STUDY OF ISOTACHOPHORETIC SEPARATION BEHAVIOR OF METAL-CATIONS BY MEANS OF PARTICLE-INDUCED X-RAY-EMISSION .5. FRACTIONATION OF PLATINUM-GROUP ELEMENTS FROM A MODEL SOLUTION OF NUCLEAR-FUEL WASTE BY MEANS OF CONTINUOUS FREE-FLOW ISOTACHOPHORESIS

The fractionation of platinum group elements from a model solution of a high-level liquid waste was investigated using a continuous free-flo w isotachophoretic analyser. The leading electrolytes used contained a lpha-hydroxyisobutyric acid (HIB) and tartaric acid as the complex-for ming agent, where 20 mM NH4+ was the leading ion and acetic acid was t he pH buffer (pH 4.8). The fractions were analysed off-line by means o f particle-induced X-ray emission (PIXE). It was found that Fe and pla tinum group elements split into two zones of cations and non-ions when HIB was used, but all of them was recovered as non-ions when tartaric acid was used. In both electrolyte systems, 100% recovery as cations was obtained for Cs+, Rb+, Ba2+, Sr2+, Na+, Cr2+, Mn2+, Ni2+, La3+, Ce 3+, Pr3+, Nd3+, Sm3+, Eu3+, Gd3+ and Y3+. It was concluded that free-f low isotachophoresis would be very useful for fractionating platinum g roup elements from other metal ions.