Caracterização e avaliação da potencialidade das cascas trituradas de pequi (caryocar brasiliense camb.) na adsorção de Íons Pb(II) em águas

Abstract

Population growth and consequently industrial activities contribute to the worsening of environmental problems. Contamination of the environment, specifically water resources, is of great concern especially the imminent possibility of water shortage on the planet. Among the various types of contaminants, metal ions constitute among the most worrying by not biodegradable, not present biological activity and generally tend to accumulate in living organisms, causing numerous diseases. This study aims to evaluate the potential of the crushed shells of Pequi (Caryocar brasiliense Camb.), in natura as a natural sorbent for the removal of Pb(II) ions in aqueous systems. The parameters evaluated were: pH of the solution, adsorbent mass (mg), and stirring time (minutes). The quantification of the content of Pb(II) before and after adsorption was performed Spectrometry Flame Atomic Absorption (FAAS) and conditions were used: pH = 7; Stirring time = 20 minutes; Weight = 25.0 mg of the adsorbent; Volume = 15 ml and particle size (115 ≤ G ≤ 100 mesh). There was a removal Pb(II) from 90% to synthetic solution from the standard solution of Pb(II) concentration with analytical grade 1000 mg L-1. The methodology was applied to the treatment of waste generated in experimental classes of Analytical Chemistry I of undergraduate courses of this Education Institution. For this test the values obtained were 85.3% removal. The value of the maximum adsorption capacity (BWC) Pb(II) ions by the adsorbent 42 mg g-1, was obtained with the construction of the adsorption isotherm, by determining graphically the maximum amount (mg) of analytic that can be adsorbed a mass of adsorbent (g). The adsorption isotherm was linearized according to the mathematical models of Langmüir and Freundlich, with linear correlation coefficients 0.9971 and 0.9904 respectively, indicating that the two are adequate to evaluate the adsorption of Pb(II) ions by crushed shells of Pequi in waters, because of the heterogeneity of the material and possibly with formation of monolayers and multilayers. For the characterization of the material were used techniques like Infrared Spectroscopy (FTIR), Thermo Gravimetric Analysis (TGA), X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The results indicate potential of the crushed shells of Pequi in nature as adsorbent for the removal of Pb(II) ions in aqueous solutions.