Removal of fluorine and lithium from hectorite by solutions spanning a wide range of pH

One-gram samples of hectorite were treated with 40 millilitres each of hydrochloric acid (6 N), acetic acid (4.5 N), distilled water, natural seawater, sodium chloride (0.6 N), and sodium hydroxide (2.5 N) for 10 days in stoppered plastic centrifuge tubes. X-ray diffraction patterns show that the structure was virtually destroyed by the hydrochloric and acetic acids. Analyses of the supernatant liquids were made to determine amounts of the elements removed by the various treatments. All treatments removed at least some SiO₂, MgO, CaO, Li₂O, and F. The acids removed most of the lithium and magnesium after 3 days. The fluorine and the magnesium released by the acetic acid began to form sellaite (MgF₂ ). After 5 days, sufficient sellaite was produced to be discernible by X-ray diffraction. The loss of silica from the sample when it was treated with sodium hydroxide amounted to about 10 percent of the total sample.