EXTRACTION OF TRIVALENT RARE-EARTH-METAL NITRATES FROM CONCENTRATED AQUEOUS SALT-SOLUTIONS BY TRIISOAMYL PHOSPHATE

Equations are proposed for describing isotherms of extraction of trivalent rare earth metal nitrates from concentrated aqueous salt solutions by neat triisoamyl phosphate, which allow for variations in the activity coefficients of the components in organic phase over a wide range of its compositions. The phase extraction constants have been determined, with a hypothetical 1 mol kg(-1) aqueous solution of a rare-earth metal nitrate and the state of pure components in organic phase with a mole fraction of 1.0 taken as standard.