An evolved fluorimetric determination of uranium in rock/mineral sample solutions containing hydrolysable elements such as Nb, Ta, Zr and Ti sequestered by bi-fluoride. (June 2020)

• Record Type: Journal Article
• Authors: Pradhan, Susanta Kumar; Ambade, Balram; Tarafder, Pranab Kumar
• Is Part Of: Applied radiation and isotopes. Volume 160(2020:Jun.)
• Publication Date: 2020-06
• Subjects: Uranium -- Refractory rock/minerals -- 2, 3-Dihydroxynaphthalene -- Pellet fluorimetry -- Ammonium bi-fluoride; Radiology -- Periodicals; Radiation -- Industrial applications -- Periodicals; Nuclear chemistry -- Periodicals; Internet resource; Periodical; 660.298
• DOI: 10.1016/j.apradiso.2020.109126
• Languages: English
• ISSNs: 0969-8043

Abstract

Abstract: The aim of the present paper is to develop a novel method for fluorimetric determination of uranium in rock/mineral solutions containing hydrolysable elements such as Nb, Ta, Zr and Ti sequestered by bi-fluoride. These rocks/minerals are decomposed with ammonium bi-fluoride (NH4 HF2 ) and sulfuric acid (H2 SO4 ) mixture. Uranium in such mineral solutions is selectively extracted into ethyl acetate with 2, 3-dihydroxynaphthalene at pH 10–12 in the presence of cetyltrimethylammonium bromide, prior to its pellet fluorimetric determination. Optimizations of certain parameters such as the effects of fluoride fluxes, mineral acids, masking agents and diverse ions are discussed in detail. This method is applied for the determination of uranium in synthetic mixtures and a set of in-house reference refractory minerals including certified reference material X1807 with a high degree of accuracy and precision. The results for the refractory minerals using the proposed method are in excellent agreement with results obtained by other standard methods. The novelty of the proposed method is that the decomposition mixture (NH4 HF2 /H2 SO4 ) inhibits the hydrolysis of hydrolysable elements by formation of their soluble fluoro complexes, and the separation of uranium using the complexing agent 2, 3-dihydroxynaphthalene is more eco-friendly compared to existing the conventional solvent extraction system using aluminum nitrate as the salting out agent. Highlights: Decomposition mixture (NH4 HF2 /H2 SO4 ) decomposes the refractory samples/minerals. Facilitates formation of soluble fluoro complexes of hydrolysable elements, e.g. Nb, Ta, Ti, Zr. Sequesters iron, a moderate quencher of uranium fluorescence, by formation of ternary fluoro sulfato ferrate(III) complexes. Uranium separation using 2, 3-dihydroxynaphthalene is more eco-friendly than conventional pellet fluorometry.