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Selective and efficient adsorption of Au (III) in aqueous solution by Zr-based metal-organic frameworks (MOFs): An unconventional way for gold recycling.
Journal of Hazardous Materials ( IF 12.2 ) Pub Date : 2020-01-22 , DOI: 10.1016/j.jhazmat.2020.122175
Ziyong Chang 1 , Fangxu Li 2 , Xiaoyue Qi 3 , Bo Jiang 4 , Jue Kou 1 , Chunbao Sun 1
Affiliation  

Recycling precious metals from secondary resources is of great environmental and economic significance. In this study, the Zr-based MOFs UiO-66-NH2 was synthesized and used to adsorb Au (III) in aqueous solution. The ultrafine particle size (∼50 nm), excellent crystallinity and huge specific surface area (1039.2 m2 ·g-1) were verified by transmission electron microscope (TEM), powder X-ray diffraction (PXRD) and surface area analysis. About 50 % Au (III) was adsorbed within 6 min and the maximum adsorption capacity at 298 K reached up to 650 mg·g-1, showing superiority to traditional adsorbents. The general order kinetics model and Liu equation were suitable to describe the adsorption process, which was spontaneous, endothermic and driven by the increasing system entropy. Electrostatic attraction between -NH3+ and Au (III) anions and inner complexation to Zr-OH played a vital role in adsorption. Au (Ⅲ) was reduced to Au° by amino groups via redox reaction certified by X-ray photoelectron spectroscopy (XPS), PXRD and high-resolution transmission electron microscopy (HRTEM) analysis. Moreover, UiO-66-NH2 displayed high selectivity, robust stability and excellent reusability, making it an ideal candidate for gold recycling in industrial practice.

中文翻译:

基于Zr的金属有机框架(MOF)对水溶液中Au(III)的选择性和高效吸附:一种非常规的金回收方法。

从二次资源中回收贵金属具有重大的环境和经济意义。在这项研究中,基于Zr的MOFs UiO-66-NH2被合成并用于吸附水溶液中的Au(III)。通过透射电子显微镜(TEM),粉末X射线衍射(PXRD)和表面积分析证实了超细粒径(〜50 nm),优异的结晶度和巨大的比表面积(1039.2 m2·g-1)。6min内吸附了约50%的Au(III),在298K下的最大吸附量达到了650mg·g-1,优于传统吸附剂。通用的动力学模型和Liu方程适用于描述吸附过程,该过程是自发的,吸热的,并且受系统熵增加的驱动。-NH3 +和Au(III)阴离子之间的静电吸引以及Zr-OH的内部络合在吸附中起着至关重要的作用。通过X射线光电子能谱(XPS),PXRD和高分辨率透射电子显微镜(HRTEM)分析证明的氧化还原反应,氨基将Au(Ⅲ)还原为Au°。而且,UiO-66-NH2具有高选择性,稳健性和出色的可重复使用性,使其成为工业实践中金回收的理想选择。
更新日期:2020-01-22
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