Effect of Porous and Nonporous Nanostructures on the Permeance of Positively Charged Nanofilm Composite Membranes

Abstract The role of the nanostructured materials incorporated in the separation layer of thin‐film composite membranes is not properly understood yet, as it requires stringent salt rejection values, proper imaging of the separation layer to realize the presence of nanostructured materials, and to know the thickness of the separation layer. Here, the scalable fabrication of high flux positively charged “polyamide composite nanofiltration” membranes with an ultrathin nanofilm separation layer of ≈14 nm produced via interfacial polymerization of polyethyleneimine and trimesoyl chloride is presented. “Polyamide nanocomposite nanofiltration” membranes are fabricated with the incorporation of different porous and nonporous nanostructures (e.g., ZIF‐8, TiO_2, and Fe₂O₃ nanoparticles, graphene oxide, multi‐walled carbon nanotube, etc.) within the nanofilm separation layer. High water permeance of 15.4 L m⁻² h⁻¹ bar⁻¹ (an increase of 33.9% compared to the pure nanofilm) is achieved with high rejection of MgCl₂ (97.6%). Such membranes with enhanced water permeance surpass the upper bound of the permeance‐rejection of the state‐of‐the‐art positively charged nanofiltration membranes applicable for ionic and molecular separation.