Reverse osmosis membrane for desalination: a mini-review

Abstract

Seawater reverse osmosis (SWRO) is the most prevalent desalination technology, offering excellent salt rejection in small, modular units with no requirement for a thermal phase change. The overall efficiency of SWRO relies heavily on the chemical makeup of the selective layer, the structural characteristics of the porous backing, and the specific manufacturing methods that translate fabrication variables into functional transport capabilities. This mini‑review presents the history of RO membrane development from the primitive cellulose acetate asymmetric sheets to the current industry standard: thin‑film composite (TFC) polyamide membranes created through interfacial polymerization, which established the current benchmark for SWRO performance. The principal fabrication routes—phase inversion for preparing porous supports and interfacial polymerization for forming the ultrathin polyamide layer—are emphasis with assurance on the parameters that control structure formation and, ultimately, salt–water selectivity. Key performance descriptors, including water flux, salt flux, and salt rejection, are introduced to support the interpretation of membrane studies reported in the literature. Finally, recent TFC modification strategies, including thin‑film nanocomposite designs based on inorganic nanofillers and MOF‑enabled interlayers, are reviewed against SWRO‑relevant objectives: increased water productivity at sustained rejection, enhanced operational stability, and reproducible process windows compatible with scalable manufacturing.