Synthesis of Na-2-mica from talc and kaolinite

Characterization and Sr2+ uptake

Stephen A. Stout, Sridhar Komarneni

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Na-2-mica, a highly charged sodium fluorophlogopite mica of ideal composition, Na2Mg6Si6Al2O20F 4·χH2O was synthesized from a mixture of talc, kaolinite, ultrafine magnesium oxide or magnesium nitrate, and sodium fluoride at a temperature of 825°C for 12 h. The resulting powders were characterized by X-ray diffraction (XRD), 27Al and 29Si magic angle spinning nuclear magnetic resonance (MAS-NMR), and scanning electron microscopy (SEM). Both magnesium sources resulted in the formation of highly charged expandable mica; however, the sample prepared with magnesium nitrate also contained forsterite as an impurity. The presence of forsterite in the sample was confirmed by a strong resonance at -62 ppm relative to the tetramethylsilane reference. Each mica had four distinctly non-equivalent Si environments. The 27Al MAS-NMR spectra indicated that all Al in the samples was tetrahedrally coordinated. Use of magnesium nitrate as a magnesium source rather than magnesium oxide resulted in slightly smaller particles; however, both sources resulted in mica flakes less than 2 μm. The cation exchange capacity (CEC) of the mica prepared from MgO was close to the theoretical value for Na-2-mica (247 meq 100 g-1); however, the CEC of the sample prepared from magnesium nitrate was much larger than expected. Part of the layer charge for these samples was the result of cation vacancies in the octahedral sheet of the mica as indicated by a Li-migration technique. Ion exchange studies indicated that both micas were highly selective for strontium, whose radioisotope St-90 is commonly present in nuclear waste.

Original languageEnglish (US)
Pages (from-to)377-381
Number of pages5
JournalJournal of Materials Chemistry
Volume13
Issue number2
DOIs
StatePublished - Feb 1 2003

Fingerprint

Talc
Kaolin
Kaolinite
Mica
Magnesium
Nitrates
Magnesium Oxide
Cations
Ion exchange
Magic angle spinning
Positive ions
Magnesia
Strontium Radioisotopes
Sodium
Nuclear magnetic resonance
Radioactive Waste
Sodium Fluoride
mica
Strontium
Radioactive wastes

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Materials Chemistry

Cite this

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abstract = "Na-2-mica, a highly charged sodium fluorophlogopite mica of ideal composition, Na2Mg6Si6Al2O20F 4·χH2O was synthesized from a mixture of talc, kaolinite, ultrafine magnesium oxide or magnesium nitrate, and sodium fluoride at a temperature of 825°C for 12 h. The resulting powders were characterized by X-ray diffraction (XRD), 27Al and 29Si magic angle spinning nuclear magnetic resonance (MAS-NMR), and scanning electron microscopy (SEM). Both magnesium sources resulted in the formation of highly charged expandable mica; however, the sample prepared with magnesium nitrate also contained forsterite as an impurity. The presence of forsterite in the sample was confirmed by a strong resonance at -62 ppm relative to the tetramethylsilane reference. Each mica had four distinctly non-equivalent Si environments. The 27Al MAS-NMR spectra indicated that all Al in the samples was tetrahedrally coordinated. Use of magnesium nitrate as a magnesium source rather than magnesium oxide resulted in slightly smaller particles; however, both sources resulted in mica flakes less than 2 μm. The cation exchange capacity (CEC) of the mica prepared from MgO was close to the theoretical value for Na-2-mica (247 meq 100 g-1); however, the CEC of the sample prepared from magnesium nitrate was much larger than expected. Part of the layer charge for these samples was the result of cation vacancies in the octahedral sheet of the mica as indicated by a Li-migration technique. Ion exchange studies indicated that both micas were highly selective for strontium, whose radioisotope St-90 is commonly present in nuclear waste.",
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Synthesis of Na-2-mica from talc and kaolinite : Characterization and Sr2+ uptake. / Stout, Stephen A.; Komarneni, Sridhar.

In: Journal of Materials Chemistry, Vol. 13, No. 2, 01.02.2003, p. 377-381.

Research output: Contribution to journalArticle

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