Fluorine removal agent and fluorine removal method for advanced treatment of industrial fluorine-containing wastewater

The invention discloses a fluorine removal agent for advanced treatment of industrial fluorine-containing wastewater, and the fluorine removal agent is prepared by the following method: dissolving a rare earth metal ion doped and modified nano-hydroxyapatite-blue algae biochar composite material in an acetic acid aqueous solution to obtain a mixed solution A; in the mixed solution A, the mass fraction of the composite material is 8-12%; dissolving polyaluminum ferric chloride, aluminum salt and iron salt in deionized water, and stirring to obtain a mixed solution B; in the mixed solution B, the mass fraction of the polyaluminum ferric chloride is 8-10%; the mass fraction of the aluminum salt is 4-5%; the mass fraction of the iron salt is 4-5%; the mixed solution B is added into the mixed solution A, the volume ratio of the mixed solution B to the mixed solution A is 1: 1, and the fluorine removal agent is obtained after stirring. The invention also discloses a defluorination method based on the defluorination