Novel Modification of PU Membranes by Cyclodextrin (CD) Crosslinking for Simultaneously Improving Selectivity and Permeability

Abstract

The pervaporation is promising in the separation of phenol and water. The modification of membrane material is very important to obtain good selectivity and permeability. The novel modified polyurethane (PU) membranes crosslinked by β-cyclodextrin (CD) were prepared. The structure, crystalline properties and swelling degrees were characterized by FTIR, XRD and swelling experiments. The pervaporation performances for phenol/water were investigated. The results showed that the hydrogen bonding and crystalline structure of CD were weakened in modified membranes. The introduction of CD was advantageous for both permeability and selectivity. With CD content increased from 0 to 2.66 wt%, total flux enhanced from 8.30 kg·μm·m−2·h−1 to 14.49 kg·μm·m−2·h−1 (increased by 70%), and separation factor increased gradually from 27.81 to 49.00 (increased by 76%). With the phenol content in the feed mixture increasing, both of total flux and separation factor of PU and modified PU membranes increased. The modification to use CD as crosslinker was effective to enhance the flux and selectivity simultaneously.