Extraction of strontium and cesium by dicarbollides, crown ethers and functionalized calixarenes

The two main classes of extractants used for the extraction of cesium and strontium are dicarbollides and crown ethers. Dicarbollides were used on a large scale for the extraction of these two elements from high-activity waste. The basic dicarbollides present drawbacks since they need to be diluted in polar solvent such as nitrobenzene and their efficiency strongly decreases as the acidity of liquid waste increases. Crown ethers enable cesium and strontium to be extracted if the concentration of sodium or the acidity of solutions are not too high. Recently, calixarenes blocked in the 1,3-alternate conformation were used for the selective extraction of cesium, even from high-salt waste matrices.