Spectroelectrochemical Sensor for Technetium Applicable to the Vadose Zone (PNNL Scope # 30948 Bryan/Hubler EMSP)
EMSL Project ID
12298
Abstract
The general aim of this project is to continue the design and implementation of a new sensor technology that offers the unprecedented levels of specificity needed for analysis of the complex chemical mixtures found at DOE sites nationwide. The new sensor concept combines the elements of electrochemistry, spectroscopy and selective partitioning into a single device that provides three levels of selectivity. The specific goal of this project is the development of a sensor for technetium (Tc) that is applicable to characterizing and monitoring the Vadose Zone and associated subsurface water at the Hanford site. The first goal is a sensor that determines technetium in the chemical form pertechnetate (TcO4-).Title: Fluorescence Studies of Tc(V) Complexes - added scope 2/21/2005.
The general aim of our work funded by EMSP is the design and implementation of a new sensor technology that offers
unprecedented levels of specificity needed for analysis of the complex chemical mixtures found at DOE sites nationwide; the
project is to develop a sensor for pertechnetate. The specific goal of this proposal is obtain the fluorescence spectra of about
5-10 Tc(V) compounds in the solid state at low temperature. These experiments will aid in our design of the films which are
critical for sensor development.
The concept for this TcO4- sensor is innovative and represents a breakthrough in sensor technology. The sensor combines thre
modes of selectivity (electrochemistry, spectroscopy, and selective partitioning) into a single sensor to substantially improve
selectivity. The sensor will consist of a basic spectroelectrochemical configuration that we have developed under our previous
EMSP grants: a waveguide with an optically transparent electrode that is coated with a thin chemically-selective film. Proof of
concept of this spectroelectrochemical sensor has been demonstrated under our previous EMSP grants for the determination of
ferrocyanide in Hanford tank waste. A prototype sensor was developed and was tested successfully using In-Farm and U-Plant
Hanford simulated wastes and then on actual tank waste. The key to adapting this generic sensor to detect TcO4- lies in the
development of unique chemistry within the chemically-selective film. This film will be developed so that TcO4- in the sample
partitions into it by electrostatic attraction. Once TcO4- is loaded into the film, it is electrochemically converted into a Tc
coordination compound that gives a strong optical signal (fluorescence) associated with an electrochemical
reduction/oxidation process. The magnitude of the fluorescence change accompanying the electrochemical modulation of
this coordination compound will quantify the concentration of Tc within the film, which is proportional to the concentration of
TcO4- in the sample. (Note - this Zheming Wang is the POC on the FLUORESCENCE work).
Project Details
Project type
Exploratory Research
Start Date
2004-12-07
End Date
2007-07-06
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Highly Oxidizing Excited States of Re and Tc Complexes
Luminescence from the trans-Dioxotechnetium(V) Chromophore