Fabrication of durable superhydrophobic epoxy/cashew nut shell liquid based coating containing flower-like zinc oxide for continuous oil/water separation

• Published in: Surface & coatings technology Vol. 366; pp. 106 - 113
• Main Authors: Lorwanishpaisarn, Narubeth, Kasemsiri, Pornnapa, Srikhao, Natwat, Jetsrisuparb, Kaewta, Knijnenburg, Jesper T.N., Hiziroglu, Salim, Pongsa, Uraiwan, Chindaprasirt, Prinya
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 25.05.2019; Elsevier BV
• Subjects: Bio-based curing agent; Contact angle; Continuous coating; Continuous oil/water separation; Curing agents; Durability; Flower-like zinc oxide; Fluid filters; Hydrophobic surfaces; Hydrophobicity; Morphology; Natural resources; Organic chemistry; Protective coatings; Separation; Stability; Stainless steels; Stearic acid; Submerging; Superhydrophobic; Surface roughness; Water purification; Zinc coatings; Zinc oxide; Zinc oxides; Continuous oil/water separation; Superhydrophobic; Bio-based curing agent; Flower-like zinc oxide
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2019.03.021

Superhydrophobic filters can be applied as cost-effective separation media to overcome oil contamination issues. In this study, superhydrophobic material based on natural resources was explored as a coating material for sustainable oil/water separation membranes. Epoxy (EP) cured with cashew nut shell liquid (CNSL, a bio-based curing agent) was coated on a stainless steel mesh (E-mesh) using a simple immersion technique. Different amounts of ZnO (0–60 wt%) were added to EP/CNSL to increase coating surface roughness. The highest water contact angle (WCA) of 149.2° was measured for the E-mesh containing 60 wt% ZnO (E-ZnO-60 mesh). Modification of coated ZnO by immersion in acetic and stearic acid can create the flower-like morphology of ZnO (F-ZnO), which even further enhanced the coating hydrophobicity. The E-mesh containing 60 wt% F-ZnO (E-F-ZnO-60 mesh) showed superhydrophobicity with a WCA of 163.8°. This high hydrophobicity was obtained after chemical and mechanical durability tests, indicating excellent coating stability. The continuous oil/water separation efficiency of E-F-ZnO-60 mesh was over 97% for 75 min after the mechanical stability testing. Based on these results, this durable superhydrophobic mesh showed promising cost-effective coating applications and oil/water separation medium. [Display omitted] •The mesh coated with epoxy/cashew nut shell liquid/ZnO achieved hydrophobicity.•The addition 60 wt% flower-like ZnO on mesh showed superhydrophobicity.•The coated mesh showed superhydrophobicity after chemical and mechanical tests.•The continuous oil/water separation efficiency of the coated mesh was over 97%.