3D Printing a Biomimetic Bridge‐Arch Solar Evaporator for Eliminating Salt Accumulation with Desalination and Agricultural Applications

Abstract

Solar‐driven water evaporation has been considered a sustainable method to obtain clean water through desalination. However, its further application is limited by the complicated preparation strategy, poor salt rejection, and durability. Herein, inspired by superfast water transportation of the Nepenthes alata peristome surface and continuous bridge‐arch design in architecture, a biomimetic 3D bridge‐arch solar evaporator is proposed to induce Marangoni flow for long‐term salt rejection. The formed double‐layer 3D liquid film on the evaporator is composed of a confined water film for water supplementation and a free‐flowing water film with ultrafast directional Marangoni convection for salt rejection, which functions cooperatively to endow the 3D evaporator with all‐in‐one function including superior solar‐driven water evaporation (1.64 kg m‐2 h‐1, 91% efficiency for pure water), efficient solar desalination, and long‐term salt‐rejecting property (continuous 200 h in 10 wt% saline water) without any post‐cleaning treatment. The design principle of the 3D structures is provided for extending the application of Marangoni‐driven salt rejection and the investigation of structure‐design‐induced liquid film control in the solar desalination field. Furthermore, excellent mechanical and chemical stability is proved, where a self‐sustainable and solar‐powered desalination–cultivation platform is developed, indicating promising application for agricultural cultivation.

A self‐salt‐cleaning architecture in cold vapor generation system for hypersaline brines

“…Consequently, the salt crystallization is not limited by Q c . It should be noted that the temperature gradient might potentially introduce the directional water flow due to the Marangoni effect 28 . It could help to reduce the salt accumulation and needs further exploration.…”

“…According to our previously reported results, an evaporation rate over 2.2 kg m À2 h À1 was obtained under one sun illumination (a similar concept was also disclosed independently by ref. [28,40]). Building on this design, here we combine the controlled water flow strategy with this tapered evaporation architecture to demonstrate a self-saltcleaning system using an "umbrella" architecture.…”

“…It should be noted that the temperature gradient might potentially introduce the directional water flow due to the Marangoni effect. 28 It could help to reduce the salt accumulation and needs further exploration. On the other hand, as illustrated by Figure 3A, the local surface evaporation, Q e (x) will result in a spatial gradient of the salinity (similar to the situation proposed by ref.…”

“…[7][8][9][10][11] In the past decade, researchers developed various advanced materials, 9,[12][13][14][15][16] improved thermal management strategies and systems, 8,12,[17][18][19][20] and cooling technologies [21][22][23] to improve the overall water productivity. Competitions in higher energy conversion efficiency and evaporation rates, 5,9,15,19,24 lower manufacturing costs, 7,[25][26][27] less maintenance requirements, 5,6,9,10,26,28 and multifunctionalization 29,30 are major goals. However, technical challenges suffered by conventional membrane technologies for RO (e.g., fouling) are still faced by solar desalination technologies.…”

“…If brines are used as the source water, the fouling of nano/micro-pores is expected to deteriorate the performance of solar desalination. Recently, several strategies were proposed to minimize this fouling issue in various solar evaporation structures (e.g., 9,13,28,37,41,43 ). For instance, a stable evaporation rate of 2.42 kg m À2 h À1 was demonstrated using a tetragonal cup shaped architecture by adding salt inhibitor, nitrilotriacetic acid into the brines.…”