Spectroelectrochemical Sensor for Pertechnetate Applicable to Hanford and Other DOE Sites.

Heineman, W. R.

Technical Information Center Oak Ridge Tennessee

关键词: Pertechnetates;    Spectroelectrochemistry;    Sensors;    Hanford Reservation;    US DOE;   

RP-ID  :  DE2005850386

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

New film materials for pertechnetate: A new film material comprised of quaternized poly(4-vinylpyridine) cross-linked with 1,10-diiododecane has been developed for use in the spectroelectrochemical sensor. Films were prepared in a one-pot synthesis by stirring poly(4-vinylpyridine), cross-linker and methyl iodide in 1-butanol for 1 h, after which the solution was spin-coating onto ITO-glass. Film thickness was varied either by changing the spin rate or by dilution of the original precursor solution. The thinnest film prepared was 30 nm; the thickest 930 nm. Spectroscopic ellipsometry was used to study the dynamics of film changes on soaking in aqueous salt solution and on preconcentrating model analyte ferrocyanide. The results document that, on hydration, films expanded by almost 90% in 0.1 M KNO3, then contracted slightly when ferrocyanide solution was introduced probably due to electrostatic cross-linking. IR spectroscopy was used to determine the extent of quaternization of the film. For a polymer solution stirred for 1 h, films were about 20% quaternized. This can be increased to (approx)30% by adding more solvent to the precursor solution and stirring for an additional hour. Solubility of the partially cross-linked material was a factor that limited the quaternization process. Use of a more appropriate solvent may enable greater quaternization. A more quaternized film should preconcentrate more pertechnetate by virtue of having a higher density of charged binding sites. Film ruggedness is critical. To investigate this, films on ITO-glass were soaked in methanol and butanol overnight, in 0.1M KNO3, and in 0.1M KNO3 adjusted to pH 12 and pH 2 for 30 days. Each film was then tested as a spectroelectrochemical sensor for model analyte ferrocyanide. The results showed only the pH 2 conditioned sensor behaved abnormally. The film soaked in pH 2 electrolyte delaminated but did not dissolve. Delamination was most likely due to the acid digestion of the ITO layer of the sensor and not to any film-based process. We have also shown that it is possible to regenerate the film by flushing with 1M KNO3 solution.