Study Of Ipp Microporous Membranes Desigening For Oil–water Separation Prepared Via Micro-molding Combining With Tips And It’s Foiling Behaviors

With the increasing concerning on the environment,an effective method for the separation of oil-water mixture is needed urgently.Hydrophobic membrane can separate oil-water mixture by “oil removing” process,and the number of articles published each year is increasing.However difficulty still exists when come to the preparation of high performance membranes desighed for the separation of surfactant stabilized oil/water emulsion.In addition the investigations published only concentrated on the preparation of superhydrophobic-superoleophilic membranes,and the characterization of oil-water separation performances.While investigations focused on the effect of micro-structure of the hydrophobic membrane on oil-water separation performance,and the influences to the fouling behaviors of different foulants on the membrane are still lacking.Therefore three aspects have been discussed in this article to provide basis for the preparation of high performance oil-water separation membrane with certain anti-fouling property.Firstly,hydrophobic isotactic polypropylene membranes with different micro-structure on the bottom surface have been prepared by combining micro-molding with thermally induced phase separation(TIPS).Conditions for the preparation of three different hydrophobic membranes: “Lotus effect” superhydrophobic membrane(L membrane),“Petal effect” superhydrophobic membrane(P membrane),normal highly hydrophobic membrane(H membrane)have been determined.The water contact angle,sliding angle and oil spread time of L membrane with micro-scale structure formed via replicating and submicro-scale structure formed via phase separation on the bottom surface is 153°,3.2°and 0.24 s respectively;The water contact angle of P membrane as high as 151°,however the water droplet can hardly move on its bottom surface,the oil spread time of P membrane is 0.4s.The water contact angle and oil spread time of H membrane is 131°and 0.6s.Moreover all of the three different hydrophobic membranes exhibit narrow pore size distribution.Secondly,the above mentioned hydrophobic membranes have been applied to the sepration of surfactant stabilized water-in-oil emulsions.The oil-water separation performances of the membranes have been evaluated.Meanwhile the cycle performances of the membrane have been tested.L membrane exhibits the best oil-water sepration performance,it has a high permeate flux and separation efficiency.The oil-water separation performances of P membrane are lower than L membrane and the performances of H membrane are the lowest.This indicated that the combination of micro-scale structure with high aspect ratio and sub-micro scale structure,has a significant effect on enhancing the oil-water separation performances of the hydrophobic membrane.Thirdly,L membrane and P membrane have been applied for the sepration of water-in-oil emulsions with bovine serum albumin(BSA)foulant.The declination degree of the oil-water separation performances has been compared.After 20 uses L membrane suffered a moderate decline while P membrane suffered a fatal decline.This indicated the high oil capillarity of L membrane forming a relatively clean oil film acting as a barrier,preventing the contact of BSA molecule concentrated in water with the membrane.For P membrane due to the lower oil capillarity and the relatively large micro-scale structure,the dispersed waterdroplets are able to approach the bottom surface of the membrane.Thus BSA molecules concentrated in waterdroplets are likely to adhere on the bottom surface of P membrane through hydrophobic-hydrophobic interaction.Finally the above mentioned hydrophobic membranes have been applied to the sepration of oil-in-water emulsions via cross flow filtration,and the fouling behaviors of different foulants(organic foulant,particle foulant,inorganic foulant)on different membranes have been studied.The fouling of the membrane has been characterized by flux-time declination curve,flux back flush recovery rate and SEM-AFM results.The final results indicated that the bioinspired micro-submicro structure on the bottom surface of L membrane can effectively prevent cake formation caused by micro-scale foulants,however it can hardly prvent pore clogging caused by nano-scale foulants.The anti-fouling property of P membrane is obviously lower than L membrane.This indicated that the micro-structure with high water adhesion on the bottom surface of P membrane,reduced the back flush efficient and anti-fouling property of the membrane.