Renewable Energy, Vol.160, 250-260, 2020
Enhancing properties of poly(2,6-dimethyl-1,4-phenylene oxide)-based anion exchange membranes with 5-mercaptotetrazole modified graphene oxides
Anion exchange membranes (AEMs) with high conductivity and superior stability against the attack from the strong alkali working medium are highly needed. The graphene oxide (GO) having the lamellar structure of about 1.5 nm in thickness was first modified with 1-(2-(dimethylamino)ethyl)-1H-tetrazole-5-thiol and followed by quaternization of the 2-(dimethylamino)ethyl group with (5-bromopentyl) tri-methylammonium bromide. The quaternized graphene oxide (QGO) was doped into quaternized poly(2,6-dimethyl-1,4-phenylene oxide) (QPPO) to fabricate the AEMs with comprehensive properties. The introduced QGO obviously changed the microphase structure of the membranes with more ion clusters for ion conduction according to the images taken by atomic force microscope. The prepared membrane doping with 0.25 wt% QGO reached a hydroxide conductivity of 75 mS cm(-1) at 80 degrees C. Moreover, the prepared hybrid membranes exhibited improved alkaline stability, enhanced Young's modulus of more than 600 MPa, and low methanol permeability in the 10(-7) cm(2) s(-1) order of magnitude compared to the pristine QPPO membrane. Working as the radical scavenger, the introduced QGO endowed the hybrid membrane with conductivity retaining rate of about 84% after immersed in 2 M KOH solution at 60 degrees C for 360 h, while the pristine QPPO membrane retained its original conductivity of 56%. (C) 2020 Elsevier Ltd. All rights reserved.
Keywords:Graphene oxide;Composite anion exchange membrane;Alkaline stability;Poly(2,6-dimethyl-1,4-phenylene oxide)