Department of Chemistry and Chemical Engineering, Hunan Institute of Science and Technology, Yueyang, 414006, Hunan, China.
Environ Sci Pollut Res Int. 2019 May;26(14):14214-14225. doi: 10.1007/s11356-019-04674-5. Epub 2019 Mar 12.
The recovery of silver from wastewater is of great significance due to its economic and environmental interest. In this work, zeolitic imidazolate framework-8 (ZIF-8) was chosen to adsorb Ag(I) from wastewater for the first time. The adsorption performance was assessed by adjusting the pH value, uptake time, initial concentration of Ag(I), as well as temperature. The saturated adsorption capacity for Ag(I) onto ZIF-8 can reach 446.7 mg·g, which shows that ZIF-8 not only possesses remarkable adsorption performance but also is superior to the reported adsorbents. The selectivity coefficients of ZIF-8 for Ag(I)/Cd(II), Ag(I)/Ni(II), and Ag(I)/Co(II) are 8.242, 8.315, and 136.3, respectively. The Sips adsorption model matches adsorption isotherms of Ag(I) onto ZIF-8 well, and the pseudo-second-order model is more suitable to illustrate the kinetics data. Thermodynamic experiment indicates that the adsorption process of Ag(I) is an exothermic reaction. Mechanism studies suggest that the redox reaction of Ag occur in the adsorption process. In addition, the study of recycling use indicates that the stable adsorption performance being maintained after recycle twice. Thus, a promising adsorbent is introduced to recover Ag(I) from wastewater in this work.
从废水中回收银具有重要的经济和环境意义。在这项工作中，沸石咪唑酯骨架-8（ZIF-8）首次被选择用于吸附废水中的Ag（I）。通过调整 pH 值、吸附时间、Ag（I）的初始浓度以及温度来评估吸附性能。ZIF-8 对 Ag（I）的饱和吸附容量可达 446.7mg·g，这表明 ZIF-8 不仅具有显著的吸附性能，而且优于报道的吸附剂。ZIF-8 对 Ag（I）/Cd（II）、Ag（I）/Ni（II）和 Ag（I）/Co（II）的选择性系数分别为 8.242、8.315 和 136.3。Sips 吸附模型很好地拟合了 Ag（I）在 ZIF-8 上的吸附等温线，而伪二阶模型更适合说明动力学数据。热力学实验表明，Ag（I）的吸附过程是一个放热反应。机理研究表明，在吸附过程中发生了 Ag 的氧化还原反应。此外，循环使用研究表明，在经过两次循环后，仍能保持稳定的吸附性能。因此，在这项工作中，介绍了一种有前途的吸附剂来从废水中回收 Ag（I）。
