Carbon-coated montmorillonite nanocomposite for the removal of chromium(VI) from aqueous solutions

Jing Wei, Chen Tu, Guodong Yuan, Dongxue Bi, Liang Xiao, Benny K.G. Theng, Hailong Wang, Yong Sik Ok

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

A carbon-coated montmorillonite nanocomposite (CMt), obtained by hydrothermal carbonization of montmorillonite suspension in glucose, was used to remove Cr(VI) from aqueous solutions. The distribution and speciation of Cr immobilized by CMt were assessed by transmission electron microscopy with energy-dispersive X-ray analysis, X-ray absorption near edge structure (XANES), and scanning transmission soft X-ray microscopy (STXM). The variation in the functional groups and molecular structures of CMt was also investigated. The capacity of CMt for adsorbing Cr(VI) was markedly superior to that of the parent montmorillonite, showing maximum uptake of 100 and 12.4 mg g−1 at pH 2 and 8, respectively. The Cr K-edge XANES and STXM analyses indicated that Cr(VI) was reduced to Cr(III) under both acidic and alkaline conditions, while a Cr(OH)3 precipitate and Cr(III)-acetate complex were the predominant species present on the CMt surface. The Fourier transform infrared spectroscopy and C K-edge XANES further suggested that the phenolic groups in CMt could serve as electron donors, facilitating Cr(VI) reduction. The combined results indicate that electrostatic attraction, Cr(VI) reduction, complexation, and precipitation are involved in the removal of Cr(VI) by CMt.

Original languageEnglish
Pages (from-to)541-549
Number of pages9
JournalJournal of Hazardous Materials
Volume368
DOIs
Publication statusPublished - 2019 Apr 15

Keywords

  • Adsorption
  • Carbon-coated montmorillonite
  • Chromium(VI)
  • STXM
  • XANES

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution
  • Health, Toxicology and Mutagenesis

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