2014 Volume 5 Issue 3 Pages 191-198
Fluoride ion in the mixed solutions of fluoride and tetrafluoroborate ions can be analyzed without the interference of aluminum ion with fluoride ion-selective electrode using Gran's plot method after the decomposition of refractory tetrafluoroborate ion. Tetrafluoroborate ion was stable at room temperature under neutral and alkaline conditions and its 20% was remaining even at pH 3 after 2 months. However, tetrafluoroborate ion was decomposed almost quantitatively after 48h by aluminum addition in the pH 3-4. This indicated that tetrafluoroborate ion was quickly decomposed by adding an aluminum compound to form fluoroaluminate.After the decomposition of tetrafluoroborate ion, fluoride ion in even wastewater from the scrubber of organic waste-liquid treatment facility was removed to meet the effluent standard (8ppm) using two-step treatment method by combining precipitation of fluoride with calcium and fluoride adsorption resin column.