Monitoring synchrotron X-ray-induced radiolysis effects on metal (Fe, W) ions in high-temperature aqueous fluids.
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.
Department of Physics, Astronomy and Materials Science, Missouri State University, Springfield, MO 65897, USA. robertmayanovic@missouristate.edu
Robert A
RA
Mayanovic
Alan J
AJ
Anderson
Hingure A N
HA
Dharmagunawardhane
Sakura
S
Pascarelli
Giuliana
G
Aquilanti
D007501:Iron / Q000737:chemistry / Q000528:radiation effects*; D010084:Oxidation-Reduction; D011830:Radiation Effects; D017356:Synchrotrons; D014414:Tungsten / Q000737:chemistry / Q000528:radiation effects*; D014867:Water / Q000737:chemistry*; D014965:X-Rays
D014867:Water; D007501:Iron; D014414:Tungsten