Adsorption of Cr(VI) on STAC-modified rectorite

作者：Hong, Hanlie; Jiang, Wei-Teh; Zhang, Xiaoling; Tie, Liyun; Li, Zhaohui^*

来源：Applied Clay Science, 2008, 42(1-2): 292-299.

DOI：10.1016/j.clay.2008.01.015

• Adsorption
• Cr(VI)
• Organoclays
• Rectorite
• Stearyl trimethylammonium chloride (STAC)

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.

• 出版日期2008-12
• 单位中国地质大学（北京）; 武汉理工大学