Superwetting materials for oil−water separation have attracted increasing research attention recently. Developing cost-effective and highefficiency filter materials to separate oil−water mixtures and stable water−oil emulsions is challenging. Herein, the TiO 2 nanoparticles were first hydrophobically modified using γ-aminopropyltriethoxysilane, and then polydimethylsiloxane was subsequently added to obtain a stable superhydrophobic coating. The superhydrophobic filter paper was obtained via roll coating. The water contact angle on the coated filter paper exceeded 152°, and the oil droplets were quickly absorbed by the coated filter paper. The superhydrophobic filter paper was used for separating various immiscible oil−water emulsions, with separation efficiencies of >99.5%. In addition, the synthesized filter paper can effectively separate various surfactant-stabilized water−oil emulsions. The separation efficiency was satisfactory even after 10 cycles. When the volume ratio of water in water−oil emulsions reached 20%, the separation efficiency exceeded 97.5%. The results indicate that the superhydrophobic/superoleophilic filter paper exhibits satisfactory oil−water separation ability and is environmentally friendly, cost effective, and easy to implement, making it suitable for continuous industrial production.

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Recently, the super-wetting materials for oil/water separation have attracted great attention. Developing a low-cost and high-efficient filter material that is challenging to separate oil/water mixtures and stable water/oil emulsions efficiently. In this paper, Nano titanium dioxide is hydrophobically modified with γ-aminopropyltriethoxysilane (KH550), and then added with polydimethylsiloxane to make stable superhydrophobic coating. A coated filter paper is obtained by roll coating. The water contact angle of the coated filter paper reaches more than 152°, and the oil droplets are quickly absorbed. The superhydrophobic/superoleophilic filter paper has the advantages of environmental protection, simple operation, low-cost, and can be used in continuous industrial production. The superhydrophobic filter paper is used for the separation of various immiscible oil-water mixtures, the separation efficiencies are more than 99.5%. In addition, the superhydrophobic filter paper can effectively separate various surfactant-stabilized water/oil emulsions. After 10 cycles, the separation effect is still satisfactory. Especially when the proportion of water in water/oil emulsion is as high as 20%, the separation efficiency can still be higher than 97.5%. The results show that the superhydrophobic filter paper has good oil-water separation ability, and has broad prospects in industrial applications.

Environmentally friendly flexible materials with functionalities such as reversibly tunable wettability have become much sought after because of their great potential for biological, chemical and electronic applications. We prepared a flexible superhydrophobic material by coating the hydrophobic nano-TiO2 particles on lignocellulosic paper. The coated paper surfaces exhibited a reversible switching between superhydrophobicity and superhydrophilicity through UV irradiation and heating, respectively. After the UV irradiation treatment for about 100 minutes, the wettability of the coated paper is switched from superhydrophobicity to superhydrophilicity. After the coated paper with superhydrophilicity is heated for 25 hours, the water contact angle (WCA) recovers to the original superhydrophobic state. Compared to the literatures, the switching time between two kinds of superwettability is significantly reduced. SEM images and XPS spectra indicate that the change in chemical composition of the coated paper surface is responsible for the reversible switching of wettability. The coated paper developed in this study is an attractive smart material with reversibly switchable wettability which has significant potential application in many fields which require tunable wettability.