Spectroelectrochemical Sensor for Technetium: Preconcentration and Quantification of Pertechnetate in Polymer-Modified Electrodes
A remote spectroelectrochemical sensor and instrumentation package is being developed for the detection of technetium as aqueous pertechnetate (TcO{sub 4}{sup -}) in the vadose zone and associated groundwater. This sensor would be used to monitor the integrity of low-level and high-level nuclear waste containment at U.S. Department of Energy sites. Electrochemical studies of TcO{sub 4}{sup -} reduction at bare indium tin oxide (ITO) optically transparent electrodes (OTEs) show a poorly formed reduction wave for cyclic voltammetry and precipitation of technetium oxide (TcO{sub 2}) on the electrode surface. Similar experiments at ITO OTEs coated with thin films containing cationic polymers show partitioning of TcO{sub 4}{sup -} into the films. Three films were investigated: poly(dimethyldiallylammonium chloride) (PDMDAAC) and quaternized poly(4-vinylpyridine) (QPVP), both immodilized in porous glass by the sol-gel process, and poly(vinylbenzyltrimethylammonium chloride) (PVTAC) copolymerized with poly(vinylalcohol). The largest enhancement in the cyclic voltammetry reduction wave for TcO{sub 4}{sup -} was for QPVP. The electrochemical mechanism changes to favor formation of a relatively long-lived soluble species that ultimately converts to TcO{sub 2}. The electrodeposition of technetium oxide in these films was shown to be a method for the quantitative spectroelectrochemical determination of TcO{sub 4}{sup -} and has been verified using radiochemistry dose measurements and scanning electron microscopy.
- Research Organization:
- Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1035441
- Report Number(s):
- PNNL-SA-42456; KP1301020
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CONTAINMENT
CONTAMINATION
DETECTION
ELECTRODEPOSITION
ELECTRODES
GLASS
INDIUM
MANAGEMENT
MONITORS
PERTECHNETATES
POLYMERS
PRECIPITATION
RADIOACTIVE WASTES
RADIOCHEMISTRY
SCANNING ELECTRON MICROSCOPY
SENSORS
SOL-GEL PROCESS
TECHNETIUM
TECHNETIUM OXIDES
THIN FILMS
TIN OXIDES
pertechnetate
spectroelectrochemical