Size-dependent ion adsorption in graphene oxide

Graphene-based materials have demonstrated promising potential for adsorption and purification applications. Graphene oxide (GO), due to its amphiphilic nature, holds the possibility for removing various kinds of contaminants, including heavy metal ions and organic pollutants from aqueous environment. Here, we present size-selective ion adsorption in GO-based laminated membranes by directly measuring the weight uptake of slats. We tuned the interlayer spacing of GO membranes via cationic control solutions using intercalation of very small salts ions (i.e. K+, Na+, Cl-) very precisely to facilities the adsorption of larger ions such as [Fe (CN)6]4- and [Fe (CN)6]3-. This study demonstrates that if the opening of nanocapillaries within the laminates is bigger than the hydrated diameter of ions, the adsorption occurs within the membranes while for smaller opening, with no ion entrance the sorption is on the surface of the membranes.