Removal of reactive red-120 and 4-(2-pyridylazo) resorcinol from aqueous samples by Fe3O4 magnetic nanoparticles using ionic liquid as modifier

► Ionic liquids modify the dye-adsorption characteristics of magnetic nanoparticles. ► Modified nanoparticles improved the sensitivity of dye measurements. ► Water-solubility is an important factor for choosing an ionic liquid as a modifier for nanoparticles.