Eficiencia de la bioadsorción de cadmio (ii) y cromo (iii) en aguas contaminadas a nivel de laboratorio mediante la utilización de cáscara de cebolla (allium cepa),

Abstract

The contamination of water bodies by heavy metals is a growing environmental problem. Due to this, there is a need to investigate new technologies and materials capable of eliminating these contaminants. In this research, the efficiency of onion peel (Allium cepa) as a bio-adsorbent of Cd (II) and Cr (III) in synthetic water was analyzed. Firstly, the bio-adsorbent material was collected and characterized by FT-IR analysis and physicochemical tests. In the bio-adsorption process, two variables were analyzed: the dose (3, 6, and 9 g/L) and the particle size (0.3 mm- 0.5 mm -2 mm) of the onion peel. Solutions were prepared with a concentration of 4 ppm of Cd and 7 ppm of Cr, with an agitation of 120 min and a speed of 120 rpm. The samples were analyzed using the iCE 3300 AAS atomic adsorption spectrometer. The most efficient removal percentages were 89.24 % for Cadmium and 91.95 % for Chromium with a dose of 3 g/L and a particle size of 0.3 mm respectively. The statistical analysis showed that there is a significant difference (p < 0.05) in the dose, particle size, and their interaction concerning the bio-adsorption of Chromium (III). Conversely, for Cadmium (II) the interaction of the two variables did not influence the bio-adsorption process. The study of the bio-adsorption kinetics was carried out, reaching equilibrium at 15 min for Cd and 30 min for Cr. The process is coupled to the pseudo-second-order mathematical model for the two metals. It is concluded that the bio-adsorbent material in its natural form has excellent efficiency in removing both metals.