Ultrasonic-mediated electrochemical design of graphene/polyacrylonitrile conductive membrane for antifouling and electrofiltration

Electrofiltration using conductive membranes can effectively alleviate membrane fouling. However, poor dispersion and aggregation in water severely constrain the ability of graphene (Gr) to synthesize conductive membranes. Herein, the water-dispersible Gr with high conductivity is tailored by ultrasonic-assisted electrochemical exfoliation and loaded onto the polyacrylonitrile (PAN) membrane by classical vacuum filtering in layers. The customization at 6 V voltage, 40 W ultrasonic power, and 23.87 g/m2 mass loading endows an optimal improvement in membrane pore structure, permeability, mechanical behavior, and electrochemical properties. The graphene/polyacrylonitrile (Gr/PAN) conductive membrane exhibits a high conductivity of 6.43 S/cm and a water flux of 450.19 L m-2 h-1. The membrane shows remarkable antifouling capabilities by achieving a 99.8% rejection rate, 89.74% flow rate recovery, and only 10.26% irreversible fouling using yeast as a pollutant model. The normalized flux of the membrane can stay high at 0.41 after electrofiltration for 120 minutes, outperforming other conductive membranes in comparison. Cyclic electrofiltration of the developed membrane exhibits a 53.85% higher normalized flux than when no electric field is present, demonstrating its potential for long-lasting antifouling under electric fields. This study offered a novel strategy for the straightforward construction of highly functional graphene-based conductive membranes utilized in electrofiltration.