Extraction Properties of Butyl Bis(dibutoxyphosphinylmethyl)phosphinate in Nitric Acid Solutions

Abstract

The extraction of HNO 3 and microamounts of U(VI), Th(IV), Sc(III), REE(III), and Am(III) nitrates from HNO 3 solutions with solutions of butyl bis(dibutoxyphosphinylmethyl)phosphinate in organic diluents was studied. The stoichiometry of the extractable complexes was determined, and the apparent extraction constants were calculated. The capability of the extractant to recover the examined elements from nitric acid solutions grows with an increase in the number of phosphoryl groups in its molecule. The recovery of the metal ions into the organic phase becomes more efficient in going to more polar organic diluents.Neutral bidentate organophosphorus compounds, alkylenediphosphine dioxides and diaryl(dialkylcarbamoylmethyl)phosphine oxides (CMPOs), exhibit high extractive power toward trivalent transplutonium (TPE) and rare-earth (REE) elements [1310]. However, low solubility of tetraphenylmethylenediphosphine dioxide (TPMDPO) in organic diluents is its essential drawback, considerably decreasing the extraction capacity of TPMDPO and restricting the feasibility of its use for recovering TPE from high-level waste (HLW) from spent nuclear fuel reprocessing [4]. Replacement of phenyl substituents at the P atom in the TPMDPO molecule by alkyl and especially alkoxy groups makes the extractant more compatible with organic diluents but drastically decreases its extraction power [3]. In particular, dibutyl phenyl(ethyl)phosphinylmethylphosphonate is fully miscible with decane, but its extraction power toward Am(III) is lower than that of TPMDPO and even of monodentate dioctyl-(isoamyl)phosphine oxide [11]. Dialkyl methylphosphonates exhibit still lower extraction power; nevertheless, they recover Am(III) from nitric acid solutions with fairly high distribution factors [12,13]. In going from monodentate dialkyl methylphosphonates to bifunctional tetraalkyl methylenediphosphonates, the extraction power toward Am(III) and REE(III) considerably increases [14].It is interesting to examine the extraction power of compounds containing, along with phosphonate centers, also other donor fragments, in particular, phosphinate groups, and to reveal how the number of phosphoryl groups in molecules of polyphosphoryl compounds affects their extraction power. To this end, we examined regular trends in the distribution of HNO 3 , U(VI), Th(IV), Sc(III), Am(III), and REE(III) between aqueous HNO 3 and solutions of butyl bis(dibutoxyphosphinylmethyl)phosphinate (L) in organic diluents.

Extraction and separation of U(VI) and Th(IV) from hydrobromic acid media using Cyanex-923 extractant

“…[4][5][6] The separation of Th, La, Eu ions was realised using the acidic extractant bis(2-ethylhexyl) phosphoric acid (DEHPA) in cyclohexane using 2-nitrobenzo-18-crown-6 [NB18 (6)]. 7 LIX-360 (HX) in kerosene and Versalic-10 was also used for extraction studies of U(VI).…”

“…7 LIX-360 (HX) in kerosene and Versalic-10 was also used for extraction studies of U(VI). 8 In addition, 2-hydroxy-1-naphthaldehyde thiosemicarbazone was used to study the extraction behaviour of Th(IV) from HNO 3 in the presence of donors, trioctylphosphine oxide (TOPO), Calix [3]OH [3]OMe [6]arene, trioctyl amine (TOA) and DMSO in ethyl acetate solvent. 9 A new chelating polymeric sorbent was developed using Merrifield chloromethylated resin anchored with di-bis(2-ethylhexyl)malonamide (DB2EHM) for the selective extraction of U(VI) and Th(IV) from an acidic stream.…”