Extraction equilibria of penicillin G in four different types of organic solvent systems

Equilibrium experiments for physical and reactive extraction of penicillin G were carried out with varying pH, overall penicillin concentration and overall amine concentration in liquid–liquid extraction systems with four different types of organic solvents, i.e. amphiprotic solvent, hydrogen-bond donor solvent, hydrogen-bond acceptor solvent, and nonpolar organic solvent. Also, physical and reactive extraction equilibrium models were suggested to find the appropriate equilibrium model for each organic solvent type. By comparison between the experimental data and the calculated results from the extraction equilibrium models, the most probable physical and reactive extraction equilibrium models were determined. The physical extraction equilibrium models for all types of the organic solvents except for nonpolar organic solvent reflected solute–solvent interaction, while the reactive extraction equilibrium models were dependent on the organic solvent type.