A bioinspired solar evaporator for continuous and efficient desalination by salt dilution and secretion

Abstract

In recent years, solar interfacial evaporation has been one of the most promising techniques to alleviate freshwater scarcity. However, the salt deposition on the evaporation surface limits the long-term operation of evaporators. Herein, inspired by the salt dilution and secretion mechanisms in halophytes, a solar evaporator with a bundle-cross-layer structured absorber and salt secretion bundles is reported. The unique bundle-cross-layer structure realizes the salt dilution by enhancing the water storage and transport, which enables the absorber to show a high and stable evaporation efficiency of 90.2% over 60 h in brine. More importantly, the salt secretion bundles can completely separate salt crystallization from the absorber by a humidity-controlled salt creeping mechanism. The solar desalination prototype equipped with this evaporator exhibited a stable water collection rate over 600 h of continuous operation, realizing zero liquid discharge in desalination. The study provides new insights into the solar evaporator design and advances other applications such as sea-salt extraction, wastewater treatment, and resource recovery.