PDF(Pubmed)
Abstract：
Solar-powered interfacial evaporation is an energy-efficient solution for water scarcity. It requires solar absorbers to facilitate upward water transport and limit the heat to the surface for efficient evaporation. Furthermore, downward salt ion transport is also desired to prevent salt accumulation. However, achieving simultaneously fast water uptake, downward salt transport, and heat localization is challenging due to highly coupled water, mass, and thermal transport. Here, we develop a structurally graded aerogel inspired by tree transport systems to collectively optimize water, salt, and thermal transport. The arched aerogel features root-like, fan-shaped microchannels for rapid water uptake and downward salt diffusion, and horizontally aligned pores near the surface for heat localization through maximizing solar absorption and minimizing conductive heat loss. These structural characteristics gave rise to consistent evaporation rates of 2.09 kg m-2 h-1 under one-sun illumination in a 3.5 wt% NaCl solution for 7 days without degradation. Even in a high-salinity solution of 20 wt% NaCl, the evaporation rates maintained stable at 1.94 kg m-2 h-1 for 8 h without salt crystal formation. This work offers a novel microstructural design to address the complex interplay of water, salt, and thermal transport.
摘要：
太阳能界面蒸发是解决水资源短缺的节能解决方案。它需要太阳能吸收器来促进水的向上传输并限制热量到表面以有效蒸发。此外，向下的盐离子传输也是所希望的,以防止盐积累。然而,同时实现快速吸水，盐向下输送，由于高度耦合的水，热局部化具有挑战性，质量,和热传输。这里,我们开发了一种受树木运输系统启发的结构分级气凝胶，以共同优化水，盐,和热传输。拱形气凝胶的特征是根状，快速吸水和向下盐扩散的扇形微通道，和表面附近的水平对齐的孔，通过最大化太阳能吸收和最小化传导热损失进行热定位。在3.5wt％的NaCl溶液中，在一个阳光照射下，这些结构特征可产生一致的蒸发速率为2.09kgm-2h-1，持续7天，而不会降解。即使在20重量%NaCl的高盐度溶液中，蒸发速率在1.94kgm-2h-1下保持稳定8小时，没有形成盐晶体。这项工作提供了一种新颖的微结构设计，以解决水的复杂相互作用，盐,和热传输。
