▎ 摘　　要

NOVELTY - Preparation of microalgae-based magnetic graphene and biochar comprises ultrasonically dispersing graphene in distilled water, adding iron(III) ion salt containing solution at room temperature, stirring for 45-60 minutes, adding iron(II) ion salt containing solution at 60-80 degrees C, stirring, reacting for 60-90 minutes, adding aqueous ammonia solution, stirring for 2 hours to adjust pH to not greater than 10, washing to neutrality, and vacuum-drying to obtain magnetic graphene; dispersing magnetic graphene, reducing agent and coupling agent in an organic alcohol aqueous solution, adding biochar, magnetic stirring for 1.5-2 hours, vacuum drying, pyrolyzing under nitrogen atmosphere at 500-700 degrees C for 1-2 hours, washing, and vacuum drying; and mixing with cultured microalgae and standing for 3-8 hours under light and nutrients conditions. USE - The method is used for preparing microalgae-based magnetic graphene and biochar for removing heavy metal ions in waste water (claimed).