Electrically conductive membranes based on carbon nanostructures for self-cleaning of biofouling

Although membranes are widely employed in separation processes, their performance can be severely deterred by fouling due to organic, inorganic and biological foulants. Periodic electrolysis is a fast and simple technique for membrane cleaning, but requires membranes with high electric conductivities. In this work, novel electrically conductive CNS/PVDF membranes were fabricated via vacuum filtration, followed by heat treatment above the melting point of PVDF, such that PVDF acts as a binder inside the CNS structure, resulting in better mechanical properties and greater wettability. Membranes that were subjected to periodic electrolysis were able to sustain higher flux through multiple filtration cycles of yeast suspensions as compared to those without electrolysis, indicating the efficiency of this technique using electrically conductive CNS/PVDF membranes. Electrolysis led to the formation of micro-bubbles on the membrane surface, which removed foulants. These self-cleaning membranes can be used to mitigate the effects of fouling in different types of separation processes. © 2015 Elsevier B.V. All rights reserved.

In this work, a cleaning technique was developed by applying novel electrically conductive CNS/PVDF membranes to periodic electrolysis. PVDF served as a binder in the entangled CNS structure. PVDF imparted greater mechanical strength to the membrane while improving its hydrophilicity. The higher tensile strength and strain at break of the No Electrolysis With electrolysis Normalized flux / % Time / min Fig. 7. Variation of normalized flux with time for CNS/PVDF membrane with and without in-situ cleaning using electrolysis.