熔融法制备铬掺杂磁铁矿及其催化UV-Fenton反应降解酸性橙Ⅱ的研究

The Preparation of Chromium-Substituted Magnetite by Melting and its UV-Fenton Catalytic Activity in Acid OrangeⅡ Degradation

在自然界,磁铁矿结构中广泛存在类质同象置换。部分置换离子显著改变磁铁矿的表面反应性,影响其对有机污染物的催化降解性能。本研究用熔融法合成一系列不同掺杂量的铬掺杂磁铁矿,利用X射线衍射(XRD)和X射线吸收精细结构谱(XAFS)等谱学技术对合成磁铁矿进行结构表征,并在中性条件下,探讨磁铁矿催化UV-Fenton反应降解酸性橙Ⅱ的性能。铬掺杂磁铁矿为立方晶系反尖晶石结构,Cr以+3价占据在八面体位。铬掺杂显著提高磁铁矿对酸性橙Ⅱ的催化降解性能,降解过程以异相UV-Fenton反应为主,遵循准一级动力学方程。反应160 min后,铬掺杂磁铁矿对酸性橙Ⅱ的矿化率达40%。

In most natural magnetite, iron cations are usually isomorphously substituted by transitional metal cations. Some substitutions vary the surface reactivity of magnetite, and accordingly affect its catalytic activity in the degradation of organic pollutants. In this study, a series of chromium-substituted magnetite were synthesized by melting and characterized by X-ray diffraction(XRD) and X-ray absorption fine structure spectroscopy(XAFS). The obtained magnetite samples have a spinel structure, where Cr3+ occupies the octahedral sites in magnetite structure. Cr-substitution noticeably improved the degradation of acid orange Ⅱ by magnetite by way of a heterogeneous Fenton reaction. The degradation process followed the pseudo-first-order kinetic reaction. After 160 min of reaction, 40% of acid orange Ⅱ was mineralized.