School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, 100083, PR China; School of Chemistry and Biological Engineering, University of Science and Technology Beijing, 100083, PR China.
School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, 100083, PR China.
J Hazard Mater. 2021 Jun 5;411:125044. doi: 10.1016/j.jhazmat.2021.125044. Epub 2021 Jan 6.
In this study, the nanocomposite adsorbent (ZnS-zeolite NaA) was prepared by a simple ion-exchange method, which modified the zeolite NaA synthesized from fly ash. The removal efficiency, adsorption mechanism of mercury ions by ZnS-zeolite NaA and release of zinc ion into aqueous solution during the adsorption process were determined. The results showed that ZnS nanoclusters were introduced the supercages of zeolite by ion exchange to synthesize the ZnS-zeolite NaA with high removal capacity for Hg in the initial pH 2-7 of solution. Determination of the adsorption kinetics and thermodynamic parameters, in combination with X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy analyses, revealed that the Hg adsorption by ZnS-zeolite NaA was Hg complexed and ion exchanged with ZnS in the ZnS-zeolite NaA to form stable HgS, and then, the released Zn was adsorbed by the zeolite, preventing Zn pollution. The Hg removal rate was greater than 99.90% with the coexistence of either Zn or Cu, Cd and Pb. After five repetitions, the Hg removal rate by the ZnS-zeolite NaA was only slightly decreased by 2%. Therefore, ZnS-zeolite NaA synthesized using fly ash has potential for broad application as a Hg adsorbent.
在这项研究中，通过简单的离子交换法制备了纳米复合材料吸附剂（ZnS-沸石 NaA），对其进行了修饰，即用粉煤灰合成的沸石 NaA。测定了 ZnS-沸石 NaA 对汞离子的去除效率、吸附机理和吸附过程中锌离子向水溶液中的释放。结果表明，通过离子交换将 ZnS 纳米簇引入沸石的超笼中，合成了 ZnS-沸石 NaA，其在溶液初始 pH 值为 2-7 时对 Hg 具有高去除能力。通过吸附动力学和热力学参数的测定，结合 X 射线衍射、X 射线光电子能谱和透射电子显微镜分析，揭示了 ZnS-沸石 NaA 对 Hg 的吸附是通过 Hg 与 ZnS 的络合和离子交换，形成稳定的 HgS，然后，释放的 Zn 被沸石吸附，防止 Zn 污染。当 Zn 或 Cu、Cd 和 Pb 共存时，Hg 的去除率大于 99.90%。重复 5 次后，ZnS-沸石 NaA 的 Hg 去除率仅略有下降 2%。因此，使用粉煤灰合成的 ZnS-沸石 NaA 作为 Hg 吸附剂具有广泛的应用潜力。
