Superwetting Materials of Oil–Water Emulsion Separation

Abstract

, as a visiting scholar. Now he is a full professor in LICP financed by "Top Hundred Talents" program of CAS. Till now, he has published more than 100 papers about the interfaces of Materials.Mr. Yifan Si joined Prof. Guo's biomimetic materials of tribology (BMT) group at University of Hubei in 2014 in pursuing his Ph.D. degree. His current scientific interests are devoted to designing and fabricating superhydrophobic nanocoatings and studying their corresponding applications. AbstractWith industrial development and population expansion, the problem of water pollution has intensified. The purification of oily water, especially oilwater emulsions, is one of the important topics of environment protection. Traditional filter membranes, to some extent, are useful for the separations of oil water mixtures but suffer from many limitations and there is no effective way to achieve emulsified oilwater separation. Superwetting materials, based on bionics, have opened a brandnew door to membrane separation techniques. The rise and maturation of nanometer-scale materials also injects new vigor into this research area. In this paper, we review the contributions to oilwater emulsion separation in recent literatures. The principles of superwetting materials in separation of oilwater mixtures have been briefly stated at first. Some classical and latest examples, as well as some great work by our group, have been emphasized. Section 3 is the key point of this article. It covers the most valuable of recent progresses in advanced materials for oilwater emulsion separation, from novel polymer membranes to nanomaterial-based membranes. Of course, special-wettability materials and non-two-dimensional separation methods have also been instructive. The aim of the optimal design of superwetting membranes is to make future researches theoretical, instructive, and practical. Finally, some challenges and the potential promising breakthroughs in this field are also succinctly highlighted.

Fabrication of Attapulgite Coated Membranes for Effective Separation of Oil‐in‐Water Emulsion in Highly Acidic, Alkaline, and Concentrated Salty Environments

“…Moreover, these microscaled oil droplets could easily roll on the surface of owing to the low oil SA, thus the size of the oil droplets would significantly increase due to the coalescence effect . Finally, the oil droplets with larger radius would leave the surface of membrane and floated up to the water surface forming an free oil layer according to the Stokes' law of resistance, achieving the whole demulsification and separation process . Here, kerosene‐in‐water emulsion was chosen as a sample.…”

Recycled Superwetting Nanostructured Copper Mesh Film: Toward Bidirectional Separation of Emulsified Oil/Water Mixtures

“…As reported, to realize the separation of emulsion, relatively small pore size would be necessary. [2b] Herein, by a simple solution immersion process, nanostructures were produced onto the copper mesh substrate to adjust the pore size. As shown in Figure b, after immersing into water solution containing NaOH and (NH 4 ) 2 S 2 O 8 for about 30 min (for more details see Figures S1 and S2 in the Supporting Information), the microscale pores become unclear and a lot of nanorods were produced on the copper lines (Figure b), which can be verified to be Cu(OH) 2 by the X‐ray diffraction (XRD) result (Figure c).…”

“…Generally, the oil/water mixtures consist of immiscible mixtures and emulsions. Compared with the immiscible oil/water mixtures, emulsified mixtures are more difficult to be separated as they are prone to be presented in multiple states under different conditions, for example, oil‐in‐water and water‐in‐oil emulsions by formulation, surfactant‐stabilized and surfactant‐free emulsions by their components . Traditional filtration membranes based on the “size‐sieving” effect have been widely used in the separation of emulsified oil/water mixtures; however, high‐energy consumption, easy fouling, low flux, and low efficiency are still difficult to be avoided for these films …”

Recent Advances in the Fabrication of Superhydrophobic Surfaces

“…Oil/water separation is becoming more and more urgent to solve the above problems caused by oil pollution. 38,149 At present, research about special wettability materials for oil/water separation has attracted much interest of scientific workers and has been reported in many publications. 23,32,38,39,51,80,113,145,150154 As a typical example, Jiang et al prepared the superhydrophobic and superoleophilic Teflon-coated mesh for oil/water separation for the first time in 2004.…”