Raquis de banano oxidado con tempo para la recuperación de itrio en soluciones acuosas.

Abstract

Yttrium (Y+3) is one of the rare earth elements (REE) recognized for its silvery, shiny appearance and properties such as lightness, ductility and malleability. Yttrium is most abundant in the Earth's crust, however, its production and application can increase the probability of the release of nanoparticles in aquatic environments, which constitutes a risk for aquatic fauna and flora. The purpose of this study was to develop a TEMPO-oxidized adsorbent from Cavendish banana rachis, in order to recover yttrium in aqueous solutions. The process began with the reception of the banana rachis, followed by its cutting, washing, drying and subsequent grinding and sieving to obtain a fine powder. The material obtained was oxidized with the TEMPO reagent, to increase its functional groups, which allow improving the adsorption capacity. To evaluate the applicability of the material, pH studies, equilibrium studies using the Langmuir and Freundlich isotherm models, and a kinetic study with the mathematical modeling of Pseudo first order (PPO) and Pseudo second order (PSO) were carried out. For the pH study, the solution was adjusted to values of 4 and 5 in duplicate, under the following conditions: 50 ppm yttrium solution with HNO3 and NaOH solutions, and then placed under mechanical stirring for 24 hours at room temperature. Where finally the pH analysis revealed that the yttrium adsorption process with the material (RBT) showed an adsorption capacity of 46.123% at pH 4, exceeding that observed at pH 5. Regarding the isotherm analysis, the Langmuir and Freundlich models were used. According to the Langmuir model, the maximum adsorption capacity of yttrium by RBT reached 244.143 mg.g-1, while the Freundlich model showed an adsorption capacity of 3.195 mg.g-1. The Langmuir model fit the experimental data best, with a correlation coefficient (R2) of 0.914. For the kinetic analysis, the Pseudo First Order (PPO) and Pseudo Second Order (PSO) models were used. Where the adsorption capacity of RBT for yttrium recovery was determined as 21.809 mg.g-1 under the PPO model and 22.284 mg.g-1 under the PSO model. The results showed that the PSO model fit the experimental data better, with a correlation coefficient (R2) of 0.964. These results were compared with studies on adsorption of copper (II) and Cd+2 ions, where the PSO model demonstrated appropriate behavior, showing high correlation coefficients (R2) and an accurate description of the adsorption kinetics. The present investigation indicates that this study analyzes the behavior of the adsorption process of yttrium Y+3 with the RBT material as a function of pH, isotherms and kinetics, providing valuable information on the efficiency and adsorption mechanism for its application in recovery. selective yttrium in aqueous solutions.