Removal of hexavalent chromium [Cr(VI)] from aqueous solutions by the diatomite-supported/unsupported magnetite nanoparticles.
Removal of hexavalent chromium [Cr(VI)] from aqueous solutions by the diatomite-supported/unsupported magnetite nanoparticles.
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DOI：
10.1016/j.jhazmat.2009.08.129
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发表时间：
2010-01
影响因子：
13.6
通讯作者：
P. Yuan;Dong Liu;Mingde Fan;Dan Yang;Runliang Zhu;Fei Ge;Jianxi Zhu;Hongping He
中科院分区：
文献类型：
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作者：
P. Yuan;Dong Liu;Mingde Fan;Dan Yang;Runliang Zhu;Fei Ge;Jianxi Zhu;Hongping He
采用共沉淀法和纯溶胶法制备了硅藻土负载/非负载磁铁矿纳米颗粒，并用x射线衍射、氮吸附、元素分析、差示扫描量热法、透射电镜和x射线光电子能谱对纳米颗粒进行了表征。无负载和负载的磁铁矿纳米颗粒的平均尺寸分别在25 nm和15nm左右。负载型磁铁矿纳米颗粒存在于硅藻壳表面或孔隙内部，具有较好的分散性和较低的共聚集性。六价铬[Cr(VI)]在合成的磁铁矿纳米颗粒上的吸附主要受物理化学过程控制，其中包括静电吸引和氧化还原过程，其中Cr（VI）被还原成三价铬[Cr(III)]。对Cr（VI）的吸附具有高度的ph依赖性，吸附动力学服从准二阶模型。硅藻土负载/不负载磁铁矿的吸附数据符合Langmuir等温线方程。负载型磁铁矿对单位质量磁铁矿的吸附能力优于无负载型磁铁矿，热稳定性优于无负载型磁铁矿。这些结果表明，硅藻土负载/不负载的磁铁矿纳米颗粒很容易制备，在去除水溶液中的Cr（VI）方面具有广阔的应用前景。
Diatomite-supported/unsupported magnetite nanoparticles were prepared by co-precipitation and hydrosol methods, and characterized by X-ray diffraction, nitrogen adsorption, elemental analysis, differential scanning calorimetry, transmission electron microscopy and X-ray photoelectron spectroscopy. The average sizes of the unsupported and supported magnetite nanoparticles are around 25 and 15nm, respectively. The supported magnetite nanoparticles exist on the surface or inside the pores of diatom shells, with better dispersing and less coaggregation than the unsupported ones. The uptake of hexavalent chromium [Cr(VI)] on the synthesized magnetite nanoparticles was mainly governed by a physico-chemical process, which included an electrostatic attraction followed by a redox process in which Cr(VI) was reduced into trivalent chromium [Cr(III)]. The adsorption of Cr(VI) was highly pH-dependent and the kinetics of the adsorption followed a pseudo-second-order model. The adsorption data of diatomite-supported/unsupported magnetite fit well with the Langmuir isotherm equation. The supported magnetite showed a better adsorption capacity per unit mass of magnetite than unsupported magnetite, and was more thermally stable than their unsupported counterparts. These results indicate that the diatomite-supported/unsupported magnetite nanoparticles are readily prepared, enabling promising applications for the removal of Cr(VI) from aqueous solution.