The partition of Eu(III) between benzene containing solvating extractants (TBP, TOPO, dioctylsulfoxide) and aqueous nitrate,
perchlorate and thiocyanate solutions containing various organic solvents miscible with water (alcohols, acetone, acetonitrile,
ethylene glycol, dimethyl sulfoxide and dimethylformamide) was investigated. Depending on the specific extraction system,
the presence of organic solvents in the mixed phase showed various effects on the distribution ratio of Eu(III). These were
discussed in terms of solute-solvent interactions. The results in the systems containing dimethylformamide and dimethyl sulfoxide
indicated complexation of Eu(III) with these solvents in the polar phase.
With the exception of the formation of coordinatively saturated adducts, synergic extractions using chelating extractants
are reviewed. Emphasis is laid on less common synergic systems. These include the formation of adducts containing also inorganic
anions, extraction of chelates in the presence of bulky organic cations, influence of various anions on the extraction of
chelates, the use of acidic synergic agents, extraction with two chelating agents, and some other systems.
Solvent extraction of175,181Hf(IV) into solutions of HBPHA** in CHCl3, tetrachloro ethane (C2H2Cl4), CCl4 and benzene from mixtures of water with DMSO or DMFA at 2M HClO4 formal acidity was studied. With diluents containing acidic hydrogen (CHCl3, C2H2Cl4) the presence of DMSO or DMFA in the extraction system leads to an increased extractability of the Hf(IV) chelate. Possible
reasons for this synergism are discussed. Extractions into benzene and CCl4, as well as those into CHCl3 and C2H2Cl4 at high DMSO and DMFA concentrations, are antagonistic. This is caused by the decrease of the partition coefficient of HBPHA,
and changes in the solvation of Hf(IV) ion in the polar phase. The latter effect is very strong at high DMSO concentrations,
and with macroconcentrations of Hf(IV) finally leads to precipitation of crystalline adducts Hf(ClO4)4·xDMSO (x=7–8).
Ion pairs of tetraphenylarsonium cation with iodide, bromide, and perrhenate anions were extracted into chloroform from mixed aqueous-organic solutions. The extraction of these ion pairs was found to increase in the presence of polar aprotic solvents in the mixed aqueous-organic phase. This effect was correlated with literature data on free energy of transfer of the Ph4As+ ion, and ascribed to ion pair/solvent and/or ion/solvent interactions in the organic phase.
175, 181Hafnium(IV) was extracted by HDBP in 2-ethylhexanol from 1–10M solutions of HClO4, HCl and HNO3, and 1–8M H2SO4. As with low polar organic phase diluents, the acidity dependence of the distribution ratio of Hf, D, passes through a minimum
for HClO4, HCl, and H2SO4 whereas only an increase of D can be observed with increasing HNO3 concentration. From the slope analysis the following complexes were found to be extracted (HDBP=HA): HfA4 at <4M HClO4 and <5M HCl, lg Kextr=9, HfX4(HA)4 (X=ClO
, Cl− or NO
) at >5M HClO4, >7M HCl and 1–10M HNO3, Hf(SO4)A2(HA)3–4 at <3M H2SO4, and Hf(SO4)2 (HA)4 at >6M H2SO4. Coextraction of sulphate with hafnium from H2SO4 solutions was evidenced in experiments with macro concentrations of Hf(IV) and35SO
Solvent extraction of137Cs,86Rb and42K by dipicrylaminate and tetraphenyl borate into nitrobenzene was studied from solutions containing various solvents miscible
with water. In all cases the distribution ratios of alkali metals were lower in mixed solutions than in water. In discussing
the results, water structure, ion-association, solubility of Cs(I) ionpairs, ionic strength, and organic phase effects were
taken into account.
Tracer concentrations of Hf(IV) were extracted by 60% TBP solution in benzene from 5M HClO4, 5M HCl, 6M HNO3 and 8M H2SO4 solutions, and by 1·10−4 M TOPO solution in benzene from 2M HClO4 and 2M HCl solutions in the presence of a variety of organic solvents miscible with the aqueous phase. Whereas for TBP these
solvents caused an increase of HF(IV) extraction, an opposite effect was observed for TOPO. The results were discussed from
the point of view of various solute-solvent and solvent-solvent interactions.
Extraction by benzene solutions of TBP of carrier-free90Y(III) from mixed aqueous-organic nitrate and perchlorate solutions was studied with special respect to the S-shaped DY versus acid concentration plots observed in aqueous systems. The presence of organic solvents in the aqueous phase enhanced
the extraction of Y(III) and also influenced the shape of the DY vs. acid concentration plots in that the minimum was shifted towards lower acid concentration, became less pronounced, and
eventually vanished completely.