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	Provedor de dados 90 (3) 42 (1) 64 (1) Autor Melo,Vander Freitas (2) Barros,Yara Jurema (1) Batista,Araína Hulmnn (1) Batista,Marcelo Augusto (1) Bigham,Jerry Marshal (1) Costa,Antonio Carlos Saraiva da (1) Gilkes,Robert (1) Guedes,Lauriane Guidolin (1) Kummer,Larissa (1) LAGES,ANDERSON S. (1) Melo,Vander de Freitas (1) Roberts,Malcolm (1) SANTANA,GENILSON P. (1) SILVA,MARCONDES SILVA E (1) Souza Junior,Ivan Granemann de (1) Mais... Palavra-chave Isomorphic substitution (5) Barite (1) Freundlich (1) Inner sphere adsorption (1) Iron oxide (1) Iron oxides (1) Kaolinite (1) Langergren (1) Manaus (1) Mass-specific magnetic susceptibility (1) Mössbauer (1) Plumbogummite (1) Polished sample (1) Sequential analysis (1) Sequential extractions (1) Short-range order materials (1) Specific surface area (1) X ray diffraction (1) Mais... Tipo do documento Info:eu-repo/semantics/article (5) Ano 2020 (1) 2018 (1) 2017 (1) 2013 (1) 2008 (1) País Brazil (5) Idioma Inglês (5)		Ordenar por:  Relevância Autor Título Ano Registros recuperados: 5 Primeira ... 1 ... Última Physical and chemical study of lattice kaolinites and their interaction with orthophosphate 42 SILVA,MARCONDES SILVA E; LAGES,ANDERSON S.; SANTANA,GENILSON P.. ABSTRACT This study covers the evaluation of the structure and the capacity in adsorbing orthophosphate ions of kaolinites collected from sampling sites in Manaus (Brazil). The kaolinites were obtained using physical fractioning (sieving/siphoning) techniques and chemical treatment with HCl, H2SO4, H2O2 and KCl. The investigation of the kaolinite lattices involved the Hinckley and Plançon indexes determined from X-ray diffraction data, Fourier transformed infrared spectroscopy, scanning electron microscopy and Mössbauer spectroscopy. The absorption capacity of orthophosphate ions was calculated by Freundlich and Langergren isotherms. A transitional state was observed in the crystallographic structure from kaolinites because of the isomorphic substitution... Tipo: Info:eu-repo/semantics/article Palavras-chave: Freundlich; Isomorphic substitution; Langergren; Manaus; Mössbauer. Ano: 2017 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652017000401391 Do Aqua Regia and EPA 3051A methods underestimate the pseudo-total P content in clay soil fraction? 64 Melo,Vander Freitas; Guedes,Lauriane Guidolin. ABSTRACT It is common the use of 3051A and aqua regia methods to assess the pseudo-total and total P contents in soil and in its fractions. However, previous study has shown the formation of large amounts of short-range order materials (SRO) in the residues of these extractions. The objective of this work was to evaluate whether phosphate resorb in the SRO formed in the residue of 3051A and aqua regia extractions in clay soil fraction. Residues obtained from the 3051A and aqua regia were recovered from filter papers. To characterize the SRO in these residues, sequential extractions were performed with 0.2 mol L-1 ammonium oxalate and 0.5 mol L-1 NaOH. The maximum pseudo-total P content extracted by aqua regia was 6800 mg kg-1. If SRO formed during this... Tipo: Info:eu-repo/semantics/article Palavras-chave: Short-range order materials; Inner sphere adsorption; Isomorphic substitution; Sequential extractions. Ano: 2020 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1413-70542020000100234 Cristallochemical characterization of synthetic Zn-substituted maghemites (g-Fe2-xZn xO3) 90 Batista,Marcelo Augusto; Costa,Antonio Carlos Saraiva da; Souza Junior,Ivan Granemann de; Bigham,Jerry Marshal. Maghemite (g-Fe2O3) is the most usually found ferrimagnetic oxide in red basalt-derived soils. The variable degrees of ionic substitution of Fe3+ for different metals (e.g. Ti4+, Al3+, Mg2+, Zn2+, and Mn2+) and non-metals in the maghemite structure influence some cristallochemical features of this iron oxide. In this study, synthetic Zn-substituted maghemites were prepared by co-precipitation in alkaline aqueous media of FeSO4.7H2O with increasing amounts of ZnSO4.7H2O to obtain the following sequence of Fe3+ for Zn2+ substitutions: 0.0, 0.025, 0.05, 0.10, 0.15, 0.20, and 0.30 mol mol-1. The objective of this work was to evaluate the cristallochemical alterations of synthetic Zn-substituted maghemites. The dark black synthetic precipitated material was... Tipo: Info:eu-repo/semantics/article Palavras-chave: Iron oxides; X ray diffraction; Mass-specific magnetic susceptibility; Specific surface area; Isomorphic substitution. Ano: 2008 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832008000200011 Lead and zinc in the structure of organic and mineral soil components 90 Kummer,Larissa; Melo,Vander de Freitas; Barros,Yara Jurema. In addition to the more reactive forms, metals can occur in the structure of minerals, and the sum of all these forms defines their total contents in different soil fractions. The isomorphic substitution of heavy metals for example alters the dimensions of the unit cell and mineral size. This study proposed a method of chemical fractionation of heavy metals, using more powerful extraction methods, to remove the organic and different mineral phases completely. Soil samples were taken from eight soil profiles (0-10, 10-20 and 20-40 cm) in a Pb mining and metallurgy area in Adrianópolis, Paraná, Brazil. The Pb and Zn concentrations were determined in the following fractions (complete phase removal in each sequential extraction): exchangeable; carbonates;... Tipo: Info:eu-repo/semantics/article Palavras-chave: Isomorphic substitution; Sequential analysis; Iron oxide; Kaolinite. Ano: 2013 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832013000200015 Identification of Heavy Metals in Crystals of Sand and Silt Fractions of Soils by Scanning Electron Microscopy (SEM EDS/WD-EPMA) 90 Batista,Araína Hulmnn; Melo,Vander Freitas; Gilkes,Robert; Roberts,Malcolm. ABSTRACT Studies of heavy metals are concentrate on clay fractions, but coarser fractions of the soil can constitute significant sources of structural forms of heavy metals. The aim of this study was to evaluate the occurrence of heavy metals in the structure of minerals of the sand and silt fractions of soils from three different parent materials (metamorphic rocks and granite) in southern Brazil using SEM/EDS - Scanning Electron Microscopy with Energy Dispersive Spectroscopy and with WD-EPMA - with Wavelength Dispersive-Electron Probe Microanalysis. We sampled soils from two areas naturally rich in heavy metals, with high mineral deposits (galena - PbS) hosted in carbonate rocks and phyllite/mica schist. The main form of Ba in the sand and silt fractions... Tipo: Info:eu-repo/semantics/article Palavras-chave: Plumbogummite; Barite; Isomorphic substitution; Polished sample. Ano: 2018 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832018000100408 Registros recuperados: 5 Primeira ... 1 ... Última

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