テノイルトリフルオロアセトンとクラウンエーテルによるランタン(III)とバリウム(II)の協同抽出分離

概要

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A new method for the separation of lanthanum(III) and barium(II) as their thenoyltrifluoroacetone (TTA) complexes with dibenzo-18-crown-6(DB18C6) in o-dichlorobenzene has been established by means of synergistic extraction and back-extraction combined with inductively coupled plasma atomic emisson spectrometry(ICP-AES). When the mixtures of La(III) and Ba(II) were extracted for 5 min at pH 4.5, only lanthanum(III) was extracted quantitatively, whereas barium(II) remained in the aqueous phase. After the phases were separated, barium(II) was extracted quantitatively for 5 min at pH 7.9 again. Then, the two phases were each shaken with 0.1 M HCl in order to back-extract lanthanum(III) and barium(II) from the organic phases; both metal ions were determined by ICP-AES. In the process, lanthanum(III) and barium(II) TTA chelates in o-dichlorobenzene formed stable adducts with DB18C6 (La(TTA)_3・nDB18C6 and Ba(TTA)_2・nDB18C6, n = 0 - 2). The stability constants(β_n) of the adducts determined by means of curve-fitting method were log β_1 = 3.7 and log β_2 = 5.9 for lanthanum(III), and log β_1 = 3.8 and log β_2 = 7.9 for barium(II). The extraction constant(log K) of lanthanum (III) adduct was - 3.7.
社団法人日本分析化学会の論文
2000-11-05