Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.
Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China; Laboratory of Physical Chemistry and Colloid Science, Wageningen University, Dreijenplein 6, 6703HB Wageningen, The Netherlands.
J Hazard Mater. 2015 May 15;288:80-8. doi: 10.1016/j.jhazmat.2015.01.068. Epub 2015 Feb 3.
Vanadium(V)-doped hexagonal turbostratic birnessites were synthesized and characterized by multiple techniques and were used to remove Pb(2+) from aqueous solutions. With increasing V content, the V(V)-doped birnessites have significantly decreased crystallinity, i.e., the thickness of crystals in the c axis decreases from 9.8 nm to ∼0.7 nm, and the amount of vacancies slightly increases from 0.063 to 0.089. The specific surface areas of these samples increase after doping while the Mn average oxidation sates are almost constant. V has a valence of +5 and tetrahedral symmetry, and exists as oxyanions, including V₆O₁₆(2-), and VO4(3-) on birnessite edge sites by forming monodentate corning-sharing complexes. Pb LIII-edge extended X-ray absorption fine structure (EXAFS) spectra analysis shows that, at low V contents (V/Mn≤0.07) Pb(2+) mainly binds with birnessite on octahedral vacancy and especially edge sites whereas at higher V contents (V/Mn>0.07) more Pb(2+) associates with V oxyanions and form vanadinite [Pb₅(VO₄)₃Cl]-like precipitates. With increasing V(V) content, the Pb(2+) binding affinity on the V-doped birnessites significantly increases, ascribing to both the formation of the vanadinite precipitates and decreased particle sizes of birnessite. These results are useful to design environmentally benign materials for treatment of metal-polluted water.
掺钒（V）六方层状水钠锰矿的合成及表征，并采用多种技术从水溶液中去除 Pb(2+)。随着 V 含量的增加，V(V)-掺杂水钠锰矿的结晶度显著降低，即晶体 c 轴的厚度从 9.8nm 减小到约 0.7nm，空位的数量从 0.063 略微增加到 0.089。这些样品的比表面积在掺杂后增加，而 Mn 的平均氧化态几乎保持不变。V 的价态为+5，呈四面体对称，以含氧阴离子形式存在，包括 V₆O₁₆(2-)和 VO4(3-)，通过形成单齿桥连共享配合物存在于水钠锰矿边缘位。Pb LIII 边扩展 X 射线吸收精细结构（EXAFS）谱分析表明，在低 V 含量（V/Mn≤0.07）下，Pb(2+)主要与八面体空位上的水钠锰矿结合，特别是边缘位，而在较高的 V 含量（V/Mn>0.07）下，更多的 Pb(2+)与 V 含氧阴离子结合，形成钒铅矿[Pb₅(VO₄)₃Cl]样沉淀。随着 V(V)含量的增加，V 掺杂水钠锰矿对 Pb(2+)的结合亲和力显著增加，这归因于钒铅矿沉淀的形成和水钠锰矿粒径的减小。这些结果有助于设计用于处理金属污染水的环境友好型材料。
