Synthetic fluoride solution and natural waters
A stock solution of 250 mg L1 fluoride was prepared by
dissolving 552.5 mg of sodium fluoride (Merck, Germany) in 1.0 L
of distilled water and all synthetic solutions for the removal
experiment and the analysis were prepared by an appropriate
dilution from the freshly prepared stock solution. Two Tunisian
underground waters were considered in the study: Louza 2 and
Gafsa SM4. The salt compositions of these waters are given in Table
2. The two waters have particularly high levels of fluorides, which
represent a permanent risk for the population which relies on
underground water (wells) for the daily consumption. The
concentration of about 3 mg L1 of fluoride was higher than the
acceptable value.