How does ion exchange separate transuranium elements from mixtures?

Ion exchange is a highly specific technique used to separate and identify transuranium elements from mixtures by exploiting their chemical properties, which are often similar to those of the lanthanoid series.1

The process relies on the principle that certain complex molecules possess a charge capable of attracting, holding, and subsequently exchanging ions of the opposite charge. In practice, this is often achieved using a cation-exchange process, where tripositive ions of the actinoids are separated on columns of resin.1

To enhance selectivity, chemists often employ a method known as differential complex formation. By introducing complexing agents, the strength of the ion-complex varies between elements; those that form more stable complexes adhere less strongly to the resin and move off the column more quickly than others. This allows for the separation of elements that would otherwise be difficult to distinguish due to their striking chemical similarities. This technique has been fundamental in confirming the actinoid concept, which posits that transuranium elements share a series of properties paralleling the lanthanoids.231