A mesh membrane coated with dual-scale superhydrophobic nano zinc oxide: Efficient oil-water separation

• Published in: Surface & coatings technology 2020-03, Vol.385, p.125394, Article 125394
• Main Authors: Velayi, Elmira, Norouzbeigi, Reza
• Format: Article
• Language: English
• Subjects: Aqueous solutions; Chemical composition; Chloroform; Contact angle; Hydrophobic surfaces; Hydrophobicity; Membranes; Mesh membrane; Oil-water separation; Photoluminescence; Reversibly switchable wettability; Scale (corrosion); Separation; Stainless steels; Surface energy; Underwater; Wetting; Zinc oxide; Zinc oxides; ZnO
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2020.125394

A stainless steel mesh membrane decorated with mico/nano dual-scale structured ZnO have been fabricated via chemical bath deposition method. The fabricated surface shows excellent superhydrophobic/superoleophilic property in the air (water contact angle (WCA) of 160.1°, oil contact angle (OCA) of 0°) and superhydrophilic /superoleophobic behavior underwater (oil contact angle of 159.5° and water contact angle of 0°) with increasing annealing temperature up to 400 °C. Compared to previous different reports, low surface energy materials were not used in this work to regulate the surface wetting characteristics. Wetting characteristics of the mesh membrane surface were evaluated by the determination of morphological features and surface chemical composition. The FESSEM, XRD, Photoluminescence, and Raman analyses were used to characterize the prepared surfaces. The superhydrophobic mesh membrane was applied to separate chloroform-water mixtures. The reverse performance was examined by the superhydrophilic/underwater superoleophobic meshes, which were used to separate n-hexane -water mixtures. The prepared mesh membranes displayed high separation efficiency (> 99.9%) and high permeate flux for both light and heavy oil-water mixtures after at least ten separation cycles. This surface also shows excellent performance for the separation of highly corrosive aqueous solution and light/ heavy oils mixtures with the separation efficiency of >99.9%. •ZnO-based coated mesh with controllable wettability was prepared by a facile method.•The on-demand wettability can be realized by annealing at different temperatures.•The mesh membranes can be used for light and heavy oil/water mixtures separation.•Separation performance remained un-changed after ten sequential separation cycles.•High separation efficiency was achieved for corrosive oil/water mixtures.