Yale University, Department of Chemical and Environmental Engineering, New Haven, CT 06511, United States; Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment, Yale University, United States.
University of Twente, Faculty of Engineering Technology, Enschede, 7500 AE, Netherlands.
J Colloid Interface Sci. 2019 Mar 1;537:465-474. doi: 10.1016/j.jcis.2018.11.018. Epub 2018 Nov 13.
As the commercial use of nano metal oxides, including iron oxides, becomes more prevalent, there is a need to understand functionality as it relates to the inherent properties of the nanomaterial. Many applications of nanomaterials rely on adsorption, ranging from catalysis to aqueous remediation. In this paper, adsorption of selenium (Se), an aqueous contaminant, is used as a model sorbate to elucidate the relationships of structure, property, and (adsorptive) function of nano-hematite (nα-FeO). As such, six nα-FeO particles were synthesized controlling for size, shape and surface area without capping agents. Sorbent characteristics of the six particles were then assessed for their impact on selenite (HSeO) and selenate (SeO) adsorption capacity and mechanism. Mechanism was assessed using in-situ attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy and extended X-ray absorption fine edge spectroscopy (EXAFS). Regression analyses were then performed to determine which characteristics best describe adsorption capacity and binding mechanisms of Se on nα-FeO. The results demonstrate that crystal surface structure, specifically presence of the {0 1 2} facet promotes adsorption of Se and the presence of {0 1 2} facets promotes SeO sorption to a greater extent than HSeO. The data further indicates that {1 1 0} facets bind HSeO with binuclear complexes while {0 1 2} facets bind HSeO via mononuclear inner-sphere complexes. Specific nα-FeO facets also likely direct the ratio of inner to outer-sphere complexes in SeO adsorption.
随着纳米金属氧化物（包括氧化铁）在商业上的应用越来越普遍，有必要了解其功能与纳米材料固有特性的关系。许多纳米材料的应用依赖于吸附，从催化到水修复都有涉及。在本文中，以硒（Se）的吸附（一种水污染物）作为模型吸附质，阐明了纳米赤铁矿（nα-FeO）的结构、性质和（吸附）功能之间的关系。因此，在没有封端剂的情况下，通过控制尺寸、形状和表面积合成了六种 nα-FeO 颗粒。然后评估了这六种颗粒的吸附剂特性，以了解其对亚硒酸盐（HSeO）和硒酸盐（SeO）吸附容量和机制的影响。使用原位衰减全反射-傅里叶变换红外（ATR-FTIR）光谱和扩展 X 射线吸收精细边缘光谱（EXAFS）评估了机制。然后进行回归分析，以确定哪些特性最能描述 Se 在 nα-FeO 上的吸附容量和结合机制。结果表明，晶体表面结构，特别是{0 1 2}面的存在促进了 Se 的吸附，并且{0 1 2}面促进了 SeO 的吸附，其程度大于 HSeO。数据还表明，{1 1 0}面通过双核配合物与 HSeO 结合，而{0 1 2}面通过单核内球配合物与 HSeO 结合。特定的 nα-FeO 面也可能直接影响 SeO 吸附中外层与内层配合物的比例。
