Pervaporation of oleyl alcohol-modified PDMS membranes: a comparison between the apparent and intrinsic performances for organics + water mixtures

摘要

Pervaporation is a promising technology for the removal and recovery of phenol and butanol, which are value-added contaminant from water. The membrane material used in the pervaporation is the key for effective performance. In this study, polydimethylsiloxane (PDMS) and oleyl alcohol (OA)-modified PDMS membranes were prepared by blending and were characterized by X-ray photoelectron spectroscopy (XPS) and swelling experiment. Their effectiveness for the separation of phenol/ butanol from water by pervaporation process was evaluated based on apparent and intrinsic separation performances. The result of XPS confirmed a physical blending between PDMS and OA. The addition of OA into PDMS membrane increased the apparent and intrinsic separation performances for phenol + water and butanol + water systems. For PDMS membranes with 5 wt% OA loading, the butanol and phenol fluxes were 69.11 and 10.34 g m(-2) h(-1) for 1 wt% butanol and 0.5 wt% phenol solution at 70 degrees C, respectively. This was 43% higher than the unmodified PDMS and due to the affinity of OA to organics. The intrinsic selectivity of membrane to phenol and permeance of phenol were significantly higher than apparent separation factor and phenol flux, which is because the driving force for phenol across membrane was low. With increasing temperature, flux increased. Separation factor for butanol decreased while that for phenol increased, which is related to estimated activation energy. OA-modified PDMS membranes showed a good operation stability at 40 degrees C and are potentially good separation membrane material for organic + water mixtures.