Effect of the degree of oxidation of graphene oxide on As(III) adsorption

Abstract

The study of the interaction between graphene oxide (GO) and arsenic is of great relevance not only in the designof adsorbent materials to remove this contaminant but also in the understanding of its combined nanotoxicity. Inthis work, we show that As(III) adsorption, primarily H3AsO3, by graphene oxide is affected by its degree ofoxidation. Three types of GO with C/O ratios between 1.35 and 1.98 were produced, resulting in importantvariations in the concentration of CeOH and CeOeC functional groups. The less oxidized material reached amaximum As(III) adsorption capacity of 123 mg/g, whereas the GO with the highest degree of oxidation reacheda value of 288 mg/g at pH 7, the highest reported in the literature. We also show that sulfates and carbonatespresent in water strongly inhibit As(III) adsorption. The interaction between graphene oxide and As(III) was alsostudied by Density Functional Theory (DFT) computer models showing that graphene oxide interacts with As(III)primarily through hydrogen bonds, having interaction energies with the hydroxyl and epoxide groups of 1508.6and 1583.6 kJ/mol, respectively. Finally, cytotoxicity tests showed that the graphene oxide maintained cellularviability of 57% with 50μg/ml, regardless of its degree of oxidation.