Science and Technology Daily （Reporter Wang Zhuhua and Qu Yizhen）
On April 14, the reporter learned from Hainan University that Huang Wei's team from State Key Laboratory of Marine Resources Utilization in South China Sea has successfully constructed tilted amphiphilic Janus evaporator, providing new possibilities for long-term, efficient, synergistic extraction of freshwater and mineral salt resources. The relevant findings were published in Chemical Engineering under the title "Amphiphilic two-sided evaporator for efficient dual-mode solar water evaporation".
Solar-powered interfacial water evaporation systems provide a green, environmentally friendly and sustainable technological solution to the global freshwater crisis. However, most of the current water evaporators have problems such as high cost, low efficiency of light-heat conversion and poor resistance to salt, which makes it difficult to realize the practical application of the technology. Exploring interfacial water evaporation systems with low cost, high energy conversion efficiency, scalability, and long-lasting salt tolerance is essential to achieve widespread use of solar desalination systems.
Huang Wei's team adopted electrospinning film as the top evaporation layer and non-woven fabric as the bottom water supply layer to construct an aphiphilic Janus structure evaporator combined with a tilted isolation structure to achieve long-term efficient water evaporation and flexible salt treatment. Such an evaporator, with adequate water transport, good energy-limited domain and flexible salt handling, can not only work stably in 10 wt% sodium chloride (NaCl) solution for 200 hours without salt crystallization, but also achieve a highly efficient salt extraction rate of 260 grams of salt per square meter per day under one sunlight.
The research team found that the electrospinning film with encapsulated structure can realize better effect on limiting the energy domain, greatly improve the performance of photothermal conversion, which can reduce the amount of material by 50% without destroying the evaporation performance. In the evaporator, the difference in hydraulic conductivity between the evaporation layer of the electrospinning film and the water supply layer of the non-woven fabric effectively suppresses the liquid flow internally due to the difference in surface tension of the liquid. In addition, the tilted isolation structure builds a salinity gradient inside the non-woven structure for unidirectional transport of ions.