Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, China.
J Hazard Mater. 2010 Sep 15;181(1-3):112-20. doi: 10.1016/j.jhazmat.2010.04.101.
The catalytic activity of natural vanadium-titanium magnetite was investigated in the decolorization of Acid Orange II by non-homogeneous Fenton process. The natural catalysts purified by magnetic separation were characterized using X-ray diffraction (XRD), polarizing microscope, X-ray absorption fine structure (XAFS) analysis and Mössbauer spectroscopy. The obtained results show that the natural samples after magnetic separation mainly contain titanomagnetite, with a small amount of ilmenite and chlorite. Titanomagnetite is doped with vanadium, whose the valency is mainly +3 and occupies the octahedral site. Batch decolorization studies were performed to evaluate the influences of various experimental parameters like initial pH, the amount of catalyst and initial concentration of hydrogen peroxide on the decolorization efficiency of Acid Orange II. The decolorization of the dye mainly relied on degradation. The degradation efficiency was strongly dependent on pH of the medium where it increased as the pH decreased in acid range. The increase of catalyst and hydrogen peroxide could accelerate the degradation. The catalytic property of natural vanadium-titanium magnetite in the degradation of Acid Orange II was stronger than that of synthetic magnetite (Fe(3)O(4)). The catalytic activity of the natural samples was greatly related to the titanomagnetite content. The degradation process was dominated by heterogeneous Fenton reaction, complying with pseudo-first-order rate law. The natural catalyst has a good catalytic stability.
采用非均相 Fenton 法研究了天然钒钛磁铁矿在酸性橙 II 脱色中的催化活性。通过磁分离对天然催化剂进行了纯化，并采用 X 射线衍射（XRD）、偏光显微镜、X 射线吸收精细结构（XAFS）分析和穆斯堡尔谱对其进行了表征。结果表明，磁分离后的天然样品主要含有钛磁铁矿，少量的钛铁矿和绿泥石。钛磁铁矿中掺杂了钒，其价态主要为+3，占据八面体位。进行了分批脱色研究，以评估初始 pH 值、催化剂用量和初始过氧化氢浓度等各种实验参数对酸性橙 II 脱色效率的影响。染料的脱色主要依赖于降解。降解效率强烈依赖于介质的 pH 值，在酸性范围内随着 pH 值的降低而增加。催化剂和过氧化氢的增加可以加速降解。天然钒钛磁铁矿在酸性橙 II 降解中的催化性能强于合成磁铁矿（Fe3O4）。天然样品的催化活性与钛磁铁矿含量密切相关。降解过程主要由非均相 Fenton 反应控制，符合准一级反应动力学规律。天然催化剂具有良好的催化稳定性。
