3D Impedimetric Microfluidic Membrane-Mimic Cassette (IM3) with Interdigitated Electrodes for Fouling Analysis at...

Area of Science:

• Membrane science and technology
• Microfluidics
• Electrochemistry

Background:

• Membrane fouling is a significant challenge in water treatment, impacting efficiency and lifespan.
• Understanding fouling mechanisms at the membrane interface is crucial but difficult.
• Existing methods often lack real-time, mechanistic insights.

Purpose of the Study:

• To develop and validate a novel 3D impedimetric microfluidic membrane-mimic (IM3) cassette for real-time membrane fouling investigation.
• To elucidate the mechanisms and dependencies of colloidal fouling using electrochemical impedance spectroscopy (EIS).
• To establish a quantitative framework linking EIS data to fouling phenomena.

Main Methods:

• Fabrication of a 3D IM3 cassette integrating a porous membrane within microfluidic channels.
• System validation using fluorescein and KCl electrolytes for reproducible measurements.
• Colloidal fouling studies with 800 nm polystyrene latex beads at varying concentrations.
• Analysis using electrochemical impedance spectroscopy (EIS) and distribution of relaxation times (DRT).
• Development of a quantitative fouling model based on EIS-derived charge-transfer resistance (Rct).

Main Results:

• The IM3 cassette demonstrated robustness and reproducibility for EIS measurements.
• Colloidal fouling exhibited a strong concentration-dependent behavior, with high particle loading causing severe pore blockage.
• DRT analysis indicated pore blockage increased interfacial resistance via a unified charge-transfer mechanism.
• A quantitative model showed maximum fouling extent increased exponentially with particle concentration.
• Fouling rate was limited by available deposition sites, not particle transport kinetics.

Conclusions:

• The IM3 cassette provides a versatile platform for mechanistic investigation of dynamic membrane fouling.
• Fouling extent is primarily governed by surface deposition driven by particle concentration.
• The developed quantitative framework links EIS data to physically meaningful fouling phenomena.
• This approach offers significant potential for optimizing membrane processes in water treatment and beyond.