本文選題：PVDF + 靜電紡絲��； 參考：《南昌大學(xué)》2015年碩士論文

【摘要】：針對當(dāng)前膜蒸餾用膜通量低、疏水性差等限制膜蒸餾技術(shù)規(guī)模化應(yīng)用的突出問題,基于靜電紡絲技術(shù)原理,開展新型聚偏氟乙烯(PVDF)靜電紡絲納米纖維疏水膜制備研究�？疾炝瞬煌徑z液體系對膜形貌結(jié)構(gòu)與性能的影響,優(yōu)化了靜電紡絲過程中的工藝參數(shù);并以制備的PVDF納米纖維疏水膜為膜蒸餾用膜,進行了直接接觸式膜蒸餾實驗研究。主要研究成果如下:(1)考察了混合溶劑(DMF/丙酮)對紡絲液表面張力、粘度、電導(dǎo)率及疏水膜性能的影響。實驗結(jié)果表明,隨著混合溶劑中丙酮含量的增加,紡絲液的表面張力、粘度及電導(dǎo)率呈下降趨勢,納米纖維間珠粒數(shù)量顯著減少;纖維直徑及膜厚度均有所增大;當(dāng)混合溶劑中二甲基甲酰胺與丙酮比例為9:1時,納米纖維膜的孔隙率為83%,膜接觸角可達142.8°,表現(xiàn)出較好的疏水性。(2)在二甲基甲酰胺與丙酮混合比例為9:1的條件下,進行了高分子聚合物含量對紡絲液基本性質(zhì)與膜形貌結(jié)構(gòu)及分離性能的影響研究。研究結(jié)果表明,提高紡絲液中PVDF含量,會降低紡絲液的表面張力與電導(dǎo)率,減少納米纖維間珠粒數(shù)量,而纖維的直徑增大;直接接觸式膜蒸餾脫鹽應(yīng)用實驗表明,PVDF質(zhì)量分?jǐn)?shù)為12wt%條件下制備的疏水膜,其通量可達62.38 kg/m2·h,產(chǎn)水電導(dǎo)率為8μS/cm,鹽截留率達到99.99%以上。(3)考察了靜電紡絲工藝參數(shù)對PVDF納米纖維疏水膜結(jié)構(gòu)形貌及分離性能的影響。當(dāng)電壓低于12 kV時,由于電場力不足,最終會產(chǎn)生較大斑塊,進一步影響膜通量;隨著電壓升高,纖維排布呈逐漸致密趨勢,但對膜的疏水性影響輕微;紡絲液流速的增加會使纖維直徑增大,納米纖維膜變厚;接受距離對膜的形貌影響較小,但接受距離的增大會導(dǎo)致纖維排列較為疏松;提高靜電紡絲接受器-轉(zhuǎn)鼓的轉(zhuǎn)速,會導(dǎo)致膜通量降低,實驗范圍內(nèi)最優(yōu)的轉(zhuǎn)速為10 r/min。在連續(xù)穩(wěn)定運行150小時膜蒸餾試驗后,通量下降了30%,但產(chǎn)水電導(dǎo)率為15μs/cm以下;連續(xù)三次膜蒸餾濃縮試驗,膜在清洗后,初始通量恢復(fù)率較高,分別達到了98%和96%。
[Abstract]:In view of the outstanding problems such as low membrane flux and poor hydrophobicity in membrane distillation at present, based on the principle of electrostatic spinning technology, the preparation of novel hydrophobic membrane of PVDF nanofibers was studied. The effects of different spinning liquid systems on the morphology, structure and properties of the membranes were investigated, and the process parameters during electrostatic spinning were optimized, and the direct contact membrane distillation experiments were carried out using the hydrophobic membranes of PVDF nanofibers as membrane distillation membranes. The main results are as follows: (1) the effects of the mixed solvent (DMF / acetone) on the surface tension, viscosity, conductivity and hydrophobic properties of the spinning solution were investigated. The results showed that with the increase of acetone content in the mixed solvent, the surface tension, viscosity and conductivity of the spinning solution decreased, the number of beads between nanofibers decreased significantly, and the fiber diameter and film thickness increased. When the ratio of dimethylformamide to acetone in mixed solvent is 9:1, the porosity of nanofiber membrane is 83 and the contact angle of the membrane is 142.8 擄, which shows good hydrophobicity at 9:1 when the mixture ratio of dimethylformamide and acetone is 9:1. The effects of polymer content on the basic properties, morphology and separation properties of the spinning solution were studied. The results show that increasing the content of PVDF in spinning solution can reduce the surface tension and conductivity of spinning solution, reduce the number of beads between nanofibers, and increase the diameter of fibers. The direct contact membrane distillation desalination experiment showed that the hydrophobic membrane was prepared under the condition of PVDF mass fraction of 12 wt%. The effects of electrospinning parameters on the morphology and separation properties of PVDF nanofibers hydrophobic membrane were investigated. The flux was 62.38 kg/m2 / h, the water conductivity was 8 渭 S / cm, and the salt rejection was 99.99%. When the voltage is lower than 12 kV, due to the lack of electric field force, large plaque will be produced, which will further affect the membrane flux, with the increase of voltage, the fiber arrangement becomes more dense, but has a slight effect on the hydrophobicity of the membrane. The increase of spinning liquid velocity will increase the diameter of the fiber and the thickness of the film. The acceptance distance will have little effect on the morphology of the film, but the increase of the acceptance distance will lead to the loose arrangement of fibers, and increase the rotational speed of the electrostatic spinning receptor-drum. The optimal rotational speed in the experimental range is 10 r / min. After 150 hours of continuous operation, the flux decreased by 30%, but the conductivity of water production was less than 15 渭 s/cm, and the recovery rate of initial flux reached 98% and 96% respectively after cleaning.
【學(xué)位授予單位】：南昌大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TQ051.893

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本文編號：1803117