Novel magnetic polysaccharide/graphene oxide @Fe3O4 gel beads for adsorbing heavy metal ions

Abstract

As a kind of potential absorbent, polysaccharide materials are limited due to weak stability, low absorption and recovery rate. Herein, a novel composite adsorbent – the magnetic composite gel beads (CMC/SA/graphene oxide@Fe3O4) were prepared by combining carboxymethyl chitosan (CMC), sodium alginate (SA) with graphene oxide@Fe3O4, and then utilized for the adsorption of Cu2+, Cd2+ and Pb2+ from the wastewater. The physicochemical property of CMC/SA/graphene oxide@Fe3O4 beads were characterized in detail. The CMC/SA/graphene oxide@Fe3O4 magnetic gel beads could separate easily from the wastewater and showed a higher stability due to the addition of graphene oxide@Fe3O4. The adsorption experiments show that the adsorption of Cu2+, Cd2+ and Pb2+ on the magnetic gel bead was well fitted with pseudo-second-order model and Langmuir isotherm model, and the maximum adsorption capacity of Cu2+, Cd2+ and Pb2+ reached 55.96, 86.28 and 189.04 mg/g, respectively. Moreover, the magnetic gel beads had selective adsorption toward Pb2+. In addition, the magnetic gel beads still obtained 90% of the adsorption rates after five cycles, and showed good adsorption efficiency in the simulated real environment. This work proves that the CMC/SA/graphene oxide@Fe3O4 magnetic gel beads as the adsorbents have promising potential in wastewater treatment.