99 Tc immobilization from off-gas waste streams using nickel-doped iron spinel
Technetium-99 ( Tc) incorporation within stable spinel phases is a novel method for Tc removal and immobilization from waste streams. In this study, transformation of Ni-doped Fe(OH) (s) to spinel minerals, e.g. trevorite (NiFe O ), is explored as a method for removing Tc from Hanford Waste Treatmen...
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Published in | Journal of hazardous materials Vol. 364; p. 69 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
Netherlands
15.02.2019
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Subjects | |
Online Access | Get full text |
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Summary: | Technetium-99 (
Tc) incorporation within stable spinel phases is a novel method for
Tc removal and immobilization from waste streams. In this study, transformation of Ni-doped Fe(OH)
(s) to spinel minerals, e.g. trevorite (NiFe
O
), is explored as a method for removing
Tc from Hanford Waste Treatment and Immobilization Plant (WTP) primary off-gas waste stream simulant. The Fe(OH)
(s) transformation process was found to reduce
Tc(VII) to
Tc(IV) and incorporate reduced Tc(VI) into the produced spinel simultaneously. Nickel doping was applied in the mineral transformation to inhibit potential reoxidation of
Tc(IV). Solid phase characterization by XRD and XANES confirmed the formation of nickel substituted ferric-spinel, and suggest incorporation of
Tc(IV) in the final spinel. Furthermore, in the primary off-gas stream, which contains both redox-sensitive contaminants Cr(VI) and
Tc(VII), results from solution analysis and solid digestion indicate that nearly 100% Cr and over 80%
Tc can be simultaneously removed by adding Fe(OH)
(s) to solution with a solid to solution ratio of 5 g/L under near neutral and alkaline conditions. The
Tc removal approach developed herein provides an alternative treatment method to eliminate the proposed recycle process of the off-gas waste stream, which ultimately can reduce WTP mission cost and operation time. |
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ISSN: | 1873-3336 |