School of Metallurgical Engineering, Anhui University of Technology, Maanshan, 243002, People's Republic of China.
Department of Materials Science and Engineering, Delft University of Technology, Mekelweg 2, 2628 CD, Delft, the Netherlands.
Environ Sci Pollut Res Int. 2018 Dec;25(34):34550-34558. doi: 10.1007/s11356-018-3393-0. Epub 2018 Oct 12.
Design of new adsorbents for complete removal of thallium(I) from wastewater is of significant importance. Based on the theory of binding ability between crown ether and metal ion, a kind of Tl(I)-selected crown ether, thio-18-crown-6 ether, was designed. Subsequently, modeling calculations were performed to investigate the microscopic interaction between 18-crown-6 ether and its sulfur-substituted derivatives with Tl. The results showed that thio-18-crown-6 ether generally showed higher affinity to Tl than 18-crown-6. The stabilities of these complexes ranked in an order of 5S-18C6 > 4S-18C6(II) > 2S-18C6(I) > 2S-18C6(II) > 6S-18C6 > 3S-18C6 > 18C6 > 1S-18C6. The binding energies of 5S-18C6 with free Zn, Pb, Cu, and Cd, which are usually impurity ions in thallium-containing wastewater, were more negative than with Tl, indicating more affinity of 5S-18C6 toward these free two-valence ions. However, after the influence of solvent (water) was taken into account, 5S-18C6 showed fairly high selectivity to Tl(I) over Zn, Pb, Cu, and Cd. Therefore, 5S-18C6 should be a proper compound which has the promising potential to be adopted for the complete and selective removal of Tl(I) from wastewater. Further synthesis and adsorption experiments are needed to verify this prediction.
设计能完全去除废水中铊（I）的新型吸附剂具有重要意义。基于冠醚与金属离子结合能力的理论，设计了一种对铊（I）具有选择性的冠醚——硫代-18-冠-6 醚。随后，通过建模计算研究了 18-冠-6 醚及其硫取代衍生物与 Tl 之间的微观相互作用。结果表明，硫代-18-冠-6 醚通常比 18-冠-6 对铊具有更高的亲和力。这些配合物的稳定性顺序为 5S-18C6 > 4S-18C6(II) > 2S-18C6(I) > 2S-18C6(II) > 6S-18C6 > 3S-18C6 > 18C6 > 1S-18C6。5S-18C6 与废水中通常含有的杂质离子（如 Zn、Pb、Cu 和 Cd）的自由二价离子的结合能比与 Tl 的结合能更负，这表明 5S-18C6 对这些自由二价离子具有更强的亲和力。然而，考虑到溶剂（水）的影响后，5S-18C6 对 Tl（I）与 Zn、Pb、Cu 和 Cd 表现出相当高的选择性。因此，5S-18C6 应该是一种合适的化合物，具有从废水中完全且选择性地去除 Tl（I）的潜力。需要进一步的合成和吸附实验来验证这一预测。
