Abstract

Conductivity measurements of the organic phase have been done for the extraction of nitric acid by tri-n-butyl
phosphate (TBP) in order to understand the third phase formation mechanism. Experiments were conducted at
different nitric acid (2-14M) and TBP (20 to 90 vol%) concentrations. Experimental results indicated that
conductivity variation of the organic phase can be correlated to the moisture as well as the species present in
the organic phases. A higher value of conductivity was observed for third phase than the other two organic
phases which is observed to be formed at high nitric acid concentration > 10M. The higher conductivity of third
phase is attributed to the movement of nitric acid in the micro-emulsion globules due to the extraction of both
nitric acid and moisture near third phase formation limit. A thermodynamic model has also been developed for
the calculation of speciation of TBP-HNO3 complex.