Abstract
The effect of diluents on extraction of cobalt from weakly acidic solutions with di-(2-ethylhexyl) phosphoric acid (D2EHPA) in various low polar diluents such as n-heptane, cyclohexane, m-xylene, toluene, o-xylene, benzene and n-heptane-benzene mixtures was studied on the basis of the regular solution theory.
As the result of the study, it was found that the dependence of the apparent thermodynamic extraction constants (logK°d,1, with an infinite dilution as the reference state, or the extraction constants (logKd,1)) and the distribution coefficients (logD) on the solubility parameters (δd) of individual diluents could be expressed by second order equations.
In the case of mixed diluents of n-heptane-benzene, it was also found that the dependence of the apparent thermodynamic extraction constants (logK°d,2, with an infinite dilution as the reference state, or the extraction constants (logKd,2)) and the distribution coefficients on the diluent composition could be semi-empirically expressed by first order equations.
