Separation and determination of niobium and tantalum by acridine

WAKAMATSU Shigeo

doi:10.2116/bunsekikagaku.9.507

A solution containing Nb is treated with 25 ml HCl (d 1.18), 25 ml 50% NH₄SCN and water to make the concentration of HCl to about 2N. This is treated with 10 ml 5% alcoholic solution of acridine and allowed to stand for 30min. at below 30°C for quantitative precipitation of Nb. This is filtered, washed with a solution composed of 1l HCl (1 : 9) and 100 ml 50% NH₄SCN and heated at 900°C for quantitative determination of Nb. Similarly, a solution containing Ta gives quantitative precipitation of Ta. The same treatment of a solution containing Nb and Ta after an addition of 15 ml saturated (NH₄)₂C₂O₄ gives quantitative precipitation of Ta but no precipitation of Nb. Therefore, nearly a complete separation of Ta from Nb is possible by one procedure. In case when more complete, separation is necessary, reprecipitation by the following procedure should be applied: The precipitate of Ta by the addition of acridine is dissolved by heating above 60°C with 25 ml HCl (d 1.18), 5 ml 3% H₂O₂ and 80 ml water, then 15 ml saturated (NH₄)₂C₂O₄ are added, cooled to 30°C, 25 ml 50% NH₄SCN and 10 ml 5% alcoholic solution of acridine are added and the solution is treated as above for quantitative precipitation of Ta but no Nb. In this method, the presence of Fe³⁺, Zn²⁺, Co²⁺, V (V), Mo(V), Mo(VI), Cr(VI), W (VI) and Cu²⁺ showed disturbing influence but those of Fe²⁺, V (IV), Cr³⁺, Mn²⁺, Ni²⁺, Al³⁺, Bi³⁺, Ca²⁺, Mg²⁺, Pb²⁺, Sb⁵⁺, Sn⁴⁺, Ti⁴⁺, etc. were without influence.

Separation and determination of niobium and tantalum by acridine

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