Beyond Hydrophilicity: Mapping Multidimensional Interplay Governing Membrane Fouling in Wastewater Reclamation

Area of Science:

• Water Treatment Technologies
• Materials Science
• Surface Chemistry

Background:

• Membrane fouling is a critical obstacle in water purification, leading to reduced efficiency and increased operational costs.
• Existing research on antifouling membrane properties lacks standardization, resulting in conflicting findings on critical membrane characteristics.
• A comprehensive understanding of how multiple membrane properties interact to influence fouling is essential for developing advanced antifouling solutions.

Purpose of the Study:

• To systematically investigate the influence of controlled membrane properties (hydrophilicity, pore size, roughness, zeta potential) on membrane fouling.
• To establish a stage-resolved fouling assessment framework to differentiate impacts on initial fouling, permeability stability, and cleaning efficiency.
• To develop a multivariate optimization strategy for designing next-generation antifouling membranes, moving beyond single-property focus.

Main Methods:

• Fabrication of 97 microfiltration/ultrafiltration membranes with precisely tuned hydrophilicity, pore size, surface roughness, and zeta potential using blending, grafting, and nanocasting.
• Implementation of a stage-resolved membrane fouling assessment to quantify fouling rates, permeability decline, and cleaning effectiveness.
• Statistical analysis to determine correlations between membrane properties and fouling behaviors across different stages.

Main Results:

• Water permeability, influenced by pore size and roughness, was found to accelerate initial fouling.
• Hydrophilicity mitigated initial fouling but negatively impacted cleaning efficiency due to increased surface energy and zeta potential, enhancing foulant adsorption.
• Surface roughness indirectly worsened cleaning by increasing permeability, while larger pores improved cleaning despite reduced normalized permeability.

Conclusions:

• Membrane fouling is a complex interplay of properties, not solely dependent on hydrophilicity.
• Hydrophilicity exhibits stage-dependent effects, beneficial for initial fouling but detrimental for cleaning.
• A multivariate approach considering pore size, roughness, and zeta potential is crucial for designing effective antifouling membranes.