Following 18O uptake in scCO2–H2O mixtures with Raman spectroscopy
The kinetics of 18O/16O isotopic exchange in scCO2 containing liquid water was followed with Raman spectroscopy using a specially designed high-pressure optical cell. Characteristic bands from the C16O18O and C18O2 molecules were identified in the supercritical phase and measured in the spectra as a function of time after introducing liquid H218O into scC16O2. Temporal dependence indicated the isotopic exchange was diffusion-limited in our cell for both molecules, and that the chemical reactions within the liquid phase were comparatively rapid. However, the ratio of concentrations of the 18O-labeled CO2 molecules, C18O2/C16O18O, was much higher than expected in the supercritical phase, suggesting the role of an intermediate step, possibly desorption, in moderating the concentrations of these species in the liquid water phase.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1047400
- Report Number(s):
- PNNL-SA-84943; AA3010000; TRN: US201216%%259
- Journal Information:
- Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy, Vol. 94
- Country of Publication:
- United States
- Language:
- English
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