Phase separation rates of aqueous two-phase systems: correlation with system properties

Area of Science:

• Chemical Engineering
• Physical Chemistry
• Separation Science

Background:

• Aqueous two-phase systems (ATPS) are widely used in bioprocessing and chemical separations.
• Understanding phase separation kinetics is critical for optimizing process design and efficiency.
• Previous studies have explored factors influencing ATPS, but a comprehensive kinetic model is needed.

Purpose of the Study:

• To investigate the kinetics of phase separation in aqueous two-phase systems.
• To determine the influence of physical properties (viscosity, density, interfacial tension) on settling velocities.
• To develop and validate a correlation for predicting phase separation rates.

Main Methods:

• Experimental investigation of phase separation in ATPS.
• Measurement of viscosity, density, and interfacial tension for each phase.
• Analysis of settling velocities under different system configurations (top-phase vs. bottom-phase continuous).
• Development and fitting of a correlation based on system parameters.

Main Results:

• Two distinct settling behaviors were observed depending on whether the PEG-rich or phosphate-rich phase was continuous.
• Phase separation rate increased with increasing tie line length (system composition).
• Density and viscosity significantly impact separation rates, especially in the top-phase continuous region.
• A developed correlation successfully described the system's behavior, with different parameters for each continuous phase scenario.

Conclusions:

• Working with a continuous bottom phase, especially the less viscous one, is advantageous for achieving faster phase separation.
• The findings provide crucial data for designing efficient equipment for ATPS applications.
• The developed correlation offers a predictive tool for optimizing ATPS processes based on physical properties and composition.