A graphene-coated magnetic nanocomposite for the enrichment of fourteen pesticides in tomato and rape samples prior to their determination by gas chromatography-mass spectrometry

Magnetic chitosan/graphene oxide (MCGO) materials were fabricated through a facile and fast process and their application as excellent adsorbents for metal ions was also demonstrated. The characteristics results of FTIR, SEM, TEM, VSM and XRD showed that MCGO was successfully prepared. The SEM and TEM revealed that magnetic chitosan had been assembled on the surface of graphene oxide layers with a high density. The XRD and VSM indicated the MCGO had enough magnetic response to meet the need of magnetic separation. The magnetic chitosan grafted with graphene oxide sheets showed an increased surface area. The MCGO was used as sorbents for the removal of Pb(II) ions from large volumes of aqueous solutions. The effects of pH, contact time, and concentration on Pb(II) ions sorption were investigated. The results indicated that Pb(II) ions sorption on MCGO was strongly dependent on pH. The abundant functional groups on the surfaces of MCGO played an important role on Pb(II) sorption. Equilibrium studies showed that the data of Pb(II) adsorption followed the Langmuir model. The maximum adsorption capacity for Pb(II) was estimated to be 76.94 mg/g. The MCGO was stable and easily recovered. Copyright © 2012 Elsevier B.V. All rights reserved.