A spacer-based approach for localized Joule heating in membrane distillation

Abstract

Membrane distillation (MD) is a versatile low-temperature separation process used for desalinating saline solutions with high salt rejection rates. Its current drawbacks include low flux and high energy demand. This study presents localized electrically induced heating using ceramic-coated metallic spacers to improve MD performance. We coated Ni-Cr spacers with MgO via electrolytic deposition and calcination, optimizing for a crack-free protective surface. Smaller wire diameter Ni-Cr exhibited superior heating. When a periodic current of 0.2 A cm−2 was applied, permeate flux increased by 15% although energy consumption only increased by 4%. Continuous supply of high-grade electrical energy added no further performance improvement as compared to periodic application. Our work highlights a spacer-based approach for localized Joule heating in MD systems without compromising membrane structure, while exploring coating systems to protect conductive spacers and optimizing schemes for electrically controlled performance.