| With the development of economy,the oily wastewater from industrial production and human life have brought huge disasters to the ecological environment and public health,in particular,it also caused a large amount of energy loss.Reasonable and efficient treatment of oily wastewater has become an urgent and important topic.At present,it is difficult to meet the requirements of high efficiency and low energy consumption for the traditional separation method.Therefore,it is urgent to develop a new,economic,environmental and efficient oil-water separation technology.Special wettability materials rely on the opposite affinity of oil and water,and the oil and water can be selectively wetting and exclusion to achieve the purpose of oil-water separation.Inspired by fish scales,superhydrophilic and underwater superoleophobic materials can not only effectively inhibit oil scale and prevent the material from being polluted by oil products,but also promote the continuous infiltration of water in the filtration process,and ensure the environmental protection,high efficiency and long life of separation materials,which is the main development direction of oil-water separation materials in the future.Based on this,the work mainly focuses on the theory and application of the surface wettability,stability and oil-water separation of stainless steel filter screen modified with polyacrylamide hydrogel.The specific work is as follows:（1）Inspired by natural Marine mussels,we prepared a self-healing hydrogel-coated screen to achieve highly efficient oil-water separation.Polydopamine（PDA）was incorporated into polyacrylamide（PAM）and uniformly coated on a stainless steel screen to prepare a self-healing hydrogel-coated screen.The results showed that the PDA-PAM hydrogel coating firmly adhered to the stainless steel screen and exhibited superhydrophilicity and underwater superoleophobicity.Regarding the PDA-PAM hydrogel modified screen with a coating time of 7 min,different types of oil-water mixtures could be driven by gravity to achieve a highly efficient oil-water separation rate of over 97%,and the water flux could reach 91,673L·m-2·h-1.After ten cycles,the separation efficiency did not decrease significantly,suggesting that the self-healing hydrogel-coated screen has excellent stability and recycling performance.This inexpensive novel filter screen with high efficiency has a wide range of potential application in the field of oil-water separation.（2）In order to enhance the wettability of the modified screen and improve the efficiency and stability of oil-water separation,a composite hydrogel modified screen with rough surface structure was prepared.First,the stainless steel filter screen was covered with a uniform layer of Si O2microspheres by vapor deposition of polydimethylsiloxane（PDMS）.Then,the Si O2/PDA-PAM composite hydrogel modified screen was prepared by the same method in（1）,and the preparation conditions were selected and optimized.The results showed that the Si O2/PDA-PAM composite hydrogel modified screen had obvious rough structure and its wettability has been enhanced,showing superhydrophilic and underwater superoleophobicity.The Si O2/PDA-PAM composite hydrogel modified screen with PDMS mass of 0.028 g·cm-2and coating time of 3 min could separate different types of oil-water mixture under gravity.The high separation efficiency is more than 99%and water flux is up to 9×104L·m-2·h-1and not less than 2×104L·m-2·h-1.The separation efficiency and water flux remained stable after10 or even 70 cycles,indicating that the Si O2/PDA-PAM composite hydrogel modified screen has excellent oil-water separation performance and stability.The oil invasion pressure and corrosion resistance were also tested,which provided a good reference for practical application.The development of this novel filter with high efficiency and high stability is of great significance to the treatment and recovery of oily wastewater.（3）To improve the binding force between the coating and the filter screen,we prepared a xerogel renaturated hydrogel modified filter screen.PAM/sodium alginate（SA）double network xerogel particles were combined with the screen by an adhesive,and the xerogel coating was further renaturated to obtain PAM-SA double network hydrogel modified screen,and the preparation process was optimized.The results showed that the PAM-SA double network xerogel renaturated hydrogel modified filter screen with 20～30μm xerogel particle size and 0.1 g/m L binder had rough surface structure,superhydrophilic and underwater superoleophobic,excellent mechanical wear resistance,stability and chemical stability.The PAM-SA double network xerogel renaturated hydrogel modified screen can separate different types of oil-water mixture under gravity,achieving up to 99%separation efficiency,and water flux maintained at 2～6×104L·m-2·h-1.After 10 cycles,the separation efficiency and water flux have not decreased significantly,indicating that PAM-SA double network xerogel hydrogel modified screen has excellent oil-water separation performance and stability.The corrosion resistance and swelling resistance of PAM-SA double network xerogel renaturated hydrogel modified screen are also tested,which provides a new way for practical water treatment application.The novel filter screen with simple preparation and high stability provides a new idea and method for the field of oil-water separation. |
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