Effect of Cd(II) on the ripening of ferrihydrite in alkaline media

To acquire a better understanding of the influence exerted by the presence of Cd + during the process of transforming ferrihydrite to goethite, the morphological and structural changes of several samples obtained by the addition of Cd + to a suspension of nascent goethite were explored, and their ch...

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Autores principales:	Alvarez, M., Horst, M.F., Sileo, E.E., Rueda, E.H.
Formato:	JOUR
Materias:	Acid reactivity Aging Cadmium incorporation Goethite HCL extraction Oxalate extraction Acid media Aging time Alkaline media Ammonium oxalate Arrhenius equation Cell parameter Cell volume Crystallization process Dissolution behavior Dissolution rates Ferrihydrites HCl solution In-line Kinetics measurements Oxalate ions Oxyhydroxides Rietveld Structural change Structural parameter Synthesis process XRD Activation energy Aging of materials Ammonium compounds Cadmium Chemical analysis Dissolution Ions Suspensions (fluids) X ray diffraction Cadmium compounds cadmium dissolution extraction method ferrihydrite goethite oxalate reaction kinetics
Acceso en línea:	http://hdl.handle.net/20.500.12110/paper_00098604_v60_n2_p99_Alvarez
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

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spelling	todo:paper_00098604_v60_n2_p99_Alvarez2023-10-03T14:08:42Z Effect of Cd(II) on the ripening of ferrihydrite in alkaline media Alvarez, M. Horst, M.F. Sileo, E.E. Rueda, E.H. Acid reactivity Aging Cadmium incorporation Goethite HCL extraction Oxalate extraction Acid media Aging time Alkaline media Ammonium oxalate Arrhenius equation Cell parameter Cell volume Crystallization process Dissolution behavior Dissolution rates Ferrihydrites Goethite HCl solution In-line Kinetics measurements Oxalate extraction Oxalate ions Oxyhydroxides Rietveld Structural change Structural parameter Synthesis process XRD Activation energy Aging of materials Ammonium compounds Cadmium Chemical analysis Dissolution Ions Suspensions (fluids) X ray diffraction Cadmium compounds cadmium dissolution extraction method ferrihydrite goethite oxalate reaction kinetics To acquire a better understanding of the influence exerted by the presence of Cd + during the process of transforming ferrihydrite to goethite, the morphological and structural changes of several samples obtained by the addition of Cd + to a suspension of nascent goethite were explored, and their chemical reactivity in acid media assessed. The samples (series Gi) were obtained by adding, at different times during the synthesis process, Cd 2+ ions to ferrihydrite (Fe5HO 8.4H 2O) formed in alkaline media. The suspensions were aged for 5 days at 70°C, and the amorphous materials were extracted using a HCl solution (series G HCl-i). The X-ray diffraction (XRD) patterns showed that a goethite-like phase was formed, and chemical analyses indicated that the Cd content, x Cd, increased with the earlier addition of the Cd + ions to the Fe oxyhydroxide suspension. Lattice parameters and cell volume, obtained by the Rietveld simulation of XRD data, indicated an enlargement of the cell parameters of goethite in line with the Cd-for-Fe substitution. In order to determine the influence of oxalate ions on the non-extracted solids, a second set of samples was also prepared that was kept in contact with an ammonium oxalate solution for 4 h (series G ox-i). The dissolution behavior of two series of Cdgoethites and of a third series, obtained from coprecipitation of Fe + and Cd + ions in alkaline media, was observed. Kinetics measurements in 4 M HCl showed that the initial dissolution rate of samples G ox-i decreased with aging time, while the opposite effect was observed for series G HCl-i. Dissolution-time curves were well described by the Kabai equation, and activation energies were calculated using the Arrhenius equation. The results indicate that the presence of Cd during the crystallization process of goethite leads to the formation of a Cd goethite with modified morphology, structural parameters, and chemical reactivity. Fil:Sileo, E.E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00098604_v60_n2_p99_Alvarez
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic	Acid reactivity Aging Cadmium incorporation Goethite HCL extraction Oxalate extraction Acid media Aging time Alkaline media Ammonium oxalate Arrhenius equation Cell parameter Cell volume Crystallization process Dissolution behavior Dissolution rates Ferrihydrites Goethite HCl solution In-line Kinetics measurements Oxalate extraction Oxalate ions Oxyhydroxides Rietveld Structural change Structural parameter Synthesis process XRD Activation energy Aging of materials Ammonium compounds Cadmium Chemical analysis Dissolution Ions Suspensions (fluids) X ray diffraction Cadmium compounds cadmium dissolution extraction method ferrihydrite goethite oxalate reaction kinetics
spellingShingle	Acid reactivity Aging Cadmium incorporation Goethite HCL extraction Oxalate extraction Acid media Aging time Alkaline media Ammonium oxalate Arrhenius equation Cell parameter Cell volume Crystallization process Dissolution behavior Dissolution rates Ferrihydrites Goethite HCl solution In-line Kinetics measurements Oxalate extraction Oxalate ions Oxyhydroxides Rietveld Structural change Structural parameter Synthesis process XRD Activation energy Aging of materials Ammonium compounds Cadmium Chemical analysis Dissolution Ions Suspensions (fluids) X ray diffraction Cadmium compounds cadmium dissolution extraction method ferrihydrite goethite oxalate reaction kinetics Alvarez, M. Horst, M.F. Sileo, E.E. Rueda, E.H. Effect of Cd(II) on the ripening of ferrihydrite in alkaline media
topic_facet	Acid reactivity Aging Cadmium incorporation Goethite HCL extraction Oxalate extraction Acid media Aging time Alkaline media Ammonium oxalate Arrhenius equation Cell parameter Cell volume Crystallization process Dissolution behavior Dissolution rates Ferrihydrites Goethite HCl solution In-line Kinetics measurements Oxalate extraction Oxalate ions Oxyhydroxides Rietveld Structural change Structural parameter Synthesis process XRD Activation energy Aging of materials Ammonium compounds Cadmium Chemical analysis Dissolution Ions Suspensions (fluids) X ray diffraction Cadmium compounds cadmium dissolution extraction method ferrihydrite goethite oxalate reaction kinetics
description	To acquire a better understanding of the influence exerted by the presence of Cd + during the process of transforming ferrihydrite to goethite, the morphological and structural changes of several samples obtained by the addition of Cd + to a suspension of nascent goethite were explored, and their chemical reactivity in acid media assessed. The samples (series Gi) were obtained by adding, at different times during the synthesis process, Cd 2+ ions to ferrihydrite (Fe5HO 8.4H 2O) formed in alkaline media. The suspensions were aged for 5 days at 70°C, and the amorphous materials were extracted using a HCl solution (series G HCl-i). The X-ray diffraction (XRD) patterns showed that a goethite-like phase was formed, and chemical analyses indicated that the Cd content, x Cd, increased with the earlier addition of the Cd + ions to the Fe oxyhydroxide suspension. Lattice parameters and cell volume, obtained by the Rietveld simulation of XRD data, indicated an enlargement of the cell parameters of goethite in line with the Cd-for-Fe substitution. In order to determine the influence of oxalate ions on the non-extracted solids, a second set of samples was also prepared that was kept in contact with an ammonium oxalate solution for 4 h (series G ox-i). The dissolution behavior of two series of Cdgoethites and of a third series, obtained from coprecipitation of Fe + and Cd + ions in alkaline media, was observed. Kinetics measurements in 4 M HCl showed that the initial dissolution rate of samples G ox-i decreased with aging time, while the opposite effect was observed for series G HCl-i. Dissolution-time curves were well described by the Kabai equation, and activation energies were calculated using the Arrhenius equation. The results indicate that the presence of Cd during the crystallization process of goethite leads to the formation of a Cd goethite with modified morphology, structural parameters, and chemical reactivity.
format	JOUR
author	Alvarez, M. Horst, M.F. Sileo, E.E. Rueda, E.H.
author_facet	Alvarez, M. Horst, M.F. Sileo, E.E. Rueda, E.H.
author_sort	Alvarez, M.
title	Effect of Cd(II) on the ripening of ferrihydrite in alkaline media
title_short	Effect of Cd(II) on the ripening of ferrihydrite in alkaline media
title_full	Effect of Cd(II) on the ripening of ferrihydrite in alkaline media
title_fullStr	Effect of Cd(II) on the ripening of ferrihydrite in alkaline media
title_full_unstemmed	Effect of Cd(II) on the ripening of ferrihydrite in alkaline media
title_sort	effect of cd(ii) on the ripening of ferrihydrite in alkaline media
url	http://hdl.handle.net/20.500.12110/paper_00098604_v60_n2_p99_Alvarez
work_keys_str_mv	AT alvarezm effectofcdiiontheripeningofferrihydriteinalkalinemedia AT horstmf effectofcdiiontheripeningofferrihydriteinalkalinemedia AT sileoee effectofcdiiontheripeningofferrihydriteinalkalinemedia AT ruedaeh effectofcdiiontheripeningofferrihydriteinalkalinemedia
_version_	1807316057450348544

Effect of Cd(II) on the ripening of ferrihydrite in alkaline media

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