Separation and recovery of NaF from fluorine containing solution by the common ion effect of Na(+)

The separation and recovery of NaF from fluorine containing solution by the common ion effect of Na(+) was studied. The solubility of NaF in the solutions of NaCl, NaNO(3), Na(2)CO(3), Na(2)SO(4) and NaOH at 30 °C was determined. It was found that when the compound containing sodium, such as Na(2)CO(3) or Na(2)SO(4) was added into NaF saturated solution to product the common ion effect of Na(+), most of the NaF can be crystallized without evaporating concentration, and the added Na(2)CO(3) or Na(2)SO(4) can be recovered by cooling crystallization. Combining cooling crystallization with the common ion effect of Na(+), different processes can be designed to recover NaF from different fluorine containing solutions. This will have a significant impact on the treatment of fluorine containing wastewater and the recycling of fluorine resources.