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Investigation on Preparation and Performance of Self-assembly Nanofiltration

Author: WangZongWen
Tutor: SuBaoWei
School: Ocean University of China
Course: Chemical processes
Keywords: Layers of self-assembly Polyelectrolyte Nanofiltration membrane Retention performance
CLC: TB383.2
Type: Master's thesis
Year: 2011
Downloads: 143
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Abstract

Polyelectrolyte layers of self-assembled multilayer films in the base film with a charge alternating deposition the different polyelectrolyte achieved. The thickness of the monolayer film, this film formation method can control at the nanometer level, the charge density and composition of the active layer of the multilayer film can be changed, can be prepared better separation membrane flux and rejection performance. In the preparation process and dynamic preparation can be prepared in less number of layers the better performance of the NF membrane cause for concern. This study were selected sodium polystyrene sulfonate (PSS) and poly dimethyl diallyl ammonium chloride (PDADMAC) overcast, cationic polyelectrolyte, polysulfone (PS) ultrafiltration membrane as the base film examines the static, dynamic and static and dynamic combination of three self-assembly preparation and scanning electron microscopy (SEM), atomic force microscopy (AFM), IR ATR (ATR.FTIR), streaming potential, contact angle characterization methods and film do significant separation performance test depth layers of self-assembly mechanism. Static preparation process, first examine the impact of the type of the base film, the base film screened more suitable for preparing the multilayer polyelectrolyte self-assembly nanofiltration membrane. Second, we examine the different types and concentrations of the supporting electrolyte multilayer films, the results showed that the supporting electrolyte selected O 5m01 / L. Of NaCl when prepared better film properties. SEM and AFM analysis showed that the preparation of self-assembled nanofiltration membrane smooth film surface roughness smaller only 10.15nm. ATR. The characteristic absorption peak of 1033cm ^{-1 at sulfonate FTIR spectra with the Duplex Number increases gradually increases, indicating the occurrence of a polyelectrolyte layer self-assembly process Ps base film. Prepared by the self-assembly of the membrane surface zeta potential value and the contact angle was a regular alternating with the preparation of the number of layers, and also reflects the alternating positive and negative polyelectrolyte assembly. Static assembly (PDADMAC / PSS) 5 in 1 OMPa, 2 g / L. Na ₂ S0 ₄'s rejection of up to 93% of the flux of the solution is maintained at 60Lm ^{2 h around; interception on the 2 g / L NaCl the only about 13%, the solution through capacity 80L / m ^{2 h. Different valence ion has a good choice of separation ability. Dynamic preparation process, first examine the influence of the preparation of pressure, and the type and concentration of the supporting electrolyte, indicating that the deposition pressure O 2MPa Mgcl2 O.5m01 / L as a supporting electrolyte prepared multilayer film having better retention performance. Secondly, examines the effect of the order of deposition, showed that the first floor the deposition PDADMAc when the (PDADMAC / PSS) multilayer film prepared by the influence of the supporting electrolyte solution having a good hydrophilic, the contact angle is significantly smaller than the first layer deposition PSS (PSS / PDADMAC) prepared multilayer films. Again, the the prepared flux changes in the the ScS deposition process and resistance analysis showed that the first two bunk deposition is critical in the preparation process. AFM, SEM analysis showed that compared to static deposition surface smooth and slightly worse, four bilayers the roughness has reached about 18 11nm. Dynamically prepared (PDADMAC / PSS) ₄ the on Na ₂ SO ₄ the retention rate of 90% under 1.0MPa, the solution through about 56 / m ^{2 h, with similar static five double membrane performance. Combination of static film's smooth and dynamic deposition faster, to carry out a combination of static and dynamic Layer-by-layer self-assembly nanofiltration membrane developed. Study indicate that the dynamic deposition of the first layer polyelectrolyte PDADMAc of the surface of the base film can bring a high positive charge, thus ensuring the alternating cation and anion polyelectrolyte self-assembly. SEM, the contact angle value reflects a combination of static and dynamic braking film density and a good hydrophilicity, AFM that its roughness is only about 5.92nm. Combining static and dynamic prepared under optimal conditions (PDADMAC / PSS) ₃ SO on 2G/LNa _{2 _{1 0MPa under 4}'s rejection of up to 90% of the flux of the solution is maintained at 50 ~ 60L / m ^{2 h. Three preparation methods comparison shows that combining static and dynamic deposition speed static and dynamic, high performance nanofiltration membrane and can be prepared in less number of layers. Dynamic, combining static and dynamic resistance analysis showed increased resistance in the preparation process is basically the same trend, the relationship between the film growth trends and preparation.}}}}}}

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