Simple in situ functionalizing magnetite nanoparticles by reactive blue-19 and their application to the effective removal of Pb2+ ions from water samples

► Magnetite nanoparticles were modified using reactive blue 19. ► In situ functionalizing method was used to the direct attachment of modifier. ► The modified nanoparticles were characterized by different methods. ► The modified nanoparticles was used as an efficient adsorbent for the adsorption of Pb2+. ► The adsorption isotherm and kinetics were investigated using different models.