The underlying mechanism in gel formation and its mathematical simulation during anionic polyacrylamide solution...

Area of Science:

• Environmental Science
• Chemical Engineering
• Materials Science

Background:

• Membrane fouling, particularly gel layer formation, is a significant challenge in ultrafiltration processes, reducing efficiency and lifespan.
• Understanding the mechanisms of gel layer formation is crucial for developing effective fouling mitigation strategies.
• Anionic polyacrylamide serves as a relevant model foulant for studying gelation phenomena in aqueous systems.

Purpose of the Study:

• To investigate the mechanisms of membrane fouling caused by gel layer formation during ultrafiltration.
• To establish and systematically assess a gel formation model for ultrafiltration processes.
• To evaluate the performance of the model using different ultrafiltration membranes.

Main Methods:

• Utilized a dead-end ultrafiltration cup setup for continuous operation.
• Employed anionic polyacrylamide as a model foulant to induce gel formation.
• Investigated gel formation on polyvinylidene fluoride (PVDF) membranes and TiO2/Al2O3-PVDF composite membranes.
• Developed and validated a mathematical model for gel layer formation.

Main Results:

• The gel formation process exhibited a characteristic "slow-rapid-slow" flux decay pattern.
• The established mathematical model demonstrated high accuracy, with R² values exceeding 0.90 for both membrane types.
• The model effectively captured the dynamic changes in flux during the fouling process.

Conclusions:

• The proposed gel layer formation mechanism and mathematical model are feasible and provide a robust framework for understanding ultrafiltration fouling.
• The findings contribute to the development of strategies for mitigating gel fouling in ultrafiltration systems.
• The study highlights the importance of characterizing foulant behavior for optimizing membrane process performance.