Graphene oxide-wrapped tungsten trioxide for adsorptive removal of methylene blue

Abstract

Graphene oxide (GO) is a graphene derivative, but different from graphene (Gr), it has a high dispersibility and a high potential to composite with other materials. In order to reveal the effect of graphene oxide (GO) on the enhancement of methylene blue (MB) adsorption, in this study, different GO contents (0, 0.3, 0.5, and 0.7 wt%) were in situ composited with tungsten oxide nanostructures prepared by a simple one-pot hydrothermal method. The physicochemical analysis implies that the in situ compositing helps create a strong interaction between GO and platform material - tungsten oxide. As the GO content increased from 0 to 0.7 wt%, the average crystallite size decreased slightly from 26.7 nm to 24.0 nm, while the microstrain increased from 0.31 to 0.53 %, respectively. Both pristine and nanocomposite samples showed good adsorption capacity with methylene blue (MB), which increases with GO content in the nanocomposites. The sample composited with 0.7 wt% GO showed the highest adsorption activity with the highest adsorption capacity of 76.1 mg/g after 150 min at the optimum condition (15 mg absorbent and 100 ml of MB 30 mg/ml). The MB adsorption kinetics is consistent with the second-order kinetics model with the maximum rate of 2.3 × 10−3 g/mg·m at the optimum condition, while the adsorption isotherm is well described by the Langmuir model with the Langmuir adsorption constant of 0.37 l/mg. These results show that the one-pot hydrothermal method is a facile and efficient method for in situ preparing the Gr-based nanocomposite absorbent.