Multifunctional hierarchical tree-like ZnO@CuxO mesh for oily wastewater treatment

Abstract

One of the main causes of water pollution is oily water which contains light and heavy oils along with organic contaminants. To address these issues, herein we have developed a multifunctional superhydrophilic-underwater superoleophobic tree-like ZnO@CuxO mesh. The XRD analysis of the ZnO@CuxO mesh revealed the existence of monoclinic CuO, cubic Cu2O and hexagonal wurtzite phase of ZnO respectively. The FESEM and TEM analysis demonstrates the tree-like structure of ZnO@CuxO grown on Cu mesh and confirms the formation of its heterostructure respectively. The ZnO@CuxO mesh manifested superhydrophilic-underwater superoleophobic behaviour which is attributed to the synergistic effect of its high surface energy and its tree-like structures. Owing to its superwettable behaviour, ZnO@CuxO mesh efficiently separates oil-water mixtures with lighter/heavier oils. The mesh demonstrates antifouling behaviour by maintaining its high separation efficiency and flux even after many cycles of use. In addition, the mesh showed excellent versatility by efficiently separating different mixtures of oil-water with high flux. Owing to the light harvesting ability and suitable charge migration mechanism, the mesh degraded the organic contaminants dissolved in the filtrate exhibiting excellent photocatalytic activity. The mesh's capacity to separate oil and water mixtures regardless of oil density, as well as its ability to degrade organic pollutants, make it a viable candidate for practical use in oily wastewater treatment.