Formation and decomposition of tetrafluoroborate ions in the presence of aluminum
Source: Journal of Material Cycles and Waste Management, Volume 12, Number 2, June 2010 , pp. 136-146(11)
Abstract:The formation and decomposition of tetrafluoroborate ions (BF 4 − ) in H3BO3-Al3+-F− solutions were investigated via experiments and thermodynamic calculations. The concentration of the formed BF 4 − increased with decreasing pH, raising the total fluoride concentration and lowering the total aluminum ion concentration. Once formed, BF 4 − was stable under neutral and alkaline conditions. Fluoride in the form of BF 4 − was converted to fluoroaluminate ions by adding an aluminum compound under acidic conditions. A method for removing fluoride in the form of BF 4 − is proposed whereby fluoroaluminate ions formed by the reaction of BF 4 − 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.
Document Type: Research Article
Affiliations: 1: Environment Conservation Research Institute, Tohoku University, Sendai, Japan 2: Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aoba, Aramaki-aza, Aoba-ku, Sendai, 980-8579, Japan, Email: email@example.com 3: Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aoba, Aramaki-aza, Aoba-ku, Sendai, 980-8579, Japan
Publication date: 2010-06-01