The Truex process uses a neutral organophosphorus bidendate extractant: n- octyl-phenyl-di-isobutyl-carbamoylmethyl-phosphine-oxide (CMPO). CMPO displays both high and low affinities for actinides(III) and lanthanides(III) at high and low nitric acid concentrations respectively. It is, then, relatively easy to obtain an An-Ln (actinide-lanthanide) mixture by the succession of extracting and stripping steps. The separation of An from Ln can then be done by selective complexing agents like DTPA (diethylenetriamino — pentaacetic acid) which seems to make more stable complexes with Ans than with Lns.

The Diamex process

The Diamex process uses malonamide extractants, the only one practically tested being di-methyl-dibutyltetradecylmalonamide (DMDBTDMA) which has very attractive properties as actinide extractant, with comparatively small technological wastes. The Diamex process has to be followed by an additional step to separate Ans from Lns.