Kinetics of solvent extraction of zirconium(IV) from chloride medium by D2EHPA in kerosene using the single drop technique

The kinetics of the title process have been investigated by the single drop technique for 1-day ageing of the aqueous phase. The flux equations have been derived for three aqueous acidities of 0.10, 1.00 and 5.00 M HCl, respectively, as: J (kmol m−2 s−1)=10−5.37 (1+0.00036 [Zr(IV)]−1)−1 [H+] [H2A2](o) (1+0.69 [Cl−]), J (kmol m−2 s−1)=10−5.77 (1+0.0056 [Zr(IV)]−1)−1 [H2A2](o) [Cl−] and J (kmol m−2 s−1)=10−6.62 (1+0.0056 [Zr(IV)]−1)−1 [H+] [H2A2](o) [Cl−]. The values of Ea (kJ mol−1), ΔH± (kJ mol−1) and ΔS± (J K−1 mol−1) for each of the above conditions have been estimated to be 8.6, 7.7 and −425; 19.2, 16.8 and −369; and 26.4, 23.4 and −330, respectively, in the higher temperature region (h.t.r) of investigation; and 89.6, 76.6 and −192; 69.5, 71.9 and −187; and 59.9, 60.1 and −205, respectively, in the lower temperature region (l.t.r). On the basis of these rate data, the mechanisms of extraction in different conditions have been suggested.