Synthesis and Evaluation of Adsorption Properties of Reduced Graphene Oxide Hydro- and Aerogels Modified by Iron Oxide Nanoparticles

The synthesis of a nanocomposite material based on graphene modified with iron oxide nanoparticles, which is an effective sorbent of organic pollutants contained in aqueous media, has been considered. The production of graphene by chemical reduction of graphene oxide (GO) is the most flexible and popular method for the synthesis of composite materials of various structures based on graphene. Chemical reduction of graphene oxide was carried out using gamma-lactone-2,3-dehydro-L-gulonic acid (ascorbic acid). The method of obtaining the composite under study includes processing the hydrogel obtained after the GO reduction in supercritical isopropanol, which makes it possible to obtain graphene aerogel containing nanoparticles of iron(II, III) oxide. The analysis of the specific surface and porosity of the obtained aerogel showed that the specific surface area of the aerogel was ~7 times higher as compared to the specific surface of the xerogel obtained by drying of the hydrogel under ordinary conditions in air. The diffractometric analysis of xerogel and aerogel samples suggests that, during supercritical drying in the organic fluid, the processes of iron hydroxide reduction to iron(II, III) oxide proceed. The sorption capacity of the obtained hydro- and aerogel was studied by the extraction of methylene blue organic dye from aqueous solutions in a static mode (batch method). The results of the experiments showed that the maximum values of the sorption capacity for the methylene blue dye were 1370 and 1326 mg/g for the hydro- and aerogel, respectively.