Recent advanced self-propelling salt-blocking technologies for passive solar-driven interfacial evaporation desalination systems

Abstract

Conventional active seawater evaporation technologies, that is, they include components with mechanical moving parts, generally involve large plants with high capital and operating costs. Recently, the passive solar-driven interfacial evaporation (PSDIE) with no active parts is considered as one of the most promising solar energy utilization and freshwater acquisition way. Especially in isolated and impoverished off-grid areas, passive desalination with economic feasibility and reliability has great application prospects. Based on the effective optical-thermal control of evaporator design and reasonable arrangement of deployment scheme, thermal localization in the vapor-liquid interface is conducive to reducing the heat dissipation into the bulk water and significantly improving the efficiency of desalination. Nonetheless, the Achilles’ heel of the technology, namely the existence of salt accumulation at the photothermal interface under the condition of high intensity work including concentrated brine water and intense solar irradiation, which inevitably reduces the availability of fresh water resources and the service life of the evaporator. Addressing this issue is of the utmost importance and arduous task to maintain uninterrupted passive evaporator operation. In this review, the outline of the state-of-the-art self-propelling salt-blocking strategies in PSDIE is mainly divided into three categories, i.e. mechanical removal, shielding effect, and force-driven fluid flow. Finally, the challenges and prospects of salt resistance in PSDIE are emphasized, providing a roadmap for the future development of solar evaporation technology. • General models and salt-blocking mechanisms of currently available solar evaporators are proposed. • Progress of three categories of self-propelling salt-blocking technologies are compared. • Future perspectives for practical passive solar-driven interfacial evaporation desalination systems are proposed.