Desalination Properties of Reverse Osmosis (RO) Thin-Film Composite Membranes Based on Sulfonated Copolymers

Abstract

Reverse osmosis (RO) thin-film composite membranes with novel sulfonated copolymers as the top active layer coated on ultrafiltration microporous membranes were prepared under various preparation conditions, including the polymer concentration, solvent, drying temperature, and polymer composition (e.g., degree of sulfonation and acid or salt form). The sulfonated copolymers are a new family of hydrophilic-hydrophobic copolymers based on poly (arylene ether). These polymers prepared via a novel synthesis involving direct copolymerization of non-sulfonated monomers with a disulfonated monomer. By tailoring morphologies consisting of hydrophilic and hydrophobic domains in such copolymers, desalination properties, such as water permeance and salt rejection, can be varied over a wide range. Thin-film composite membranes were prepared via brush coating of dilute sulfonated copolymer solutions on commercial microporous polysulfone membrane. These thin-film comoposite membranes exhibit high water permeance and high salt rejection.