Polyvinyl alcohol/attapulgite interlayer modulated interfacial polymerization on a highly porous PAN support for efficient desalination

Interlayered thin film nanocomposite nanofiltration (TFNi-NF) membranes have the potential to overcome the permeability and selectivity limitations of conventional NF membranes. This work is the first attempt to construct the polyvinyl alcohol/attapulgite (PVA/ATP) nanocomposite interlayer by chemical cross-linking between PVA and glutaraldehyde (GA) in which the nanomaterial ATP was connected with covalent bonds. Meanwhile, the support layer of the NF membranes was chosen to be a microporous membrane with high porosity and a three-dimensional (3D) network porous structure prepared by the innovative atomization-assisted non-solvent induced phase separation (AA-NIPS) method, greatly enhancing the water transport channels. The ATP acted as a multifunctional regulator to tune the porous structure of the PVA/ATP nanocomposite interlayer through physicochemical interactions. By manipulating monomer diffusion behavior, a dense polyamide (PA) layer with only 12 nm in thickness was prepared, leading to enhanced permeability and rejection for divalent ions. In addition, the structure and performance of the TFNi-NF membranes are highly tunable by changing the ATP loading. The prepared TFNi-NF membranes have shown great potential for seawater desalination and the separation and purification of aqueous electrolytes.