Composition and structural aspects of naturally occurring ferrihydrite
Composition and structural aspects of naturally occurring ferrihydrite
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DOI：
10.1016/j.crte.2010.11.001
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发表时间：
2011-02-01
影响因子：
1.4
通讯作者：
Brown, Gordon E., Jr.
中科院分区：
文献类型：
--
作者：
Cismasu, A. Cristina;Michel, F. Marc;Brown, Gordon E., Jr.
采用高能X射线全散射和对分布函数分析、扫描透射X射线显微镜（STXM）、透射电子显微镜（TEM）、BET N（2）比表面积测量、和化学提取，以便对它们的结构和物理性质作为组成的函数进行限制。总体而言，天然样品的短程和中程有序性与合成水铁矿相当。然而，随着Al，Si和有机质含量的增加，颗粒尺寸减小，结构紊乱增加。二氧化硅被怀疑有一个显着的影响，由于其对铁聚合和颗粒生长的抑制作用的结晶度的水铁矿，它可能是复杂的水铁矿纳米粒子的表面。另一方面，铝可以替代天然水铁矿中的Fe（3+）。有机物是普遍的，密切相关的水铁矿聚集体，其存在下，在水铁矿沉淀可能有助于额外的结构紊乱。杂质含量的增加不仅影响水铁矿的粒度和结构有序性，而且还可能对其表面活性产生显著影响。(C)2010年科学院。出版社：Elsevier Masson SAS All rights reserved.
A series of naturally occurring ferrihydrites sampled from an acid mine drainage environment were characterized and compared with synthetic 2-line ferrihydrite using high energy X-ray total scattering and pair distribution function analysis, Scanning Transmission X-ray Microscopy (STXM), Transmission Electron Microscopy (TEM), BET N(2) surface area measurements, and chemical extractions in order to place constraints on their structural and physical properties as a function of composition. Overall, the short- and intermediate-range ordering of the natural samples is comparable to synthetic ferrihydrite. However, with increasing Al, Si, and organic matter contents, a decrease in particle size and an increase in structural disorder were observed. Silica is suspected to have a pronounced effect on the crystallinity of ferrihydrite as a result of its inhibitory effect on Fe polymerization and particle growth, and it is likely complexed at the surfaces of ferrihydrite nanoparticles. Aluminum, on the other hand may substitute for Fe(3+) in natural ferrihydrite. Organic matter is pervasive and intimately associated with ferrihydrite aggregates, and its presence during ferrihydrite precipitation may have contributed to additional structural disorder. The increase in impurity content affects not only the particle size and structural order of ferrihydrite but may also have a significant effect on its surface reactivity. (C) 2010 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.