Thermo-XRD-analysis of Co-, Ni- and Cu-montmorillonite treated with anionic alizarinate: Curve-fitting

M. Epstein, I. Lapides, S. Yariv*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Co- and Ni-montmorillonites adsorb in aqueous suspensions up to 13 mmol alizarinate per 100 g clay, onto the broken-bonds whereas Cu-clay adsorbs up to 25 mmol dye per 100 g clay into the interlayer space. Unloaded Co-, Ni- and Cu-clays and samples loaded with increasing amounts of alizarinate, were gradually heated in air to 360°C and analyzed by X-ray diffraction. All diffractograms were curve-fitted. Fitted diffractograms of non-heated samples, showed two peak components labeled C and D, ≈1.22 and ≈1.32 nm, characterizing tactoids with mono- and non-complete bilayers of water, respectively. After heating at 120°C component D decreased or disappeared and two new components A and B appeared at ≈0.99 and ≈1.08 nm, representing collapsed tactoids and tactoids with interlamellar oxy-cations, respectively. At 250°C, C and D decreased or disappeared but A and B appeared in all fitted diffractograms. Co- and Ni-clay after heating at 360°C did not show C and D. Components A and B proved that these clays collapsed indicating that initially there was no alizarinate in the interlayers. At 360°C, C and D persisted in the fitted-diffractograms of Cu-clay, representing tactoids with interlamellar charcoal formed from the partial oxidation of adsorbed dye initially located in the interlayers.

Original languageEnglish
Pages (from-to)585-594
Number of pages10
JournalJournal of Thermal Analysis and Calorimetry
Volume82
Issue number3
DOIs
StatePublished - Nov 2005

Keywords

  • Alizarin
  • Co-montmorillonite
  • Cu-montmorillonite
  • Curve-fitting
  • Ni-montmorillonite
  • Thermo-XRD-analysis

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