Cyclodextrin-modified layered double hydroxide thin-film nanocomposite desalination membrane for boron removal

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

“…Salt ion rejection efficiency, largely dominated by size and Donnan exclusivities, after prolonged operation of the PA_0.3HMMT TFN membrane is ordered as follows: Mg 2+ (96.3 ± 0.2%) > SO 4 2− (85.7 ± 0.2%) > Cl − (82.0 ± 0.2%) ≥ Na + (80.8 ± 2%) (Figure 5e). Nonetheless, the ion rejection efficiency declines by approximately 20% in the PA_0.7HMMT TFN membrane due to potential defects on the PA thin film and possible leaching of the agglomerated nanofillers from the surface.…”

“…The advent of polyamide thin-film composite (PA-TFC) membranes, discovered empirically in the 1970s, revolutionized the desalination process due to their superior performance compared to cellulosic alternatives. , Substantial progress is currently being made in manipulating the interfacial polycondensation reaction to produce either fully aromatic or semiaromatic PA with customized surface roughness and cross-link density. These are crucial factors that influence the inherent permeability and water/ion permselectivity of the membrane. − Previous research has unequivocally established that the selection of cosolvents and fabrication techniques are critical strategies for effectively managing the thickness of PA film and the size of the nanopores. − In a seminal study, Choi et al (2015) successfully prepared a PA membrane via molecular layer-by-layer assembly utilizing polyelectrolytes, which resulted in a remarkable 98.2% NaCl rejection and 23.0 L m –2 h –1 water flux . Further research in this domain is focused on enhancing water permeance by reducing the thickness to the nanoscale and introducing nanovoids into the sublayers using techniques such as electrospray, nanofoaming, and nanobubbling. ,− Of these, spray-assisted fabrication has been shown to provide tunable thickness and pore size while ensuring high dispersibility of nanofillers. − Nevertheless, the degradation of the PA layer due to chlorination remains the primary factor inhibiting the widespread adoption of this membrane technology in heavily polluted environments, where chlorine cleaning is a necessity. , …”

“…The strategic integration of nanofillers and the interfacial polymerization process can effectively overcome the shortcomings of PA-TFC and PA-thin-film nanocomposite (TFN) membranes. The applications of nanofillers such as covalent organic frameworks (COFs), metal–organic frameworks (MOFs), layered double hydroxides (LDHs), carbon-based nanoparticles, and graphene oxides have been extensively researched for enhanced separation performance. ,,− Traditionally, the incorporation of nanofillers can be done either in the aqueous or organic phase for interfacial polymerization, predeposition in the sublayer, or as coating postpolymerization . Other strategies like molecular plug, steric hindrance, surface tailoring, and surface charge introduction have also been reported to enhance chlorine-resistance in membranes. − …”