Controllable synthesis of WO3 with different crystalline phases and its applications on methylene blue removal from aqueous solution

A facile, controllable and scalable method to prepare tungsten trioxides (WO3) with different crystalline phase, including cubic WO3 (c-WO3) and monoclinic WO3 (m-WO3), that possesses excellent methylene blue (MB) removal ability has been successfully developed. The as-synthesized materials were well characterized by using XRD, SEM, BET, FTIR and XPS. Interestingly, c-WO3 and m-WO3 has shown distinct way on MB removal. The c-WO3 possesses excellent adsorption performance on MB, while the m-WO3 exhibits great photocatalytic degradation ability on MB. For c-WO3, the dosage impact, operating pH and temperature were further studied by using the adsorption batch experiments. The adsorption isotherm and kinetic data shows that the adsorption behavior follows the monolayer Langmuir isotherm model and pseudo-second-order kinetic model, respectively. Meanwhile, the maximum adsorption capacity of MB on the c-WO3 is measured to be 35.95 mg/g at 45(circle)C. Moreover, for m-WO3, 40 mg/L MB can be effectively degraded within 2 h under the visible light irradiation. Meanwhile, m-WO3 also exhibits good recyclability and stability during the photocatalytic reactions. The adsorption and photocatalytic mechanism of c-WO3 and m-WO3 were also proposed in this study. The present work not only gives a new perspective on the performance of different crystalline phase WO3, but also provides a promising alternative material for the different purpose on organic pollutants removal from aqueous solutions. (C) 2017 Elsevier B.V. All rights reserved.