2023-06-15 マサチューセッツ工科大学(MIT)
◆この材料は、砂漠や干ばつ地域で受動的な水収集装置として使用することができます。また、エアコンユニットに組み込むことで省エネで除湿することも可能です。この発見は、エネルギーと水の課題に対する解決策として大きな可能性を秘めています。
＜関連情報＞
- https://news.mit.edu/2023/salty-gel-could-harvest-water-desert-air-0615
- https://onlinelibrary.wiley.com/doi/10.1002/adma.202211783
吸湿性ハイドロゲルの膨潤による塩分負荷の最大化による極端な吸水性 Extreme Water Uptake of Hygroscopic Hydrogels through Maximized Swelling-Induced Salt Loading
Gustav Graeber, Carlos D. Díaz-Marín, Leon C. Gaugler, Yang Zhong, Bachir El Fil, Xinyue Liu, Evelyn N. Wang
Advanced Materials Published: 18 May 2023
DOI:https://doi.org/10.1002/adma.202211783
Abstract
Hygroscopic hydrogels are emerging as scalable and low-cost sorbents for atmospheric water harvesting, dehumidification, passive cooling, and thermal energy storage. However, devices using these materials still exhibit insufficient performance, partly due to the limited water vapor uptake of the hydrogels. Here, the swelling dynamics of hydrogels in aqueous lithiumchloride solutions, the implications on hydrogel salt loading, and the resulting vapor uptake of the synthesized hydrogel–salt composites are characterized. By tuning the salt concentration of the swelling solutions and the cross-linking properties of the gels, hygroscopic hydrogels with extremely high salt loadings are synthesized, which enable unprecedented water uptakes of 1.79 and 3.86 gg−1 at relative humidity (RH) of 30% and 70%, respectively. At 30% RH, this exceeds previously reported water uptakes of metal–organic frameworks by over 100% and of hydrogels by 15%, bringing the uptake within 93% of the fundamental limit of hygroscopic salts while avoiding leakage problems common in salt solutions. By modeling the salt-vapor equilibria, the maximum leakage-free RH is elucidated as a function of hydrogel uptake and swelling ratio. These insights guide the design of hydrogels with exceptional hygroscopicity that enable sorption-based devices to tackle water scarcity and the global energy crisis.
