Construction Of Supertough/Superwettability Interface Of Polymeric Membranes For Oil/Water Separation

With the ever-increasing industrial oily wastewater and the more frequent oil spill accidents,separation of oil/water mixtures has gained considerable attention.Besides the traditional techniques,mesh and non-woven fabrics materials with special wettability now have been applied to free oil/water separation.However,they are unable to separate the surfactant-stabilized oil/water emulsions.Given that polymeric membranes with limited separation pore size and continuous separation process,this study started from preparation of polymer membranes with special wettability,selecting PVDF membrane as the research object.First,pure PVDF membrane with multi-scaled surface structure via NIPS and templating method was fabricated to obtain the superhydrophocity,and then flexible PVDF membrane decorated by nanoTiO2 modified by fluorine silane was prepaed to gain the rubost superhydrophobic surface.Subsequently,we studied the resistance of PVDF membrane to physical and chemical damage,and the oil/water separation performances as well.Following details are the specific research contents and results:(1)Superhydrophobic PVDF membrane with multi-scaled surface structure and application for oil/water separationOn the basis of nonsolvent induce phase separation method,a super hydrophobic PVDF membrane with multi-scaled surface structure was produced via peeling off PET NWF.Because of the bi-continuous microstructure,flexible PVDF membrane prepared shows the best pore connectivity and unimodal pore size distribution,and applies to various water-in-oil emulsions as displaying efficient separation and recyclability.(2)Superhydrophobic PVDF membrane with super robust surface for oil/water separationSuperhydrophobic PVDF membrane prepared via NIPS and template stripping method shows good oil/water separation efficiency.However,the delicate membrane surface would be easily damaged by external physical or chemical enviroment due to the flexibility and creep of polymer.Therefore,we modified nano-TiO2 via fluorine silane and gained the robust hydrophobic membrane surface via a spin coating method.It was found that the PVDF membrane porous surface infused by nano-Ti O2 exhibited excellent long-term resistance to physical and chemical damage,and demonstrated great capacity for oil/water separation.The continuous water-in-oil emulsions separation was achieved via a cross flow mode.In addition,the strategy of assembling inorganic particles on flexible polymeric surfaces can also be applied to rubost superhydrophilic or anti-bactirial modification on polymeric porous membranes.