The role of nano-perovskite in the negligible thorium release in seawater from Greek bauxite residue (red mud)

Platon Gkamaletsos; Athanasios Godelitsas; Takeshi Kasama; Alexei Kuzmin; Markus Lagos; Theo J. Mertzimekis; Jörg Göttlicher; Ralph Steininger; Stelios Xanthos; Yiannis Pontikes; George N. Angelopoulos; Charalampos Zarkadas; Aleksandr Komelkov; Evangelos Tzamos; Anestis Filippidis

doi:10.1038/srep21737

The role of nano-perovskite in the negligible thorium release in seawater from Greek bauxite residue (red mud)

Platon Gkamaletsos, Athanasios Godelitsas, Takeshi Kasama, Alexei Kuzmin, Markus Lagos, Theo J. Mertzimekis, Jörg Göttlicher, Ralph Steininger, Stelios Xanthos, Yiannis Pontikes, George N. Angelopoulos, Charalampos Zarkadas, Aleksandr Komelkov, Evangelos Tzamos, Anestis Filippidis

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Abstract

We present new data about the chemical and structural characteristics of bauxite residue (BR) from Greek Al industry, using a combination of microscopic, analytical, and spectroscopic techniques. SEM-EDS indicated a homogeneous dominant "Al-Fe-Ca-Ti-Si-Na-Cr matrix", appearing at the microscale. The bulk chemical analyses showed considerable levels of Th (111 mu g g(-1)), along with minor U (15 mu g g(-1)), which are responsible for radioactivity (355 and 133 Bq kg(-1) for Th-232 and U-238, respectively) with a total dose rate of 295 nGy h(-1). Leaching experiments, in conjunction with SF-ICP-MS, using Mediterranean seawater from Greece, indicated significant release of V, depending on S/L ratio, and negligible release of Th at least after 12 months leaching. STEM-EDS/EELS & HR-STEM-HAADF study of the leached BR at the nanoscale revealed that the significant immobility of Th4+ is due to its incorporation into an insoluble perovskite-type phase with major composition of Ca0.8Na0.2TiO3 and crystallites observed in nanoscale. The Th L-III-edge EXAFS spectra demonstrated that Th4+ ions, which are hosted in this novel nano-perovskite of BR, occupy Ca2+ sites, rather than Ti4+ sites. That is most likely the reason of no Th release in Mediterranean seawater.

Original language	English
Article number	21737
Journal	Scientific Reports
Volume	6
Number of pages	13
ISSN	2045-2322
DOIs	https://doi.org/10.1038/srep21737
Publication status	Published - 2016

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Gkamaletsos, P., Godelitsas, A., Kasama, T., Kuzmin, A., Lagos, M., Mertzimekis, T. J., Göttlicher, J., Steininger, R., Xanthos, S., Pontikes, Y., Angelopoulos, G. N., Zarkadas, C., Komelkov, A., Tzamos, E., & Filippidis, A. (2016). The role of nano-perovskite in the negligible thorium release in seawater from Greek bauxite residue (red mud). Scientific Reports, 6, [21737]. https://doi.org/10.1038/srep21737

Gkamaletsos, Platon ; Godelitsas, Athanasios ; Kasama, Takeshi ; Kuzmin, Alexei ; Lagos, Markus ; Mertzimekis, Theo J. ; Göttlicher, Jörg ; Steininger, Ralph ; Xanthos, Stelios ; Pontikes, Yiannis ; Angelopoulos, George N. ; Zarkadas, Charalampos ; Komelkov, Aleksandr ; Tzamos, Evangelos ; Filippidis, Anestis. / The role of nano-perovskite in the negligible thorium release in seawater from Greek bauxite residue (red mud). In: Scientific Reports. 2016 ; Vol. 6.

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title = "The role of nano-perovskite in the negligible thorium release in seawater from Greek bauxite residue (red mud)",

abstract = "We present new data about the chemical and structural characteristics of bauxite residue (BR) from Greek Al industry, using a combination of microscopic, analytical, and spectroscopic techniques. SEM-EDS indicated a homogeneous dominant {"}Al-Fe-Ca-Ti-Si-Na-Cr matrix{"}, appearing at the microscale. The bulk chemical analyses showed considerable levels of Th (111 mu g g(-1)), along with minor U (15 mu g g(-1)), which are responsible for radioactivity (355 and 133 Bq kg(-1) for Th-232 and U-238, respectively) with a total dose rate of 295 nGy h(-1). Leaching experiments, in conjunction with SF-ICP-MS, using Mediterranean seawater from Greece, indicated significant release of V, depending on S/L ratio, and negligible release of Th at least after 12 months leaching. STEM-EDS/EELS & HR-STEM-HAADF study of the leached BR at the nanoscale revealed that the significant immobility of Th4+ is due to its incorporation into an insoluble perovskite-type phase with major composition of Ca0.8Na0.2TiO3 and crystallites observed in nanoscale. The Th L-III-edge EXAFS spectra demonstrated that Th4+ ions, which are hosted in this novel nano-perovskite of BR, occupy Ca2+ sites, rather than Ti4+ sites. That is most likely the reason of no Th release in Mediterranean seawater.",

author = "Platon Gkamaletsos and Athanasios Godelitsas and Takeshi Kasama and Alexei Kuzmin and Markus Lagos and Mertzimekis, {Theo J.} and J{\"o}rg G{\"o}ttlicher and Ralph Steininger and Stelios Xanthos and Yiannis Pontikes and Angelopoulos, {George N.} and Charalampos Zarkadas and Aleksandr Komelkov and Evangelos Tzamos and Anestis Filippidis",

year = "2016",

doi = "10.1038/srep21737",

language = "English",

volume = "6",

journal = "Scientific Reports",

issn = "2045-2322",

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Gkamaletsos, P, Godelitsas, A, Kasama, T, Kuzmin, A, Lagos, M, Mertzimekis, TJ, Göttlicher, J, Steininger, R, Xanthos, S, Pontikes, Y, Angelopoulos, GN, Zarkadas, C, Komelkov, A, Tzamos, E & Filippidis, A 2016, 'The role of nano-perovskite in the negligible thorium release in seawater from Greek bauxite residue (red mud)', Scientific Reports, vol. 6, 21737. https://doi.org/10.1038/srep21737

The role of nano-perovskite in the negligible thorium release in seawater from Greek bauxite residue (red mud). / Gkamaletsos, Platon; Godelitsas, Athanasios; Kasama, Takeshi; Kuzmin, Alexei; Lagos, Markus; Mertzimekis, Theo J.; Göttlicher, Jörg; Steininger, Ralph; Xanthos, Stelios; Pontikes, Yiannis; Angelopoulos, George N.; Zarkadas, Charalampos; Komelkov, Aleksandr; Tzamos, Evangelos; Filippidis, Anestis.

In: Scientific Reports, Vol. 6, 21737, 2016.

Research output: Contribution to journal › Journal article › Research › peer-review

TY - JOUR

T1 - The role of nano-perovskite in the negligible thorium release in seawater from Greek bauxite residue (red mud)

AU - Gkamaletsos, Platon

AU - Godelitsas, Athanasios

AU - Kasama, Takeshi

AU - Kuzmin, Alexei

AU - Lagos, Markus

AU - Mertzimekis, Theo J.

AU - Göttlicher, Jörg

AU - Steininger, Ralph

AU - Xanthos, Stelios

AU - Pontikes, Yiannis

AU - Angelopoulos, George N.

AU - Zarkadas, Charalampos

AU - Komelkov, Aleksandr

AU - Tzamos, Evangelos

AU - Filippidis, Anestis

PY - 2016

Y1 - 2016

N2 - We present new data about the chemical and structural characteristics of bauxite residue (BR) from Greek Al industry, using a combination of microscopic, analytical, and spectroscopic techniques. SEM-EDS indicated a homogeneous dominant "Al-Fe-Ca-Ti-Si-Na-Cr matrix", appearing at the microscale. The bulk chemical analyses showed considerable levels of Th (111 mu g g(-1)), along with minor U (15 mu g g(-1)), which are responsible for radioactivity (355 and 133 Bq kg(-1) for Th-232 and U-238, respectively) with a total dose rate of 295 nGy h(-1). Leaching experiments, in conjunction with SF-ICP-MS, using Mediterranean seawater from Greece, indicated significant release of V, depending on S/L ratio, and negligible release of Th at least after 12 months leaching. STEM-EDS/EELS & HR-STEM-HAADF study of the leached BR at the nanoscale revealed that the significant immobility of Th4+ is due to its incorporation into an insoluble perovskite-type phase with major composition of Ca0.8Na0.2TiO3 and crystallites observed in nanoscale. The Th L-III-edge EXAFS spectra demonstrated that Th4+ ions, which are hosted in this novel nano-perovskite of BR, occupy Ca2+ sites, rather than Ti4+ sites. That is most likely the reason of no Th release in Mediterranean seawater.

AB - We present new data about the chemical and structural characteristics of bauxite residue (BR) from Greek Al industry, using a combination of microscopic, analytical, and spectroscopic techniques. SEM-EDS indicated a homogeneous dominant "Al-Fe-Ca-Ti-Si-Na-Cr matrix", appearing at the microscale. The bulk chemical analyses showed considerable levels of Th (111 mu g g(-1)), along with minor U (15 mu g g(-1)), which are responsible for radioactivity (355 and 133 Bq kg(-1) for Th-232 and U-238, respectively) with a total dose rate of 295 nGy h(-1). Leaching experiments, in conjunction with SF-ICP-MS, using Mediterranean seawater from Greece, indicated significant release of V, depending on S/L ratio, and negligible release of Th at least after 12 months leaching. STEM-EDS/EELS & HR-STEM-HAADF study of the leached BR at the nanoscale revealed that the significant immobility of Th4+ is due to its incorporation into an insoluble perovskite-type phase with major composition of Ca0.8Na0.2TiO3 and crystallites observed in nanoscale. The Th L-III-edge EXAFS spectra demonstrated that Th4+ ions, which are hosted in this novel nano-perovskite of BR, occupy Ca2+ sites, rather than Ti4+ sites. That is most likely the reason of no Th release in Mediterranean seawater.

U2 - 10.1038/srep21737

DO - 10.1038/srep21737

M3 - Journal article

C2 - 26899139

VL - 6

JO - Scientific Reports

JF - Scientific Reports

SN - 2045-2322

M1 - 21737

ER -