Design And Fabrication Of The Aqueous Channel Incorporated Biomimetic Membranes

Seawater desalination is one of the ways to solve the shortage of water resourcesin the world, and the key technology of desalination is that the performance ofmembrane. Development of new composite membrane materials to reduce the energyconsumption and achieve high efficiency and portable water purification technology,is the research focus and the development trend in the field of membrane materials.Carbon nanotube (CNT) and Aquaporin (AQP) are two ideal molecules of waterchannels. They have the super water permeability and single permeability. The newcomposite membrane doped carbon nanotubes and aquaporin overcomes theshortcomings of the traditional separation membranes can’t improve the water fluxand rejection at the same time. In this paper, carbon nanotubes composite film dopedwith different content and different diameter is prepared and supported phospholipidbilayers maintaining water channel protein active is prepared, and they arecharacterized and tested respectively.In this paper the different content and different diameter of carbon nanotubes aredoped to casting solutions containing polyethersulfone (PES). The compositemembrane is obtained through the gas phase inversion method. And they arecharacterized by the contact angle, attenuated total reflection infrared (ATR-FTIR),Scanning electron microscope (SEM), Atomic force microscope (AFM), the waterflux and rejection. The obtained results are as follows:With the increase of the carbon nanotube content, the contact angle of thecomposite film showed a decreasing trend, but the decline is not obvious. ATR-FTIRverifys that the carbon nanotubes really dope into the composite film. SEM surfaceand cross-section of the figure show that the holes of the composite film surface firstincrease and then decrease, and the porosity first increase and then decrease. AFMrepresents that the roughness of the composite membrane increases. In the sodiumsulfate, magnesium sulfate and sodium chloride solution, the composite membrane flux and salt rejection presents the trend of first increase and then decrease withincreasing nanotube content in the homogeneous solution. Under the same carbonnanotubes content, the composite membrane presents the minimum water flux and themaximum salt rejection in the sodium sulfate solution, the maximum water flux andthe minimum salt rejection in the sodium chloride solution.With the increase of the carbon nanotube diameter, the contact angle of thecomposite film showed the increasing trend, but the growth is not obvious. SEMsurface and cross-section of the figure show that the layers exist dense obvious fingerhole and downward large circular hole and the clear sponge-like pore structure areemerged. The change is not obvious with the increase of the carbon nanotube diameter.AFM represents that the changes of the roughness of the composite membrane don’tshow the consistent regularity. In the sodium sulfate, magnesium sulfate and sodiumchloride solution, the composite membrane flux presents the trend of decrease andthen the salt rejection presents the trend of increase with increasing nanotube diameterin the homogeneous solution. Under the same carbon nanotubes content, thecomposite membrane presents the minimum water flux and the maximum saltrejection in the sodium sulfate solution, the maximum water flux and the minimumsalt rejection in the sodium chloride solution.This article obtains the best quality condition of phospholipid bilayers at lowconcentrations, the optimum temperature for the time of2h mica substrate. Then thebest preparation conditions are applied to the nanofiltration membrane (NF90, NF270,NTR7250, NTR7450). The morphology and hydrophily of the phospholipid bilayersmembrane are characterized. The obtained results are as follows: the roughness ofNTR7450membrane respectively for the base of the spreading of the bilayermembrane is less than the other three kinds of nanofiltration membrane. We can seethe NTR7450membrane as the substrate of the spreading SPB is the least amount ofdefects. The infrared phospholipid characteristic peak appearance characterizes thepresence of functional groups of the bilayer membrane. The contact angle of the fourkinds nanofiltration membranes forming SPB decrease and increase theirhydrophilicity, further provide evidence of phospholipid bilayer membrane in four nanofiltration membranes indeed formed.