PRECIPITATION AND DETERMINATION OF TANTALUM AND NIOBIUM FROM HOMOGENEOUS SOLUTION WITH 3:3':4':5:7-PENTAHYDROXYFLAVANONE
trated acidic solution(6-9N) does not precipitate tantalum and niobium; however, on heating or boiling, in the pres ence of air, this flavanone is transformed into 3:3':4':5:7pentahydroxyflavone, which precipitates any tantalum and niobium present in the solution. Under the precipitation conditions, racemization of the flavanone also takes place. The racemized flavanone which is less soluble than the original d-form may accompany the tantalum and niobium precipitates without affecting the quantitative determination of these elements. The precipitation of the tantalum and niobium complexes can be controlled by regulating the acidity and the duration of boiling, as well as the concentration of the flavanone. Experimental data and procedures are given for the precipitation and determination from homogeneous solution of tantalum and niobium complexes. Zirconium and molybdenum do not interfere with the determination. Titanium must be absent or present only in minute quantity. Since the generation of the precipitating reagent, flavone, from the flavanone is comparatively slow, the precipitation of tantalum and niobium is uniform throughout the solution. By this technique, adsorption and co-precipitation of potassium and suifate ions in the solution are shown to be negligible. This is ln contrast to the less effective dropwise addition of the flavone reported by earlier investigators, in which adsorption and co-precipitation were pronounced. In the present study, tantalum and niobium oxides were fused with potassium bisulfate. There is no necessity of using hydrofluoric acid to dissolve these oxides, and therefore no polyethylene apparatus is required. (auth)
- Research Organization:
- Aeronautical Research Labs., Wright-Patterson AFB, Ohio
- NSA Number:
- NSA-15-023472
- OSTI ID:
- 4057515
- Journal Information:
- Talanta (England), Journal Name: Talanta (England) Vol. Vol: 7; ISSN TLNTA
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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Related Subjects
ADSORPTION
AIR
BOILING
CHEMISTRY
COMPOUNDS
CONFIGURATION
FLAVONOID COMPOUNDS
HEATING
HYDROFLUORIC ACID
HYDROXIDES
IONS
MOLYBDENUM
NAPHTHALENE
NIOBIUM
NIOBIUM OXIDES
ORGANIC COMPOUNDS
POTASSIUM
PRECIPITATION
QUANTITATIVE ANALYSIS
RACEMIZATION
SOLUTIONS
STEREOCHEMISTRY
SULFATES
SULFONIC ACIDS
TANTALUM
TANTALUM OXIDES
ZIRCONIUM