Assessment of cadmium and iron adsorption in sediment, employing a flow injection analysis system with on line filtration and detection by flame atomic absorption spectrometry and thermospray flame furnace atomic absorption spectrometry.

Abstract This work presents an evaluation of iron and cadmium adsorption in sediment of the Furnas Hydroelectric Plant Reservatory located in Alfenas, Minas Gerais (Brazil). The metal determination was done employing a flow injection analysis (FIA) with an on-line filtering system. As detection techniques, flame atomic absorption spectrometry (FAAS) for iron and thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) for cadmium determinations were used. The developed methodology presented good limits of detection, being 190 μg L −1 for iron and 1.36 μg L −1 for cadmium, and high sampling frequency for both metals 144 and 60 readings h −1 for iron and cadmium, respectively. Both metals obey the Langmuir model, with maximum adsorptive capacity of 0⋅169 mg g −1 for iron and 7⋅991 mg g −1 for cadmium. For iron, a pseudo-first-order kinetic model was obtained with a theoretical Q e  = 9⋅8355 mg g −1 (experimental Q e  = 9⋅5432 mg  g −1 ), while for cadmium, a pseudo-second-order kinetic model was obtained, with a theoretical Q e  = 0.3123 mg g −1 (experimental Q e  = 0⋅3052 mg g −1 ).