期刊
APPLIED CLAY SCIENCE
卷 42, 期 1-2, 页码 292-299出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.clay.2008.01.015
关键词
Adsorption; Cr(VI); Organoclays; Rectorite; Stearyl trimethylammonium chloride (STAC)
资金
- Key Project of Chinese Ministry of Education [107076]
Adsorption of Cr(VI) on stearyl trimethylammonium chloride modified rectorite (STAC-rectorite) was investigated by batch studies, X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) analyses. The Cr(VI) adsorption on STAC-rectorite is well described by the Freundlich isotherm. The adsorption capacity reached as high as 21 g/kg for Cr(VI), or 400 mmol/kg of chromate. The enthalpy change of adsorption (Delta H) is -9.4 kJ/mol, indicating retention of Cr(VI) on STAC-rectorite is via physical adsorption. Higher Cr(VI) adsorption on STAC-rectorite occurred in acidic solutions (pH 4) and the amount of adsorbed Cr(VI) decreased rapidly with increasing pH as a higher (OH)(-) concentration will compete against Cr(VI) for adsorption sites, thus, inhibiting formation of Cr(VI)-STAC complex. FTIR analysis shows that the adsorbed STAC forms an admicelle surfactant surface coverage, which is responsible for Cr(VI) adsorption. Band position shifting of Si-O vibration and H-O vibration of water molecules before and after reaction with Cr(VI) indicates that the adsorbed Cr(VI) influences the strength of the Si-O chemical bonds in the siloxane layer and H-O bonds of intercalated water molecules. (C) 2008 Elsevier B.V. All rights reserved.
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