Fouling Resistant and Directly Heatable MD Membranes with Hydrophilic and Conductive Surface

Membrane distillation (MD) is promising technique for treatment of waters contaminated with high salt concentration, such as ground water, produced water, and brines generated from desalination. Like all membrane processes, MD suffers from fouling that leads to performance degradation. The hydrophobic nature of the MD membrane surface allows for adsorption of NOM and other organic foulants that clog membrane pores, and can lead to membrane wetting, irreversibly degrading their performance. Here, we present a method of synthesizing composite MD membranes with hydrophilic or hydrophobic conductive carbon nanotube thin film surfaces layered on a hydrophobic MD support. We demonstrate that the hydrophilic surface reduces fouling caused by humic acids, while still maintaining the same performance as a bare MD membrane. Finally, we demonstrate a novel method of generating the thermal driving force in the MD process by heating the carbon nanotube thin film surface directly via joule heating. The direct heating of the MD surface eliminates the need to heat the bulk feed solution, allows for high recovery in single pass, and could significantly reduce the complexity and construction cost of MD plants.