Source: School of Chemical Engineering and Technology
Written by: School of Chemical Engineering and Technology
Edited by: Wang Dongmei

Oil/water separation is a global challenge on account of the frequent crude oil spill accidents and the increasing amount of industrial wastewater. Traditional polymeric membranes face enormous challenge due to their energy-intensive separation process and easy to be contaminated. Membrane with superhydrophilicity as well as gravity-driven separation process have attracted intensive attentions owing to its superior advantages like anti-pollution, easy recycle, anti-clogging, etc..

In recent years, Prof. Shu-Shen Lyu’s group from School of Chemical Engineering and Technology at Sun Yat-sen University devoted themselves to the fundamental research in superhydrophilic materials and their potential applications. To date, they have made an important progress in the field of oil/water separation.

1. A new route for surface modification: Fluorine-induced superhydrophilicity. On the basis of the Fluorine-induced superhydrophilicity (FIS) originating from the bottom of TiO2 nanotube arrays, they have provided a novel approach to produce superhydrophilic materials and have demonstrated the FIS method via combining both experiment and theoretical computation. Simulation results showed that hydrogen bonds are formed between water molecules and oxy-fluoridized (semi)metallic interfaces. The value of this FIS has been demonstrated through the successful surface treatment for Ti, Zn, Fe, Co, Ni, and Si.

It is the first attempt to fabricate superhydrophilic interfaces via fluorine decoration, and it has worked out to be efficient. Furthermore, FIS ideas can be expanded to fabricate various superhydrophilic interfaces in the form of −Y−M−X (X = F, Cl, et al.; M = (semi)metals; Y = O, S, N, et al.), and potentially, other superhydrophilic materials can be designed by an easy operation. FIS shows remarkable stability stored under normal lab conditions, and this FIS can bear about 100 °C temperature. This relative stable fluorine-induced superhydrophilic surface can be potentially applied in self-cleaning, anti-fogging, anti-biofouling, oil/water separation, and so on. This work has been published at The Journal of Physical Chemistry C. (Zhi-Yong Luo, Kai-Xuan Chen, Dong-Chuan Mo and Shu-Shen Lyu. J. Phys. Chem. C , 2016, 120, 11882. IF = 4.772).


2. Sythesize, for the first time, the oxy-chloridized superhydrophilic Cu foam for oil/water separation. On the basis of the Fluorine-induced superhydrophilicity (FIS), they synthesized superhydrophilic Cu foam (SCuF) composed of oxy-chloridized hierarchical nanoparticles with metal Cu core and Cu2O/CuO1-x/2Clx shell via the combination of anodization, HCl etching and calcination, in which the Cl-terminated groups were formed at the surface of Cu-NPs in the form of -O-Cu-Cl or even -Cu-Cl. This SCuF shows ultrahigh water permeability and remarkable oil/water separation performance (separation efficiency > 99%). Moreover, the properties of SCuF for repeated use, anti-corrosion and anti-scratch are also excellent. This SCuF has great potential in industrial applications. This work has been published at Journal of Materials Chemistry A. (Zhi-Yong Luo, Kai-Xuan Chen, Jun-Hui Wang, Dong-Chuan Mo and Shu-Shen Lyu. J. Mater. Chem. A, 2016, 4, 10566. IF = 8.262).


3. Decorate Cu mesh with superhydrophilic core-shell Ni nanoparticles for oil/water separation. In the previous reports, (001) crystal facet exposure of TiO2, which was mainly due to the existence of fluorine, had been demonstrated. Therefore, fluorine may be the key factor to form nanoparticles with exposed lattice plane. Herein, they synthesized a superhydrophilic copper mesh decorated with Ni-NPs via simple electrodeposition in fluorine-containing electrolyte; the polygonal Ni-NP consists of a metal Ni core and a NiO/Ni(OH)2 shell, which is mainly due the crystal facet exposure of Ni-NP. This multicomponent mesh shows remarkable underwater ultralow adhesive superoleophobicity as well as excellent oil/water separation performance. After optimizing the factors (electrodeposition time and applied voltage) of preparation, the oil content in separated water is lower than 3 ppm. The stability and the properties for repeated use of superhydrophilic Cu mesh are also excellent. It is the extension of fluorine-induced superhydrophilicity. This work has been published at The Journal of Physical Chemistry C. (Zhi-Yong Luo, Kai-Xuan Chen, Ya-Qiao Wang, Jun-Hui Wang, Dong-Chuan Mo and Shu-Shen Lyu. J. Phys. Chem. C , 2016, 120, 12685. IF = 4.772)