School of Metallurgy and Environment, Central South University, Changsha, 410083, PR China.
School of Environmental Science and Engineering, Guangzhou University, Guangzhou, 510006, PR China.
Chemosphere. 2021 Jun;273:129678. doi: 10.1016/j.chemosphere.2021.129678. Epub 2021 Jan 19.
Electrostatic and complexation effects have been considered as the primary adsorption mechanisms for defluorination using aluminum based materials, while the effect of ion exchange between anions and fluorine ion has been mostly ignored, although synthesized alumina materials usually contain a large amount of anions, such as SO, NO, and Cl. In this study, the effect of anions exchanges and its key role on defluorination were systematically investigated for adsorption by aluminas loaded with various typical anions (SO, NO and Cl). Experimental results showed that SO- loading alumina had the best defluorination performance (94.5 mg/g), much higher than NO (45.0 mg/g) and Cl (19.1 mg/g). The contribution ratio of ion exchange between SO and F was as high as 20-60% in all potential defluorination mechanisms. By using Density Functional Theory calculation, the detailed mechanism revealed that the ion exchange process was mainly driven by the tridentate chelation of SO which reduced the exchange energy ( [Formula: see text] 4.8 eV). Our study clearly demonstrated that ion exchange between SO and F is a critical mechanism in defluorination using aluminum-based materials and provides a potential alternative method to enhance the adsorption performance of modified alumina.
静电和络合作用被认为是使用基于铝的材料进行除氟的主要吸附机制，而阴离子与氟离子之间的离子交换作用大多被忽略，尽管合成的氧化铝材料通常含有大量的阴离子，如 SO、NO 和 Cl。在这项研究中，系统研究了负载各种典型阴离子（SO、NO 和 Cl）的氧化铝吸附过程中阴离子交换及其关键作用。实验结果表明，负载 SO 的氧化铝具有最佳的除氟性能（94.5mg/g），远高于 NO（45.0mg/g）和 Cl（19.1mg/g）。在所有潜在的除氟机制中，SO 和 F 之间的离子交换的贡献比例高达 20-60%。通过使用密度泛函理论计算，详细的机制表明，离子交换过程主要是由 SO 的三齿螯合驱动的，这降低了交换能（ [Formula: see text] 4.8eV）。我们的研究清楚地表明，SO 和 F 之间的离子交换是基于铝的材料除氟的关键机制，并为增强改性氧化铝的吸附性能提供了一种潜在的替代方法。
