Simultaneous removal of Cd(II) and ionic dyes from aqueous solution using magnetic graphene oxide nanocomposite as an adsorbent

Abstract

Heavy metal and ionic dyes commonly co-exist and constitute the most important and dangerous source of environmental pollution. Graphene oxide has the potential in the application to remove heavy metal ions and ionic dyes in wastewater, but it suffers from separation inconvenience. In this paper, magnetic graphene oxide (MGO) was synthesized and used as an adsorbent for simultaneous removal of Cd(II) and ionic dyes including methylene blue (MB) and orange G (OG). MGO adsorbent was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results showed that kinetic data followed a pseudo-second-order model and equilibrium data were well fitted by the Langmuir model. In mono-component system, the maximum sorption capacities in ultrapure water for Cd(II), MB and OG were 91.29mg/g, 64.23mg/g and 20.85mg/g, respectively. The sorption capacity suppressed for Cd(II) with increasing MB concentration and almost was not affected for MB with increasing Cd(II) concentration in Cd(II)–MB binary system. However, the sorption capacity enhanced for OG with increasing Cd(II) concentration and for Cd(II) was independent on the concentration of OG in Cd(II)–OG binary system. In tap water samples, the sorption capacity for Cd(II) was 65.39% of that in ultrapure water. However, the tap water samples had little interference with the performance of MGO toward MB and OG, indicating that MGO was suitable for removal of ionic dyes from real water.