Mechanisms and Kinetics of Organic Aging in High-Level Nuclear Waste (PNNL Scope #29531)
EMSL Project ID
4794
Abstract
Examine the aging of organic chemicals in high-level nuclear wastes stored in tanks at Hanford and develop a mechanistic model describing the reactions and kinetics.The part of the work involving EMSL is the research on Thermochemical Property Measurements of Hydrogen Peroxide and the Hydroxyl Radical in
Aqueous Solution:
Photo-induced decomposition of hydrogen peroxide leads to the prompt formation of reactive hydroxyl radicals. The
photoacoustic signal generated by pulsed irradiation of an aqueous hydrogen peroxide solution is proportional to the
combined photo-induced volume changes from both the enthalpy and the molecular transformation of the
dissociation reaction. The magnitude of the photoacoustic signal arising from enthalpy of the reaction is due to local
heating of the solution and is dependent on the thermoelastic properties of the solution. One the other hand, the
magnitude of the photoacoustic signal arising from the molecular volume change is independent of the thermoelastic
properties of the solution since no heat is evolved in molecular transformations. Because the thermoelastic
properties of aqueous solutions change substantially over a narrow temperature range variable temperature
photoacoustic calorimetry provides an experimental approach to measure these two thermodynamic properties
simultaneously. This presentation will demonstrate how the thermochemical properties of a short-lived transient
hydroxyl radical can be measured by a variation of the thermoelastic properties of an aqueous solution as a function
of temperature.
Project Details
Project type
Exploratory Research
Start Date
2003-09-01
End Date
2004-09-10
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members