| The frequent occurrence of oil spills and other accidents,and the increase in the discharge of industrial oily wastewater and domestic sewage have not only caused great waste of resources,but also caused enormous damage to the fragile ecological environment and biodiversity.Traditional oil-water separation methods include gravity method,centrifugal method,local combustion,etc.But all methods have unavoidable disadvantages,such as high price,low separation rate,secondary pollution and so on.Therefore,materials and installations which can effectively solve the above problems and avoid the defects of traditional oil-water separation methods are urgently needed.After the initial development stage,special wettability materials have been successfully applied to oil-water separation and have attracted wide attention all over the world.Compared with the traditional oil-water separation methods,special wettability materials for oil-water separation are based on the differences surface energy between oil phase and water phase,so such separation methods can achieve higher separation rate.Meanwhile,expensive,secondary pollution and other problems can be avoided owing to such materials.In our study,copper foam was selected as the substrate.Around the special wettability and the application in oil-water separation various properties and mechanisms of the special wettability materials by one-step hydrothermal method and chemical modification or pre-wetting methods were investigated.1.By simple chemical etching and one-step hydrothermal method,and adjusting the amount of urea,uniform and dense titanium dioxide nanorods were successfully prepared on metal copper foam surface.2.By means of chemical modification,the materials after hydrothermal treatment were modified by 1H,1H,2H,2H-perfluorooctyl trichlorosilane and superhydrophobic-superolephilic porous materials were successfully fabricated.The water contact angle on the surface is 154°,the sliding angle is 4.8°,and the contact angle of oil is about 0°.This porous material not only has good low adhesion and self-cleaning performance,but also has good oil-water separation performance.Taking diesel as an example,the separation rate can reach 93%.3.By simple chemical etching and one-step hydrothermal method,the uniform and compact titanium dioxide nanorods were deposited on the copper foam surface.Meanwhile,the hierarchical microstructures were constructed successfully.The copper foams after hydrothermal treatment are easily wetted by oil or water.When it is pre-wetted by first liquid phase and placed in the second liquid phase without being replaced by the second liquid phase.By simple pre-wetting,special wettability porous materials with dual superlyophobic(underwater superoleophobic and undero il superhydrophobic)were obtained.The oil contact angle underwater on this surface is 160°,and the water contact angle underoil on this surface is 159°.Our experiments confirm that the critical factor to realize dual superlyophobic is that the material can be wetted and will not be replaced by the second liquid phase after being wetted first liquid phase.4.By simply pre-wetting,regardless of the relative specific gravity of oil and water,oil-water mixtures can be separated continuously and efficiently,and the separation rate can reach 99%without surface modification.This material has good cycling performance,durability and other advantages.That is to say,we can use an environmentally friendly and low-cost method to achieve the continuous,efficient oil-water separation. |
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