Controlled fabrication of hierarchical WO3 hydrates with excellent adsorption performance

Abstract

Hierarchical WO₃ hydrates have been synthesized via an ion exchange method using Na₂WO₄·2H₂O as a precursor. The morphologies and phase structures of WO₃ hydrates can be controlled by tuning the concentration of Na₂WO₄·2H₂O solution. The as-synthesized urchin-like WO₃·0.33H₂O and flower-like WO₃·H₂O possess high specific surface area and numerous adsorption functional groups, such as WO and O–H bonds, on the surface. These characteristics result in excellent adsorption performance for both organic dyes and heavy metal ions from wastewater. The maximum uptake capacities of the urchin-like WO₃·0.33H₂O for methylene blue and Pb²⁺ are 247.3 and 248.9 mg g⁻¹, respectively and those of the flower-like WO₃·H₂O are 117.8 and 315.0 mg g⁻¹, respectively. The formation mechanism of such hierarchical mesoporous urchin-like WO₃·0.33H₂O and adsorption mechanism are studied in this paper.