Preparation of nanocavity-contained thin film composite nanofiltration membranes with enhanced permeability and divalent to monovalent ion selectivity

Abstract

Using hydroxypropyl-β-cyclodextrins (OH-β-CD) as aqueous phase additive, nanocavity-contained thin film composite (TFC) nanofiltration (NF) membranes were prepared by interfacial polymerization of piperazine (PIP) and trimesoyl chloride (TMC). Attenuated total reflectance Fourier transform infrared and X-ray photoelectron spectroscopy analysis confirmed the successful incorporation of OH-β-CDs into the thin polyamide rejection layers. The rejection layer morphologies and structures, surface properties and separation performances of the prepared TFC membranes were greatly influenced by the OH-β-CD mass ratio in aqueous phase during interfacial polymerization. With appropriate OH-β-CD mass ratios (20–60%), the prepared TFC membranes showed enhanced water flux, reduced RNaCl, increased RNa2SO4 and RMgSO4, which led to highly improved divalent to monovalent ions selectivity. These nanocavity-contained TFC membranes exhibited the potential to apply in desalination pretreatment.