Abstract
The extraction of cerium(III) from aqueous solutions containing potassium thiocyanate by tributyl phosphate (TBP) or trioctyl phosphine oxide (TOPO) in kerosene or benzene has been investigated under different conditions. IR spectral studies have been carried out on the organic extracts. The distribution coefficient of cerium(III) for TBP increases monotonously with increasing aqueous thiocyanate concentration. As a result, it is found that the equilibrium equation for the extraction by TBP can be expressed as follows: Ce 3+(aq) + 3NCS −1(aq) ⇌ Ce(NCS) 3(aq), Ce(NCS) 3(aq) + 4TBP(org) ⇌ Ce(NCS) 3·4TBP(org). A similar result was also obtained for the extraction by TOPO, although the extraction efficiency of TOPO is higher than that of TBP. The IR results indicate that the thiocyanate ion coordinates to the cerium ion through the N atom and that the cerium ion combines with the phosphoryl O atom of the extractants.
Published Version
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