Magalhães F, Pereira M C, Fabris J D, Bottrel S E C, Sansiviero M T C, Amaya A, Tancredi N, Lago R M
Departamento de Química, ICEx, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
J Hazard Mater. 2009 Jun 15;165(1-3):1016-22. doi: 10.1016/j.jhazmat.2008.10.087. Epub 2008 Oct 31.
Highly reactive carbon/Fe composites were prepared from tar used as a carbon source, and hematite (alpha-Fe(2)O(3)), a widespread naturally available iron oxide. Tar was impregnated on hematite and thermally treated under N(2) atmosphere. Mössbauer, powder X-ray diffraction and magnetization data suggested that treatment at 400 and 600 degrees C produced only magnetite (Fe(3)O(4)) whereas at 800 degrees C mainly metallic iron (Fe(0)) was produced. Raman, TG and XRD analyses of the different composites revealed the presence of amorphous and graphitic carbon highly dispersed on the iron oxide surface. The composites obtained at 800 degrees C were very efficient in reducing aqueous Cr(VI), as CrO(4)(2-), even compared to finely ground commercial Fe(0). XPS and Mössbauer data showed that after five consecutive reuses, the composites deactivated, due to the surface oxidation of Fe(0). A simple treatment at 800 degrees C completely regenerated the composite by reducing Fe(3+) species allowing several reuses.
以焦油为碳源，赤铁矿（α-Fe₂O₃，一种广泛存在的天然氧化铁）制备了高活性碳/铁复合材料。将焦油浸渍在赤铁矿上，并在氮气气氛下进行热处理。穆斯堡尔谱、粉末X射线衍射和磁化数据表明，在400℃和600℃处理仅生成磁铁矿（Fe₃O₄），而在800℃主要生成金属铁（Fe(0)）。对不同复合材料的拉曼光谱、热重分析和X射线衍射分析表明，在氧化铁表面存在高度分散的无定形碳和石墨化碳。即使与细磨的商业Fe(0)相比，在800℃获得的复合材料在还原水溶液中的Cr(VI)（以CrO₄²⁻形式存在）方面也非常有效。X射线光电子能谱和穆斯堡尔谱数据表明，经过连续五次重复使用后，由于Fe(0)的表面氧化，复合材料失活。在800℃进行简单处理，通过还原Fe³⁺物种使复合材料完全再生，从而可以进行多次重复使用。
