Method for selectively removing fluorine ions in stainless steel pickling wastewater

The invention discloses a method for selectively removing fluorine ions in stainless steel pickling wastewater, and relates to a method for removing fluorine ions in wastewater. The method comprises the following two steps of separating the fluorine ions from a great deal of pickling wastewater which cannot be directly discharged, and concentrating and regenerating by using a modified hydrotalcite adsorbent. By adopting the method disclosed by the invention, the property that the modified magnesium aluminum hydrotalcite has different adsorption capacities upon different anions in water solutions is utilized. The method comprises the following steps: feeding hydrotalcite into main acid wastewater containing nitric acid, sulfuric acid and hydrofluoric acid to preferentially adsorb the fluorine ions, performing decompression filtration to separate the hydrotalcite from the solution, putting into a small amount of sodium carbonate solution to exchange the fluorine ions with carbonate ions into the solution, furth