Fabrication of multifunctional WO₃.H₂O flower-like micro/nanostructures for the oily wastewater treatment

A multifunctional flower-like WO₃.H₂O coated mesh with superhydrophilic/underwater superoleophobic properties was fabricated for oily wastewater treatment. The XRD and the FESEM analysis demonstrated the orthorhombic phase and flower-like structure of WO₃.H₂O. The AFM study confirmed the rough surface structure of the mesh. The mesh displayed outstanding superhydrophilic-underwater superoleophobic behavior. The special wettability of flower-like WO₃.H₂O mesh may be attributed to its intrinsic high surface energy and hierarchical flower-like rough structure. The mesh with the flower-like structure maintained its excellent underwater oil repellency even after many cycles of different mechanical tests. The consistency in underwater superoleophobicity of the flower-like WO₃.H₂O coated mesh in different pH and saline environments as well as in long-term storage tests demonstrates its excellent chemical and long-term durability. In addition to the separation of oil-water mixtures with lighter and heavier oils, the mesh can also be employed as a primary unit for emulsion separation. Moreover, the flower-like WO₃.H₂O coated mesh could also remove efficiently the organic contaminant by the synergistic effect of adsorption and photocatalytic activity. These excellent performances enable the mesh to be employed for sustainable oil-water separation in the practical field.