Ciprofloxacin derived task specific ionic liquid as highly selective extractant of thorium versus uranium

Abstract

A selective extraction system of thorium(IV), formed with a TSIL derived from ciprofloxacin and [BMIM][NTf2] as a co-solvent, is described. Under acidic conditions, this IL solution was able to complex selectively this metal versus the rest of the other metals of the periodic table. The synthesis of the TSIL was detailed using known procedures and it was isolated in good overall yield. The extraction coefficients (K) were determined by a microextractive survey at 25 °C. Spectroscopic analyses of thorium(IV) and uranium(IV) complexes were performed in order to demonstrate the strength of the metal-TSIL interaction, which was supported by DFT-based computational optimization of the formation of the experimentally observed complexes. Kinetic analysis, loading tests for the extractive protocol, as well as the optimization for recycling were also performed to justify the conditions of a laboratory prototype for this selective extraction of thorium(IV) salts.