Preparation and use of chemically modified MCM-41 and silica gel as selective adsorbents for Hg(II) ions.
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.
Department of Chemistry, Faculty of Science, Chulalongkorn University, Payathai Road, Bangkok 10330, Thailand.
Mahitti
M
Puanngam
Fuangfa
F
Unob
D000327:Adsorption; D000588:Amines / Q000737:chemistry; D002712:Chlorides / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008628:Mercury / Q000737:chemistry*; D058428:Silica Gel; D012822:Silicon Dioxide / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
D000588:Amines; D002712:Chlorides; C509968:MCM-41; D014874:Water Pollutants, Chemical; D058428:Silica Gel; D012822:Silicon Dioxide; D008628:Mercury