Collection of Czechoslovak Chemical Communications - digital archive 

Abstract

Extraction of microamounts of ^{152, 154} Eu from the aqueous solutions of perchloric acid (c(HClO₄) = 0.1-0.5 mol l^-1) was studied in the presence of 3 . 10^-4 -0.3 mol l^-1 of polyethylene glycol PEG 400 (L) by the nitrobenzene solutions of Co(III)-dicarbolide (3.3'-commo-bis(undecahydro-1,2-dicarba-3-cobalta-closo-dodecarborate) (-1), {(π-(3)-1,2-B₉C₂H₁₁)₂Co}^-, henceforth only B^-) of the concentration c(dicarbolide) = 10^-3-10^-1 mol l^-1. Maxima of the Eu distribution ratio dependence on the concentration of polyethylene glycol are explained by the competition reactions between the positively charged europium complexes (EuL³⁺, EuLH_-1²⁺, and EuL₂³⁺, EuL₂H_-2²⁺, or EuL₃³⁺) and protonized polyethylene glycol (HL⁺) in the organic phase. The respective equilibrium extraction constants were determined.