Poly (ionic liquid)-coated Cu(OH)2 nanoneedle mesh with corrosion resistance for oil/water separation

Copper mesh with special wettability has attracted enormous attention in the field of oil/water separation, and the construction of Cu(OH)2 nanostructures on the surface of copper mesh is an effective way to obtain such kind of functional material. However, the poor chemical stability of Cu(OH)2 limits its wide use in the field of oil/ water separation. In this paper, Poly (ionic liquid) (PIL) was proposed as protective layer for Cu(OH)2, aiming to afford highly stable and performant separating material. Initially, the PIL was prepared by free radical polymerization of ionic liquid monomer 3-ethyl-1-vinylimidazolium bromide, and then was coated on the Cu@Cu (OH)2 filter material, which was prepared by depositing super-hydrophilic Cu(OH)2 nanoneedles on copper mesh. The structures of Cu@Cu(OH)2 and Cu@Cu(OH)2-PIL before and after immersion in acidic, alkaline, and salty solutions were analyzed by XRD, SEM, XPS, and etc. It was found that the immersion of Cu@Cu(OH)2 in NaOH and NaCl solutions collapsed the Cu(OH)2 layer seriously and that in HCl solution caused the complete reaction between the Cu(OH)2 layer and HCl, thereby depriving the ability of oil/water separation. However, the PIL-coated Cu@Cu(OH)2-PIL still retains complete Cu(OH)2 nanoneedles layer after immersion in NaOH and NaCl solutions, and also partially remains some Cu(OH)2 after immersion in HCl solution. The performance test suggests that the prepared Cu@Cu(OH)2-PIL filter material not only can separate oil/water mixtures in wastewater environment, but also can separate organic solvents (hexadecane/methanol mixtures) with different polarity. Therefore, the novel designed filter material shows wider promise for application.