An EXAFS spectroscopic study of aqueous antimony(III)-chloride complexation at temperatures from 25 to 250°C

Eric H. Oelkers*, David M. Sherman, K. Vala Ragnarsdottir, Claire Collins

*Corresponding author for this work

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37 Citations (Scopus)

Abstract

The X-ray adsorption fine structure (EXAFS) spectroscopy of antimony(III)-chloride solutions were obtained at temperatures from 25 to 250°C at pressures corresponding to the liquid-vapor equilibrium curve for H2O. Two solution compositions were considered: solution A consisted of 0.042 M SbCl3+2.9 M HCl and solution B consisted of 0.1 M SbCl3+2.29 M HCl. Interpretation of resulting spectra indicates the presence of aqueous Sb-Cl inner sphere complexes at all investigated temperatures. The average number of chlorine ions in these complexes increases with increasing temperature over the range 25 to 250°C from ∼3.0 to ∼ 3.4 and from ∼2.6 to ∼ 2.9 for solutions A and B, respectively. These results also indicate an increasing average number of chloride ions per complex with increasing aqueous chloride concentration. The Sb-Cl interatomic distances for the two solutions are approximately equal and decrease from 2.42 to 2.38 A with increasing temperature over this range. This latter observation is consistent with theoretical models of aqueous complexation that predict decreasing aqueous species electrostatic radii with increasing temperature.

Original languageEnglish
Pages (from-to)21-27
Number of pages7
JournalChemical Geology
Volume151
Issue number1-4
DOIs
Publication statusPublished - 1998

Bibliographical note

Funding Information:
We are indebted to Mike Henderson of the University of Manchester for his generous advice, assistance, and encouragement while designing the furnaces and preparing these experiments. Gleb Pokrovski and Eve Valsami-Jones helped run several of the EXAFS spectra. We would like to thank Jacques Schott, Terry Seward, Roy Wogelius, and Eleonora Paris for encouragement and enlightening discussion during the course of this study. The patience and expert advice of Andy Dent, Gert van Dorsen, and Fred Mosselmans, station managers at Daresbury are gratefully acknowledged. Kim George of the glass laboratory at the Department of Biology at Bristol is thanked for sealing the quartz tubes. Finally thanks are also due Fred Wheeler (Bristol) and Claude Lurde (Toulouse) for building and modifying the furnaces used during this study. This study was funded by the CLRC and the Leverhulme Foundation in the U.K., the CNRS in France, and the Deutsche Forschungsgemeinschaft in Germany.

Other keywords

  • Antimony(III)-chloride solutions
  • Aqueous complexation
  • Hydrothermal solutions
  • X-ray adsorption fine structure (EXAFS) spectroscopy

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