Fabrication Of Superhydrophobic-Superoleophilic Cu Foam And Research On Oil/Water Separation

Water pollution and oil pollution are becoming serious in the natural world, which caused human health and resource waste problems. Therefore, oil/water separation technique has a significant theoretical and practical value. Different effect mechanisms of material special wettability on water and oil were utilized to realize oil/water separation. In this work, superhydrophobic-superoleophilic surface was obtained on Cu foam using oxidation and chemical etch special machining techniques respectively. Two kinds of oil/water separating equipment were designed based on this surface, and a series of studies were conducted on the two superhydrophobic-superoleophilic surface preparing methods and the two kinds of oily water separating equipment as follows:(1) Oxidation was proposed to fabricate superhydrophobic-superoleophilic surface on Cu foam in view of the massive precious metal, strong acid, strong base and fluorine substance required by traditional superhydrophobic surface preparing methods. Based on this proposed method, the change law of wettability along oxidation time was studied; the microstructure characteristics and the chemical constituents of the prepared superhydrophobic-superoleophilic surface on Cu foam were analyzed, also the special morphology's formation reason on the surface was explored; the corrosion resistance and the water pressure resistance of the prepared surface were tested. From the experiment results, the Cu foam surface after oxidation has hydrophilic property, while after modified by low surface energy, it turns into a superhydrophobic-superoleophilic surface with a water contact angle of 155±3°, good corrosion resistance and water pressure resistance.(2) Chemical etching method was proposed to prepare superhydrophobic-superoleophilic surface on Cu foam in view of the low efficiency, the high cost and the prone to failure of super-hydrophobicity of the existing super-hydrophobic surface preparing methods. Based on this method, the change law of wettability along etch time was studied; the microstructure characteristics and the chemical constituents of the prepared superhydrophobic-superoleophilic surface on Cu foam were analyzed considering etchant prefer to etch the bared crystal defects such as grain boundary and dislocation on the metal surface; the corrosion resistance and the water pressure resistance of the prepared surface were tested. From the experiment results, the Cu foam surface after chemical etching has hydrophilic property, while after modified by low surface energy, it turns into a superhydrophobic-superoleophilic surface with good corrosion resistance and water pressure resistance around 1.2 kPa.(3) Gravity driving oil/water separation device aim at heavy oil/water mixture was designed and assembled based on the prepared superhydrophobic-superoleophilic surface on Cu foam, the oil/water separating conditions and mechanism of the developed device was researched, also the separation efficiency and durability test of the separated oil was implemented. From the test results, the developed equipment not only could finish oil/water separation successfully but also has a high separation efficiency and recycling ability, which could be reused for 12 times.(4) A widespread spilled oil collecting device without being squeezed, pre-collecting oil/water mixture and secondary pollution, which only relies on surface tension and gravity drive force to realize oil/water separation, was designed to overcome the disadvantages of the traditional oil/water separating method and the existing oil/water separating method using extreme wettability material. The oil/water separating principle, the wind wave resistance and the recycling ability of the developed device was analyzed. From the analysis result, the developed device, with efficiency above 91%, good wave/wind resistance and recycling ability, could collect a variety of oil automatically only relying on surface tension and gravity drive force.