Polarographic Determination of Zirconium and Hafnium with EDTA
Zirconium (IV) and hafnium (IV) ions undergo hydrolysis and polymerization in aqueous solutions so readily that in the absence of complexing agents precipitation begins at pH 3 and is complete at pH 5. But in the presence of Na salts of ethylenediaminetetraacetic acid (EDTA), the precipitation is prevented at pH values up to 9-10. By application of the polarographic method to a Cd EDTA system, the determination of Zr and Hf was extended to solutions of concentration as low as 10-6M, or 0.1 ppm. Results were compared with those obtained by potentiometric titration of the free Cd ion in the concentration range of 10-3 to 104M. The electrolytic solution was prepared by addition of desired amounts of 0.012M CdCl2, 0.010M EDTA, 0.3 ml of 0.4% thymol, then 0.01M Zr or Hf chloride of a desired volume to 10 ml 0.5M acetic acid, with a calibrated microburet, and adjusting the pH by drop-wise addition of N NaOH. After addition of each drop of NaOH, the solution was allowed to attain constant pH before addition of more reagent. The mixture was allowed to stand for 2 hr to attain equilibrium. pH was checked again before the polarographic measurement and total volume was adjusted to 50 ml with water so that the resulting solution contained 0.012 M Cd and 0.010M EDTA and a desired concentration with respect to Zr and Hf. The ionic strength was maintained constant at 0.1. For comparison, Zr and Hf were potentiometrically determined with EDTA, using Cd amalgam as an indicator electrode and saturated calomel electrode as the reference electrode. A relative deviation of 4 to 9% was observed over the concentration range of 10-3 to 10-4M, and no reliable data were obtained for Zr and Hf at concentrations less than 10-1M.
- Research Organization:
- National Taiwan Univ., Taipei
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-17-033824
- OSTI ID:
- 4659102
- Journal Information:
- Journal of the Chinese Chemical Society, Journal Name: Journal of the Chinese Chemical Society Journal Issue: 4 Vol. 8; ISSN 0009-4536
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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Related Subjects
ACETIC ACID
ACIDITY
CADMIUM CHLORIDES
CHELATES
EDTA
EFFICIENCY
ELECTRIC POTENTIAL
ELECTROLYTES
HAFNIUM
HAFNIUM CHLORIDES
HAFNIUM COMPLEXES
HYDROLYSIS
PHENOLS
POLAROGRAPHY
POLYMERIZATION
PRECIPITATION
QUALITATIVE ANALYSIS
QUANTITATIVE ANALYSIS
SODIUM HYDROXIDES
SOLUTIONS
STANDARDS
THYMOL
WATER
ZIRCONIUM
ZIRCONIUM CHLORIDES
ZIRCONIUM COMPLEXES