Insights of the adsorbents surface chemical properties effect on water adsorption isotherms
Insights of the adsorbents surface chemical properties effect on water adsorption isotherms
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DOI：
10.1016/j.ijheatmasstransfer.2022.122842
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发表时间：
2022
影响因子：
5.2
通讯作者：
Tahmid Hasan Rupam;M. Palash;A. Chakraborty;B. Saha
中科院分区：
文献类型：
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作者：
Tahmid Hasan Rupam;M. Palash;A. Chakraborty;B. Saha
金属有机骨架(MOF)因其S形状的水吸附等温线而被广泛应用于吸附型热转化的吸附材料中。在使用MOF/水对时，除了S形状的等温线外，还有另外两个关键特征需要记住，即平衡吸收和水吸附等温线的疏水长度。因此，本研究合成了三种不同的金属有机骨架，即MOF-801、富马酸铝和MIL-100(Fe)，并用热重法测定了它们对水的吸附。利用四步变温吸附过程，计算了每对吸附过程中每一步的熵产。用反相气相色谱方法测定了MOF的表面性质。我们明确地证明了吸附剂的表面能组分与它们各自的水吸附等温线之间的关系。结果表明，平衡吸附与表面的结合功成正比，而疏水长度与表面的酸碱性质有关。这些信息对于设计有效的基于吸附的热转化应用的最佳MOF吸附剂是至关重要的。
The usage of metal organic frameworks (MOFs) as adsorbent materials for adsorption-based heat transformation applications is gaining popularity among the research society due to their S-shaped water adsorption isotherms. Apart from the S-shaped isotherms, there are other two key features that need to be kept in mind when working with MOF/water pair, namely the equilibrium uptake and the hydrophobic length of the water adsorption isotherms. Therefore, in this study, three different metal organic frameworks, namely MOF–801, aluminum fumarate, and MIL–100(Fe), are synthesized, and water adsorption onto these adsorbents is measured thermogravimetrically. Utilizing the four-step temperature swing adsorption process, the entropy generation in each step is calculated for each pair. Surface properties of the MOFs are measured using the inverse gas chromatography method. We explicitly demonstrated the relation between surface energy components of the adsorbents and their respective water adsorption isotherms. It has been found that the equilibrium uptake is proportional to the surfaces’ work of adhesions, while the hydrophobic length shows a relation with the surface acid-base properties. This information is crucial for designing an optimum MOF adsorbent for an efficient adsorption-based heat transformation application.