The effect of ionic strength on the extraction of thorium(IV) from perchlorate solution by didodecylphosphoric acid (HDDPA)

Extraction of Th(IV) ion from perchlorate media at high ionic strength (I = 1.00, 3.00 and 5.00 M) using didodecylphosphoric acid was studied. The effect of HDDPA concentration, ionic strength, pcH and temperature on the extraction processes have been studied in perchlorate media. From the equation of the extraction process, (Kex) extraction constant can be calculated from the distribution ratio Dc values at different temperatures. Enthalpy, free energy and entropy changes were determined. The composition of the complex formed were established to correspond to [Th(X)4(HR2)Y]org, where X=ClO4−, Y = 1 or 2, HR2 is HDDPA molecule and R2 is deprotonated HDDPA molecule.