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dc.contributor.authorUngerer, M.J.
dc.contributor.authorVan Sittert, C.G.C.E.
dc.contributor.authorVan der Westhuizen, D.J.
dc.contributor.authorKrieg, H.M.
dc.date.accessioned2017-08-23T07:36:56Z
dc.date.available2017-08-23T07:36:56Z
dc.date.issued2017
dc.identifier.citationUngerer, M.J. et al. 2017. Molecular modelling of tantalum in an aqueous phase. Journal of the Southern African Institute of Mining and Metallurgy, 117(6):541-544. [http://dx.doi.org/10.17159/2411-9717/2017/v117n6a4]en_US
dc.identifier.issn2225-6253
dc.identifier.issn2411-9717 (Online)
dc.identifier.urihttp://hdl.handle.net/10394/25423
dc.identifier.urihttp://dx.doi.org/10.17159/2411-9717/2017/v117n6a4
dc.identifier.urihttp://www.scielo.org.za/pdf/jsaimm/v117n6/07.pdf
dc.description.abstractThe transition metals tantalum (Ta) and niobium (Nb) are of significant importance, for example in the nuclear energy sector where they are used as cladding materials, as well as in capacitors and specialized materials. For these applications a high-purity metal is needed. The separation of Ta and Nb is always a challenge since they are found together in nature and have similar chemical and physical properties, resulting in costly and laborious separation processes. A technology that has been used successfully for the separation of these metals entails solvent extraction (SX)1. While separation was achieved in a previous SX study using a sulphuric acid (H2SO4) medium with the extractants diiso-octyl phosphinic acid (PA) and di-(2-ethylhexyl) phosphoric acid (D2EHPA), due to the absence of speciation data for Ta and Nb it is not clear how the separation occurred. One method that might be suitable for determining the speciation of a reaction is molecular modelling. Calculations based on the densityfunctional theory (DFT) are now used not only for light elements and small molecules, but also metal complexes, heavy metals, and especially metal separation in SX2. In this study the aqueous phase used during SX was investigated by studying periodic systems of Ta, as a metal and in salt form, when it is in contact with H2O and H2SO4. The results were used to predict the reaction mechanism occurring during SX. Results showed that (i) in a 1:1 acid-water ratio, the deprotonation of H2SO4 was endothermic, (ii) in a 1:5 ratio deprotonation was exothermic forming HSO4 -, and (iii) in a 1:10 ratio double deprotonation occurred to form SO42- exothermicallyen_US
dc.language.isoenen_US
dc.publisherSAIMMen_US
dc.subjectTantalumen_US
dc.subjectNiobiumen_US
dc.subjectSolvent extractionen_US
dc.subjectReaction mechanismen_US
dc.subjectMolecular modellingen_US
dc.titleMolecular modelling of tantalum in an aqueous phaseen_US
dc.typeArticleen_US
dc.contributor.researchID20068980 - Ungerer, Maria Johanna
dc.contributor.researchID10073817 - Van Sittert, Cornelia Gertina Catharina Elizabeth
dc.contributor.researchID12839981 - Van der Westhuizen, Derik Jacobus
dc.contributor.researchID11087137 - Krieg, Henning Manfred


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