Mathematical modeling of polymer-induced flocculation by charge neutralization

Area of Science:

• Colloid and Surface Science
• Chemical Engineering
• Materials Science

Background:

• Flocculation of colloidal suspensions is crucial in many industrial processes.
• Existing models often simplify interactions between particles, especially in the presence of polymers.
• Accurate modeling requires incorporating electrostatic and van der Waals forces, alongside polymer effects.

Purpose of the Study:

• To develop and validate a comprehensive mathematical model for colloidal flocculation.
• To investigate flocculation mechanisms in the presence of salts and polymers.
• To accurately predict floc size distribution and kinetics.

Main Methods:

• Incorporation of classical DLVO theory into a discrete population balance model for salt-induced flocculation.
• Modification of DLVO theory to include adsorbed polymer layers for polymer-induced flocculation via charge neutralization.
• Dynamic scaling of experimental data to determine the fractal dimension of aggregates.
• Validation against experimental data for hematite suspensions with KCl and polyacrylic acid.

Main Results:

• The model accurately predicts flocculation kinetics and mean aggregate size evolution.
• Close agreement between model predictions and experimental results for hematite suspensions.
• Demonstrated ability to describe flocculation driven by simple charge neutralization with polymers.
• Sensitivity analysis highlights the impact of surface potential and fractal dimension on flocculation.

Conclusions:

• The developed mathematical model provides a robust framework for understanding and predicting colloidal flocculation.
• The model's ability to incorporate salt and polymer effects enhances its applicability to diverse systems.
• Accurate parameter estimation, including Hamaker constant and fractal dimension, is key to realistic simulations.