Patent Number: 050826026
Section: summary

BACKGROUND OF THE INVENTION This invention relates to a process for regenerating a spent extraction solvent containing anions and cations used in e.g. nuclear power plants by separating and removing these ions from the extraction solvent and an apparatus used therefor. This invention is particularly suitable for separating and removing ions contained in an organic solvent for reprocessing in large amounts. Heretofore, an extraction solvent was regenerated by cleaning the extraction solvent with an alkaline cleaning agent such as sodium carbonate, triethanolamine, etc. by using a liquid-liquid extraction apparatus such as a mixer-settler, etc. (e.g. U.S. Pat. No. 4,059,671). But such a cleaning agent has problems in that it easily precipitates metal ions contained in the deteriorated solvent, the resulting precipitate is collected at an interface of the solvent and the cleaning agent thus interfering with the removal action of captured impurities and making the separation of the solvent and the cleaning agent worse. SUMMARY OF THE INVENTION It is an object of this invention to provide a process and an apparatus for regenerating a spent reprocessing extraction solvent without causing interference with cleaning operation accompanied by production of a precipitate in an alkaline circumstance. This invention provides a process for regenerating a spent organic solvent containing anions and cations by separating and removing these ions from the organic solvent which comprises: forming one or more alkaline aqueous solution phases for capturing anions via a first hydrophobic porous membrane and forming one or more acidic aqueous solution phases for capturing cations in the organic solvent containing cations via a second hydrophobic porous membrane and anions, capturing the cations by the acidic aqueous solution phases and the anions by the alkaline aqueous solution phases simultaneously through the first and second hydrophobic porous membranes, and collecting the acidic aqueous solution phases for removing the cations therefrom and collecting the alkaline aqueous solution phases for removing the anions therefrom. This invention also provides an apparatus used for such a process.