Supramolecular membranes: A robust platform to develop separation strategies towards water-based applications

Supramolecular membranes are considered a promising platform for the development of separation strategies with higher efficacy. Overall, the need for efficient and cost-effective separation tools are becoming increasingly urgent because the clean water is turning into a scarcity rather than a commodity. Therefore, advanced separation methods are required on priority to meet the water resources demand of the growing world population. Herein, supramolecular membrane-based separation methods offer a unique solution to this problematic issue. The proposed applications include water desalination, wastewater treatment, and separation and purification of high-value compounds and emerging pollutants, which can alleviate the global problem of freshwater scarcity. Ideally, supramolecular membranes combine a high flux with a high selectivity requiring thin defect-free membranes. Owing to the unique physiochemical and structural properties in combination with reversible and highly selective nature, supramolecular materials are gaining high research interests to engineer multifunctional separation membranes. These materials provide excellent features to the separating membranes when used with commercial crosslinked polyamide network membranes and are cost-effective from the operational viewpoint. However, despite many advantages of supramolecular membrane-based separation methods, several shortcomings remain, including potential contamination and interference of potential contaminants during analytical stages. In this review we discussed self-assembled supramolecular materials in general, supramolecular block copolymers, water-based self-assembled materials and self-assembled polyelectrolyte materials in particular, considering their development approaches and nonporous water-based membrane applications. The present review also evaluates technologies identifying the recent progress and their commercial aspects in ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) applications.