Zhong Yuan-Hong, Liang Xiao-Liang, Zhu Jian-Xi, He Hong-Ping, Yuan Peng
Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
Huan Jing Ke Xue. 2010 Jun;31(6):1568-74.
A series of vanadium-doped magnetite (Fe3-x VxO4, x < 0.4) synthesized by an oxidation-precipitation method, were characterized using chemical analysis, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), as well as thermogravimetric and differential scanning calorimetry (TG-DSC) analyses. The obtained results show that the synthetic Fe3-x VxO4 has spinel structure while vanadium mostly replaces Fe3+ in the octahedral sites. The synthetic Fe3-x VxO4 is magnetic material, with crystal size ranging from 28 to 35 nm. The substitution of vanadium in the magnetite structure increases the amount of surface hydroxyls. The experimental adsorption results indicate that, in neutral pH condition, the maximum adsorption capacities of Fe3-x VxO4 increase obviously with the increase of vanadium concentration in magnetite while the adsorption isotherm complies well with the Langmuir model. The adsorption of methylene blue (MB) on Fe3-x VxO4 can get equilibrium in the first 25 min, supporting a pseudo-second order equation. Moreover, the rise of the solution pH value results in an increase of the adsorption capability of MB on Fe3-x VxO4.
通过氧化沉淀法合成了一系列钒掺杂磁铁矿（Fe3-x VxO4，x < 0.4），并采用化学分析、X射线衍射（XRD）、傅里叶变换红外光谱（FTIR）以及热重和差示扫描量热法（TG-DSC）分析对其进行了表征。所得结果表明，合成的Fe3-x VxO4具有尖晶石结构，而钒主要取代八面体位置的Fe3+。合成的Fe3-x VxO4是磁性材料，晶体尺寸范围为28至35 nm。磁铁矿结构中钒的取代增加了表面羟基的数量。实验吸附结果表明，在中性pH条件下，Fe3-x VxO4的最大吸附容量随着磁铁矿中钒浓度的增加而明显增加，且吸附等温线与朗缪尔模型吻合良好。亚甲基蓝（MB）在Fe3-x VxO4上的吸附在最初25分钟内即可达到平衡，符合准二级方程。此外，溶液pH值的升高导致MB在Fe3-x VxO4上的吸附能力增强。
