Lu Hengyi, Shi Wen, Zhang James H, Chen Amylynn C, Guan Weixin, Lei Chuxin, Greer Julia R, Boriskina Svetlana V, Yu Guihua
Materials Science and Engineering Program and Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA.
Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
Adv Mater. 2022 Sep;34(37):e2205344. doi: 10.1002/adma.202205344. Epub 2022 Aug 11.
The ubiquitous nature of atmospheric moisture makes it a significant water resource available at any geographical location. Atmospheric water harvesting (AWH) technology, which extracts moisture from the ambient air to generate clean water, is a promising strategy to realize decentralized water production. The high water uptake by salt-based sorbents makes them attractive for AWH, especially in arid environments. However, they often have relatively high desorption heat, rendering water release an energy-intensive process. A LiCl-incorporating polyacrylamide hydrogel (PAM-LiCl) capable of effective moisture harvesting from arid environments is proposed. The interactions between the hydrophilic hydrogel network and the captured water generate more free and weakly bonded water, significantly lowering the desorption heat compared with conventional neat salt sorbents. Benefiting from the affinity for swelling of the polymer backbones, the developed PAM-LiCl achieves a high water uptake of ≈1.1 g g at 20% RH with fast sorption kinetics of ≈0.008 g g min and further demonstrates a daily water yield up to ≈7 g g at this condition. These findings provide a new pathway for the synthesis of materials with efficient water absorption/desorption properties, to reach energy-efficient water release for AWH in arid climates.
大气水分的普遍存在使其成为任何地理位置都可获取的重要水资源。大气取水（AWH）技术是一种实现分散式水生产的很有前景的策略，该技术可从周围空气中提取水分以产生清洁水。基于盐的吸附剂对水的高吸收能力使其在大气取水方面具有吸引力，尤其是在干旱环境中。然而，它们通常具有相对较高的解吸热，这使得水的释放成为一个能源密集型过程。本文提出了一种能够在干旱环境中有效取水的含LiCl的聚丙烯酰胺水凝胶（PAM-LiCl）。亲水性水凝胶网络与捕获的水之间的相互作用产生了更多自由且结合较弱的水，与传统的纯盐吸附剂相比，显著降低了解吸热。得益于聚合物主链的溶胀亲和力，所制备的PAM-LiCl在20%相对湿度下实现了约1.1 g/g的高吸水量，吸附动力学较快，约为0.008 g/g·min，并且在此条件下进一步证明日产水量高达约7 g/g。这些发现为合成具有高效吸水/解吸性能的材料提供了一条新途径，以实现干旱气候下大气取水的节能型水释放。
