Electrospray Fabrication of Ultrathin Chlorine-Resistant Polyamide Brackish Water Desalination Membrane with Protonated Montmorillonite Nanoplates

This research presents an innovative approach to the in situ interfacial polymerization of m-phenylenediamine (MPD) and trimesoyl chloride (TMC) through the application of an electrospray fabrication method. The process incorporates exfoliated protonated montmorillonite nanoclay (MMT-H+) to modulate the diffusivity and reaction kinetics of the monomers, resulting in the successful fabrication of sub-5 nm polyamide thin films. The inclusion of 0.03% w/v MMT-H+ nanoplates in the thin-film nanocomposite membrane (PA_0.3HMMT) yields a remarkable resistance to chlorine degradation, withstanding up to 6,000 ppm·h of free chlorine exposure. This resistance prevents possible hydrolysis of the polyamide active layer during membrane cleaning. The resultant TFN membrane exhibits a high salt rejection of over 93.0% in brackish water reverse osmosis applications. Interestingly, chlorine treatment enhances the water permeance of the PA_0.3HMMT TFN membrane by 10.2% upon 2,000 ppm·h free chlorine exposure, without compromising salt rejection performance. The combination of the electrospray fabrication technique and MMT-H+ nanoclay integration offers a sustainable membrane solution for both seawater desalination and wastewater treatment. This study thus highlights the potential for significant advancements in water treatment technologies.