Abstract
The formation of precipitates of dibutyldithiophosphate–diisooctyldithiophosphate of nickel(II) and iron(II) are investigated by the potentiometric method. Solubility products for Ni-containing and Fe-containing precipitates of ammonium dibutyldithiophosphate and diisooctyldithiophosphate are calculated. It is shown that an increase in temperature differently affects the deposition process, notably, solubility for complexes of Fe(II) ions decreases overall the ionic strength range (I = 0÷0,75), while it decreases for Ni(II) ions only at low values of this characteristic (I = 0÷0,25), and the precipitate dissolves at a high ionic strength. Thermodynamic characteristics of the precipitate formation of dibutyldithiophosphate–diisoocryldithiophosphate of iron(II) and nickel(II), notably, the variation in the Gibbs energy, enthalpy, and entropy are calculated based on the data on the solubility product. It is shown that the solvation of components exerts the determining effect on the mentioned process, and it is largest in range I = 0,50÷0,75 in the case of iron(II) ions and at I = 0÷÷0,25 in the case of nickel (II) ions.