Preparation and adsorption properties of magnetic graphene oxide composites for the removal of methylene blue from water

Abstract

Using graphite powder, chitosan, and diatomite as raw materials, graphene oxide was first prepared by Hummer’s method and GO was carboxylated and modified into hydroxylated graphene oxide (GOH). It was then modified into GOH via carboxylation, and then diatomite (DE) and the prepared magnetic chitosan (MCS) were supported on GOH by blending to generate the magnetic graphene oxide composite GOH/DMCS. This novel composite was then studied to determine its methylene blue wastewater adsorption capability. Results showed that at 45 °C, a dosage of adsorbent of 1 g L−1, and a pH of 12, the adsorption of methylene blue dye by GOH/DMCS reached equilibrium after 120 min, and the maximum adsorption amount was 205.34 mg·g−1. The adsorbent was then cycled eight times to test its reusability, and the adsorption efficiency remained greater than 86%. The adsorption process of methylene blue by GOH/DMCS fit well to a pseudo second-order kinetic model. These results showed that the adsorption rate was more sensitive to the initial concentration of methylene blue dye, which implies a chemical adsorption process. The adsorption process conformed to the Langmuir isotherm adsorption model, indicating that the adsorption was monolayer surface adsorption.