Shigeto Nakamura

Synergic extraction of lanthanide(III) ions with 2-thenoyltrifluoroacetone in the presence of 2,2′-bipyridine or pyridine

Abstract The synergic extraction of various tervalent lanthanides (Ln), La, Ce, Nd, Sm, Gd, Tb, Yb and Lu, with 2-thenoyltrifluoroacetone (Htta) in the presence of a bidentate heterocyclic amine, 2,2′-bipyridine (bipy), in benzene was investigated. The synergic enhancement was attributed to the formation of the adducts, Ln(tta)3(bipy). The synergic extraction of La(III), Sm(III) and Lu(III) with Htta and a unidentate amine, pyridine (py), was also studied and the formation of the adducts, Ln(tta)3py and Ln(tta)3(py)2, was observed. The adduct formation constants, βs,1 and βs,2, were determined. The βs,2 values for py decrease with increasing atomic number of Ln(III), but βs,1 values for bipy increase with increasing atomic number of Ln(III). The synergic extraction constants and the separation factors in the bipy system were also determined.

Mutual Separation of Lanthanoid Elements by Centrifugal Partition Chromatography

Abstract Multistage separation based on liquid-liquid extraction has been investigated by means of centrifugal partition chromatography (CPC). A kerosene solution of 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (EHPA) was employed as a stationary phase without any solid support. Metal ions eluted by the aqueous mobile phase were detected by the post-column reaction with Arsenazo III. The retention volumes are approximately linear with the distribution ratios of metals. The mutual separation of adjacent lanthanoids was accomplished by CPC.

Solvent effect on the synergic extraction of thulium(III) with acetylacetone and 1,10-phenanthroline

Abstract The synergic extraction equilibrium of Tm(III) with acetylacetone (Hacac) and 1,10-phenanthroline (phen) in various organic solvents has been studied. The adduct formation constants, βs, for Tm(acac)3− phen, were determined in heptane, cyclohexane, carbon tetrachloride, benzene and chloroform. The solvent effect on βs is explained in connection with the activity coefficients of the neutral ligand, the chelate, and the adduct in the organic solvent. The activity coefficients can be calculated from the corresponding solubility parameters on the basis of the regular solution theory, and the solubility parameters of the solutes were estimated from their two-phase partition coefficients. It is demonstrated that βs in different organic solvents except those having a specific interaction with the solute, such as chloroform, can be calculated by the present approach.

A new trend in the synergistic extraction of rare-earth(III) complexes with various β-diketones and 1,10-phenanthroline

Abstract The synergistic extraction of rare-earth (RE) [La(III), Sm(III), Tb(III) and Lu(III)] complexes, with three β-diketones (HA) [hexafluoroacetylacetone (Hhfa), pivaloyl-trifluoroacetone (Hpta) and benzoylacetone] in the presence of a bidentate ligand (S), 1,10-phenanthroline, in benzene was investigated. The general composition of the adducts formed is expressed as RE(A)3S. RE(A)3(S)2 is also observed in La-Hhfa, La-Hpta and Sm-Hhfa systems. The adduct formation contains βs,1 and βs,2 and the synergistic extraction constants Kex,s,1 were determined. The trend of these constants is discussed in terms of the RE(III), β-diketone, neutral bidentate ligand and organic solvent.

Effect of an acidic chelating agent in the synergic extraction systems of rare earth(III)β-diketones-2,2′-bipyridine

Abstract The extraction of rare earth elements (RE), La(m), Sm(III), Tb(III), Tm(III) and Lu(III), with four β-diketoncs (HA), hexafluoroacetylacetone (Hhfa), pivaloyltrifluoroacetone (Hpta), benzoyl- acetone (Hba) and acetylacetone (Hacac), in the presence or absence of 2,2′-bipyridine (bpy) in benzene was studied. The extraction constants (Kex) for RE(III) with Hhfa, Hpta and Hacac were determined and compared with each other. The order of Kex is Hacac

Extraction of Platinum(IV) with Trioctylamine and its Application to Liquid Membrane Transport

Abstract The extraction and stripping behavior of platinum(IV) between trioctylamine (TOA) in kerosene and different aqueous media has been investigated. Perchlorate anion was found to be most effective for the stripping of platinum under acidic and neutral conditions. The transport of platinum was performed through a supported liquid membrane (SLM) impregnated with TOA as a mobile carrier. Platinum was almost quantitatively transported from the hydrochloric acid solution to the stripping solutions containing perchlorate anion against its large concentration gradient without accumulation in the liquid membrane layer. The transport behavior of platinum was greatly improved by the addition of 1-octanol in SLM, and the permeation rate was mainly controlled by diffusion in the aqueous boundary layer.

Synergic extraction of thulium(III) with thenoyltrifluoroacetone and neutral unidentate and bidentate heterocyclic amines

Synergic extraction of thulium(III) with 2- thenoyttrifluoroacetone(Htta) and neutral bidenrate heterocyclic amine, such as 1,10-phenanthroline(phen), 2,9-dimethyl-1,10-phenanthroline(dmp) and 2,2′-bipyridine(bpy), as well as unidentate amine, pyridine(py), in benzene and cyclohexane was investigated. Synergism was found to be due to formation of the ternary complex, Tm(tta)3S for the bidentate amines and Tm(tta)3S2 for py, in the organic phase, where S denotes a neutral ligand. Adduct formation constants (βs) in all systems were determined. The values of βs,1 for bidentate amines are very large and decrease in the following order: phen > bpy > dmp, and the value of βs,1 for bpy is larger than that of βs,2 for py.

Synergistic extraction of manganese(II) with thenoyltrifluoroacetone and neutral unidentate and bidentate ligands

Synergistic effect of neutral bidentate ligands, L, such as 1,10-phenanthroline(phen), 2,9-dimethyl-1,10-phenanthroline(dmp), and 2,2′-bipyridine(bpy), and of neutral unidentate ligands TBP and TOPO have been studied in the extraction of Mn(II) labeled with54Mn, using 2-thenoyl-trifluoroacetone(HTTA) in various organic solvents. The following factors play an important role in the synergistic extraction involving bidentate ligands; two-phase partition of bidentate ligands, their protonation and complex formation with Mn(II) in the aqueous phase. The mixed ligand complex, Mn(TTA)2L, is formed in all bidentate ligand systems. The adduct formation constant (αS,1) decreases in the following order; phen (lg αS,1=12.64) > dmp(11.32)> · bpy(8.54) in the cyclohexane system. This order is ascribed to the bacisity and the steric effect of the bidentate ligands. Organic solvents influence both the adduct formation and the partition of the ligands, and αS,1 decreases in the order cyclohexane>carbon tetrachloride>chlorobenzen ∼= benzene>chloroform.

Transport of palladium(II) through trioctylamine liquid membrane

Abstract The permeation behavior of palladium(II) through a supported liquid membrane (SLM) impregnated with trioctylamine (TOA) in kerosene has been investigated. By selecting perchloric or nitric acid as a stripping agent, Pd(II) was transported through the SLM containing 0.5 M TOA and 20% 1-octanol without remaining in the liquid membrane. The permeation rate (k f. obs) of Pd(II) for HNO3 was faster than that for HClO4. Palladium(II) was concentrated across the SLM from the 0.5 M CHI solution into the HClO4 or HNO3 solution.

Transport of Europium(III) through Supported Liquid Membrane Containing Diisodecylphosphoric Acid

Abstract Carrier mediated transport of europium has been investigated by the use of a flat-sheet membrane impregnated with diisodecylphosphoric acid (DIDPA). The addition of 1-octanol to the membrane improves the stripping process, and hence europium can be quantitatively transported from the feed solution of 0.1 M HNO3 into the product solution of 5 M HNO3. Its concentration in the feed solution decreases as [Eu] f,t = [Eu] f,0 exp (-k obs t). The apparent rate constant (k obs) increases with increasing carrier concentration and becomes nearly constant above 0.05 M DIDPA The europium flux is proportional to initial europium concentrations less than 10−3 M, and becomes constant at high concentrations.