Membrane desalination (MD) processes are actively researched for desalination applications, especially for hypersaline waters. Membranes that allow surface heating holds great promise in MD because they overcome several inherent limitations of the conventional MD technology: low thermal efficiency, low single pass recovery, unable for magnification. Application of electrothermal surface heating material in MD further broaden its application, as it allows easier control and higher intensity of energy input. However, existing surface heating materials face major challenges in MD: low electrochemical stability and unable for high energy input.

In this study, we report the development of a novel electrothermal surface heating element by in situ growth of nano-thin protective coating, which provides high thermal conductivity, high electric insulation, and anti-corrosion properties, all critical for application in saline solutions. In a bench-scale MD module powered with a low voltage AC supply of household frequency, we demonstrate that the synthesized material is able to support an ultra-high power intensity (50 kW/m²) to desalinate hypersaline solutions (100 – 250 g/L) at exceptionally high membrane flux, single-pass water recovery, and thermal efficiency, while exhibiting excellent material stability. We also demonstrate a simple method to grow high-quality coating at large-scale, and its application in a novel spiral wound MD module, whose compactness greatly reduces system footprint. This work collaborated with Dr. Jun Lou and Dr. Pulickel M. Ajayanfrom Rice University for surface heating material synthesis. We also got help from Dr. Menachem Elimelech’s lab for MD simulation.