Voltage-controlled organic solvent nanofiltration using conjugated microporous polymer membranes

Area of Science:

• Materials Science
• Chemical Engineering
• Separation Science

Background:

• Voltage-controlled nanofiltration is effective for separations but underexplored in organic solvents due to poor solute dissociation.
• Organic solvent nanofiltration (OSN) requires advanced membrane technologies for efficient molecular separation.

Purpose of the Study:

• To investigate voltage-controlled OSN using conductive conjugated microporous polymer (CMP) membranes.
• To understand the mechanisms behind voltage-enhanced solute rejection in organic solvents.

Main Methods:

• Fabrication of conductive and robust conjugated microporous polymer (CMP) membranes.
• Experimental investigation of voltage-controlled OSN performance in methanol.
• Analysis of solute rejection mechanisms including ion migration and Donnan-like equilibrium.

Main Results:

• Applied voltage significantly enhanced solute rejection in OSN, with methylene blue rejection increasing from 8.3% to 91.3% in methanol at 5V.
• Solvent permeance slightly decreased with increasing voltage due to solvent molecule electron density.
• Solute dissociation degree was found to significantly impact voltage-controlled rejection effectiveness.

Conclusions:

• Conductive CMP membranes enable effective voltage-controlled OSN, overcoming challenges of poor solute dissociation.
• A dual-barrier mechanism involving ion migration and interface equilibrium drives enhanced rejection under voltage.
• This approach shows potential for challenging separations of dyes, pharmaceuticals, and agrochemicals in OSN.