Remoção de eteramina utilizando biocarvões de torta de murumuru e tucumã

Abstract

The mining industry is one of the most important sectors in the Brazilian economy, and its operation requires high water consumption in the mining and processing stages. The mineral concentration process requires the use of chemical reagents, such as etheramine, which present high pollution potential. The waste containing etheramine is toxic to aquatic organisms, corrosive to the skin and may cause eye irritation. Biochars are carbonaceous materials, generated in the thermochemical conversion of lignocellulosic biomasses, which present potential as a promoting agent for the decontamination of aqueous effluents by adsorption. Thus, biochars from Tucumã (T) and Murumuru (M) fruits were used in the removal of the cationic collector, etheramine, from aqueous solutions. The adsorbents were characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and Zeta Potential (ZP) techniques. The collector was characterized by FTIR technique. The batch tests were conducted according to the statistical experimental design Central Composite Design (CCD). The effects of the parameters adsorbent mass, adsorbate concentration and solution pH were investigated by Pareto chart analysis, and the optimal condition of the parameters was investigated by Response Surface Methodology (RSM) and by calculation of the analytical response. The data were better adjusted to the quadratic model. The results showed that adsorption was more efficient at initial etheramine concentration of 600 mg L-1, adsorbent mass of 0.01 g and pH of 10 and 12 for the T and M chars, respectively. The adsorption kinetics conducted under the optimized conditions showed that the system reaches equilibrium in approximately 10 and 4 hours for T and M chars, respectively. The kinetic data were better adjusted to the Elovich model and the Pseudo second order for T and M, respectively. The adsorption isotherm conducted under the optimized conditions at system equilibrium showed that the maximum etheramine adsorption capacity of the chars was of 860 and 1440 mg g-1 for T and M, respectively. The isotherm data, for both chars, were better adjusted to the Sips model. The calculation of Eads suggested that the mechanism governing the removal in the studied systems is ion exchange. The reuse tests showed that after four cycles the M material increases its adsorption capacity, while the T material decreases it. When compared to literature data, the results showed that the Tucumã and Murumuru biochars presented the greatest capacity for etheramine removal among the untreated materials, being a lower cost and more sustainable alternative than activated carbons and modified adsorbents, once they are produced from agroindustrial waste. However, in order to efficiently guarantee the reuse of the adsorbents, once the desorption step was not efficient, other techniques must be studied to ensure that a larger amount of reagent may return to the ore processing operations.