Extraction of Phenol Using Trialkylphosphine Oxides (Cyanex 923) in Kerosene

Abstract
A group of extractants based on phosphine oxides have been reported as an alternative to conventional polar solvents for phenol liquid-liquid extraction. Among phosphoryl extractants, Cyanex 923 (a mixture of four trialkylphosphine oxides, alkyl = normal, C6, C8) has proved to combine high extraction efficiency and low water solubility (1, 2), obviating the necessity of removing the solvent from the aqueous raffinate, a need asso- ciated with the use of methyl isobutyl ketone and isopropyl ether, the solvents most widely employed for this application (3, 4).