The effect of temperature on the extraction of Co2+, Zn2+, Cd1+ and Hg2+ by salicylaldoxime diluted with carbon tetrachloride was investigated radiometrically. It is found that the extraction constants
at 25°C increase linearly with l/r, where r is the effective coordination radius of the metal cation. The thermodynamic data
calculated from the effect of temperature on the extraction showed that, 1) the extraction process is endothermic, 2) the
dehydration of the metal cation in the extraction process is the predominating factor in determining the enthalpy variation
and 3) the entropy variation is a contribution of the degree of order caused by the hydration of the proton and the highly
ordered chelate structure of the extracted species.