Solar desalination technology is considered to be one of the sustainable methods for obtaining fresh water resources. In recent years, researchers have carried out research on the design of solar evaporator materials, water/steam/salt channels, and light and heat regulation, which have improved the evaporation rate and light-to-heat conversion efficiency of the evaporator. However, the solar evaporator faces the problems of cumbersome preparation of the evaporator, poor weather resistance of materials, and low long-term salt resistance and durability in the process of facing practical applications.
Recently, Song Yanlin’s group, a researcher at the Green Printing Laboratory of the Institute of Chemistry, Chinese Academy of Sciences3D printingBased on the technical construction of the three-dimensional conical asymmetric structure evaporation system, the realization of high-efficiency solar energy utilization and high water evaporation under high salinity (), the bridge-arch solar evaporator was further designed to realize the one-step preparation of the evaporator, which has excellent Weather resistance and long-term salt resistance under high salinity. A double-layer continuous water film is formed on the surface of the evaporator. The lower confinement layer is used to maintain the continuity of the water film to quickly replenish the liquid. The Marangoni convection caused by the temperature gradient in the upper layer can inhibit the accumulation of salt in the high-temperature area, thereby achieving Stable salt discharge for a long time.
Even if the evaporator uses 10 wt% NaCl high-salinity brine to evaporate continuously for 200 hours, no salt is analyzed on the surface of the evaporator, which provides a new strategy for the realization of automatic continuous seawater desalination.The clean water obtained by the evaporator reaches the consumption of WHO
standard
, Can be used for crop planting; this seawater desalination technology provides a new idea for the development of island agriculture.
Researchers built DLP continuous3D printingThe system (Research, 2018, 2018, 4795604) prints out a 3D bridge arch evaporator with a pit-like structure of Nepenthes on the surface, which plays a key role in ensuring continuous evaporation. The photothermal material is embedded in the base material during the printing process, which can ensure long-term use.
They also tested the evaporation performance of evaporators with different structures. The evaporation rate of the evaporator with excellent parameters was 1.64 kg m-2 h-1, and the light-to-heat conversion efficiency was 91%. Observation of the temperature distribution on the surface of the evaporator found that the surface of the evaporator formed a temperature gradient distribution from the top of the bridge to the bottom of the bridge.
The continuous water film formed on the surface of the evaporator is composed of two upper and lower layers under the action of the pits and grooves of the imitated pitcher plant: the lower confinement layer and the upper free-flowing layer. The lower confinement layer maintains the continuity of the water film to quickly replenish the liquid; the upper free-flowing layer causes the Marangoni convection speed due to the temperature gradient to be fast enough to inhibit the accumulation of salt in the high temperature area and achieve long-term stable salt discharge. Even if it was continuously evaporated for 200 h in 10 wt% NaCl brine, no salt analysis was found on the surface of the evaporator structure, which provides a new strategy for the realization of automatic continuous seawater desalination.
The research also innovatively developed the application of solar evaporators for seawater desalination, built a seawater desalination-crop planting linkage system, and used the obtained clean water for crop planting, providing a promising solution for sustainable island agricultural planting.The obtained clean water meets the WHO drinking standards, and the cytotoxicity test verifies its
biology
safety.
The work was published on Advanced Materials with the title “3D Printing a Biomimetic Bridge-Arch Solar Evaporator for Eliminating Salt Accumulation with Desalination and Agricultural Applications”. The first author of the paper is Zou Miaomiao, a master student of the Institute of Chemistry, Chinese Academy of Sciences, and the corresponding authors are Researcher Song Yanlin and Associate Researcher Wu Lei. This work was supported by the Ministry of Science and Technology, the National Natural Science Foundation of China, the Beijing National Research Center for Molecular Sciences, and the Youth Innovation Promotion Association of the Chinese Academy of Sciences.
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