Carboxyl groups do not play the major role in binding metal cations by graphene oxide

Abstract

In this study, we investigate chemical interactions of Mn2+ ions with graphene oxides, prepared by Hummers (HGO) and Brodie (BGO) methods in aqueous solutions by means of the NMR relaxation....

Epoxy Coatings Containing Modified Graphene for Electromagnetic Shielding

“…Considering the first modification approach, small molecules or functional groups, the introduction of new functionality on the graphene backbone results in a decrease of thermal stability. Both HMDA and PB afforded similar results with a residual mass of over 65% at 900 • C. As expected, the oxidation of graphene resulted in the introduction of functional groups hydroxyl [34,35], carboxyl [34,36,37], and oxirane [38], but the registered weight loss is lower than that afforded by the graphene functionalized by the radical grafting of benzoyl peroxide radicals and HMDA addition. The TGA results for polymer functionalized graphene indicate a relatively low polymer to graphene ratio in the case of methyl methacrylate and hexyl methacrylate.…”

High-Throughput Preparation of Uncontaminated Graphene-Oxide Aqueous Dispersions with Antioxidant Properties by Semi-Automated Diffusion Dialysis

“…Compared with manganese, the EDTA quantity was at a 400-fold excess. As well, for highly oxidized samples, 1 g GO contains 5 to 8 mmol of acidic groups [ 72 ], which correlates to the found sub-mmol/g quantity (1.4 ± 0.2 mmol/g), see the Supplementary Materials, Section S1.1 (Figure S5) ; it is much lower than the EDTA concentration (up to 500 times). Therefore, the thermodynamic equilibrium shifts towards a more stable EDTA complex.…”

“…We suggest that interlayer ions chelated with GO surface moieties, mainly carboxyl and hydroxyl functional groups, would provide competitive binding with excess EDTA and then released due to diffusion [ 71 ]. It is well-known that GO coordinate Mn 2+ preventing its hydrolysis [ 72 ]. It is impossible to unequivocally answer which form of the element is associated with EDTA; the speciation analysis [ 73 ] was beyond the scope of this work.…”

“…As for a GO binding site, the presence of carboxyl groups response to metal sorption activity [ 68 , 79 ] and vic-diol transformed to enols can bind divalent metal ions [ 72 ]. Presumably, the substantial factor for the high efficiency of EDTA for GO purification is its excess and much more sorption and binding capacities in comparison with GO.…”

Improvement of Cs detection performance and formation of CsCl and Cs nanoparticles by tuning graphene oxide quantum dot-based nanocomposite

“…18 More current work also strongly suggested a possibility that the other functional groups (not only carboxyl) have played a signicant role for binding to metal ions. 43 The as-formed enols as the product resulted from reorganization of GO structure might serve as a chelating agent for the metal cations. 3.3.2.…”