Strong adsorption of chlorotetracycline on magnetite nanoparticles

► Fe3O4 MNPs selectively adsorb CTC through chelation between CTC and Fe atoms. ► Fe3O4 MNPs remain high adsorption ability to CTC in environmental water samples. ► Fe3O4 MNPs sorbed with CTC are easily collected from water under a magnetic field. ► The collected Fe3O4 MNPs are regenerated by treatment with H2O2 or calcination.