Preparation and use of chemically modified MCM-41 and silica gel as selective adsorbents for Hg(II) ions

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• 作者：Mahitti Puanngam ; Fuangfa Unob
• 关键词：Silica gel ; Mesoporous silica ; MCM-41 ; Extraction ; Mercuric ions
• 刊名：Journal of Hazardous Materials
• 出版年：2008
• 出版时间：15 June 2008
• 年：2008
• 卷：154
• 期：1-3
• 页码：578-587
• 全文大小：809 K

文摘

Adsorbents for Hg(II) ion extraction were prepared using amorphous silica gel and ordered MCM-41. Grafting with 2-(3-(2-aminoethylthio)propylthio)ethanamine was used to functionalize the silica. The functionalized adsorbents were characterized by nitrogen adsorption, X-ray diffraction, ¹³C MAS NMR spectroscopy and thermogravimetric analysis. The adsorption properties of the modified silica gel and MCM-41 were compared using batch method. The effect of pH, stirring time, ionic strength and foreign ions were studied. The extraction of Hg(II) ions occurred rapidly with the modified MCM-41 and the optimal pH range for the extraction by the modified materials was pH 4–7. Foreign ions, especially Cl⁻ had some effect on the extraction efficiency of the modified silica gel and the modified MCM-41. The adsorption behavior of both adsorbents could be described by a Langmuir model at 298 K, and the maximum adsorption capacity of the modified silica gel and MCM-41 at pH 3 was 0.79 and 0.70 mmol g⁻¹, respectively. The modified MCM-41 showed a larger Langmuir constant than that of the modified silica gel, indicating a better ability for Hg(II) ion adsorption. The results indicate that the structure of the materials affects the adsorption behavior. These materials show a potential for the application as effective and selective adsorbents for Hg(II) removal from water.