Protein fouling and solvent permeation: mechanistic investigations in membrane filtration

• Main Author: Ng, Angie Qi Qi
• Other Authors: Chong Tzyy Haur
• Format: Thesis-Doctor of Philosophy
• Language: English
• Published: Nanyang Technological University 2025
• Subjects: Chemistry; Engineering; High-concentration proteins; Biopharmaceutical; Electrical impedance spectroscopy; Membrane filtration; Solvent permeation
• Online Access: https://hdl.handle.net/10356/182360
• Institution: Nanyang Technological University

Membrane fouling, characterized by the accumulation of materials on the membrane, poses a significant impediment to the widespread utilization of membrane technology. While recognized as a cost-effective and energy efficient alternative to conventional separation processes such as chromatography or distillation, the persistent challenge of fouling hinders the integration of membrane technology in various applications. In view this problem, this research comprises of a comprehensive exploration of the underlying mechanisms contributing to membrane fouling. With numerous approach including experimental techniques, simulations and machine learning, our investigations help not only to understand membrane fouling, but serves to propose strategies for its mitigation, hence improving operational efficiency. This thesis commences with a comprehensive review summarizing effect of various parameters on protein fouling mechanisms in ultrafiltration and microfiltration. The thesis explores gap analysis done from current literature review and lists out four objectives for the studies to be carried out. Studies regarding membrane fouling for high concentrations of BSA are done by in-situ electrical impedance spectroscopy (EIS) to gain mechanistic insights into the fouling process. Other than using experimental methods, machine learning techniques such as the random forest (RF) model and the neural network (NN) model enhances the understanding of the parameters affecting membrane fouling, without the need for any governing equations. Moving on from aqueous system of protein filtration, studies are performed on protein filtration in mixed solvent systems, using both simulations and experimental methods to understand protein fouling mechanisms and solvent interactions. Finally, the EIS is used to observe the permeation mechanisms of organic solvents through membranes, to address the issue of organic solvent nanofiltration (OSN) as well as understand solvent interactions without foulants