Magnetic Graphene Nanocomposites for Capturing Heavy Metal Ions From Polluted Water

A facile method to fabricate magnetic graphene nanocomposites decorated with monodispersed core@double-shell nanoparticles is developed in this work. High-resolution transmission electron microscopy and energy filtered elemental mapping revealed a core@double-shell structure of the nanoparticles with the core and inner shell being crystalline iron and iron oxide, and the outer shell of amorphous Si-S-O compound. This magnetic graphene nanocomposites shows an extremely fast chromium (VI) removal efficiency (completely removed in 5 min) from the waste water and a significantly high adsorption capacity (20.9 mg/g from 10 wt% nanoparticle loading). This material shows great advantages as compared to traditional adsorbents, such as active carbon, biomass, iron oxide that often require hours even days to remove the heavy metal ions. Also, we are able to separate the magnetic graphene nanocomposites from waste water easily by a permanent magnet within a few minutes.