Optimization of the Electrodeposition Conditions for Mercury Removal from Vegetal Biomass with Response Surface Methodology

It was evaluated the technical viability of mercury removal by electrodeposition from vegetal biomass samples obtained from mining zones which had 10±0.3 µgHg g -1 . Each sample was treated by mixed acid to destroy the organic matter and liberate the metal in its inorganic form for the later removal of Hg by means of a cell of electrolysis with a rotary electrode of copper as cathode. Mercury concentration was determined by Cold Vapor Atomic Absorption Spectrophotometry (CVAAS). Response surface methodology (RSM) was applied to evaluate the simple and combined effects of three independent parameters (voltage, time and concentration) on the removal efficiency and optimizing the operating conditions. Analysis of variance showed a high coefficient of determination ( r 2 = 0.925 ) indicating that the second order regression model explains 92.5 % of the variability in results. The maximum efficiency of removal (91.2 %) predicted by the model was found for the initial concentration of 1.0 µg mL -1 , 66.6 mins and 34.3 V. Model Validation was carried out under the following conditions: 1.0 µg mL -1 , 60 mins and 30 V, which are close to the maximum efficiency with a removal percentage of 87.1 %.