Use of The Electrodialysis Process For Fluoride Ion And Salt Removal From Multi-Constituent Aqueous Solutions

Fluorine is a common chemical element. According to WHO guidelines, the F^- ion content in drinking water cannot be higher than 1.5 mg/dm³. Excess of fluorine leads to many health problems: Alzheimer’s disease, neurological disorders or fluorosis (dental or skeletal). Fluoride can be removed from aqueous solutions by means of various methods (adsorption, precipitation, ion-exchange or membrane techniques). The aim of this paper was to evaluate the efficiency of electrodialysis in fluoride removal under the presence of organic substances. During experiments solutions containing fluorides (5, 10, 100 and 200 mg F^-/dm³), mineral salt (0.5 g NaCl/dm³) and organic matter (5, 10 and 15 mg/dm³ of humic acids) were used. The research was conducted with the use of the PC Cell BED-1 System. The current density was equal to 1.72 mA/cm². It has been shown that electrodialysis is an efficient technique of fluoride removal provided that the initial concentration of F^- ions is not higher than 10 mg F^-/dm³. The impact of organic matter on the process run and efficiency was dependent on the fluoride content in the treated solution.