Enhance the anti-scaling performance of conductive heating vacuum membrane distillation by carbon nanotube-based electroactive membrane

Membrane distillation (MD) is an emerging technology for the brine desalination. Directly heating feed liquid at the membrane-water interface for improving the performance of MD has been demonstrated, while the problem of membrane scaling remained. Herein, carbon nanotube-based electroactive membranes were prepared and characterized by a variety of methods. It was then used in a conductive heating vacuum membrane distillation system. We firstly increased the flux by optimizing system configuration, placing a spacer in the feed channel, and setting vent holes on the thermal conducting layer. Then, aiming at silicates and sulfates scaling in MD, the electroactive membranes and titanium were used as working electrodes and the counter electrode, respectively, to discuss the electrochemical anti-scaling performance and mechanism. Results showed that the silicate scale on the membrane surface can be effectively cleaned by using the electroactive membrane as the cathode and applying a potential of 5 V to destroy the structure of the silicate through an electrochemical reaction. With the electroactive membrane as the anode, the scaling of calcium sulfate can be mitigated by providing a continuous potential through electrostatic repulsion. This paper may provide further insights into inorganic scaling control in conductive heating vacuum membrane distillation process.