Avaliação da adsorção de metais em sedimentos de amostras coletadas no reservatório da usina hidrelétrica de Furnas

Abstract

In this work, the adsorption of metals in the bottom sediment of "Furnas Hydroelectric Plant – MG (Pontalete-MG – Arm in junction of Sapucaí and Verde rivers)" reservoir was investigated. A toxic metal, cadmium and other essential, iron were studied. A Flow Injection System, with on line filtration and thermo spray flame furnace atomic absorption spectrometry (TS-FF-AAS) detection, to determine cadmium was developed. Iron was determined by the FIA same system, nevertheless by flame atomic absorption spectrometry (FAAS) detector. Both developed methods showed satisfactory sensibility and feasibility. On the isotherm studies was observed that for the both elements, iron and cadmium, the Langmuir model is the one that best describes the adsorption process, indicating that the adsorption occurs in a monolayer. In kinetic studies it was observed that the pseudo-first and pseudo-second order models best describe the reaction kinects for the metal iron and cadmium, respectively, where the amount of adsorbed iron ions per unit mass (Qe) obtained experimentally was 9.5432 mg g-1 close the Qe theoretical of 9.8355 mg g-1. For cadmium the experimental obtained values were (Qe) 0.3052 mg g-1, also close to the theoretical Qe 0.3123 mg g-1. It is concluded that, in case of need or addition of these elements in the lacustrine environment, the sediment may act as a regulator of metal concentration (bioavailability) in water column, due to the equilibrium adsorption / desorption in water / sediment interface