Solvent extraction kinetics of Ag(I) with methyl ketonic p-tert-octylcalix[4]arene in the modified Lewis cell technique

Abstract

The solvent extraction kinetics of Ag(I) with methyl ketonic p-tert-octylcalix[4]arene as a hydrophobic extractant have been studied using a modified Lewis cell system. The effects of different parameters affecting the extraction efficiency such as the stirring speed, the temperature, and the Ag concentration were all investigated. The initial Ag(I) extraction efficiency was found to rapidly increase on increasing the stirring speed in the Lewis cell to 170 rpm after which a plateau in the efficiency occurred. That is, Ag(I) extraction was influenced by diffusion up to 170 rpm, with the diffusion contribution being minimized over 170 rpm. Thus, for the cell configuration employed, 170 rpm represents the crossover point between diffusion and chemical reaction control at the liquid–liquid interface. The results are thus in accord with the efficiency of Ag(I) extraction by methyl ketonic p-tert-octylcalix[4]arene being governed by a mixed regime (diffusion and chemical reaction) for the liquid–liquid extraction system investigated. Furthermore, study of the thermodynamic parameters indicated that the adsorption process was spontaneous and exothermic in nature. Overall, using a modified Lewis cell system it has been possible to identify the factors influencing the efficiency of extraction under different conditions for the above liquid–liquid extraction system.