| With the rapid development of economy,crude oil plays a more and more important role in modern industry.However,with the frequent occurrence of offshore oil leakage,it not only has a huge impact on the ecological environment and public health,but also causes a lot of energy losses.In this case,how to treat oily wastewater reasonably and efficiently has become an urgent and important research topic.Compared with the traditional oil-water separation technology,extreme wettability materials have the advantages of high separation efficiency and wide selectivity.However,there are still some shortcomings in the preparation of oil-water separation materials,such as high cost,complex process,difficult to large-scale preparation,and the material itself is generally poor chemical stability,single performance,easy to pollution,difficult to use in extreme conditions.In view of the above problems,this project focuses on the preparation method of extremely wettable metallic mesh and its application in oil-water separation.Chemical oxidation method is adopted to prepare super hydrophilic and super hydrophobic stainless steel filter mesh,and they are applied in oil-water separation.The main work is as followsFirstly,the process and mechanism of preparing extreme wettability stainless steel meshes have been explored.The black oxide was formed on the surface of the stainless steel mesh prepared by oxidation reaction,and the black surface deepened with the increase of reaction time;the analysis by EDS and XPS showed that the rough structure was composed of Cr OOH,Cr(OH)3,Cr2O3,Fe OOH and Fe2O3.The surface showed micro-nano rough structure,superhydrophilic,and superhydrophobic after modification.The optimal reaction conditions were explored.Then,the wettability of the prepared meshes have been tested.The results showed that two kinds of stainless steel meshes,superhydrophilic and superhydrophobic meshes,have been successfully prepared.The contact angle of the former was about 8 °for water droplets,and the contact angle for kinds of oils under water was more than150°;the contact angle of the latter was 162° for water droplets,and the rolling angle was 6°,showing excellent superhydrophobicity and low adhesion;the oil droplets(hexadecane)could spread rapidly.Aditionly,the water pressure resistance and stability of the prepared superhydrophobic-superhydrophilic stainless steel meshes have been tested.The results showed that it could withstand the hydrostatic pressure of 1.79 k Pa;for different p H droplets,the contact angle of the prepared samples was still above 150°;the wettability had no obvious change whether it was immersed in seawater for 120 h or placed in air for 30 days;after a total of 10 m friction test,the water droplets' contact angle on the surface of the samples was still above 150°.Finally,two kinds of stainless steel mesh have been used in oil-water separation test.The results showed that it has good separation efficiency for five different kinds of oil,and the separation purity was high,the existence of water is not detected in the separated oil,and the content of oil in the separated water was very small;the prepared mesh had good recycling ability,and could maintain high separation efficiency,and the micro-nano rough structure of the surface was still maintained;the preparation method was simple and effective The mesh could also be used for oil-water separation in harsh environment,with separation efficiency of above 95% for strong acid solution/oil,strong alkali solution/oil,high concentration salt solution/oil and hot water/oil mixture. |
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