Characterization of Lead Uptake by Nano-Sized Hydroxyapatite: A Molecular Scale Perspective
Characterization of Lead Uptake by Nano-Sized Hydroxyapatite: A Molecular Scale Perspective
复制标题
纳米羟基磷灰石吸收铅的表征：分子尺度视角
DOI：
10.1021/acsearthspacechem.8b00020
复制
发表时间：
2018-06-01
影响因子：
3.4
通讯作者：
Li, Wei
中科院分区：
文献类型：
--
作者：
Guan, Dong-Xing;Ren, Chao;Li, Wei
螯合有毒金属（例如，羟基磷灰石（HAP）修复铅污染土壤的研究受到广泛关注。本研究采用批处理法、X射线衍射（XRD）、傅立叶变换红外光谱（FTIR）和高分辨透射电子显微镜（HRTEM）对HAP吸收Pb的行为进行了综合研究。结果表明，铅的吸收机制不仅涉及表面吸附和沉淀，但也纳入依赖于初始铅浓度。在低Pb浓度下（例如，0.1 mM）时，表面吸附可能对总Pb吸收有相当大的贡献，因为在XRD分析中没有观察到变化。在0.5- 5.7mM的中等浓度下，通过XRD分析证明磷酸铅沉淀物的形成，在2 θ处具有类似于30.3度的新峰，并且可以指示为结晶羟基焦磷铁矿（HPY）。这也与在2.5-5.7 mM的Pb水平下Pb吸附/Ca溶解的比率（0.9-1.0）一致。在较高的Pb浓度（>= 6.6 mM）下，观察到较大的Pb吸附/Ca溶解比率（1.2-1.9），并且令人惊讶的是，表示HPY的XRD信号减弱。这可能意味着，铅已纳入通过取代钙网站到HAP晶格不同的溶解沉淀过程中发生在中等铅浓度范围。高分辨透射电镜直接观察到的高钙含量的PbxCa_（5-x）（PO_4）（3）OH固溶体进一步支持了这一论点。总体而言，本研究提供的基础地球化学的分子水平上的理解与铅与HAP相互作用，可以提高HAP材料的应用效率的环境修复。
Sequestration of toxic metals (e.g., Pb) by hydroxyapatite (HAP) has attracted wide attention in soil remediation. In this study, a comprehensive investigation on Pb uptake by HAP was conducted using combined batch method, X-ray diffraction (XRD), Fourier-transform infrared, and high-resolution transmission electron microscopy (HRTEM). Results revealed that the Pb uptake mechanism involves not only surface adsorption and precipitation but also incorporation depending on the initial Pb concentration. At low Pb concentrations (e.g., 0.1 mM), surface adsorption may contribute considerably to the total Pb uptake as no changes were observed in the XRD analysis. At medium concentrations of 0.5-5.7 mM, formation of lead phosphate precipitates was evidenced by XRD analysis with new peaks at 2 theta of similar to 30.3 degrees and can be indexed to crystalline hydroxypyromorphite (HPY). This was also consistent with the ratios (0.9-1.0) of Pb-sorbed/Ca-dissolved at Pb level of 2.5-5.7 mM. At higher Pb concentrations (>= 6.6 mM), larger ratios (1.2-1.9) of Pb-sorbed/Ca-dissolved were observed, and surprisingly, the XRD signal denoting HPY was weakened. This may imply that Pb has incorporated through substituting the Ca sites into the HAP crystal lattice different from the dissolution-precipitation process occurring at the medium Pb concentration range. Direct observation of PbxCa5-x(PO4)(3)OH solid solutions with high Ca content from HRTEM further supported this argument. Overall, the molecular level understanding of the fundamental geochemistry for Pb interaction with HAP provided by this research could improve the efficiency of the application of HAP material for environmental remediation.