Effect of ionic liquids on the extraction of americium by diphenyl (dibutyl) carbamoylmethyl phosphine oxide in dichloro
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Effect of ionic liquids on the extraction of americium by diphenyl (dibutyl) carbamoylmethyl phosphine oxide in dichloroethane from nitric acid solutions G. A. Pribylova • I. V. Smirnov • A. P. Novikov
Received: 31 January 2012 / Published online: 14 September 2012 Ó Akade´miai Kiado´, Budapest, Hungary 2012
Abstract The present paper demonstrates that room temperature ionic liquids (RTIL) added at 1–5 wt% to a diphenyl (dibutyl) carbamoylmethylphosphine oxide (Ph2Bu2) solution increase the extraction coefficients of americium from nitric acid by more than two orders of magnitude. Moreover, the use of the RTIL—1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide makes the extraction possible even from 8 M HNO3. This is an important attribute of such extraction system from the point of its possible application for radiochemical analysis of technological samples and environmental solutions, since many methods are based on transferring the solid samples into an 8 M HNO3 solution. The extraction data obtained revealed that three Ph2Bu2 ligands are included into the coordination sphere of americium, two of which represent a compound with the nitrate anion and one with the RTIL anion. Keywords Liquid–liquid extraction Actinides Americium Room temperature ionic liquids Diphenyl (dibutyl) carbamoylmethylphosphine oxide
Introduction Nowadays, experts in radiochemistry pay increasing attention to the modernization of extraction technologies used to treat G. A. Pribylova A. P. Novikov (&) Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, Kosygin Str. 19, 119991 Moscow, Russia e-mail: [email protected] I. V. Smirnov Khlopin Radium Institute, 2nd Murinskii Avenue, 28, 194021 St. Petersburg, Russia
spent fuel. However, safety concerns of the nuclear fuel cycle include also the development of analytical methods for controlling technological and environmental samples. Methods of radiochemical analysis are distinguished by compactness and low volumes of organic substances used. Therefore, for these purposes the use of rather expensive reagents at present is possible. Room temperature ionic liquids (RTIL) which have acquired considerable interest as diluents for traditional extractants relate to these reagents [1]. RTIL belong to molten salts class because so far as melted salts are consisted of entirely ions, but melt at or below 100 °C. RTIL usually consist of asymmetric organic cations and organic or nonorganic anions. According to the literature, the use of RTIL as polar diluents during solvent extraction significantly increases the distribution coefficients of elements. However, enhanced distribution coefficients are not always desirable because extraction selectivity may be adversely affected. Problems with back extraction may also be the case. As has been shown in our previous paper [2], small additions of RTIL to traditional diluents increase the actinides extraction by bidentate neutral organophosphorus reagents significantly as well. Therefore, the objective of
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