Removal of fluoride ions by batch electrodialysis

Abstract

REMOVAL OF FLUORIDE IONS BY BATCH ELECTRODIALYSIS Suitability of conventional batch electrodialysis to fluoride removal from aqueous solutions has been investigated. The experiments were conducted with the use of laboratory installation PCCell BED-1 System at a constant current density (1.56 or 2.34 mA/cm 2). The influence of initial fluoride and salt (NaCl) concentration, as well as the presence of organic matter on the process performance was studied. It was found that the separation efficiency increased upon decrease of initial fluoride content in model solutions. Permissible final concentration of fluorides in the product water (1.5 mg/dm 3) was obtained for experiments with solutions of initial fluoride concentration equal to 5 mg F-/dm 3 and 10 mg F-/dm 3. The presence of humic acids in fluoride solutions subjected to electrodialysis treatment has no adverse effect on the defluorization and desalination efficiency. The calculated electrical energy demand depended on composition of fluoride solution and varied from 0.121 to 0.895 kWh/m 3 .

The effect of nitrate on fluoride removal by batch electrodialysis

“…Nitrate and fluoride, due to their low content in comparison to chloride concentration, had minor impact on energy consumption. Referring to our previous study [21], it is worth noting, that the energy demand determined for ED treatment of fluoride solutions (5 and 10 mg F -/dm 3 + 0.5 g NaCl/dm 3 ) with use of classical ion-exchange membranes amounted to approximately 0.2 kWh/m 3 . The difference between EC values previously calculated and given in Table 2 (for the same composition of treated solution) arises from higher electrical resistance of monovalent permselective ion-exchange membrane in comparison to the resistance of standard ion-exchange membranes.…”

Fluorine in the Water Environment - Hazards and Removal Methods

“…Badania nad zastosowaniem ED do usuwania fluorków z roztworów wodnych prowadzą też Majewska-Nowak i in. [51,52]. Badano roztwory zawierające 5, 10, 100 i 200 mg F -/l, sól mineralną (0,5 g NaCl/l) oraz substancje organiczne (5, 10 i 15 mg/l kwasów humusowych).…”

Ultrafiltration of Aqueous Solutions of Food Dye Using Polymeric Membranes Prepared with Surfactants

“…Asymmetric membranes have led to an extraordinary development of membrane separation processes [3]. Membrane technologies interact with the field of surfactants in membrane conditioning and washing operations [4].…”

“…Thus the reverse osmosis process is similar to dehydration by hyperfiltration, ultrafiltration resembles the methods of concentration, purification and fractionation of molecules or colloids, and microfiltration is recognized for the separation of suspensions. So membrane processes can be a viable alternative to other separation processes [5][6][7][8].…”