LIQUID MEMBRANE TRANSPORT OF CEPHALOSPORIN ANTIBIOTICS: EFFECT OF SOLUTE CHEMICAL NATURE ON CARRIER SPECIFICITY

Cephalosporin antibiotics were transported from a dilute aqueous solution (feed phase) through a bulk liquid membrane containing Aliquat-336 as an anion exchange carrier in n-butyl acetate as the solvent to another aqueous solution (receiving phase) of lower pH. Under appreciable pH gradient of the feed and receiving phases, facilitated uphill transport could be obtained. Under the optimal pH condition, the intial solute flux across the bulk liquid membrane could be correlated well with the hydrophobicity of the solutes. A linear correlation exists between the initial solute flux and hydrophobicity, indicating that the solute of higher hydrophobic nature are transported at a higher rate in the bulk liquid membrane involving the specific carrier. The correlation appears to be derived from a linear dependenc of solute hydrophobicity on equilibrium constant of the reactive extraction system being exploited in the bulk liquid membrane.