Electric-field-assisted arrangement of carbon nanotube inside PDMS membrane matrix for efficient bio-ethanol recovery via pervaporation

Abstract

Pervaporation is recognized as an efficient technology for solvent recovery and biorefinery from aqueous solutions. However, due to the low permeability and slow mass transfer of traditional polymeric membranes, pervaporation process is still restricted for practical application. Herein, we prepared electric-field arranged K-MWCNTs/PDMS MMMs to utilize the fast mass transfer property of CNTs surface to achieve high-efficient ethanol recovery via pervaporation. Before served as fillers, MWCNTs-NH2 were first functionalized with silane coupling agent to improve the surface affinity between K-MWCNTs and PDMS matrix. The correlation between electric field property, K-MWCNTs arrangement behavior and ethanol separation performance was thoroughly investigated. Results indicated that electric-field arranged K-MWCNTs/PDMS MMMs presented superior hydrophobicity (contact angle reached 130.5° at 6 wt% K-MWCNTs loading) and lower water swelling degree compared with pure PDMS membranes. By introducing electric field, K-MWCNTs achieved ordered morphology in casting solutions and the final MMMs, which is supposed to generate more mass transfer pathways for small molecules and thus help boost the mass transfer of membranes. When the electric-field parameters were set as10kHz, 1500 V/cm and exposure time maintained around 5 min, the electric-field arranged K-MWCNTs/PDMS MMMs (2 wt% loading, 50 ℃, 6 wt% feed ethanol concentration) could achieve superior and stable ethanol recovery performance with separation factor reaching 11 and total flux increased by ∼ 40 % from 982 g·m−2·h−1 to 1348 g·m−2·h−1 compared with MMMs prepared without electric field. In view of this, we here fabricated a novel electric-field arranged K-MWCNTs/PDMS MMM and provide a facile method in achieving better dispersion of K-MWCNTs in MMMs for high-efficient ethanol recovery.