Boron Removal Using Spherulitic Polyamide Organic–Inorganic Thin‐Film Nanocomposite Desalination Membranes

Abstract

This research investigates the development of ultrathin polyamide (PA) desalination membranes via electrospray fabrication, balancing the trade‐offs between selectivity and permeability. The unique contribution to the improvement of desalination performance is the integration of protonated montmorillonite nanoclay (MMT‐H+) and hyperbranched amino‐polyol cellulose nanocrystals (APCNC) as co‐nanofillers during the in situ interfacial polymerization process. Synergistic effect of the nanofillers is demonstrated in the resultant spherulitic PA thin‐film nanocomposite (TFN) membrane, achieving salt rejection of up to 99.7% against simulated brackish water. Moreover, the membrane's superior boron removal efficiency at neutral pH, observed at 76.7% in a single‐stage desalination process, is attributed to the reduced membrane pore size, disruption of water‐boron association by the spherulites, and complexation and electrostatic interaction with the abundant hydroxyl and amine groups along the APCNC polymeric chains. This process eliminates the need for pH adjustment, thereby enhancing the membrane's practicality and efficiency. The findings of this study provide significant insights into the interactions between boron and the membrane surface, laying the groundwork for the development of effective TFN desalination membranes for water purification and boron removal. The implication of these findings extends beyond academic interest, offering a promising strategy for addressing the global water scarcity crisis.