Adsorption of Cr(VI) on STAC-modified rectorite

Hanlie Hong, Wei-Teh Jiang, Xiaoling Zhang, Liyun Tie, Zhaohui Li

Research output: Contribution to journalArticle

79 Citations (Scopus)

Abstract

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 (ΔH) 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.

Original languageEnglish
Pages (from-to)292-299
Number of pages8
JournalApplied Clay Science
Volume42
Issue number1-2
DOIs
Publication statusPublished - 2008 Dec 1

All Science Journal Classification (ASJC) codes

  • Geology
  • Geochemistry and Petrology

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