Multifunctional TiO₂-Based Superoleophobic/Superhydrophilic Coating for Oil–Water Separation and Oil Purification

Abstract

Materials that possess distinguishable superwettability toward oil and water have aroused widespread attention for their application in oil–water separation. Among them, a superoleophobic/superhydrophilic material is considered as the ideal candidate because of its antioil-fouling and water-wetting behavior; however, the fabrication is a challenge and there has been insufficient attention given to multipurpose applications in treating intricate mixtures. Herein, for the first time, a multifunctional superoleophobic/superhydrophilic coating integrated with a photocatalysis property was fabricated by the combination of polarity component-enhanced fluorosurfactant and titanium dioxide (TiO2) nanoparticles. The coating applied on stainless steel mesh preserves the ability to separate immiscible oil–water mixtures, whereas the coated cotton preserves the ability to separate both surfactant-stabilized oil-in-water and water-in-oil emulsions. Notably, benefiting from the photocatalysis property of titanium dioxide, the coating also can be used in liquid purification. Contaminated oil can be separated and purified by a separation–purification process, during which the oil-soluble contamination is degraded under ultraviolet (UV) irradiation. The multipurpose coating provides an alternative solution for oil–water remediations, which has prospects in intricate liquid treatment in industrial and domestic applications.

Advanced Materials with Special Wettability toward Intelligent Oily Wastewater Remediation

“…Consequently, the obtained membrane possessed high degradation rate of rhodamine B (98%) and high oil/water separation efficiency of 99%. Li et al combined TiO 2 nanoparticles with fluorosurfactant fabricating a multifunctional coating with superoleophobicity/superhydrophilicity in air . The coating can be applied to different substrates and can separate different oil/water mixtures by using different substrates.…”

“…(a) Scheme of the separation and purification process. (b) Separation and purification process using the hexadecane–water mixture containing Sudan Red III contamination as the test feed . Reproduced with permission from ref .…”

Micro/Nanoscale Structured Superhydrophilic and Underwater Superoleophobic Hybrid-Coated Mesh for High-Efficiency Oil/Water Separation

“…To fabricate superoleophobic or superhydrophobic surfaces, materials with a low surface energy and micro–nano binary rough structures are required [ 36 , 37 , 38 ]. Thus, superoleophobic or superhydrophobic surfaces are generally fabricated by constructing a rough structure on a low-energy surface or grafting low-energy materials from a rough surface [ 39 , 40 , 41 ]. From the perspective of pure surface chemistry, a superlyophilic surface requires the surface tension of the solid and liquid to be close, while superoleophobic or superhydrophobic surfaces require the surface tension of the solid to be less than a quarter that of the liquid material [ 42 ].…”

Facile synthesis of superhydrophobic MS/TiO2/PDMS sponge for efficient oil–water separation

“…Meanwhile, hydrophobic nanoparticles, such as TiO 2 (Chen et al 2016), SiO 2 (Yeom & Kim 2016), Ag (Qin et al 2018), ZnO (Tran & Lee 2017), Fe 3 O 4 (Li et al 2018), and attapulgite particles have been used to modify the surface of sponges. Especially, oleophilic TiO 2 nanoparticles, which are widely used as a functional material with good chemical stability, was adsorbed to the surface of the MS's skeleton to enhance the surface roughness of the sponge and the adsorption performance for oil spill cleanup (Padervand et al 2011;Ge et al 2014;Li et al 2020). The nanoscale protrusion of hydrophobic TiO 2 forms a rough surface similar to lotus leaf, which enhances their superhydrophobicity.…”