科研之友
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摘要
Fluorine is a common chemical element that is freely soluble in water. An excess of fluorine leads to many health problems and for that reason the fluoride content in drinking water cannot be higher than 1.5 mg/dm(3). The purpose of this paper was to evaluate the influence of natural organic matter (NOM) on fluoride transport through anion-exchange membranes in the course of conventional electrodialysis (ED). The ED installation operated in a batch mode with no concentration gradient between the diluate and concentrate cells at the start-up of the process. Model solutions with a variable content of fluoride (5-200 mg F-/dm(3)) and humic acids (5-15 mg/dm(3)) were used in the ED treatment. Each tested solution also contained mineral salt (0.5 g NaCl/dm(3)). During experiments the commercial PC-Cell BED-1-System, equipped with classic ion-exchange membranes PC-SA and PC-SK, was used. The constant current density (1.72 mA/cm(2)) was applied for all ED trials. The fluoride concentration, conductivity, colour intensity, and voltage variation were monitored in the course of the ED process. The obtained results showed that the solution composition could have an influence on fluoride removal efficiency and batch electrodialysis performance. In the event of a high initial fluoride content, the presence of humic acids in model solutions led to an improvement of the fluoride transport rate across the ED stack. It was also revealed that the mechanism of fluoride removal by electrodialysis under the presence of humic acids has a manifold nature, resulting from mutual interactions between mineral salts, organic matter and ion-exchange membranes.
- 出版日期2017-3
