Electrically induced modulation of pore size and surface potential in conductive nanofiltration membranes for enhanced dye/salt selective separation

Abstract

Precise modulation of the pore size sieving and electrostatic repulsion forces within nanofiltration membranes is crucial for achieving efficient dye desalination processes. This work presents a novel approach to enhance the dye desalination performance of nanofiltration membranes through electrical stimulation, fundamentally overcoming the current precision limitations in membrane material fabrication and modification. Specifically, polyaniline tetramer (AT) nanoparticles were incorporated into the interlayer channels of reduced graphene oxide (rGO) to fabricate a conductive nanofiltration membrane with electro-responsive characteristics for dynamic pore size and charge modulation. This membrane enables flexible modulation of the membrane pore size and charge through adjustment of the external voltage. Under a voltage of 2.5V, the membrane exhibits pronounced differences in the rejection for dyes and salts. Specifically, the separation factors for Congo red (CR)/Na₂SO₄ and CR/NaCl reach 231.4 and 245.2, respectively, whereas the flux increase by a factor of approximately 10.5 compared with that for an rGO membrane. This work contributes to a deeper understanding of engineering control of smart nanofiltration membranes and provides new insights into the design of separation mechanisms for dye desalting. These findings hold promising potential for applications in ion separation, material purification, and resource recovery, among other related fields.