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Mutual Separation and Determination of Th(IV) and U(VI) Using Arsenazo III as a Dye Collector Reagent by Flotation‐Spectrophotometric Method
Author(s) -
Hosseini Mohammad Saeid,
Yavari Hamid Reza
Publication year - 2007
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.200700104
Subject(s) - chemistry , reagent , absorbance , molar absorptivity , thorium , metal ions in aqueous solution , uranium , metal , detection limit , methanol , spectrophotometry , nuclear chemistry , analytical chemistry (journal) , chromatography , physics , materials science , organic chemistry , optics , metallurgy
This paper reports a simple and highly selective method for the separation, preconcentration, and determination of trace amounts of thorium and uranium in some complex samples via staircase flotation. The method is based on the initial flotation of the Th(IV)‐arsenazo III complex in the presence of U(VI) from a solution of 5 mol dm −3 HCl, then reduction of U(VI) to U(IV) and repetition of the flotation step. In both steps, the floated complex was dissolved in a 5‐mL portion of methanol and its absorbance was measured at 655 nm, spectrophotometrically. For a 30‐mL portion of the sample, Beer's law was obeyed over the concentration ranges of 3.40 × 10 −7 to 3.06 × 10 −6 mol dm −3 for Th(IV) and3.40 × 10 −7 to 3.40 × 10 −6 mol dm −3 for U(IV) with the apparent molar absorptivity of 4.20 × 10 5 dm 3 mol −1 cm −1 and 3.59 × 10 5 dm 3 mol −1 cm −1 , respectively. The RSDs (n = 7) corresponding to 1.7 × 10 −6 mol dm −3 of Th(IV) and U(IV) were obtained as 1.7% and 1.87%. The detection limits (7 blanks) for both the metal ions were found to be 1.7 × 10 −7 mol dm −3 . The important benefit of the method is that the determinations are free from the interference of almost all cations and anions found in the complex matrixes, such as seawater samples. The proposed method was also applied to reference materials, and the determinations were shown to have good agreement with the certified values.