Effect of Diethanolamine on The Extraction Properties of Reverse Micelles with Sodium Bis(2-ethylhexyl) Sulfosuccinate

Abstract

The effect of the addition of diethanolamine (DEA) on the extraction of water and bovine serum albumin (BSA) with the reverse micellar system, sodium bis(2-ethylhexyl)sulfosuccinate (AOT), was investigated using the two phase partition method. The addition of DEA in the aqueous phase affected the extraction of water in the organic reverse micellar phase which increased significantly with a decrease in pH reaching a constant value at pH values lower than 8. This behavior is in good agreement with the extraction behavior of DEA into the organic phase under changing pH. Furthermore, the increase in the water extracted in the organic phase was proportional to the DEA concentration extracted in the organic phase. The increase in water extraction with DEA can be explained by the pH change extraction model taking into consideration DEA dissociation equilibria and the extraction of DEA plus water by the formation of an ion-pair between the DEA ammonium ion and the anionic AOT molecule. The extraction of BSA is enhanced by the addition of DEA at low concentration. With an increase in the quantity of added DEA, the pH range for BSA extraction is extended to a higher pH range. BSA extraction increased with an increase in the DEA concentration over a low concentration range, but decreased with concentration over the high concentration range. The back-extraction of BSA was achieved at approximately 90% by the addition of a high concentration of DEA. The extraction and back-extraction of BSA can be controlled by the concentration of DEA.