Salt-Rejecting Solar Interfacial Evaporation

Abstract

Summary Solar evaporation offers a promising approach to drive the distillation process, and nanotechnology may help overcome operational issues such as salt fouling. Here, we discuss the opportunities presented by salt-rejecting solar evaporation to enhance the sustainability of desalination. Within this framework, phase diagrams and salt crystallization physics are first revisited to understand the phase transitions of water as well as the formation and growth of salt crystals. We then examine salting-out and salt-free evaporating systems toward better solar desalination. The salt-rejecting techniques to be covered include subsequent flushing, self-cleaning, local crystallization, gravity-assisted cleaning, anti-clogging layer, Janus membranes, concentrating and diffusion, and gap separation. The principles of these systems are fully addressed, and the performance requirements are elaborated together with the advantages but also the limitations. Finally, the remaining challenges and future research opportunities for the further development of solar evaporation technology are highlighted.