【摘要】：聚偏氟乙烯(PVDF)因突出的化學、機械和熱穩(wěn)定性等功能性而廣泛用于膜材料制備，但由于其較低的表面能、強疏水性導致在膜分離過程中容易產生膜污染，限制了其進一步的發(fā)展應用。目前，工業(yè)中廣泛采用對PVDF膜進行共混改性、化學改性、光接枝等改性，提高其親水性和抗污染性。 本文利用紫外光輻照將含有親水性基團羰基和聚乙二醇的聚乙二醇甲基丙烯酸甲酯(PEGMA)接枝到疏水性的PVDF超濾膜表面，完成膜的親水改性。同時還發(fā)現，通過加入交聯(lián)劑N,N-亞甲基雙丙烯酰胺(MBAA)可以減少接枝層的溶脹性。該方法采用紫外光輻照接枝，不會損壞膜材料的本體性能，，并且工藝簡單、成本較低。本文主要研究不同改性條件下的膜改性效果，通過各種測試手段對該型膜進行表征，利用乳化油溶液和牛血清蛋白(BSA)溶液分離效率和抗污染性，還將改性膜用酸堿及次氯酸鈉溶液進行接枝層的穩(wěn)定性測試。 實驗通過紫外光輻照將PEGMA接枝到膜上，利用傅里葉紅外光譜(FTIR)對產物進行檢測，結果表明，PEGMA成功的接枝到膜表面；通過場發(fā)射掃描電鏡(FESEM)的結果表明，接枝改性后膜的孔徑縮小和孔隙率降低。在膜表面潤濕性方面，研究結果表明經PEGMA接枝改性后膜的親水性增強，隨著接枝濃度和時間的延長，膜表面接觸角不斷下降，如原膜的接觸角為77°左右，經80g/L的PEGMA接枝60min后接觸角為58°左右。對于水通量，實驗發(fā)現經PEGMA接枝后，隨著接枝濃度和接枝時間的增加，膜純水通量不斷在下降，如原膜的純水通量為184.9L/m2·h左右，經40g/L的PEGMA接枝60min后，純水通量為162.2L/m2·h左右；加入MBAA后，膜的吸水率出現相反的趨勢，接枝濃度和接枝時間的增加，膜的吸水率在不斷的下降，且加入MBAA后比單純PEGMA接枝接觸角略微上升，純水通量略微下降。在模擬污染實驗中，在過濾BSA溶液時，原膜在起始過濾時截留率低于改性膜，而隨過濾時間延長，原膜的截留率高于改性膜，而單純PEGMA接枝后的截留率低于加入MBAA后接枝膜的截留率。 以乳化油溶液和BSA溶液為過濾介質研究膜的抗污染性的過程中，結果表明，膜的抗污染能力的大小順序為原膜PEGMA+MBAA的接枝膜PEGMA接枝膜。將膜浸泡于酸堿及次氯化鈉溶液中，通過對比，發(fā)現改性膜在這三種溶液中的穩(wěn)定性順序為酸性環(huán)境強氧化性環(huán)境堿性環(huán)境。 本項目研究成果不僅可以拓寬制備高性能超濾膜的技術思路，還可以為膜材料探尋、分離工藝設計、膜工藝的運行管理等相關的研究提供技術支持。
[Abstract]:Polyvinylidene fluoride (PVDF) (PVDF) is widely used in the preparation of membrane materials because of its outstanding chemical, mechanical and thermal properties. However, because of its low surface energy and strong hydrophobicity, it is easy to cause membrane fouling during membrane separation. It limits its further development and application. At present, the modification of PVDF membrane by blending, chemical modification and light grafting is widely used in industry to improve its hydrophilicity and pollution resistance. In this paper, (PEGMA) containing hydrophilic group carbonyl group and polyethylene glycol was grafted onto the surface of hydrophobic PVDF ultrafiltration membrane by UV irradiation, and the hydrophilic modification of the membrane was completed. It was also found that the swelling of the grafted layer could be reduced by adding the crosslinking agent N- N- methylene bisacrylamide (MBAA). This method can not damage the bulk properties of the film by UV irradiation, and the process is simple and the cost is low. In this paper, the effect of membrane modification under different modification conditions was studied. The membrane was characterized by various test methods, and the separation efficiency and antifouling property of the membrane were obtained by using emulsified oil solution and bovine serum protein (BSA) solution. The stability of the grafted layer was tested by acid-base and sodium hypochlorite solution. PEGMA was grafted onto the film by UV irradiation, and the product was detected by Fourier transform infrared spectroscopy (FTIR). The results showed that the grafted PEGMA was successfully grafted to the surface of the film, and the results of field emission scanning electron microscopy (FESEM) showed that, The pore size and porosity of the graft modified membranes were reduced. In terms of surface wettability, the results show that the hydrophilicity of the membrane modified by PEGMA is enhanced, and the contact angle of the membrane surface decreases with the prolongation of the grafting concentration and time, such as the contact angle of the original membrane is about 77 擄. The contact angle of 60min grafted with PEGMA of 80g/L is about 58 擄. For the water flux, it was found that the pure water flux of the membrane decreased with the increase of the grafting concentration and grafting time after grafting with PEGMA, such as the pure water flux of the original membrane was about 184.9L/m2 h, and the pure water flux of the original membrane was about 162.2L/m2 h after the grafting of 60min with PEGMA of 40g/L. With the addition of MBAA, the water absorption of the membrane showed a reverse trend. With the increase of grafting concentration and grafting time, the water absorption of the membrane decreased, and the contact angle of MBAA increased slightly compared with that of pure PEGMA, and the pure water flux decreased slightly. In the simulated pollution experiment, when the BSA solution was filtered, the rejection rate of the original membrane was lower than that of the modified membrane at the beginning of filtration, but with the increase of the filtration time, the rejection rate of the original membrane was higher than that of the modified membrane. However, the rejection rate of PEGMA grafted membranes was lower than that of MBAA grafted membranes. The antifouling ability of the membrane was studied by using emulsified oil solution and BSA solution as the filtration medium. The results showed that the order of the antifouling ability of the membrane was the PEGMA graft membrane of the original membrane PEGMA MBAA. The membrane was immersed in acid-base solution and sodium hypochloride solution. By comparison, it was found that the stability of the modified membrane in these three solutions was in the order of acidic environment, strong oxidizing environment and alkaline environment. The research results of this project can not only broaden the technical thinking of preparing high performance ultrafiltration membrane, but also provide technical support for the research of membrane material exploration, separation process design, membrane process operation management and so on.
【學位授予單位】：東華大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TQ051.893;X505

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