He Hongping, Zhong Yuanhong, Liang Xiaoliang, Tan Wei, Zhu Jianxi, Wang Christina Yan
1] CAS Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China [2] Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou 510640, China.
1] CAS Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China [2] University of Chinese Academy of Sciences, Beijing 100049, China [3] Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou 510640, China.
Sci Rep. 2015 May 11;5:10139. doi: 10.1038/srep10139.
Iron (hydr)oxides are ubiquitous earth materials that have high adsorption capacities for toxic elements and degradation ability towards organic contaminants. Many studies have investigated the reactivity of synthetic magnetite, while little is known about natural magnetite. Here, we first report the reactivity of natural magnetites with a variety of elemental impurities for catalyzing the decomposition of H2O2 to produce hydroxyl free radicals (•OH) and the consequent degradation of p-nitrophenol (p-NP). We observed that these natural magnetites show higher catalytic performance than that of the synthetic pure magnetite. The catalytic ability of natural magnetite with high phase purity depends on the surface site density while that for the magnetites with exsolutions relies on the mineralogical nature of the exsolved phases. The pleonaste exsolution can promote the generation of •OH and the consequent degradation of p-NP; the ilmenite exsolution has little effect on the decomposition of H2O2, but can increase the adsorption of p-NP on magnetite. Our results imply that natural magnetite is an efficient catalyst for the degradation of organic contaminants in nature.
铁（氢）氧化物是普遍存在的地球物质，对有毒元素具有高吸附能力，对有机污染物具有降解能力。许多研究调查了合成磁铁矿的反应活性，而对天然磁铁矿却知之甚少。在此，我们首次报道了含有各种元素杂质的天然磁铁矿催化过氧化氢分解产生羟基自由基（•OH）以及随后对对硝基苯酚（p-NP）的降解反应活性。我们观察到这些天然磁铁矿显示出比合成纯磁铁矿更高的催化性能。具有高相纯度的天然磁铁矿的催化能力取决于表面位点密度，而对于出溶的磁铁矿，其催化能力则取决于出溶相矿物学性质。铁尖晶石出溶可促进•OH的生成以及随后对p-NP的降解；钛铁矿出溶对过氧化氢的分解影响不大，但可增加p-NP在磁铁矿上的吸附。我们的结果表明天然磁铁矿是自然界中有机污染物降解的高效催化剂。
