A novel conductive composite membrane with polypyrrole (PPy) and stainless-steel mesh: Fabrication, performance, and anti-fouling mechanism

To achieve chemical free cleaning of fouled membrane, a novel electronic-conductive composite membrane was prepared by electrochemical polymerizing polypyrrole (PPy) onto stainless-steel mesh (SSM) in the present study. The permeability of the fabricated conductive membrane can be tuned by adjusting the cycles of electrochemical cyclic voltammetry to a desired permeability level. The membrane has a significantly higher conductivity superior SSM. The anti-fouling performance was tested by using the membrane as the cathode under 2 V during backwash. The results show that under the power-on mode during backwash, the fouling formed during filtering sodium alginate (SA), bovine serum albumin (BSA), humic acid (HA) solution, and secondary effluent can be significantly more reversible than otherwise. According to size exclusion chromatography analysis, large molecular fraction in SA and small organic fractions in HA can be more effectively removed than under normal backwash. Anti-fouling mechanisms unveiled based on atomic force microscopy and Fourier transform infrared spectroscopy analysis suggest that the change of the dipole moment of PPy under applied voltage led to the increase of the electronegativity and hydrophilicity of the membrane surface, which improved hydraulic reversibility of membrane fouling. The fabrication method developed in the present study demonstrates a promising process preparing conductive membranes orientating chemical free cleaning.