Obtenção do óxido de grafeno com superfície modificada para aplicações em catálise ambiental

Abstract

Currently, industries face challenges regarding the destination of effluents generated by production processes, as they may contain several Persistent Organic Pollutants (POPs) that seriously affect human health and the natural ecosystem, when incorrectly disposed of. With this, new materials have been developed for the treatment of effluents, such as nanocatalysts composed of Graphene Oxide (OG), as they have a relevant adsorption capacity, in addition to the possibility of surface modification, to be used in Fenton-like reactions heterogeneous. The OG was synthesized from the exfoliation of commercial graphite, using the modified Hummers method and soon after the iron was anchored with oxalic acid on the surface of the OG, obtaining the OG-Ox-Fe, in order to carry out tests of adsorption and degradation of the Methylene Blue (AM) model molecule. Thus, the characterizations by MEV, FTIR-ATR, Raman, Bohem and TG titration, showed the presence of functional groups and iron in the modified OG, showing the success of the synthesis. By the adsorption tests, for OG and OG-Ox-Fe, the OG with the best adsorption of AM stood out, being 491.62 mg.g-1 and 270.89 mg.g-1 respectively. In assessing the adsorption capacity of AM, for both materials, the data are better suited to the Langmuir isotherm model when compared to the Freundlich model. Based on the results found, the adsorption of AM for both materials is a thermodynamically favorable process, spontaneous, exothermic and with reduced disorder and randomness at the adsorbent interface with the solution. In addition, for the tests of Fenton-like reactions, the best experimental conditions were the use of 200 mg of catalyst, 1,5 mL of H2O2, 25ºC in 100 mL of AM 100 mg L-1 solution. Regarding the reuse of the catalyst, OG-Ox-Fe proved to be efficient in the four reuse cycles performed, without a considerable loss of material.