feed using 2 M NaCl as the draw solution under pressure retarded osmosis (PRO) and forward osmosis (FO) modes, respectively. This performance surpasses the state-of-the-art commercially available FO membranes. The sPPSU-TFC membranes also show exciting performance for synthetic seawater (3.5 wt% NaCl) desalination and water reclamation from real municipal wastewater. The newly developed PET-woven sPPSU-TFC membranes may have great potential to become a new generation membrane for osmotically driven processes.