Thin film composite membranes containing intrinsic CD cavities in the selective layer

Abstract

In this work, β-cyclodextrin functionalized with multiple ethylenediamine groups (β-CD-EDA) is synthesized and employed as a novel amine monomer for the preparation of thin film composite (TFC) membrane via the interfacial polymerization (IP) with trimesoyl chloride (TMC), to incorporate uniformly-distributed intrinsic CD cavities into the polymer network of the selective layer. The chemical structure of the synthesized β-CD-EDA is confirmed by HMRS, FTIR, TGA XPS and 1H NMR. The chemical properties, surface morphology and the separation performance of TFC membranes prepared with β-CD (TFC_β-CD) and β-CD-EDA (TFC_β-CD-EDA) as aqueous monomers are investigated and compared. The effects of the IP time and β-CD-EDA concentration on the membrane properties are investigated to optimize the membrane performance. The separation performances of TFC_β-CD-EDA membrane are further evaluated with feed solutions containing different solutes. It is found that TFC_β-CD-EDA membranes demonstrated competitive water permeabilities and high rejections to common divalent anionic salts and small organics, contributed by the CD cavities that enable the fast transport of water molecules but restrict larger ions or molecules. Besides, excellent fouling resistance of TFC_β-CD-EDA membrane is also found, because of the embedded CD rings with plentiful hydroxyls. This work is therefore believed to provide a facile method for the development of high-performance TFC membrane with pore-containing selective layer.