Remoção de Ni2+ de soluções aquosas utilizando o talo do cacho do açaí (Euterpe oleracea) como Biossorvente

Abstract

This work used as biosorbent the stem of the açaí bunch (Euterpe oleracea) – TCA – in natura for phytoremediation of the heavy metal Ni2+ from synthetic solutions. The material was characterized using Fourier Transform (FTIR), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) techniques. The result of the infrared analysis revealed the presence of hydroxylic and carboxylic functional main groups fundamental in the biosorption process. The SEM analysis showed a material with a rough and porous structure with a visible variety of pore sizes and the EDS semi-quantitatively detected the presence of elements such as C, O and Ca, characteristic of lignocellulosic materials, in addition to the presence of Ni2+ after the process of adsorption. The adsorption behavior of Ni2+ ion in aqueous solution by the açaí bunch stem (ACT) was carried out in batch and investigated influences such as concentration, dosage, granulometry, contact time and pH. At a concentration of 25 mg.L-1 and pH between 6 and 7 TCA showed removal efficiency above 80%. Langmuir, Freundlich and Dubinin-Radushkevich models were applied to describe the equilibrium isotherms using linear regression analysis. The adsorption kinetic mechanism was better represented by the pseudo-second order kinetics. Monolayer adsorption according to the Langmuir model better described the biosorption process in TCA with a correlation coefficient (R2) close to 1 and a maximum adsorption capacity of 8.62 mg.g-1. The process kinetics showed a better fit to the pseudo-second order model, indicating chemisorption, with R2 close to 1, adsorption capacity (qe) = 6.60 mg.g-1 and adsorption rate constant (K2) = 0.082 g.mg-1.min-1. The TCA in natura presented satisfactory results for the treatment of wastewater, a fact that reinforces its environmental proposal.