Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China; Institute of Bio- and Geosciences, Agrosphere (IBG-3), Forschungszentrum Jülich GmbH, Wilhelm-Johnen-Straße, 52425, Jülich, Germany.
Institute of Environment Remediation and Human Health, And College of Ecology and Environment, Southwest Forestry University, Kunming, 650224, China.
Chemosphere. 2022 Mar;291(Pt 1):132771. doi: 10.1016/j.chemosphere.2021.132771. Epub 2021 Nov 2.
In this study, a two-step functionalizing strategy by combining co-condensation with grafting procedures was employed to synthesize well-ordered Amino- and Thiol-Bifunctionalized SBA-15 (ATBS) mesoporous silica. Its physicochemical properties, performance, and mechanisms in immobilization of toxic metals Pb and Cd in water and soil were investigated. After bi-functionalization, X-ray diffractometer, transmission electron microscope, and N adsorption-desorption measurements confirmed that the ATBS maintained a highly-ordered mesoporous structure, large surface area and pore volume. The elemental analysis, Fourier transform infrared spectroscopy and X-ray Photoelectron Spectroscopy (XPS) evidenced the successful incorporation of amine and thiol groups into ATBS. These structure and functional characteristics of ATBS benefited Pb and Cd sorption. Sorption isotherms of Pb and Cd were better fit with Sips and Redlich-Peterson models. Sorption kinetics suggested that Pb sorption was mainly regulated by chemical reactions, whereas both diffusion process and chemical reactions were rate-regulating steps in Cd sorption. ATBS showed the maximum sorption capacities for Pb and Cd at 120 and 38 mg g, respectively. The sorption mechanisms revealed by XPS measurements suggested that Cd sorption was mainly attributed to thiol groups while Pb was efficiently bond to both thiol and amino groups. High and stable sorption efficiencies were attained in the pH range of 4-6, with a higher affinity towards Pb than Cd. Furthermore, its ability to immobilize Pb and Cd in soils was examined with an incubation experiment, which showed that ATBS reduced 30-56% of MgCl-extractable Pb and Cd in a contaminated soil. The synthesized sorbent via the two-step functionalizing strategy shows high sorption efficiency towards Pb and Cd, and thus it has potential application in remediating Pb and Cd contaminated water and soils.
在这项研究中，采用两步官能化策略，通过缩合与接枝过程相结合，合成了有序的 Amino-和 Thiol-双官能化 SBA-15（ATBS）介孔硅。研究了其在水中和土壤中固定有毒金属 Pb 和 Cd 的物理化学性质、性能和机制。经过双官能化后，X 射线衍射仪、透射电子显微镜和 N 吸附-脱附测量证实，ATBS 保持了高度有序的介孔结构、大的表面积和孔体积。元素分析、傅里叶变换红外光谱和 X 射线光电子能谱（XPS）证明了胺基和巯基成功地结合到 ATBS 中。ATBS 的这些结构和功能特性有利于 Pb 和 Cd 的吸附。Pb 和 Cd 的吸附等温线更符合 Sips 和 Redlich-Peterson 模型。吸附动力学表明，Pb 的吸附主要受化学反应控制，而 Cd 的吸附则是扩散过程和化学反应共同调节。ATBS 对 Pb 和 Cd 的最大吸附容量分别为 120 和 38 mg g。XPS 测量揭示的吸附机制表明，Cd 的吸附主要归因于巯基，而 Pb 则与巯基和氨基都有效键合。在 pH 4-6 的范围内，吸附效率高且稳定，对 Pb 的亲和力高于 Cd。此外，还用一个孵育实验考察了其在土壤中固定 Pb 和 Cd 的能力，结果表明，ATBS 可降低污染土壤中 30-56%的 MgCl 可提取的 Pb 和 Cd。通过两步官能化策略合成的吸附剂对 Pb 和 Cd 具有高的吸附效率，因此在修复 Pb 和 Cd 污染的水和土壤方面具有潜在的应用前景。
