Electrostatically-coupled graphene oxide nanocomposite cation exchange membrane

Abstract

We report the preparation of an electrostatically-coupled graphene oxide nanocomposite cation exchange membrane (CEM) based on sulfonic group containing graphene oxide (SGO) (45 wt % loading) and polyvinylidene fluoride (PVDF), where the ion exchange groups were provided by the SGO additive. SGO was prepared via the mixing of graphene oxide (GO) with a mixture derived from 3,4-dihydroxy-L-phenylalanine (L-DOPA) and poly(sodium 4-styrenesulfonate) (PSS). A mold-casting technique was developed to fabricate the free-standing nanocomposite CEM. The presence of sulfonic groups in the nanocomposite was confirmed with FTIR spectroscopy. Energy dispersive spectroscopy analysis showed the SGO was distributed across the entire membrane matrix, with minimal aggregation. The resultant SGO/PVDF nanocomposite CEM membrane demonstrated high hydrophilicity and high water uptake, but low swelling ratio. Furthermore, evaluation of the electrochemical properties of the nanocomposite CEM showed favorable ion exchange capacity (0.63 ± 0.08 meq/g), permselectivity (0.95 ± 0.04), and area resistance (2.8 ± 0.2 Ω cm 2 ). The nanocomposite CEM show good potential for use in electromembrane desalination applications.

Metal Cation‐Modified Graphene Oxide as Precursor for Advanced Materials: Thin Films of Graphene/Prussian Blue Analogues

“…The GO exhibits an extended layered structure with polar hydrophilic groups (À OH, À COOH, epoxy), as well as a huge surface area which gives it high adsorption performance. [45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62] Metal cations can interact with GO structure through four different mechanisms: [48] i) through electrostatic interactions between the positively charged metal cations and negatively charged functional groups; ii) through electrostatic interactions between the positively charged metal cations and the π electrons of the graphitic basal plane (a cation-π interaction); iii) through the basal epoxide functional groups, due to the wellknown capacity of metal cation induced ring-opening of the epoxy groups; iv) through coordination of metal cation and the oxygen groups. The main purpose of this work is to take advantage of those characteristics to incorporate metal cations (Cu 2 + or Fe 3 + ) into the GO structure, and afterward to use those GO/metal cations compounds as precursors to graphene/PB(A) materials.…”

“…The metallic species into the modified films is demonstrated to be effective reactants to produce PB(A) through a heterogeneous electrochemical reaction with [Fe(CN) 6 ] 3À , yielding graphene/ PB(A) nanocomposite thin films. Several recent works have been published dealing with the incorporation of different metal cations into GO structure, [45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62] through different adsorption processes or ion-exchange reactions, aiming ion-exchange membranes, [51,52] materials for water purification [53,54] and desalinization processes. [55,56] For example, Klimová et al [57] conducted a study of sorption of different ions on the graphene oxide, showing high sorption capacity, mainly due to the metal coordination with ketone and carboxylic acid groups; Dimiev et al [58][59][60][61] use the NMR relaxation technique to monitor reactions between aqueous dispersed GO and different transition metal cations, demonstrating both covalent and electrostatic interactions, directly dependent on several factors such as the concentration of GO and metals; the pH; the chemical nature of the metals; the ionic charge of cations.…”

Incorporation of Natural Lithium‐Ion Trappers into Graphene Oxide Nanosheets

“…For instance, significantly improved nanofiltration properties and desalination capabilities [29] were reported as a result of employing natural polyphenols such as tannic acid [30] and polydopamine. [31] However, the use of some guest compounds is limited by various compelling challenges such as their high cost and non-uniform distribution of particles in a confined area when industrialization is a criterion. [3a,27] In this paper, the inclusion of a natural crown ether-like structured ion trapper (natural ionophore) in GO membrane has led to the strategic design of 2D material followed by the process of achieving the lithium-rich feed.…”

Graphene-PSS/l-DOPA nanocomposite cation exchange membranes for electrodialysis desalination

“…This had not been reported until we successfully demonstrated the concept in our recent work where a nanocomposite cation exchange membrane (CEM) was prepared based on modified graphene oxide (SGO) nanosheets and inert polyvinylidene (PVDF). 22 Having demonstrated a proof of concept, the possibility of using reduced GO has not been investigated yet; particularly the exploration of the implications of the difference in nanostructure of chemically reduced graphene oxide nanosheets, such as partial removal of oxygen containing groups and reduction of interlayer spaces, on the CEM properties and performance.…”