PVDF超濾膜改性及其應(yīng)用研究
發(fā)布時(shí)間：2019-03-16 12:01
【摘要】：膜分離技術(shù)是以物質(zhì)分離、濃縮和提純?yōu)槟康牡慕?jīng)濟(jì)、環(huán)保、高效的分離手段。目前,聚偏氟乙烯(PVDF)已經(jīng)是當(dāng)今世界上應(yīng)用最廣泛的膜分離材料之一,它具有抗氧化活性強(qiáng),耐化學(xué)性優(yōu)異,熱穩(wěn)定性強(qiáng),機(jī)械強(qiáng)度大,成膜性能良好等優(yōu)良性能,但由于其表面能低,疏水性強(qiáng)而使其容易受到蛋白質(zhì)和水處理系統(tǒng)中其他雜質(zhì)的污染,導(dǎo)致膜通量下降,膜的使用壽命減小,更換成本增加,這就限制了 PVDF膜在水處理領(lǐng)域的應(yīng)用。因此,PVDF的疏水性成為其在膜技術(shù)應(yīng)用中的主要障礙。為了使PVDF膜更好的運(yùn)用在污水處理技術(shù)中,本文結(jié)合共混和原位共沉兩種方法對(duì)PVDF膜進(jìn)行親水化改性,并提出了一種穩(wěn)定性較好的復(fù)合膜制備方法。本研究以聚偏氟乙烯(PVDF)為聚合物,氧化石墨烯(GO)為添加劑,聚乙烯吡咯烷酮(PVP30)為致孔劑,N,N-二甲基乙酰胺(DMAc)為溶劑配制鑄膜液,借助相轉(zhuǎn)化法制備了聚偏氟乙烯/氧化石墨烯超濾膜(PVDF/GO,PGM),并通過原位共沉反應(yīng)在PVDF膜和PGM表面沉積Ag2C03得到Ag2C03@PVDF/GO復(fù)合膜(AgC-PGM)和Ag2C03@PVDF復(fù)合膜(AgC-PVDF)。選用3種模擬污染物(牛血清蛋白BSA、腐植酸HA和甲苯)對(duì)復(fù)合膜的基本性能和分離性能進(jìn)行了考察,并通過膜阻力計(jì)算、污染物的靜態(tài)吸附和修正污染指數(shù)(MFI)值比較等評(píng)價(jià)了復(fù)合膜的抗污染性能,同時(shí)利用傅立葉紅外光譜(FT-IR)、場發(fā)射掃描電子顯微鏡(FESEM)等表征了其微觀結(jié)構(gòu),最后利用校區(qū)湖水考察了復(fù)合膜對(duì)地表水的分離性能,用三維熒光光譜驗(yàn)證了溶解性有機(jī)物(DOM)去除實(shí)效。結(jié)果表明,當(dāng)添加GO質(zhì)量為0.4wt.%,AgN03(5.0 mM)與Na2C03(2.5mM)共沉反應(yīng)3次得到AgC-PGM呈現(xiàn)出了較高的親水性和純水通量,與PVDF膜(132.8 L/m2·h)相比,其純水通量提高了 78.8%,對(duì)BSA截留率穩(wěn)定在75%以上。與PVDF膜相比,復(fù)合膜AgC-PGM對(duì)水的接觸角降低了近10°,親水性顯著增加;對(duì)BSA溶液的通量衰減率降低了 45%,通量恢復(fù)率增加到近80%;阻力結(jié)果顯示,復(fù)合膜總阻力較PVDF膜有顯著降低,且不可逆阻力顯著下降,抗污染性能得到提高。通過分離校區(qū)湖水發(fā)現(xiàn),AgC-PGM不僅凸顯了去除蛋白質(zhì)和溶解性有機(jī)物(DOM)的能力,而且出水COD和UV254均達(dá)到了自然水體一級(jí)標(biāo)準(zhǔn),這意味著AgC-PGM是具有高抗污染和高分離性的復(fù)合膜材料。
[Abstract]:Membrane separation is an economical, environmentally friendly and efficient separation method for the purpose of material separation, concentration and purification. At present, polyvinylidene fluoride (PVDF) is one of the most widely used membrane separation materials in the world. It has excellent properties such as strong anti-oxidation activity, excellent chemical resistance, strong thermal stability, high mechanical strength, good film-forming properties, and so on. However, due to its low surface energy and strong hydrophobicity, it is vulnerable to contamination by protein and other impurities in the water treatment system, resulting in a decrease in membrane flux, a decrease in the service life of the membrane, and an increase in the replacement cost. This limits the application of PVDF membrane in the field of water treatment. Therefore, the hydrophobicity of PVDF has become the main obstacle in the application of membrane technology. In order to make PVDF membrane better used in wastewater treatment, the hydrophilic modification of PVDF membrane was carried out by blending and in-situ co-precipitation, and a method of preparing composite membrane with good stability was put forward. In this study, polyvinylidene fluoride (PVDF) was used as polymer, graphene oxide (GO) as additive, polyvinylpyrrolidone (PVP30) as pore-forming agent, N, N-dimethylacetamide (DMAc) as solvent. Polyvinylidene fluoride / graphene oxide ultrafiltration membrane (PVDF/GO,PGM) was prepared by phase inversion method. Ag2C03@PVDF/GO composite membrane (AgC-PGM) and Ag2C03@PVDF composite membrane (AgC-PVDF) were prepared by in-situ co-deposition of Ag2C03 on the surface of PVDF and PGM. Three simulated contaminants (bovine serum protein BSA, humic acid HA and toluene) were used to investigate the basic properties and separation properties of the composite membrane, and the resistance of the membrane was calculated. The static adsorption of pollutants and the comparison of the modified pollution index (MFI) values were used to evaluate the anti-fouling performance of the composite membranes. The microstructure of the composite membranes was characterized by Fourier transform infrared spectroscopy (FT-IR) and field emission scanning electron microscope (FESEM). Finally, the separation performance of the composite membrane on surface water was investigated by using the lake water of campus, and the effect of (DOM) removal of dissolved organic matter was verified by three-dimensional fluorescence spectrum. The results showed that when the mass of GO was 0.4 wt.%, Agn03 (5.0 mM) reacted with Na2C03 (2.5mM) for three times to obtain a higher hydrophilicity and pure water flux, compared with PVDF membrane (132.8 L / m ~ 2 路h), the results showed that Agn03 (5.0 mM) reacted with Na2C03 (2.5mM) for three times, showing higher hydrophilicity and pure water flux. The pure water flux increased by 78.8% and the retention rate of BSA was over 75%. Compared with the PVDF membrane, the water contact angle of the composite membrane AgC-PGM decreased by nearly 10 擄, and the hydrophilicity of the composite membrane increased significantly, and the flux decay rate of the BSA solution decreased by 45% and the flux recovery rate increased to nearly 80%. The resistance results showed that the total resistance of the composite membrane was significantly lower than that of the PVDF membrane, and the irreversible resistance was significantly decreased, and the anti-fouling performance of the composite membrane was improved. It was found that AgC-PGM not only showed the ability of removing protein and dissolved organic matter (DOM), but also reached the first class standard of natural water body for COD and UV254 in effluent by separating the lake water from campus. This means that AgC-PGM is a composite membrane material with high anti-fouling and high separation.
【學(xué)位授予單位】：天津工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：X703
本文編號(hào)：2441316
[Abstract]:Membrane separation is an economical, environmentally friendly and efficient separation method for the purpose of material separation, concentration and purification. At present, polyvinylidene fluoride (PVDF) is one of the most widely used membrane separation materials in the world. It has excellent properties such as strong anti-oxidation activity, excellent chemical resistance, strong thermal stability, high mechanical strength, good film-forming properties, and so on. However, due to its low surface energy and strong hydrophobicity, it is vulnerable to contamination by protein and other impurities in the water treatment system, resulting in a decrease in membrane flux, a decrease in the service life of the membrane, and an increase in the replacement cost. This limits the application of PVDF membrane in the field of water treatment. Therefore, the hydrophobicity of PVDF has become the main obstacle in the application of membrane technology. In order to make PVDF membrane better used in wastewater treatment, the hydrophilic modification of PVDF membrane was carried out by blending and in-situ co-precipitation, and a method of preparing composite membrane with good stability was put forward. In this study, polyvinylidene fluoride (PVDF) was used as polymer, graphene oxide (GO) as additive, polyvinylpyrrolidone (PVP30) as pore-forming agent, N, N-dimethylacetamide (DMAc) as solvent. Polyvinylidene fluoride / graphene oxide ultrafiltration membrane (PVDF/GO,PGM) was prepared by phase inversion method. Ag2C03@PVDF/GO composite membrane (AgC-PGM) and Ag2C03@PVDF composite membrane (AgC-PVDF) were prepared by in-situ co-deposition of Ag2C03 on the surface of PVDF and PGM. Three simulated contaminants (bovine serum protein BSA, humic acid HA and toluene) were used to investigate the basic properties and separation properties of the composite membrane, and the resistance of the membrane was calculated. The static adsorption of pollutants and the comparison of the modified pollution index (MFI) values were used to evaluate the anti-fouling performance of the composite membranes. The microstructure of the composite membranes was characterized by Fourier transform infrared spectroscopy (FT-IR) and field emission scanning electron microscope (FESEM). Finally, the separation performance of the composite membrane on surface water was investigated by using the lake water of campus, and the effect of (DOM) removal of dissolved organic matter was verified by three-dimensional fluorescence spectrum. The results showed that when the mass of GO was 0.4 wt.%, Agn03 (5.0 mM) reacted with Na2C03 (2.5mM) for three times to obtain a higher hydrophilicity and pure water flux, compared with PVDF membrane (132.8 L / m ~ 2 路h), the results showed that Agn03 (5.0 mM) reacted with Na2C03 (2.5mM) for three times, showing higher hydrophilicity and pure water flux. The pure water flux increased by 78.8% and the retention rate of BSA was over 75%. Compared with the PVDF membrane, the water contact angle of the composite membrane AgC-PGM decreased by nearly 10 擄, and the hydrophilicity of the composite membrane increased significantly, and the flux decay rate of the BSA solution decreased by 45% and the flux recovery rate increased to nearly 80%. The resistance results showed that the total resistance of the composite membrane was significantly lower than that of the PVDF membrane, and the irreversible resistance was significantly decreased, and the anti-fouling performance of the composite membrane was improved. It was found that AgC-PGM not only showed the ability of removing protein and dissolved organic matter (DOM), but also reached the first class standard of natural water body for COD and UV254 in effluent by separating the lake water from campus. This means that AgC-PGM is a composite membrane material with high anti-fouling and high separation.
【學(xué)位授予單位】：天津工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：X703
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