Application of 11B MAS-NMR to the characterization of boron in coal fly ash generated from Nantun coal

Shunsuke Kashiwakura, Takafumi Takahashi, Hideki Maekawa, Tetsuya Nagasaka

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)

Abstract

Boron and its compounds are environmentally hazardous substance and are well-known condensed products that appear in coal fly ash during combustion of coal in coal-fired electric power stations. In a previous study, we suggested that boron in coal fly ash obtained from Nantun coal in China, identified as Ash-N, may exist on the surface of relatively large coal fly ash particles or as very fine particles generated by homogeneous nucleation. Although the characterization of boron in coal fly ash is important for its effective stabilization or removal, its detection is quite difficult because of its low concentration in coal fly ash and its light atomic weight. In the present work, solid-state magic angle spinning nuclear magnetic resonance (MAS-NMR) technique has been applied to reveal the local chemical structures of boron in Ash-N. In the 11B MAS-NMR spectrum of Ash-N, two peaks which are attributed to a three-oxygen coordinated boron unit (BO3) and a four-oxygen coordinated boron unit (BO4) were observed with high resolution. We have estimated quadrupole parameters of the BO3 unit in Ash-N using computer simulation, and we have fingerprinted these moieties with the parameters of borates. The result of the present analysis shows that calcium- or magnesium-bearing orthoborate or pyroborate are the most likely forms of boron in Ash-N.

Original languageEnglish
Pages (from-to)1006-1011
Number of pages6
JournalFuel
Volume89
Issue number5
DOIs
Publication statusPublished - 2010 May

Keywords

  • Boron
  • Coal fly ash
  • MAS-NMR
  • Speciation

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Fuel Technology
  • Energy Engineering and Power Technology
  • Organic Chemistry

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