Polyester-based thin-film composite membranes for nanofiltration of saline water: A review

Polyester-based membranes are entering into the limelight of prospective membrane technologies as a feasible alternative to conventional polyamide-based membranes for nanofiltration (NF). Various monomers, including β-cyclodextrin (β-CD) and triethanolamine (TEOA), among other hydroxyl terminated compounds, can be substituted for the monomer in aqueous solution during interfacial polymerization (IP) or even incorporated into what would normally be ultrafiltration (UF) membranes. When a polyester selective layer is fabricated, it presents distinct physicochemical properties and a loosening of the active layer compared to a conventional polyamide-based active layer that usually allows for greater water flux while still maintaining reasonable levels of salt/dye rejection. This review presents an overview of the mechanism that governs the formation of polyester-based membranes, discusses potential benefits and downfalls of such membranes for nanofiltration, and evaluates the practicability of various applications, including salt/dye separation, dye wastewater treatment, and more.