Open AccessMonitoring synchrotron X‐ray‐induced radiolysis effects on metal (Fe, W) ions in high‐temperature aqueous fluids
Author(s) -
Mayanovic Robert A.,
Anderson Alan J.,
Dharmagunawardhane Hingure A. N.,
Pascarelli Sakura,
Aquilanti Giuliana
Publication year - 2012
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s0909049512029093
Subject(s) - radiolysis , aqueous solution , x ray absorption spectroscopy , chemistry , ion , kinetics , tungsten , synchrotron , analytical chemistry (journal) , chemical kinetics , absorption spectroscopy , inorganic chemistry , physics , organic chemistry , chromatography , quantum mechanics , nuclear physics
Radiolysis‐induced effects on aqueous tungsten ions are observed to form a precipitate within seconds upon exposure to a synchrotron X‐ray micro‐beam in a WO 3 + H 2 O system at 873 K and 200 MPa. In situ Fe K ‐edge energy‐dispersive X‐ray absorption spectroscopy (ED‐XAS) measurements were made on Fe(II)Cl 2 aqueous solutions to 773 K in order to study the kinetics of high‐temperature reactions of Fe 2+ and Fe 3+ ions with transient radiolysis species. The radiolytic reactions in a fluid sample within a hydrothermal diamond anvil cell result in oxidation of the Fe 2+ ion at 573 K and reduction of Fe 3+ at temperatures between 673 and 773 K and of the Fe 2+ ion at 773 K. The edge‐energy drift evident in the ED‐XAS data directly reflects the kinetics of reactions resulting in oxidation and/or reduction of the Fe 2+ and Fe 3+ ions in the aqueous solutions at high temperatures. The oxidation and reduction trends are found to be highly consistent, making reliable determinations of reaction kinetics possible.