Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.
Department of Ecosystem Science and Management, University of Wyoming, Laramie, WY 82071, USA.
J Hazard Mater. 2015 Oct 15;296:221-229. doi: 10.1016/j.jhazmat.2015.04.055. Epub 2015 Apr 23.
Fe-doped cryptomelanes were synthesized by refluxing at ambient pressure, followed by characterization with multiple techniques and test in photocatalytic degradation of phenol. The introduction of Fe(III) into the structure of cryptomelane results in a decrease in particle size and the contents of Mn and K(+), and an increase in the Mn average oxidation state (AOS), specific surface area and UV-vis light absorption ability. Mn and Fe K-edge extended X-ray absorption fine structure spectroscopy analysis indicates that some Fe(III) is incorporated into the framework of cryptomelane by replacing Mn(III) while the remaining Fe(3+) is adsorbed in the tunnel cavity. These Fe-doped cryptomelanes have significantly improved the photocatalytic degradation rate of phenol, with the sample of ∼3.04 wt.% Fe doping being the most reactive and achieving a degradation rate of 36% higher than that of the un-doped one. The enhanced reactivity can be ascribed to the increase in the coherent scattering domain size of the crystals, Mn AOS and light absorption, as well as the presence of sufficient K(+) in the tunnel. The results imply that metal doping is an effective way to improve the performance of cryptomelane in pollutants removal and has the potential for modification of Mn oxide materials.
通过回流在常压下合成了掺铁的cryptomelane，并用多种技术进行了表征，并在苯酚的光催化降解中进行了测试。Fe(III)的引入导致cryptomelane的粒径减小，Mn 和 K(+)的含量减少，Mn 的平均氧化态（AOS）、比表面积和紫外可见光吸收能力增加。Mn 和 Fe K 边扩展 X 射线吸收精细结构光谱分析表明，一些 Fe(III)通过取代 Mn(III)进入 cryptomelane 的骨架，而剩余的 Fe(3+)则吸附在隧道腔中。这些掺铁的 cryptomelane 显著提高了苯酚的光催化降解率，掺约 3.04wt.%Fe 的样品的反应性最高，降解率比未掺杂的样品高 36%。增强的反应性可归因于晶体的相干散射畴尺寸、Mn AOS 和光吸收的增加，以及隧道中存在足够的 K(+)。结果表明，金属掺杂是提高 cryptomelane 在污染物去除中的性能的有效方法，并且有可能对 Mn 氧化物材料进行改性。
