Modelling and optimisation of preparative chromatographic purification of europium.

A model commonly used to describe the separation of biomolecules was used to simulate the harsh environment when eluting neodymium, samarium, europium and gadolinium with a hot acid. After calibration, the model was used to optimise the preparative separation of europium, as this is the most valuable of the four elements. A kinetic dispersive model with a Langmuir mobile phase modulator isotherm was used to describe the process. The equilibration constant, the stoichiometric coefficient and the column capacity for the components were calibrated. The model fitted the experimental observations well. Optimisation was achieved using a differential evolution method. As the two objective functions used in optimising the process, productivity and yield, are competing objectives, the result was not a single set point but a Pareto front.