THE MECHANISM OF EXTRACTION OF Zr(NO_3)_4 WITH DMHMP

Zirconium nitrate can be extracted by Di (1-) methylheptyl methyl phosphonate (DMHMP), a neutral organophosphorus extractant, in nitric acid solutions. Three kinds of extraction complexes are found in the organic phase: Zr (NO3)4·2DMHMP, Zr(NO3)4 ·2DMHMP·2HNO3 and Zr (NO3)4·2DMHMP·3HNO3. Using the log-function extrapolation combined with the optimum computing method, the equilibrium constants of the extracting reactions are determined: K020 = 1.09×103, K022 = 6.25×103, K023= 1.50×104. Stability constants of the complex ions Zr (NO3)*4 f-i are evaluated successively:β1=2.13,