Sorption of rare earth elements onto basaluminite: The role of sulfate and pH
Scandium, yttrium and lanthanides (REE) are critical raw materials in increasing demand for modern technology, so identifying and developing new sources of REE has become a pressing need. REE concentrations in acid mine drainage (AMD) are several orders of magnitude higher than those in natural water, and their recovery is of economic interest. Passive remediation systems designed to minimize AMD impact on the ecosystem retain REE in solid waste, where basaluminite, Al4SO4(OH)10·5H2O, is the mineral responsible for the scavenge. However, no information about the retention mechanisms of REE is currently available in the literature. The objective of the present work is to study the adsorption of lanthanides, yttrium and scandium onto synthetic basaluminite over a pH range of 4–7 at room conditions. Since sulfate is ubiquitous in AMD, the adsorption has been investigated with variable sulfate concentrations. Experimental results show that sorption onto basaluminite is strongly dependent on pH, starting at pH 5 for lanthanides and yttrium and at pH 4 for scandium. At any given pH values, sorption increases with sulfate concentration. Distribution coefficients, defined as KD = [REEsorbed]/[REEsolution], are higher for Sc, and across the lanthanide series, the distribution coefficients increase from La to Lu according to decreasing ionic radius, where yttrium is considered close to Ho. Experimental results were modeled using a sorption model that considers mass law equations where the strong sulfate aqueous complex, MSO4 +, is adsorbed by exchanging a proton with the mineral surface. The dependence of the experimental results on pH suggests the formation of monodentate binding for Y and lanthanides. The bidentate complex for Sc is deduced by the two proton exchange per mol of Sc extracted from the experiments. The thermodynamic constants for the surface complexation reactions were obtained from experiments with high sulfate concentration and were successfully applied to the experiment with low sulfate content and different solid-liquid ratios. Therefore, the model can be applied to interpret the REE geochemistry in natural systems with variable pH and sulfate concentrations. © 2019 Elsevier Ltd
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2019-08-01
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Subjects: | Fractionation, Lanthanides, Monodentate surface species, Scandium, Non-electrostatic model, Sorption edge, Sorption model, Yttrium, |
Online Access: | http://hdl.handle.net/10261/202016 |
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dig-idaea-es-10261-2020162022-06-03T07:08:55Z Sorption of rare earth elements onto basaluminite: The role of sulfate and pH Lozano, Alba Ayora, Carlos Fernández-Martínez, Alejandro Lozano, Alba [0000-0003-4050-6906] Ayora, Carlos [0000-0003-0238-7723] Fractionation Lanthanides Monodentate surface species Scandium Non-electrostatic model Sorption edge Sorption model Yttrium Scandium, yttrium and lanthanides (REE) are critical raw materials in increasing demand for modern technology, so identifying and developing new sources of REE has become a pressing need. REE concentrations in acid mine drainage (AMD) are several orders of magnitude higher than those in natural water, and their recovery is of economic interest. Passive remediation systems designed to minimize AMD impact on the ecosystem retain REE in solid waste, where basaluminite, Al4SO4(OH)10·5H2O, is the mineral responsible for the scavenge. However, no information about the retention mechanisms of REE is currently available in the literature. The objective of the present work is to study the adsorption of lanthanides, yttrium and scandium onto synthetic basaluminite over a pH range of 4–7 at room conditions. Since sulfate is ubiquitous in AMD, the adsorption has been investigated with variable sulfate concentrations. Experimental results show that sorption onto basaluminite is strongly dependent on pH, starting at pH 5 for lanthanides and yttrium and at pH 4 for scandium. At any given pH values, sorption increases with sulfate concentration. Distribution coefficients, defined as KD = [REEsorbed]/[REEsolution], are higher for Sc, and across the lanthanide series, the distribution coefficients increase from La to Lu according to decreasing ionic radius, where yttrium is considered close to Ho. Experimental results were modeled using a sorption model that considers mass law equations where the strong sulfate aqueous complex, MSO4 +, is adsorbed by exchanging a proton with the mineral surface. The dependence of the experimental results on pH suggests the formation of monodentate binding for Y and lanthanides. The bidentate complex for Sc is deduced by the two proton exchange per mol of Sc extracted from the experiments. The thermodynamic constants for the surface complexation reactions were obtained from experiments with high sulfate concentration and were successfully applied to the experiment with low sulfate content and different solid-liquid ratios. Therefore, the model can be applied to interpret the REE geochemistry in natural systems with variable pH and sulfate concentrations. © 2019 Elsevier Ltd This work was funded by the European EIT ‘Morerecovery’ and the Spanish SCYRE (CGL2016-78783-C2-R)] projects. A. L. was also funded by the FPI grant (BES-2014-069978) Ministry of Science, Innovation and Universities (Spain). The authors wish to thank J. Bellés, M. Cabañas, R. Bartrolí and N. Moreno (IDAEA-CSIC) for their analytical assistance. The manuscript has been greatly improved with the comments of Prof. Villalobos and three anonymous reviewers. Peer reviewed 2020-02-26T10:36:36Z 2020-02-26T10:36:36Z 2019-08-01 artículo http://purl.org/coar/resource_type/c_6501 Geochimica et Cosmochimica 258: 50-62 (2019) http://hdl.handle.net/10261/202016 10.1016/j.gca.2019.05.016 en Postprint https://doi.org/10.1016/j.gca.2019.05.016 Sí open Elsevier |
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Fractionation Lanthanides Monodentate surface species Scandium Non-electrostatic model Sorption edge Sorption model Yttrium Fractionation Lanthanides Monodentate surface species Scandium Non-electrostatic model Sorption edge Sorption model Yttrium |
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Fractionation Lanthanides Monodentate surface species Scandium Non-electrostatic model Sorption edge Sorption model Yttrium Fractionation Lanthanides Monodentate surface species Scandium Non-electrostatic model Sorption edge Sorption model Yttrium Lozano, Alba Ayora, Carlos Fernández-Martínez, Alejandro Sorption of rare earth elements onto basaluminite: The role of sulfate and pH |
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Scandium, yttrium and lanthanides (REE) are critical raw materials in increasing demand for modern technology, so identifying and developing new sources of REE has become a pressing need. REE concentrations in acid mine drainage (AMD) are several orders of magnitude higher than those in natural water, and their recovery is of economic interest. Passive remediation systems designed to minimize AMD impact on the ecosystem retain REE in solid waste, where basaluminite, Al4SO4(OH)10·5H2O, is the mineral responsible for the scavenge. However, no information about the retention mechanisms of REE is currently available in the literature. The objective of the present work is to study the adsorption of lanthanides, yttrium and scandium onto synthetic basaluminite over a pH range of 4–7 at room conditions. Since sulfate is ubiquitous in AMD, the adsorption has been investigated with variable sulfate concentrations. Experimental results show that sorption onto basaluminite is strongly dependent on pH, starting at pH 5 for lanthanides and yttrium and at pH 4 for scandium. At any given pH values, sorption increases with sulfate concentration. Distribution coefficients, defined as KD = [REEsorbed]/[REEsolution], are higher for Sc, and across the lanthanide series, the distribution coefficients increase from La to Lu according to decreasing ionic radius, where yttrium is considered close to Ho. Experimental results were modeled using a sorption model that considers mass law equations where the strong sulfate aqueous complex, MSO4 +, is adsorbed by exchanging a proton with the mineral surface. The dependence of the experimental results on pH suggests the formation of monodentate binding for Y and lanthanides. The bidentate complex for Sc is deduced by the two proton exchange per mol of Sc extracted from the experiments. The thermodynamic constants for the surface complexation reactions were obtained from experiments with high sulfate concentration and were successfully applied to the experiment with low sulfate content and different solid-liquid ratios. Therefore, the model can be applied to interpret the REE geochemistry in natural systems with variable pH and sulfate concentrations. © 2019 Elsevier Ltd |
author2 |
Lozano, Alba [0000-0003-4050-6906] |
author_facet |
Lozano, Alba [0000-0003-4050-6906] Lozano, Alba Ayora, Carlos Fernández-Martínez, Alejandro |
format |
artículo |
topic_facet |
Fractionation Lanthanides Monodentate surface species Scandium Non-electrostatic model Sorption edge Sorption model Yttrium |
author |
Lozano, Alba Ayora, Carlos Fernández-Martínez, Alejandro |
author_sort |
Lozano, Alba |
title |
Sorption of rare earth elements onto basaluminite: The role of sulfate and pH |
title_short |
Sorption of rare earth elements onto basaluminite: The role of sulfate and pH |
title_full |
Sorption of rare earth elements onto basaluminite: The role of sulfate and pH |
title_fullStr |
Sorption of rare earth elements onto basaluminite: The role of sulfate and pH |
title_full_unstemmed |
Sorption of rare earth elements onto basaluminite: The role of sulfate and pH |
title_sort |
sorption of rare earth elements onto basaluminite: the role of sulfate and ph |
publisher |
Elsevier |
publishDate |
2019-08-01 |
url |
http://hdl.handle.net/10261/202016 |
work_keys_str_mv |
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