Análisis de los parámetros termodinámicos en el proceso de adsorción de cadmio en oxido de grafeno a nivel de laboratorio

Abstract

The objective of this research was to analyze the main thermodynamic parameters of cadmium adsorption in Graphene Oxide (OG) through different contact tests between the metal and the adsorbent material in order to study the adsorption capacity of this system and its decontaminating potential. The adsorbent material was gotten through the Hummers method, while the cadmium corresponds an analytical grade standard, then the adsorption process was carried out with the variation of pH and temperature verifying the reaction kinetics, equilibrium time and effect that the variables produce. Firstly, graphene oxide is synthesized using graphite powder, sulfuric acid, potassium permanganate and hydrogen peroxide, followed by washing with hydrochloric acid and distilled water. The adsorption process began with the variation of the temperature in three different values, a concentration of 5mg/L of cadmium and 0.5 g of OG at constant pH and agitation of 125rpm until equilibrium was reached. This is followed by a variation in pH under conditions of 10 mg/L cadmium, 0.1 g OG and ambient temperature; the cadmium concentration was measured in the atomic absorption spectrophotometry equipment. The results obtained indicate that both pH and temperature influence adsorption observing peaks of greater or lesser adsorption, however, in none of the conditions analyzed was it possible to get a good efficiency because the adsorption capacity could not be maintained over time and a continuous adsorption and desorption of cadmium on the surface of the material is verified, Therefore, it is considered that this process was inefficient and it is recommended to increase the variables to the process for expanding the research with functionalized graphene oxide to expand the adsorption efficiency.