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.