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Chromium(III/VI) binding to magnetite, hausmannite, and jacobsite nanomaterials.

机译：铬（III / VI）与磁铁矿，方锰矿和菱锰矿纳米材料的结合。

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摘要

Chromium is a very versatile metal that is used for many applications in the world. Two of the most common ions of chromium that occur naturally are Cr(III) and Cr(VI). These two oxidation states have very different heath effects in living organisms. Cr(III) is relatively non-toxic to living organisms however, Cr(VI) is very toxic to most living organisms This study was conducted to find a simple and cost effective method to sequester these two common ionic species of chromium from sources of water that are adjacent to or that are affected by other water sources contaminated by these two ions. In this study an investigation was conducted to observe the binding between three different engineered nanomaterials (Magnetite, Hausmannite and Jacobsite) to both hexavalent and trivalent chromium. A traditional synthesis was used to make these nanomaterials, which consisted of a titration of iron(II) chloride for the Magnetite, manganese sulfate for the Hausmannite, and a combination of the two previous salts in a 2:1 ratio for the Jacobsite. Magnetite (Fe 3O4) and Hausmannite (Mn3O4) were synthesized using two different aging processes and Jacobsite (MnFe2O 4) was synthesized using only one process. The first aging process involves a traditional heating source in an open vessel at 90ºC for 60 minutes. The second ageing technique used was a microwave assisted hydrothermal synthesis method using a closed vessel at 90ºC for 30 minutes. The Jacobsite was aged using only the microwave technique.The batch studies showed that the binding to the three different materials were pH dependent. The studies showed that Cr(III) and Cr(VI) bind to the nanomaterials differently at different pHs. In addition, the binding of the Cr(III) to the nano-Magnetite showed identical behavior binding to both the open vessel and the hydrothermally synthesized nanoparticles with pH. But the Cr(VI) showed differences in the binding to the open vessel and the closed vessel nano-Magnetite, with higher binding at lower pHs observed with the open vessel nanomaterials compared to the closed vessel nanomaterials. The Hausmannite micro-waved aged material had a better affinity for the hexavalent chromium then the open aged system. The studies with Cr(III) showed that the ion had greater affinity with the Hausmannite material than with Cr(VI). The Jacobsite showed favorable binding to Cr(VI) then it did to Cr(III) at higher pHs. The studies showed that all the materials exhibited the majority of their binding to chromium at around pH 4. Further data was obtained from batch studies included time dependency, isotherm capacities and interference studies. Overall the nanomaterials adsorbed both chromium species, and two of them (Magnetite and Hausmannite) reduced the hazardous Cr(VI) to Cr(III) determined by X-ray absorption spectroscopy. The materials were effective at removing both chromium ions from solution ns containing competing anions.
机译：铬是一种用途广泛的金属，在世界范围内被广泛使用。自然产生的铬中最常见的两个离子是Cr（III）和Cr（VI）。这两种氧化态在活生物体中具有非常不同的健康影响。 Cr（III）对活生物体无毒，但是Cr（VI）对大多数活生物体有毒。本研究旨在找到一种简单且经济高效的方法从水源中隔离这两种常见的离子型铬与这两个离子污染的其他水源相邻或受其影响的离子。在这项研究中，进行了一项调查，以观察三种不同的工程纳米材料（磁铁矿，Hausmannite和Jacobsite）与六价铬和三价铬之间的结合。传统的合成方法用于制备这些纳米材料，包括滴定氯化磁铁矿的氯化铁（II），滴定于Hausmannite的硫酸锰，以及按雅各布矿的2：1比例混合的前两种盐。使用两种不同的时效工艺合成了磁铁矿（Fe 3O4）和Hausmannite（Mn3O4），仅使用一种工艺合成了雅各铁矿（MnFe2O 4）。第一个老化过程涉及在敞口容器中于90°C下放置60分钟的传统加热源。所使用的第二种时效技术是微波辅助水热合成法，使用密闭容器在90°C下加热30分钟。 Jacobsite仅使用微波技术进行时效处理。批处理研究表明，与三种不同材料的结合均取决于pH。研究表明，Cr（III）和Cr（VI）在不同的pH值下与纳米材料的结合不同。此外，Cr（III）与纳米磁铁矿的结合表现出相同的行为，即与开放容器和具有pH的水热合成纳米粒子结合。但是Cr（VI）在与开放容器和封闭容器纳米磁铁矿的结合方面表现出差异，与封闭容器纳米材料相比，在较低pH下观察到开放容器纳米材料具有更高的结合力。 Hausmannite微波时效材料对六价铬的亲和力比开放时效系统好。对Cr（III）的研究表明，该离子与Hausmannite材料的亲合力大于与Cr（VI）的亲和力。雅各布矿在较高的pH值下表现出与Cr（VI）的良好结合，然后与Cr（III）结合。研究表明，所有材料在pH约为4时都表现出大多数与铬的结合。从批处理研究获得的其他数据包括时间依赖性，等温线容量和干扰研究。总体而言，纳米材料吸收了两种铬，其中两种（磁铁矿和Hausmannite）将X-射线吸收光谱法测定的有害Cr（VI）还原为Cr（III）。该材料可有效地从含有竞争性阴离子的溶液ns中除去两种铬离子。

著录项

  • 作者

    Hernandez, Jeffrey.;

  • 作者单位

    The University of Texas at El Paso.;

  • 授予单位 The University of Texas at El Paso.;
  • 学科 Chemistry Analytical.Environmental Sciences.
  • 学位 M.S.
  • 年度 2010
  • 页码 92 p.
  • 总页数 92
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 语言学;
  • 关键词

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