Antimony transport in hydrothermal solutions: an EXAFS study of antimony(V) complexation in alkaline sulfide and sulfide-chloride brines at temperatures from 25 degrees C to 300 degrees C at P-sat

DM Sherman*, KV Ragnarsdottir, EH Oelkers

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)

35 Citations (Scopus)

Abstract

Existing electrochemical data suggest that under alkaline conditions, Sb(V) sulfide complexes may be stable under conditions as reducing as those found in hydrothermal ore solutions. To assess the nature of Sb(V) complexes in such solutions, X-ray absorption fine structure spectra (EXAFS) of antimony(V) solutions were obtained at temperatures from 25 degrees C to 300 degrees C at pressures corresponding to the liquid-vapour equilibrium curve for H2O. Three solution compositions were considered: Solution A consisted of 0.1 m Sb + 1.15 m Na2S; solution B had the composition of 0.05 m Sb + 0.2 m NaHS + 0.06 m NaOH; and solution C consisted of 0.05 m Sb + 0.2 m NaHS + 0.06 m NaOH + 1 m NaCl. At temperatures <150 degrees C, the inner coordination shell of aqueous Sb(V) contains four sulfur atoms corresponding to the Sb(HS): complex. Above 150 degrees C, SH- ligands are replaced by OH- to form mixed-ligand Sb complexes. Antimony(V) atoms are found in a second coordination shell at temperatures greater than 250 degrees C, indicating the existence of aqueous polyatomic clusters. No antimony(V) chloride complexation was found in the presence of HS-. (C) 2000 Elsevier Science B.V. All rights reserved.

Original languageEnglish
Pages (from-to)161-167
Number of pages7
JournalChemical Geology
Volume167
Issue number1-2
Publication statusPublished - 5 Jun 2000
EventSymposium on Direct Observation and Measurement of Hydrothermal Reactions held at the 8th VM Goldschmidt Conference - TOULOUSE, France
Duration: 30 Aug 19983 Sep 1998

Keywords

  • antimony
  • hydrothermal
  • EXAFS
  • X-RAY-ABSORPTION
  • SPECIATION
  • 350-DEGREES-C
  • ELECTROLYTES
  • ENVIRONMENT
  • SOLUBILITY
  • CONSTANTS
  • STIBNITE

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