Towards the Recovery of l-Aspartic Acid from Aqueous Solution: Exploiting pH-Dependent Solubility via Carbon Dioxide Addition

Abstract

While the use of gas antisolvents has been described widely in the literature for precipitation of solutes from organic solutions, fewer studies describe their use on aqueous solutions. The primary objective of this initial investigation was to explore the use of carbon dioxide gas to exploit the pH-dependent solubility of l-aspartic acid for its separation from aqueous solution. Experimental data are presented and discussed for the aqueous solubilities of l-aspartic acid at 25°C over the pH range 2 to 6. A minimum solubility of 0.039 M was found near the isoelectric point at pH=2.79; solubilities increased moving away from the isoelectric pH to higher and lower pH values. Preliminary data that demonstrate using carbon dioxide as an acidulent to precipitate l-aspartic acid from aqueous solution are also presented. These preliminary data are used to draw inferences regarding the characteristics of compounds that might exploit this separation technique.

Keywords:

• Amino Acids
• Antisolvent
• Precipitation

Acknowledgment

The authors thank Clemson University for financial support for this work.