Rigid POSS intercalated graphene oxide membranes with hydrophilic/hydrophobic heterostructure for efficient pervaporation desalination

Abstract

Graphene oxide (GO) membranes exhibit fascinating properties in pervaporation desalination due to the unimpeded water permeation in two-dimensional (2D) interlaminar channels. The precise construction of interlayer mass transfer nanochannels and regulation of their microenvironment are crucial to break through the trade-off effect of pervaporation desalination performance and achieve high stability of GO membranes. Herein, aminopropylisobutyl polyhedral oligomeric silsesquioxane (NH2-POSS) was intercalated into GO interlayers with glutaraldehyde as crosslinking reagent to fabricate POSS@GO hybrid membranes. The intercalation of POSS into GO interlayers provided enlarged interlayer spacing for water permeation and appropriate steric hindrance for ion rejection as well as better swelling resistance, which promoted both of water permeation flux and salt rejection of GO membranes. The optimized POSS@GO hybrid membrane displayed an outstanding water flux of 112.7 kg/(m2·h) and 99.98 % salt rejection in desalinating 3.5 wt% NaCl solution at 80 °C. Benefiting from the formation of hydrophilic/hydrophobic heterostructure and crosslinking with glutaraldehyde, POSS@GO hybrid membranes could toughly resist membrane swelling and exhibited stable and reliable desalination performance. Desirable stability of pervaporation desalination performance was acquired in the 24 h long-term separation experiment at 80 °C. The study might provide some new insight in designing high-efficiency 2D laminar membranes for pervaporation desalination by elaborate regulation of transport channel size without sacrificing interlayer spacing based on the construction of appropriate hydrophilic/hydrophobic heterostructure.