Hybrid membranes with 2D vertical continuous channels from layered double hydroxides array for high-efficiency ethanol dehydration

Abstract

Hybrid membranes with 2D vertical continuous channels are expected to achieve high separation performance, but remain unexplored. In this study, 2D vertical continuous channels from layered double hydroxide (LDH) array were constructed in hybrid membranes for pervaporation dehydration. Vertically aligned LDH array that anchored onto the polyacrylonitrile substrate via in situ hydrothermal synthesis was employed to provide intrinsic continuous channels with an interlayer distance between water and ethanol. Sodium alginate impregnated into interstitial space of LDH array ensured a leakage-free and mechanical strength of membranes. The height of LDH array within hybrid membranes could be facilely manipulated from 1.5 μm to 3.6 μm through altering the hydrothermal reaction time and Co2+/Al3+ ratio. Comparing hybrid membranes with randomly oriented LDH, the hybrid membrane with vertically aligned LDH array exhibites optimal water permeability of 7742 Barrer together with a desirable selectivity of 1903 when the reaction time is 10 h, and Co2+/Al3+ ratio is 2. This study provided an innovative avenue to fabricating high-performance hybrid membranes with 2D vertical continuous channels.