Influence of Module Design and Concentration Polarization on Pore Size Determination for Nanofiltration Membranes

Area of Science:

• Chemical Engineering
• Separation Processes

Background:

• Nanofiltration (NF) is a key pressure-driven membrane separation technique.
• Understanding hydrodynamics, concentration polarization, and solute rejection is crucial for NF process design and scale-up.

Purpose of the Study:

• To characterize concentration polarization and determine pore size using the Donnan steric pore model in different NF modules.
• To evaluate the impact of optimized channel design on NF performance and retention rate accuracy.

Main Methods:

• Utilized two distinct membrane modules for characterization.
• Applied the Donnan steric pore model for pore-size determination.
• Investigated concentration polarization under varying hydrodynamic conditions.

Main Results:

• An optimized channel design enabled reliable determination of true retention rates by mitigating concentration polarization.
• Observed retention rates closely matched intrinsic retention rates, even at reduced mass transfer coefficients.
• Effective results were achieved at significantly lower cross-flow rates.

Conclusions:

• Optimized module design enhances the accuracy of nanofiltration performance prediction.
• Reduced cross-flow rates are feasible for reliable lab-scale NF studies.
• The findings facilitate improved design and scale-up of nanofiltration processes.