Biomimetic super-lyophobic and super-lyophilic materials applied for oil/water separation: a new strategy beyond nature

Abstract

Oil spills and industrial organic pollutants have induced severe water pollution and threatened every species in the ecological system. To deal with oily water, special wettability stimulated materials have been developed over the past decade to separate oil-and-water mixtures. Basically, synergy between the surface chemical composition and surface topography are commonly known as the key factors to realize the opposite wettability to oils and water and dominate the selective wetting or absorption of oils/water. In this review, we mainly focus on the development of materials with either super-lyophobicity or super-lyophilicity properties in oil/water separation applications where they can be classified into four kinds as follows (in terms of the surface wettability of water and oils): (i) superhydrophobic and superoleophilic materials, (ii) superhydrophilic and under water superoleophobic materials, (iii) superhydrophilic and superoleophobic materials, and (iv) smart oil/water separation materials with switchable wettability. These materials have already been applied to the separation of oil-and-water mixtures: from simple oil/water layered mixtures to oil/water emulsions (including oil-in-water emulsions and water-in-oil emulsions), and from non-intelligent materials to intelligent materials. Moreover, they also exhibit high absorption capacity or separation efficiency and selectivity, simple and fast separation/absorption ability, excellent recyclability, economical efficiency and outstanding durability under harsh conditions. Then, related theories are proposed to understand the physical mechanisms that occur during the oil/water separation process. Finally, some challenges and promising breakthroughs in this field are also discussed. It is expected that special wettability stimulated oil/water separation materials can achieve industrial scale production and be put into use for oil spills and industrial oily wastewater treatment in the near future.

Facile Fabrication of Superhydrophobic/Superoleophilic Cotton for Highly Efficient Oil/Water Separation

“…Superhydrophobic surfaces are governed by a specific micro-nano structured surface topography and low surface energy (Wang et al 2015b). To form a rough micro/nano surface, TEOS treatment was carried out by in-situ hydrolysis on raw cotton fiber surface using PVP as coupling agent (Fig.…”

Vibrations and Spatial Patterns Change Effective Wetting Properties of Superhydrophobic and Regular Membranes

“…One of the recent applications of surfaces with tailored wettability is in separation of oil-water mixtures [37]. Porous media/meshes, which are selectively wetted by either water or organic solvents, can be used in this process.…”

Oil‐Water Separation: A Gift from the Desert

“…Materials with super-wetting properties for water or oil (e.g., materials with superhydrophobicsuperoleophilic or superhydrophilic-superoleophobic surfaces) have recently attracted increasing attention for use in oil-water separation applications because of the different interface effects of water and oil. [ 1,2 ] Superhydrophobic-superoleophilic mesh fi lms were the fi rst such materials to be used. [9][10][11] However, such "oil-removing" materials easily become blocked by the oil that adheres to the mesh as it passes through.…”

“…Sand also contains Oil-water separation is the subject of theoretical and practical research around the world because of the frequency with which oil spills occur and the increasing amounts of oily industrial wastewater that are produced. [1][2][3][4][5][6][7] For example, the Gulf of Mexico oil spill in 2010 resulted in 780 × 10 6 L of oil being released into the sea. [ 8 ] This accident caused huge economic losses and had serious effects on the environment.…”