Instituto de Química
URI Permanente desta comunidadehttps://repositorio.ufrn.br/handle/123456789/31488
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Navegando Instituto de Química por Assunto "Adsorption isotherms"
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Artigo 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, GasparThe 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 temperaturesArtigo Kinetics and thermodynamics of Cu(II) adsorptionon oil shale wastes(Elsevier, 2008-01) Melo, Marcus Antônio de Freitas; Pimentel, Patrícia Mendonça; Melo, Dulce Maria de Araújo; Assunção, Ary Leonídio do Carmo; Henrique, Daniele de Macedo; Silva Júnior, Carlos Neco da; González, GasparThe oil shale waste material, retorted shale, was utilized as an adsorbent for Cu(II) removal from aqueous solution. The kinetics and thermodynamic adsorption was investigated during a series of batch adsorption experiments. The removal efficiency was controlled by solution pH, temperature, initial ion concentration and contact time. Two simple kinetic models, pseudo-first-and second-order, were used to investigate the adsorption mechanisms. The pseudo-second-order chemical reaction kinetics provides the best correlation with the experimental data. Langmuir and Freundlich models were used to fit the equilibrium data, which showed that Langmuir best-fitted these data. Thermodynamic parameters such as free energy, enthalpy and entropy were calculated to predict the nature of the adsorption processArtigo Removal of lead ions from aqueous solution by retorted shale(Elsevier, 2007-09-15) Melo, Marcus Antônio de Freitas; Pimentel, Patrícia Mendonça; González, Gaspar; Melo, Dulce Maria de Araújo; Silva Júnior, Carlos Neco da; Assunção, Ary Leonídio do CarmoThe equilibrium and kinetic properties of Pb2+ion adsorption by retorted shale (RS) have been investigated during a series of batchadsorption experiments. The effects of pH, contact time and adsorbate initial concentration were evaluated. The pseudo-second-order modelwas used to predict the rate constants of adsorption system. Langmuir and Freundlich models were used to fit the equilibrium data, whichshowed that Langmuir best-fitted these data. Thermodynamic parameters of adsorption indicate spontaneous and endothermic nature of theprocess