Development and performance of stable PANI/MWNT conductive membrane for contaminants degradation and anti-fouling behavior

Electrically conductive membranes (ECMs) have the potential to conduct and distribute an externally applied potential across the membrane surface, which enable some phenomena at the membrane/water interface, including increase in electrostatic repulsive forces between foulants and the membrane surface, and electrochemical oxidation and reduction of toxic contaminants. The objective of this study was to develop highly stable and conductive polyaniline/multiwall carbon nanotubes (PANI/MWNT) membranes through vacuum filtration assisted layer-by-layer assembly technique coupled with heat treatment, and to demonstrate its application in electrochemical filtration systems to degrade contaminants and reduce membrane fouling. The PANI/MWNT conductive membrane was assembled for ten bilayers through the comprehensive evaluation of surface conductivity, pure water flux, pore size distribution and electrochemical properties. The surface conductivity, pure water flux and average pore size of the membrane were 732.0 S/m, 596.6 L/m2·h·bar and 72.0 nm, respectively. The stability evaluation revealed that the conductive membrane exhibited excellent physical, electrochemical and chemical stability. The degradation rate of methylene blue, methyl orange and phenol can achieve 94.9%, 96.1% and 95.6% under the applied voltage of 2.5 V, much higher than the traditional electrochemical oxidation process. Anti-fouling test conducted with humic acid showed that the fouling was effectively alleviated and the flux recovery rate increased from 63.3% to 78.0% when a negative bias was applied. This study provides a new insight for the multifunctional application of ECMs and offers a promising enhancement to existing membrane-based water treatment processes.