Navegando por Autor "González, Gaspar"
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Artigo Characterization of retorted shale for use in heavy metal removal(Elsevier, 2010-04) Melo, Marcus Antônio de Freitas; Pimentel, Patrícia Mendonça; Oliveira, Rosane Maria Pessoa Betânio; Melo, Dulce Maria de Araújo; Anjos, Marcelino José dos; González, GasparThere has been a growing interest in the use of cost-effective materials to remove heavy metals from wastewater. In this study, retorted shale, a solid residue of the thermal transformation of oil shale, was characterized with the objective of preparing heavy metal adsorbents. The fine residue was characterized using different techniques including thermogravimetric analyses, BET, FTIR, XRD, SEM, and TEM. Batch adsorption studies in wastewater were performed. The SRTXRF technique was used to determine element concentration. Removal was approximately 50–70% for Cr, Fe, Co, Ni, Cu, and Zn and > 90% for Hg and Pb. Thus, retorted shale can be used as an efficient adsorbent for heavy metal removal from wastewaterArtigo 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