## Abstract

In this paper, the adsorption of europium on a natural bentonite was studied and modelled using the component additivity (CA) approach of the surface complexation theory. The experimental results were modelled considering the formation of monodentate species at the edge sites of the bentonite and two exchange reactions at the interlayer sites. The CA approach was compared to the most common approach of the surface complexation theory (the general composite (GC)), by modelling in a predictive way, experimental results obtained from the literature. This comparison allowed us to conclude that (i) the CA approach successfully described the behaviour of europium on montmorillonite on a restricted pH range and on a large range of concentrations, (ii) five surface stoechiometries for the GC approach were necessary to model the europium sorption versus four surface stoechiometries for the CA approach, (iii) some improvement of the CA approach are necessary concerning the consideration of impurities.

## Abstract

Complex formation of humic acids (HA)_{n} with La^{3+} and Eu^{3+} was studied. Commercial (HA)_{n} was purified and characterized. The stability constants were determined at several pH values and 0.2 M NaClO_{4} ionic strength by the Shubert’s method of radiochemical ionic exchange. The slopes of the lines

_{n}]. The values of log

_{n}].

## Abstract

Application study for the evaluation of sorption characteristics of sawdust as an economical sorbent material used for decontamination
of radioisotopes cesium and europium from aqueous solution has been carried out in the present work. In this respect, sawdust
(untreated and treated by HNO_{3}) has been prepared from the commercial processing of wood for furniture production. Pore properties of the activated carbon
such as BET surface area, pore volume, pore size distribution, and pore diameter were characterized by N_{2} adsorption and DFT software. Radiotracer method onto sawdust from aqueous solutions was studied in a batch technique with
respect to pH, contact time, temperature. The kinetics of adsorption of Eu^{3+} and Cs^{+} have been discussed using five kinetic models namely, pseudo-first-order model, pseudo-second-order model, Elovich equation,
intraparticle diffusion model, and modified Freundlich equation that have been tested in order to analysis the experimental
data. Kinetic parameters and correlation coefficients were determined. It was shown that the second-order kinetic equation
could describe the sorption kinetics for two metal ions. The metal uptake process was found to be controlled by intraparticle
diffusion. Thermodynamic parameters, such as Δ*H*, Δ*G* and Δ*S*, have been calculated by using the thermodynamic equilibrium coefficient obtained at different temperatures. The obtained
results indicated that endothermic nature of sorption process for both ^{152+154}Eu and ^{134}Cs onto sawdust.

## Abstract

Extraction of microamounts of europium and americium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H^{+}B^{−}) in the presence of 1,2-(diphenylphosphino)ethane dioxide (DPPEtDO, L) has been investigated. The equilibrium data have been
explained assuming that the species HL^{+}, HL_{2}
^{+}, ML_{2}
^{3+} and ML_{4}
^{3+} (M^{3+} = Eu^{3+}, Am^{3+}) are extracted into the organic phase. The values of extraction and stability constants of the species in nitrobenzene saturated
with water have been determined. It was found that the stability constants of the corresponding complexes EuL_{n}
^{3+} and AmL_{n}
^{3+}, where *n* = 2, 4 and L is DPPEtDO, in water-saturated nitrobenzene are comparable.

## Abstract

Solvent extraction of microamounts of europium and cerium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H^{+}B^{−}) in the presence of polyethylene glycol PEG 600 (L) has been investigated. The equilibrium data have been explained assuming
that the complexes HL^{+}, H_{2}L^{2+} and ML^{3+} (M^{3+} = Eu^{3+}, Ce^{3+}; L = PEG 600) are extracted into the organic phase. The values of extraction and stability constants of the species in nitrobenzene
saturated with water have been determined. It was found that the stability constants of the EuL^{3+} and CeL^{3+} cationic complex species (L = PEG 600) in water-saturated nitrobenzene are the same.

## Abstract

Solvent extraction of microamounts of europium and cerium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H^{+}B^{−}) in the presence of polyethylene glycol PEG 1000 (L) has been investigated. The equilibrium data have been explained assuming
that the species H_{2}L^{2+} and ML^{3+} (M^{3+} = Eu^{3+}, Ce^{3+}) are extracted into the organic phase. The values of extraction and stability constants of the complexes in nitrobenzene
saturated with water have been determined. It was found that the stability constants of the cationic complex species EuL^{3+} and CeL^{3+} in water-saturated nitrobenzene are practically the same.

## Abstract

Extraction of microamounts of europium and americium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H^{+}B^{−}) in the presence of tetraisopropyl methylene diphosphonate [T(iPr)MDP, L] has been investigated. The equilibrium data have
been explained assuming that the complexes HL^{+}, HL_{2}
^{+}, ML_{2}
^{3+}, ML_{3}
^{3+} and ML_{4}
^{3+} (M^{3+} = Eu^{3+}, Am^{3+}) are extracted into the organic phase. The values of extraction and stability constants of the species in nitrobenzene saturated
with water have been determined. It was found that the stability constants of the corresponding complexes EuL_{n}
^{3+} and AmL_{n}
^{3+}, where *n* = 2, 3, 4 and L is T(iPr)MDP, in water-saturated nitrobenzene are comparable.

## Abstract

Extraction of microamounts of europium and americium by a phenyltrifluoromethyl sulfone (FS 13) solution of hydrogen dicarbollylcobaltate
(H^{+}B^{−}) in the presence of octyl-phenyl-*N,N*-diisobutylcarbamoylmethyl phosphine oxide (“classical” CMPO, L) has been investigated. The equilibrium data have been explained
assuming that the complexes

^{3+}= Eu

^{3+}, Am

^{3+}) are extracted into the organic phase. The values of extraction and stability constants of the cationic complex species in FS 13 saturated with water have been determined. It was found that the stability constants of the corresponding complexes

*n*= 2, 3, 4 and L is “classical” CMPO, in water-saturated FS 13 are comparable.

## Abstract

Extraction of microamounts of europium and americium by a phenyltrifluoromethyl sulfone (FS 13) solution of hydrogen dicarbollylcobaltate
(H^{+}B^{−}) in the presence of *N*,*N*′-diethyl-*N*,*N*′-diphenyl-2,6-dipicolinamide (EtPhDPA, L) has been investigated. The equilibrium data have been explained assuming that the
species HL^{+}, HL_{2}
^{+}, ML_{2}
^{3+}, ML_{3}
^{3+} and ML_{4}
^{3+} (M^{3+} = Eu^{3+}, Am^{3+}) are extracted into the organic phase. The values of extraction and stability constants of the cationic complexes in FS 13
saturated with water have been determined. It was found that the stability constants of the corresponding complexes EuL_{n}
^{3+} and AmL_{n}
^{3+}, where *n* = 2, 3, 4 and L is EtPhDPA, in water-saturated FS 13 are comparable.

## Abstract

Extraction of microamounts of europium and americium by a phenyltrifluoromethyl sulfone (FS 13) solution of hydrogen dicarbollylcobaltate
(H^{+}B^{−}) in the presence of *N,N,N′,N′*-tetraethyl-2,6-dipicolinamide (TEtDPA, L) has been investigated. The equilibrium data have been explained assuming that the
species HL^{+},

^{3+}= Eu

^{3+}, Am

^{3+}) are extracted into the organic phase. The values of extraction and stability constants of the cationic complex species in FS 13 saturated with water have been determined. It was found that the stability constants of the corresponding complexes

*n*= 2, 3 and L is TEtDPA, in the mentioned FS 13 medium are comparable.