Interafacially grown ultrathin high flux polymeric nanofilm for molecular separation: An improved trade-off between permeance and selectivity

Abstract

Polymeric membranes with enhance permeability and selectivity are highly anticipated approach for liquid separation. Polymeric membranes for controlled molecular weight cut-off and high liquid permeance are desirable to separate small organic molecules and multivalent ions from a water stream. This demands active polymeric layer to be defect-free, thin, narrow pores and pore size distribution and surface charge to maximize membrane performance. We described an interfacial polymerization reaction between phloroglucinol (PG) and 1,3,5-trimesyol chloride (TMC) at water-hexane interface to form polymeric layer. Controlling the monomer concentration at the interphase resulted into the formation of the defect free polymeric thin film down to 20 nm (nanofilm). Electron and force microscopy suggested the presence crumpled and crater morphology of the polymeric nanofilm. FT-IR analysis clearly suggested the formation of ester bonds. Pressure driven transport data demostrate that polyaryl nanofilm shows high water permeance of ∼108 Lm−2h−1 bar−1 and demonstrates the high rejection (>90 %) of molecules (Molecular weight cutoff > 585 gmol−1) and high permeance of ∼92 Lm−2h−1 bar−1. High rejection (>95) of multivalent ions (K3[Fe(CN)6]) achieved as compared to monovalent (∼2%) and divalent salt (∼14%) with the water permeance of ∼94 Lm−2h−1 bar−1.