Obtención de carbón activado a partir de geles de taninos aplicados a la adsorción de oro en soluciones acuosas

Abstract

In the present titration work, the main objective was to obtain an activated carbon from grape seed tannin gels, to be applied in the adsorption of gold in aqueous solutions. Gold recovery is an essential process within the mining industry, the most persistent challenge lies in the lack of selectivity of the materials used for this application, resulting in the undesired adsorption of metals that do not compete with the industry. The development of a carbon derived from tannin gels is presented as a promising material that maintains an eco-friendly approach compared to other conventional methods. However, to enhance its efficiency, it is necessary to apply an activation process that optimizes its structural and adsorption properties. Tannin gels derived from grape seeds were obtained, which were treated by a thermal process known as pyrolysis to obtain carbon and then activated with potassium hydroxide (KOH) thus improving both its structural and adsorption properties. This treatment significantly improved both the physical and chemical properties of the carbon, increasing its adsorbent capacity. The characterization of the material was carried out under analytical techniques called attrition percentage to evaluate its mechanical strength, scanning electron microscopy (SEM) to analyze its morphology and surface structure, X-ray diffraction (XRD) that allowed to identify its crystalline composition, Fourier transform infrared spectroscopy (FTIR) to determine the presence of different functional groups and zero charge potential (pHpzc) to establish its electrochemical behavior under different pH conditions. The pH study was evaluated to determine the pH at which the maximum adsorption capacity of the material is obtained, demonstrating that its maximum adsorption capacity is found at pH 9, where its capacity improves greatly. This study demonstrates that activation with KOH is an effective technique to improve the structural and adsorbent properties of carbons. Through different analytical tests, a significant increase in its stability and resistance to pH variations is evident with a minimum reduction in its performance. The results confirm its potential for applications aimed at the adsorption of gold in aqueous solutions with 14.306% and qe of 5.933 mg.g-1, thus offering an eco-friendly alternative to the conventional techniques normally used.