REACTIVE EXTRACTION OF 6-AMINOPENICILLANIC ACID WITH ALIQUAT-336 - EQUILIBRIUM AND KINETICS

The reactive extraction of 6-aminopenicillanic acid (6-APA) from aqueo us buffer solution has been studied using a liquid anion exchanger, tr icaprylylmethyl ammonium chloride (Aliquat-336) in n-butyl acetate as the solvent. The extraction equilibrium constant and partition coeffic ient increase with increase in pH up to a limiting value of pH, beyond which extraction decreases due to coextraction of OH- and buffer anio ns and hydrolytic decomposition of 6-APA. The experimental data could be predicted from an equilibrium model which takes into account the id eal behaviour of the two liquid phases. The coextraction of the buffer anion under low pH conditions was found to be negligible. The extract ion rate measured in a stirred cell of constant interfacial area appea rs to be dependent on the interfacial mass transfer of the reactive sp ecies as well as on the interfacial reaction through its dependence on the concentration of 6-APA in the aqueous and organic phases, respect ively.