Efficient removal of arsenate by versatile magnetic graphene oxide composites

Abstract

The magnetic graphene oxide (MGO) composites were prepared by coprecipitation of FeCl₃·6H₂O and FeCl₂·4H₂O on graphene oxide (GO) nanosheets and characterized in detail. The Fe₃O₄ was uniformly deposited on the surface of GO. The synthesized MGO composites were used as a versatile adsorbent for As(V) removal from aqueous solutions. The results showed that the adsorption of As(V) on MGO is an endothermic process and the adsorption kinetic fitted the pseudo-second-order model well. The MGO composites had a good adsorption capability for As(V) removal and the adsorption isotherms were described by the Langmuir model better than by the Freundlich model. The adsorption of As(V) on MGO decreased with ascending pH due to the electrostatic interaction. In addition, the adsorption of As(V) on MGO was greatly affected by the nature and concentration of coexisting cations and anions. The presence of coexisting anions showed an inhibiting effect on As(V) adsorption, which was more efficient at low pH, whereas the presence of coexisting cations showed an enhancing effect on As(V) adsorption, which was more efficient at high pH. The results of this work indicated that the combination of the excellent adsorption capacity of GO and the magnetic properties of Fe₃O₄ nanoparticles is very important in drinking water treatment due to the easy magnetic separation of MGO from aqueous solutions.