Ultra salt-resistant solar desalination system via large-scale easy assembly of microstructural units

Abstract

Solar desalination is a zero-pollution, low-energy, off-grid water purification technology. However, the salt residue after water evaporation seriously threatens the continuous use of a solar thermal system. While the salt accumulation issue has been alleviated by complex processing methods and sophisticated material design, such endeavors significantly increased the cost of processing and manufacturing. Herein, we used the gaps created by imperfect chimerism during the easy assembly of microstructural units to provide a pathway for salt excretion and resolve the salt accumulation issue. A convenient solution for manufacturing a large-scale salt-resistant (SR) system is proposed based on the easy assembly of microstructural units. The SR system achieved record-high energy efficiencies of ∼91.5% and ∼84.42% in up to 20 wt% and 25 wt% sodium chloride solution, respectively, under 1 sun irradiation. Hydrophilic photothermal materials worked stably in 3.5 wt% and supersaturated salt water for more than 180 days and 2000 minutes, respectively, without salt accumulation. The cost of freshwater production by the integrated solar desalination system could be as low as ∼$1 m⁻³. The SR system fabricated via the one-step easy assembly of photothermal materials provides a promising method for the large-scale application of solar desalination.