Environmentally benign development of superhydrophilic and underwater superoleophobic mesh for effective oil/water separation

Superhydrophilic and underwater superoleophobic materials for oil/water separation have recently attracted much attention due to the urgent needs of water protection. However, the environmental problems, complex preparation process and poor stabilities seriously restricted the practical applications. Herein, a waterborne organic–inorganic composite coating was prepared by mechanical mixing a silicone acrylic emulsion with nano-silica particles. The silica particles could be introduced to polymeric latexes to generate the cross-linked structure due to the polycondensation between hydroxyl groups. A simple spray technique was applied to deposit the as-prepared composite coating on a stainless steel mesh which exhibited a favourable superhydrophilicity (nearly 0°) and underwater superoleophobicity (above 155°) towards various oil droplets. The coated mesh presented a high separation efficiency of above 99% towards a series of light oil–water mixtures and it also showed a good recyclability after 30 separation cycles. Furthermore, the coated mesh kept excellent underwater superoleophobicity under a series of pH solutions and immersion tests in water and 3.5 wt% NaCl solution. Therefore, the as-prepared mesh is highlighted in its simple and environmental fabrication, high separation efficiency, good recyclability, excellent chemical stability and water resistance, exhibiting a bright prospect for scalable production.