Thermodynamics of the extraction and solvation of molecules

In the context of the problem of the effect of solvents on extraction constants K, an incremental analysis was performed of the Gibbs energies of transfer of various extraction complexes of UO2(NO3)(2), UO2Cl2, Co(NO3)(2), CoCl2, Th(NO3)(4), and HNO3 with RnXO extracting agents (tri-n-butyl phosphate, di-n-octyl sulfoxide, and triisoamylphosphine oxide) from CCl4 into n-C7H16, C6H6, and CHCl3. It was shown that the energy of transfer is proportional to the number of carbon atoms in the extraction complex. In another approach, with extraction complexes with 2-n-nonylpyridine-N-oxide taken into consideration, the energy of transfer was found to be proportional to the number of extracting agent molecules in the extraction complex. It was noted that the separation of the contribution of the XO group from the Gibbs energy of solvation reduces the description of the effect of the medium on the extraction constant to consideration of the XO desolvation in the extraction process. A method for reducing the extraction constant to a single solvent is proposed. Linear correlations between the logK values for two extracting agents for the same solvent (S = const) and different salts were found.