Tran Thi Yen, Younis Sherif A, Heynderickx Philippe M, Kim Ki-Hyun
Department of Civil and Environmental Engineering, Hanyang University, Seoul 04763, Republic of Korea.
Department of Civil and Environmental Engineering, Hanyang University, Seoul 04763, Republic of Korea; Analysis and Evaluation Department, Egyptian Petroleum Research Institute, 11727 Nasr City, Cairo, Egypt.
J Hazard Mater. 2022 Feb 15;424(Pt B):127459. doi: 10.1016/j.jhazmat.2021.127459. Epub 2021 Oct 11.
In this research, the adsorption behavior of formaldehyde (FA) onto two types of metal-organic frameworks (MOFs: MOF-199 [M199] and UiO-66-NH [U6N]) is investigated against changes in the key process variables (e.g., FA partial pressure (0.5-10 Pa), temperature (30-120 °C), and relative humidity (RH: 0%, 50%, and 100%)). The results revealed that the FA adsorption behavior onto both MOFs is exothermic in nature. Besides, their relative dominance for FA uptake varies interactively with the changes in RH and FA partial pressure levels. As the FA levels increase in dry conditions, their breakthrough volumes (BTV (100% BT)) exhibit contrasting trends: The values of U6N decreased noticeably from 5232 and 3792 L·atm·g, while those of M199 increased from 4152 to 5772 L·atm·g. The superiority of U6N over M199 in the lower FA level (at<5 Pa) is supported by the Lewis acid-base interactions with amine groups (U6N) in line with kinetic/isotherm studies. Such superiority is also persistent at higher (10 Pa) FA level under all humid conditions in line with its higher moisture stability. However, in dry conditions, the reversal of relative dominance in which M199 exhibits enhanced efficacy for 10 Pa FA uptake (relative to U6N) should reflect its breathing effects with the potent role of pore-diffusion mechanism. This study offers valuable insights into the construction of tunable adsorbents with enhanced adsorptivity toward key targets.
在本研究中，研究了两种金属有机框架材料（MOF：MOF-199 [M199] 和 UiO-66-NH [U6N]）对甲醛（FA）的吸附行为随关键过程变量（如 FA 分压（0.5 - 10 Pa）、温度（30 - 120 °C）和相对湿度（RH：0%、50% 和 100%））的变化情况。结果表明，两种 MOF 对 FA 的吸附行为本质上都是放热的。此外，它们对 FA 吸附的相对优势随 RH 和 FA 分压水平的变化而交互变化。在干燥条件下，随着 FA 水平的增加，它们的穿透体积（BTV（100%BT））呈现出相反的趋势：U6N 的值从 5232 和 3792 L·atm·g 显著下降，而 M199 的值从 4152 增加到 5772 L·atm·g。根据动力学/等温线研究，U6N 在较低 FA 水平（<5 Pa）下相对于 M199 的优势是由其与胺基（U6N）的路易斯酸碱相互作用所支持的。在所有潮湿条件下，在较高（10 Pa）FA 水平下，这种优势也持续存在，这与其较高的水分稳定性有关。然而，在干燥条件下，相对优势的逆转，即 M199 在 10 Pa FA 的吸附方面表现出更高的效率（相对于 U6N），应反映其呼吸效应以及孔扩散机制的重要作用。本研究为构建对关键目标具有增强吸附性的可调谐吸附剂提供了有价值的见解。
