Zou Hongqi, Meng Xiangtong, Zhao Xin, Qiu Jieshan
State Key Laboratory of Organic-Inorganic Composites, State Key Laboratory of Chemical Resource Engineering, College of Chemical Engineering, Beijing University of Chemical Technology, Beijing, 100029, China.
Adv Mater. 2023 Feb;35(5):e2207262. doi: 10.1002/adma.202207262. Epub 2022 Dec 16.
Solar-driven water evaporation technology holds great potential for mitigating the global water scarcity due to its high energy conversion efficiency. Lowering the vaporization enthalpy of water is key to boost the performance of solar-driven desalination. Herein, a highly hydratable hydrogel (PMH) network, consisting of modified needle coke as photothermal material and polyvinyl alcohol (PVA) as hydratable matrix, is crafted via simple physical cross-linking method. When capitalizing on the PMH as evaporator for 3.5 wt% NaCl solution, a high evaporation rate of 3.18 kg m h under one sun illumination is deliver ed, unexpectedly outperforming that in pure water (2.53 kg m h ). More importantly, the PMH shows a robust desalination durability, thus enabling a self-cleaning system. Further investigations reveal that the outstanding evaporation performance of PMH in brine roots in its hydrability tuned by chaotropic Cl , wherein the Cl can mediate the hydration chemistry of PVA in PMH and suppress related crystallinity, thus contributing to the increased content of intermediate water and the lowered vaporization enthalpy of brine. This work first scrutinizes the Hofmeister effect on the evaporation behavior of PMH evaporator in brine and provides insights for high-efficiency solar-driven interfacial desalination.
太阳能驱动的水蒸发技术因其高能量转换效率在缓解全球水资源短缺方面具有巨大潜力。降低水的汽化焓是提高太阳能驱动海水淡化性能的关键。在此，通过简单的物理交联方法制备了一种高度水合的水凝胶（PMH）网络，它由作为光热材料的改性针状焦和作为水合基质的聚乙烯醇（PVA）组成。当将PMH用作3.5 wt% NaCl溶液的蒸发器时，在一个太阳光照下可实现3.18 kg m⁻² h⁻¹的高蒸发速率，出乎意料地优于在纯水中的蒸发速率（2.53 kg m⁻² h⁻¹）。更重要的是，PMH表现出强大的脱盐耐久性，从而实现了自清洁系统。进一步的研究表明，PMH在盐水中出色的蒸发性能源于由离液序列高的Cl⁻调节的水合能力，其中Cl⁻可以介导PMH中PVA的水合化学并抑制相关结晶度，从而有助于增加中间水的含量并降低盐水的汽化焓。这项工作首次审视了霍夫迈斯特效应对PMH蒸发器在盐水中蒸发行为的影响，并为高效太阳能驱动界面脱盐提供了见解。
