The structure and composition of solid complexes comprising of Nd(III), Ca(II) and D-gluconate isolated from solutions relevant to radioactive waste disposal

Éva Böszörményi, Jorge Lado, Csilla Dudás, Bence Kutus, Márton Szabados, Gábor Varga, István Pálinkó, Pál Sipos

Research output: Contribution to journalArticle

Abstract

Certain complexing agents (such as D-gluconate, D-isosaccharinate, etc.) as well as actinides and lanthanides are simultaneously present in cementitious radioactive waste repositories and (in the presence of water) are capable of forming complex compounds. Such processes may immobilize radionuclides and are of importance in the thermodynamic modelling of the aqueous chemistry of waste repositories. Nd(III) is considered to be a suitable model for trivalent lanthanides and actinides, due to the similarity of their ionic radii. In the current work, solid complexes isolated from aqueous solution containing Nd(III), Ca(II) and D-gluconate (Gluc-) were investigated. In an aqueous solution containing Nd(III) and Gluc-, the formation of a precipitate was observed at pH ≥ 8. This precipitate was found to redissolve around pH ~ 11, but reprecipitated when Ca(II) ions were added to the solution. In order to gain an insight in binary and ternary aqueous systems, in the present work we report the structure of these solid complexes obtained from XRD, FT-IR, Raman, SEM-EDAX and UV-DRS measurements. The structure of these solids, where possible, was compared with those identified in solution. The compositions of these complexes are suggested to be NdGlucH-1(OH) · 2H2O and CaNdGlucH-1(OH)3 · 2H2O, respectively. In these, the chemical environment of the Nd(III) was found to be the same as that in the NdGlucH-1(OH)0(aq) solution species.

Original languageEnglish
JournalPure and Applied Chemistry
DOIs
Publication statusAccepted/In press - Jan 1 2020

    Fingerprint

Keywords

  • D-gluconate
  • ICSC-36
  • calcium
  • neodymium
  • radioactive waste repositories
  • solid complexes
  • structure

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)

Cite this