BORA, M M and BORTHAKUR, S and Rao, P G and DUTTA , N N
(2008)
Study on the reactive extraction and stripping kinetics of certain �-lactam antibiotics.
Chemical Engineering and Processing, 47.
pp. 1-8.
Abstract
The extraction equilibrium and stripping of certain �-lactam antibiotics such as 7-aminocephalosporanic acid (7-ACA), 7-aminodeacetoxy
cephalosporanic acid (7-ADCA), 6-aminopenicillanic acid (6-APA), cephalosporin-C (CPC) and cephalexin from aqueous solution of phosphate
and carbonate buffers were studied with Aliquat-336 (tricaprylylmethylammonium chloride) dissolved in n-butylacetate as the solvent over an
aqueous phase pH range of 5–10. The extraction equilibrium constant Kp was found to increase with aqueous phase pH, which is attributed to the
increase in ionisation of the �-lactam. A systematic study on kinetic of stripping or re-extraction of 7-ADCA and cephalexin from the extracted
phase was carried out using an aqueous solution of citrate buffer at different pH values and was found to be pH dependent which is also attributable
to ionisation behaviour of the �-lactams. Such observation is considered important, as re-extraction at an appropriate pH value is possible. The rate
of stripping was found to be weakly dependent on Cl− concentration of the aqueous phase and the same was analysed with a simple mass transfer
model based on film theory.
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