The effects of electrophoresis, bubbles and electroosmosis for conductive membrane performance in the electro-filtration process

The electro-filtration process of conductive membranes is considered to be a promising method to achieve efficient water treatment. However, the mechanism in this process is still unclear. In this study, the permeability and selectivity of conductive membranes were investigated in the electro-filtration process. Results showed that the increased voltage would enhance the electrophoresis, thereby improving both the membrane flux and the foulants rejection, thus breaking through the trade-off between membrane permeability and selectivity. The bubbles generated by applying current could break the cake layer, which enhanced the membrane permeability but reduced the membrane selectivity. Since a lot of foulants passed through the membrane when the cake layer was broken, the internal fouling of the membrane would be aggravated, resulting in a decrease in membrane permeability and an increase in membrane selectivity. Additionally, the generated bubbles might adhere to the membrane surface to decrease the liquid-liquid mass transfer area on the membrane surface, thus leading to a decrease in membrane permeability. The presence of electrolyte would cause electroosmosis, thereby increasing the membrane permeability. However, excessive electrolyte concentration could inhibit the electrophoretic effect and enhance the effect of bubbles, thus decreasing membrane filtration performance. This study provides a theoretical basis for the application of conductive membranes in the electro-filtration process.

Automated summary

The study found that increasing voltage can enhance the flux and foulants rejection of conductive membranes in the electro-filtration process, while the bubbles generated can disrupt the cake layer on the membrane surface, affecting membrane permeability and selectivity.