CAREER: Continuous atmospheric water harvesting through gels

美国西南部的地表水水位降到了1200年来的最低点，因此迫切需要寻找替代水源。其中一个来源是大气中的水蒸气。即使在干旱地区，也有大量的水，如果加以利用，将成为重要的新水源。一个太阳能电池板大小的装置可能会收集足够的水来满足一个人的日常饮用需求。然而，挑战在于将水蒸气转化为液体并对其进行净化需要大量的能量和先进的材料。此外，最先进的方法的产水量非常低，特别是在干旱、低湿度地区。这笔资金将支持一项研究，研究一种完全不同的方法，利用容易合成的凝胶材料和天然太阳能，可以大幅提高产水量。此外，这种方法将在美国最干旱的城市内华达州的拉斯维加斯进行测试，这是一个最需要替代水源的大都市地区。此外，该项目还将与当地教育界合作，向当地高中分发集水站，为研究工作提供有价值的真实数据。该项目的目标是通过对运输和材料科学的重点研究，展示水凝胶膜的大气水收集方法如何提供有利的水生产。利用太阳来蒸馏收集的水，太阳能的产水极限大约是每平方米设备占地面积每天10升。所提出的方法使用单独的，专门的捕获和蒸馏膜以及存储池来隔离任务并提高性能。中心假设是，需要高孔隙弹性扩散率和可调导热系数的凝胶膜来最大化水通量。为了验证这一假设，该项目将(1)研究膜周围的热量和质量传输，并开发新的模型，以结合相关的物理学；(2)揭示新的聚合物物理学，决定膜内的材料传输瓶颈；(3)研究不同条件下的系统行为，并发现可行的原型设计。这项工作将包括传热传质实验和材料测试，以及用有限元方法进行计算建模。这项工作还将涉及当地水质专家，并将向更大的社区宣传这种收集方法的有效示范，以引起人们对替代水源的兴趣。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With the lowest surface water levels in the Southwestern US in 1,200 years, there is an urgent need to tap into alternative water sources. One source is the water vapor in the atmosphere. Even in arid regions, there is a vast quantity of water that, if tapped, would represent an important new source. Potentially, a solar-panel-sized device could collect enough water to satisfy one’s daily drinking requirement. However, the challenge is that transforming water vapor into liquid form and purifying it requires a sizeable amount of energy and advanced materials. Additionally, the water production rates with state-of-the-art approaches are very low, especially in arid, low-humidity regions. The funding will support an investigation into a fundamentally different approach utilizing easily synthesized gel materials and natural solar energy that could provide substantially increased water production rates. Furthermore, this approach would be tested in the driest city in the US—Las Vegas, Nevada—a metropolitan area where alternative water sources are needed most. In addition, this project will involve the local educational community by distributing water harvesting stations to local high schools to provide valuable real-world data that will support the research effort.The objective of this project is to demonstrate how a flow-through atmospheric water harvesting approach with hydrogel membranes can provide advantageous water production through a focused study of transport and material science. Using the sun to distill captured water, the solar limit of water production is approximately 10 liters per day per square meter of device footprint. The proposed approach uses separate, specialized capture and distillation membranes as well as a storage basin to segregate tasks and improve performance. The central hypothesis is that gel membranes of high poroelastic diffusivity and tunable thermal conductivity are needed to maximize water flux. To test this hypothesis, the project will (1) study heat and mass transport around the membranes and develop new models to incorporate relevant physics, (2) uncover new polymer physics that dictate material transport bottlenecks within membranes, and (3) investigate system behavior in varying conditions and discover viable prototype designs. The work will include a mixture of heat and mass transfer experiments and material testing as well as computational modeling with the finite element method. The work will also involve local water quality experts and an effective demonstration of this harvesting approach will be communicated with the greater community to generate interest in alternative sourcing of water.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.