Calcium ions enhanced mussel-inspired underwater superoleophobic coating with superior mechanical stability and hot water repellence for efficient oil/water separation

The presented study proposed a simple, eco-friendly, and inexpensive route for improvement in mechanical robustness and hot solutions resistance of underwater superoleophobic mesh. The robustly underwater superoleophobic mesh was fabricated by introducing polydopamine (PDA)-calcium (Ca) complex aggregations to form hierarchical micro/nano-structures on the mesh surface. The wettability, appearance, roughness, and chemical composition of the obtained mesh were investigated. The generated coating reveals ultralow underwater oil adhesion and superior resistance to ultraviolet irradiation, hot water, oils, mechanical abrasion and folding. Moreover, the fabricated mesh can separate all sorts of oil/hot (95 ℃) water mixtures with high efficiencies (>97.8%) and satisfactory oil intrusion pressure. Especially, the decorated mesh can maintain high efficiency (>98.2%) after the separation of 80 cycles to oil/hot water mixtures, showing outstanding stability. Besides, the developed mesh can be applied as a separation material for gravity driven penetration of corrosive water from oil with high efficiency (>97%). We believe that the fabricated mesh with good stability and excellent separation performance has great potential to solve large-scale water contamination resulted from oil leaking accidents and oily water emission.