Development of high performance electrochemical solvent extraction method

A high performance electrochemical solvent extraction method was developed based on the quantitative transfer of ions from an aqueous, W, to an organic solution, O. It was realized by applying a potential difference, E, between W and O. The electrolytic cell used was similar to that reported for the rapid and coulometric ion transfer at the W/O solution interface. The cell was composed of a porous Teflon tube (with a 1.0mm inner diameter and 50cm length), a silver wire (0.8mm diameter) inserted into the tube, a platinum wire placed outside the tube, O where the tube was immersed and a reference electrode, RE, in the O. When W containing ions was forced to flow through the narrow gap between the tube and silver wire, and E was applied by using the silver wire and RE, a very rapid quantitative ion transfer was attained. For example, when 1,2-dichloroethane containing bis(diphenylphosphinyl)ethane, BDPPE, was used as O, more than 99% of the UO22+ in W was extracted during the residence (e.g., 40 s) of W in the cell. The fundamental feature of the extraction system was investigated, taking into account the application of the system to the extraction of actinide, lanthanide, Sr or Cs ions. In order to facilitate the ion transfer, BDPPE, bis(diphenylphosphinyl)methane or dibenzo-18-crown-6 was added to O. The use of a column electrode system connected before the extraction system was examined in order to adjust the oxidation state of the element to that desired.