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  本文選題：聚乙烯醇　切入點：微孔膜　出處：《長春工業(yè)大學(xué)》2017年碩士論文

【摘要】：超濾膜廣泛應(yīng)用在食品、生物醫(yī)藥、廢水處理以及超純水的制備等領(lǐng)域。聚偏氟乙烯(PVDF)由于它具有高的機械強度,熱穩(wěn)定性,抗化學(xué)腐蝕力等優(yōu)點,成為科學(xué)家們所關(guān)注的超濾膜材料。但是PVDF膜的本身的性質(zhì)制約了它在水溶液系統(tǒng)的分離與純化。主要問題就是PVDF具有低的表面能,PVDF本身疏水性很強,常常會導(dǎo)致膜純水通量的降低。諸如含有蛋白質(zhì)的料液通過膜材料的時候,蛋白質(zhì)會容易在膜的表面以及膜孔上吸附,不利于膜的分離性能的提高,膜易受到污染,膜的使用壽命降低,運行的經(jīng)濟成本大大升高。因此科學(xué)家致力于對PVDF膜進行親水改性,以制備高性能的膜,這一方法具有重大意義。本文從凝膠浴的組成以及鑄膜液組成兩方面入手對PVDF膜進行親水改性,制備了親水性的PVDF膜,并表征了膜的性能。結(jié)果如下:首先從改變凝膠浴方面使用PVA水溶液作為凝膠浴對PVDF膜進行親水改性。使用不同用量的PVA水溶液作為凝膠浴,通過浸沒沉淀相轉(zhuǎn)化法制備了不同結(jié)構(gòu)與性能的親水微孔膜,即CPVA-PVDF-X膜(X為PVA在水中的質(zhì)量分數(shù))。運用電鏡、TGA、ATR-FTI、機械強度、水接觸角、超濾實驗等表征膜的綜合性能。實驗證實,凝膠浴中PVA水溶液濃度越高,膜的斷面指狀孔所占面積越少,海綿狀孔所占面積越多;膜的熱穩(wěn)定性提高;膜的機械性能增強;孔徑分布變窄;PVDF膜純水通量降低,BSA截留能力提升,膜的抗污染性能提高。隨后,為了避免PVA在浸泡過程中溶解于水中,將上述制備的親水微孔膜進行表面交聯(lián)處理,制備了CCPVA-PVDF-X膜。并對交聯(lián)后的膜進行掃面電鏡觀察、TGA、紅外檢測、機械強度、接觸角(CA)和超濾實驗表征。結(jié)果表面交聯(lián)后的膜的機械強度、BSA截留率以及膜的抗污染性能與未交聯(lián)的相比增強。最后從改變鑄膜液的組成方面入手,利用PVA對SiO_2進行親水改性后合成改性SiO_2,將不同質(zhì)量分數(shù)的改性SiO_2與PVDF鑄膜液混合,制備了PVA-SiO_2/PVDF膜。運用掃面電鏡觀察、紅外測試、水接觸角測試和超濾實驗表征膜的綜合性能。結(jié)果顯示,改性SiO_2與普通SiO_2相比更親水;隨著鑄膜液改性SiO_2濃度的增加,膜親水性變強,而膜的通量先出現(xiàn)增長的趨勢之后又減少。M5親水性最強;純水通量最高;膜抗污染性能最強。
[Abstract]:UF membrane is widely used in food, biomedicine, wastewater treatment and preparation of ultrapure water.Polyvinylidene fluoride PVDF (PVDF) has become the ultrafiltration membrane material for its high mechanical strength, thermal stability and chemical corrosion resistance.However, the properties of PVDF membrane restrict its separation and purification in aqueous solution system.The main problem is that PVDF has low surface energy and high hydrophobicity, which often leads to the decrease of pure water flux.For example, when the material containing protein passes through the membrane material, the protein will be easily adsorbed on the surface of the membrane and on the membrane pore, which is not conducive to the improvement of the separation performance of the membrane, the membrane is liable to be contaminated, and the service life of the membrane is reduced.The economic cost of operation is greatly increased.Therefore, it is of great significance to prepare high performance PVDF membranes by hydrophilic modification.In this paper, the hydrophilic modification of PVDF membrane was carried out from the composition of gel bath and the composition of casting membrane. The hydrophilic PVDF membrane was prepared, and the properties of the membrane were characterized.The results are as follows: firstly, the hydrophilic modification of PVDF membrane was carried out by using PVA aqueous solution as gel bath to change the gel bath.Hydrophilic microporous membranes with different structures and properties were prepared by immersion precipitation phase inversion method using different PVA aqueous solution as gel bath, that is, CPVA-PVDF-X membrane X was the mass fraction of PVA in water.The comprehensive properties of the membrane were characterized by electron microscope (TEM) TGAN ATR-FTI, mechanical strength, water contact angle and ultrafiltration test.The experimental results show that the higher the concentration of PVA aqueous solution in gel bath, the less the area of finger pore, the more the area of sponge pore, the better the thermal stability of membrane and the more mechanical property of membrane.The pore size distribution becomes narrower and the pure water flux of PVDF membrane decreases and the retention ability of BSA increases, and the fouling resistance of PVDF membrane is improved.Subsequently, in order to prevent PVA from dissolving in water during soaking, the hydrophilic microporous membrane was cross-linked and the CCPVA-PVDF-X membrane was prepared.The cross-linked films were characterized by scanning electron microscopy (SEM), IR, mechanical strength, contact angle (CAA) and ultrafiltration (UF).Results the mechanical strength and BSA rejection rate of the membranes after surface crosslinking were higher than those of the uncrosslinked membranes.Finally, by changing the composition of casting solution, the modified SiO-2 was synthesized by hydrophilic modification of SiO_2 by PVA. The PVA-SiO_2/PVDF membrane was prepared by mixing the modified SiO_2 with the cast solution of PVDF with different mass fraction.The comprehensive properties of the membrane were characterized by SEM, IR, water contact angle and ultrafiltration.The results showed that the modified SiO_2 was more hydrophilic than that of the ordinary SiO_2, and the hydrophilicity of the modified SiO_2 increased with the increase of the concentration of modified SiO_2 in the casting solution, while the flux of the membrane first increased and then decreased, the hydrophilicity of M5 was the strongest, and the pure water flux was the highest.The membrane has the strongest anti-fouling performance.
【學(xué)位授予單位】：長春工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TQ051.893

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