The extraction of zinc from chloride solutions using dibutyl butylphosphonate (DBBP) in Exxsol D100

The reaction of zinc chloride with dibutyl butylphosphonate in Exxsol D100 has been studied. The distribution coefficient of zinc is independent of eq uilibrium pH, thus, suggesting a solvation extraction reaction. Experimenta l data indicate that this reaction is exothermic (Delta H degrees= -28.4 kJ /mol). Slope analysis for the system at various DBBP concentrations reveals the formation in the loaded organic phases of species which probable 1:2 ( Zn:DBBP) stoichiometries. This was confirmed by results obtained at full DB BP Zn-loading capacity. The stoichiometric factor of water in the extractio n reaction is found to be 4, whereas experimental data also indicated that two chloride ions are involved for each metal extracted, resulting in a ZnC l2. 2L . 4H(2)O stoichiometry (L represents the extractant).