Enhancing water permeability and antifouling performance of thin–film composite membrane by tailoring the support layer

Abstract The properties of support layers are critical for the desalination performance of thin–film composite (TFC) membranes. For instance, surface characteristics of the support layers significantly impact the formed polyamide (PA) rejection layer by interfacial polymerization, thereby affecting the water transport and fouling behaviors of the TFC desalination membranes. In this work, the relationship between the support layer's properties and final separation and antifouling properties of TFC membranes was comprehensively investigated. A sulfonated polysulfone (sPSf) polymer was utilized to control the properties of the polysulfone (PSf) support layers. The sPSf modified support layer (PSf–X series) exhibited enhanced surface hydrophilicity, smaller surface pores, larger overall porosity, and higher water flux compared with the pristine PSf support layer. After interfacial polymerization on the PSf–X series support layers, the TFC–X series membranes showed enhanced hydrophilicity, smoother surfaces, enhanced water permeability and antifouling performance without major loss of NaCl rejection. Meanwhile, the forward osmosis (FO) desalination performance of TFC–X series was significantly improved due to the enhanced water permeability and reduced internal concentration polarization associated with the more porous support layer. A computational fluid dynamic model based on the finite element method was also developed to fit the forward water and reverse salt fluxes to the experimental results. The prepared TFC membrane containing sPSf in the support layer displayed improved water permeability and antifouling performance in FO applications. This work explores the relationship between the support layer properties and the separation performance of TFC membranes. It provides an effective strategy to enhance the water permeability and antifouling of TFC membranes by tailoring the support layers.