Formation and decomposition of tetrafluoroborate ions in the presence of aluminum

Junya Katagiri, Siqingaowa Borjigin, Toshiaki Yoshioka, Tadaaki Mizoguchi

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


The formation and decomposition of tetrafluoroborate ions (BF4-) in H3BO3-Al3+-F- solutions were investigated via experiments and thermodynamic calculations. The concentration of the formed BF4- increased with decreasing pH, raising the total fluoride concentration and lowering the total aluminum ion concentration. Once formed, BF4- was stable under neutral and alkaline conditions. Fluoride in the form of BF4- was converted to fluoroaluminate ions by adding an aluminum compound under acidic conditions. A method for removing fluoride in the form of BF4- is proposed whereby fluoroaluminate ions formed by the reaction of BF4- with aluminum are decomposed with calcium ions. This process was applied to the treatment of wastewater from flue gas desulfurization plants, and resulted in a satisfying level of reduction in the range of the fluoride emission limit of 8 mg/l.

Original languageEnglish
Pages (from-to)136-146
Number of pages11
JournalJournal of Material Cycles and Waste Management
Issue number2
Publication statusPublished - 2010 Jul 14


  • Aluminum
  • Boron
  • Decomposition
  • Fluoride
  • Formation
  • Tetrafluoroborate ion

ASJC Scopus subject areas

  • Waste Management and Disposal
  • Mechanics of Materials


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