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Solvent extraction of lanthanum(III), europium(III) and lutetium(III) by bis(4-acyl-5-hydroxypyrazoles) derivatives

“…For log D < 0, the value of the slope is obviously higher. Taking into account the study of Khol'kin, that suggests the extraction of a binuclear species in this case, several extraction processes were tested corresponding to the extraction of La 2 (L-10-L) 3 , La 2 (L-10-L) 2 (L-10-LH) 2 or La 2 (L-10-L)(L-10-LH) 4 . The corresponding A xy functions were calculated and plotted versus pH (Figs.…”

“…The corresponding A xy functions were calculated and plotted versus pH (Figs. [3][4][5]. Compared with the theoretical value of 6.0, A 25 versus pH shows a slope close to 7 and the corresponding process must be rejected.…”

“…They cannot be treated by the slope analysis method. Therefore, to determine the major extracted complex, several assumptions were made and the A xy functions were calculated accordingly: the species Eu(L-10-L)(L-10-LH), Eu(L-10-LH) 3 , Eu 2 (L-10-L) 3 , Eu 2 (L-10-L) 2 (L-10-LH) 2 , Eu 2 (L-10-L)(L-10-LH) 4 , Eu 3 (L-10-L) 4 (L-10-LH) , Eu 3 (L-10-L) 3 (L-10-LH) 3 and Eu 3 (L-10-L) 2 (L-10-LH) 5 were considered. Two assumptions only are acceptable: Eu(L-10-L)(L-10-LH), since A 12 versus pH has a 3.35 slope for a theoretical slope of 3 (Fig.…”

“…Moreover, since currently thousand operations of extraction are necessary to isolate each element of the lanthanides series from the natural mixture, the improvement of the intra-group separation of lanthanides is also a relevant objective [2][3][4][5][6][7][8]. It is within this scope that some extractants, able to extract totally or separately the trivalent elements 4f, have been tested.…”

Separation of Micro-Macrocomponent Systems: 149Pm – Nd, 161Tb-Gd, 166Ho-Dy and 177Lu-Yb by Extraction Chromatography

“…The organic phosphorus compounds that are most frequently used as stationary phases in the lanthanides separation are HDEHP, TBP, Diphenyl(dialkylcarbamoylmethyl) phosphine oxides, etc., however the best separation factors (> 2.5) between adjacent rare earths are obtained with HDEHP as stationary phase fixed in Kiselguhr, Corvic (poly(vinyl chloride-vinyl acetate)copolymer), Kel-F (polychlorotrifluoroethane), Zorbax-SIL,(porous silica), PMS (polymethysilane) or Celite® (diatomaceous earth) and as mobile phases solutions containing acids (HNO 3 , HCl, HClO 4 ) [1,5,13,[19][20][21][22]. In general, the separations of all the rare earth elements at a tracer level on HDEHP-solid support are satisfactory by gradient elution; however some difficulties have been reported in the separation of consecutive lanthanides such as: Nd-Pm, Dy-Ho and Yb-Lu depending on the type of support used and the column length [20][21][22]. Ketring performed a very neat separation of Nd/Pm, Dy/Ho and Yb/Lu using the Ln % by weight) supported on an inert polymeric absorbent (60 % by weight), nervertheless the precise conditions of these separations have not been reported [5].…”