Solvent extraction separation of uranium (VI) with p-t-butyl calix[8]arene and octaacetatecalix[8]arene and beta-diketone (HTTA)

Abstract

Macrocyclic calixarenes are among the recent extractants introduced to offer a differeni concqx on extraction selectivity based on a correspondence bctween the cavity size of calixarene and the extracted metal cation_ On the other harx1 the selective extraction of uranium has attracted extensive attention from rhernieS because of its importance m relation to energy problems and environment. We have studied a new method for the solvent extraction separation of the UO22+ion by two calbcPtiarenes from acetate solution. Octaacetatecalix[8]arerie bearing acetate group on the lower him have been synthesized and the extractability (%E) and selectivity towards uranyl ion (UO 22+ ) was estimated in a two phase (acetate-toluene) solvent extraction system. %E for these calixarenes/HTTA systems increases from 4 and saturation is reached at around pH 6-7 were more than 90% of extractability was obtained. The solvent extraction of UO22+ with these calixarenes and thenoyltrifluoroacetone (HTTA) in toluene lias bem studied in the presence or absence of alkali ions (Na+, ir). The efficiency of extraction increases drastically in the presence of alkili ions, due to the formation of heteronuclear cornplexes. Synergistic extraction was observed with calixarenes and thenoyltrifluoroacetone (HTTA). We also found that the selectivity of acetatecalix[8]arene /bua is superior to p-tcrc butylcalix[Marendlrtta. Absorption spectra show shifts of characteristics bands of calixarene from ultraviolet region to visible region with gap of 100 nm when HTTA is introduced in the solution.