Konch Tukhar Jyoti, Dutta Trisha, Buragohain Madhurjya, Raidongia Kalyan
Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India.
Centre for Nanotechnology, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India.
ACS Omega. 2021 Jul 29;6(31):20379-20387. doi: 10.1021/acsomega.1c02398. eCollection 2021 Aug 10.
In the form of leaves, nature designs the finest photothermal evaporators, and the tremendous evaporation efficiency of leaves is supported by a precisely designed network of veins. Here, we have demonstrated that the vein network of a natural leaf can be extracted through a simple water-assisted digestion process and exploited for low-energy steam generation. The naked leaf veins exhibit a remarkable flux (evaporation rate, 1.5 kg·m·h) of capillary evaporation under ambient conditions (25 °C and 30% RH), close to the photothermal material-based evaporators reported in the recent literature. Even inside a dark box, naked veins exhibit an evaporation rate up to 4.5 kg·m·h (at 30% relative humidity (RH) and a wind speed of 22 km·h). The mechanistic studies performed with variable atmospheric conditions (temperature, humidity, and wind speed) suggest the evaporation process through the naked veins to be a kinetic-limited process. Naked veins with remarkable evaporation efficiency are found to be suitable for applications like water desalination and streaming potential harvesting. Experiments with the naked veins also unveiled that the biofluidic channels in leaves not only exhibit the characteristics of surface charge-governed ionic transport but also support an exceptional water transport velocity of 1444 μm·s.
以树叶的形式，大自然设计出了最精巧的光热蒸发器，而树叶极高的蒸发效率得益于精心设计的叶脉网络。在此，我们证明了天然树叶的叶脉网络可以通过简单的水辅助消化过程提取出来，并用于低能耗蒸汽的产生。裸露的叶脉在环境条件（25℃和30%相对湿度）下表现出显著的毛细蒸发通量（蒸发速率为1.5 kg·m⁻²·h⁻¹），接近近期文献报道的基于光热材料的蒸发器。即使在暗箱中，裸露的叶脉也表现出高达4.5 kg·m⁻²·h⁻¹的蒸发速率（在30%相对湿度和22 km·h的风速下）。在不同大气条件（温度、湿度和风速）下进行的机理研究表明，通过裸露叶脉的蒸发过程是一个动力学受限过程。发现具有显著蒸发效率的裸露叶脉适用于海水淡化和流动电势收集等应用。对裸露叶脉的实验还揭示，树叶中的生物流体通道不仅表现出表面电荷控制的离子传输特性，还支持高达1444 μm·s⁻¹的非凡水传输速度。
