Navegando por Autor "Gonzales, Gaspar"

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Adsorption of chromium ions on oil shale waste
(Brazilian Journal Of Petroleum And Gas, 2011) Melo, Marcus Antônio de Freitas; Pimentel, Patrícia Mendonça; Oliveira, Rosane Maria Pessoa Betânio; Melo, Dulce Maria de Araújo; Assunção, Ary Leonídio do Carmo; Gonzales, Gaspar
The adsorption of chromium (III) ions onto retorted shale, a waste product of the pyrolysis of oil shale, was investigated as a function of initial pH, temperature, and initial metal ion concentration. Adsorption experiments were carried out in a batch system and the uptake of the metallic ion was studied by using an initial concentration range of 200-500 mg L-1. The pseudo-first and pseudo-second order models were used to predict the rate constants of the adsorption system. Both Langmuir and Freundlich models were used to fit the equilibrium data; however, the former resulted in best fitting. Thermodynamic parameters such as enthalpy, free energy, and entropy changes were calculated. The values of such parameters showed that Cr(III) adsorption was favored at high temperatures

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