Kinetics and Mechanism on Removal of Aluminum from Phosphoric Medium by Solvent Extraction using Lewis Cells

The kinetics of the forward extraction of aluminum ion had been investigated using Lewis cells. The influences of the aluminum concentration, temperature, and interfacial area were studied. The extracted species was demonstrated to be AlL3·(HL)3 by stoichiometry studies and the mechanism of the extraction was explained. The results indicated that the extraction process was under mixed-control by the extraction reaction at the interface and the diffusion of the resultant in the organic phase. The activation energy was calculated to be 23.26 kJ/mol and was concordant with the mixed-control regime. Further analysis suggested that the reaction orders with respect to aluminum and extractant were 1 and 2, respectively, and the extraction rate constant was 10−4.526 L2·g−2·s−1. The total rate of the extraction reaction for AlL3·(HL)3 was given based on kinetic steps.