Modifying the surface of Fe3O4/SiO2 magnetic nanoparticles with C18/NH2 mixed group to get an efficient sorbent for anionic organic pollutants

► The mixed groups both contribute to the adsorption of targets which brings about high extraction ability of the sorbent. ► The silica coat can provide more bonding sites for functional groups and enhance the stability of the sorbent. ► The Fe3O4 core endues the sorbent with magnetic separation ability which simplifies the extraction greatly.