PVDF超疏水性膜制備及應(yīng)用研究
發(fā)布時(shí)間：2018-07-26 13:39
【摘要】：溫室氣體CO_2成為全世界關(guān)注的熱點(diǎn),碳減排成為亟待解決的問題。膜吸收法脫除煙氣中的CO_2具有運(yùn)行費(fèi)用低、避免環(huán)境二次污染的特點(diǎn),但CO_2脫除效率受膜潤濕行為的影響。超疏水性膜能夠有效地減緩膜潤濕行為,在膜吸收法碳捕集中有廣闊的應(yīng)用前景。傳統(tǒng)的聚偏氟乙烯(PVDF)膜具有很好的疏水性,但卻不能滿足膜吸收法碳捕集的需要,因此,進(jìn)一步提高PVDF膜的疏水性是其應(yīng)用于碳捕集的關(guān)鍵。本文通過相轉(zhuǎn)化法制備PVDF基膜,再經(jīng)表面涂覆改性,增強(qiáng)了PVDF膜的疏水性,能夠在膜吸收法碳捕集中穩(wěn)定運(yùn)行。首先,采用相轉(zhuǎn)化法制備PVDF基膜,研究了凝固浴組成、致孔劑種類及添加量、PVDF固含量、鑄膜液擠出速率對PVDF基膜疏水性、氣通量、孔徑及孔隙率的影響,確定了最佳基膜制備工藝,制備了氣通量大、疏水性高的PVDF基膜。研究結(jié)果表明:以60wt.%的乙醇配制乙醇/乙酸乙烯酯為凝固浴,PVDF固含量為16wt.%,添加劑為5wt.%的PEG-400,鑄膜液擠出速率為6mL·min-1時(shí),制得基膜孔徑小(0.975μm)且孔隙率大(75.12%),使得膜氣通量也變大,達(dá)到276.09m3·m~(-2)·h~(-1),其中最為顯著的變化是接觸角增大到131.43°,具有較強(qiáng)的疏水性。其次,采用表面涂覆法對PVDF基膜進(jìn)行超疏水改性,通過測試孔徑、孔隙率、氣通量及接觸角,研究了分散劑、無機(jī)納米粒子種類及添加量、膠黏劑聚二甲基硅氧烷(PDMS)添加量、硅烷偶聯(lián)劑(KH-550)添加量對超疏水性PVDF膜性能的影響,優(yōu)化涂覆工藝,制備了性能良好的PVDF超疏水性膜。研究結(jié)果表明:以異丙醇為分散劑,納米CaCO3添加量為1wt.%,PDMS添加量為1.5wt.%,KH-550添加量為1wt.%,制得涂覆液,噴涂于PVDF基膜表面,接觸角由131.43°提高到147.06°,疏水性顯著提高,氣通量為264.12m3·m~(-2)·h~(-1),膜孔徑為0.959μm,孔隙率74.88%,氣通量、孔徑及孔隙率相較于未改性前均有所降低。最后,進(jìn)行膜吸收法脫除模擬煙氣中CO_2實(shí)驗(yàn)研究,考察了吸收液與膜的匹配性;研究了吸收液種類,濃度,煙氣流量對CO_2脫除率的影響。結(jié)果表明:氨基乙酸鉀(PG)吸收液與改性PVDF膜的匹配性最好;相同濃度PG和MEA吸收液的CO_2脫除率前者高于后者,吸收液濃度為2mol·L-1最宜,煙氣流量增大CO_2脫除率降低。當(dāng)PG吸收液濃度為2mol·L-1,煙氣流量為0.06m3·h-1時(shí),CO_2脫除率達(dá)81.43%。
[Abstract]:Greenhouse gas CO_2 has become a hot spot all over the world, and carbon emission reduction has become an urgent problem. The removal of CO_2 from flue gas by membrane absorption method has the characteristics of low operating cost and avoiding secondary environmental pollution, but the removal efficiency of CO_2 is affected by the membrane wetting behavior. Superhydrophobic membranes can effectively slow down the wetting behavior of membranes and have a broad application prospect in carbon capture by membrane absorption. The traditional polyvinylidene fluoride (PVDF) membrane has good hydrophobicity, but it can not meet the needs of carbon capture by membrane absorption method. Therefore, further improving the hydrophobicity of PVDF membrane is the key to its application in carbon capture. In this paper, PVDF substrate was prepared by phase inversion method, and then modified by surface coating. The hydrophobicity of PVDF film was enhanced, and the membrane could be concentrated and stable in carbon capture by membrane absorption method. Firstly, the phase inversion method was used to prepare PVDF substrate. The effects of coagulation bath composition, kinds of pore-forming agents and the amount of PVDF solid added, the extrusion rate of casting liquid on the hydrophobicity, gas flux, pore size and porosity of PVDF substrate were studied. The optimum preparation process was determined and the PVDF substrate with high gas flux and high hydrophobicity was prepared. The results showed that when ethanol / vinyl acetate was prepared with 60 wt.% ethanol as coagulation bath, the solid content of ethanol / vinyl acetate was 16wt.10, the additive was PEG-400 with 5wt.% additive, and the extrusion rate of casting solution was 6mL min-1, the pore size of the base membrane was 0.975 渭 m and the porosity was 75.12%, which resulted in the increase of membrane gas flux. When 276.09m3 m-2 h-1 is reached, the most significant change is the increase of contact angle to 131.43 擄, which has strong hydrophobicity. Secondly, the superhydrophobic modification of PVDF substrate was carried out by surface coating. By measuring pore size, porosity, gas flux and contact angle, the dispersant, the type and amount of inorganic nanoparticles and the amount of polydimethylsiloxane (PDMS) were studied. The effect of the amount of silane coupling agent (KH-550) on the properties of superhydrophobic PVDF films was investigated. The excellent PVDF superhydrophobic films were prepared by optimizing the coating process. The results showed that the coating solution was prepared by using isopropanol as dispersant, nano-scale CaCO3 was 1.5wt.and KH-550 was 1wt.5. the contact angle was increased from 131.43 擄to 147.06 擄, and the hydrophobicity was improved significantly. The gas flux is 264.12m3 m ~ (-2) h ~ (-1), the membrane pore size is 0.959 渭 m, the porosity is 74.88, and the air flux, pore size and porosity are lower than those before modification. Finally, the experimental study on the removal of CO_2 from simulated flue gas by membrane absorption method was carried out, and the matching between the absorbent and the membrane was investigated, and the effects of the type, concentration and flow rate of the absorbent on the removal rate of CO_2 were studied. The results showed that the potassium aminoacetate (PG) absorbent had the best match with the modified PVDF membrane, the CO_2 removal rate of the same concentration PG and MEA absorbent was higher than that of the latter, the optimum concentration of the absorbent was 2mol L-1, and the removal rate of CO_2 decreased with the increase of flue gas flow. When the concentration of PG absorbent is 2mol L-1 and the flue gas flow rate is 0.06m3 h-1, the removal rate of CO2 is 81.43.
【學(xué)位授予單位】：東北電力大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TQ051.893
本文編號：2146187
[Abstract]:Greenhouse gas CO_2 has become a hot spot all over the world, and carbon emission reduction has become an urgent problem. The removal of CO_2 from flue gas by membrane absorption method has the characteristics of low operating cost and avoiding secondary environmental pollution, but the removal efficiency of CO_2 is affected by the membrane wetting behavior. Superhydrophobic membranes can effectively slow down the wetting behavior of membranes and have a broad application prospect in carbon capture by membrane absorption. The traditional polyvinylidene fluoride (PVDF) membrane has good hydrophobicity, but it can not meet the needs of carbon capture by membrane absorption method. Therefore, further improving the hydrophobicity of PVDF membrane is the key to its application in carbon capture. In this paper, PVDF substrate was prepared by phase inversion method, and then modified by surface coating. The hydrophobicity of PVDF film was enhanced, and the membrane could be concentrated and stable in carbon capture by membrane absorption method. Firstly, the phase inversion method was used to prepare PVDF substrate. The effects of coagulation bath composition, kinds of pore-forming agents and the amount of PVDF solid added, the extrusion rate of casting liquid on the hydrophobicity, gas flux, pore size and porosity of PVDF substrate were studied. The optimum preparation process was determined and the PVDF substrate with high gas flux and high hydrophobicity was prepared. The results showed that when ethanol / vinyl acetate was prepared with 60 wt.% ethanol as coagulation bath, the solid content of ethanol / vinyl acetate was 16wt.10, the additive was PEG-400 with 5wt.% additive, and the extrusion rate of casting solution was 6mL min-1, the pore size of the base membrane was 0.975 渭 m and the porosity was 75.12%, which resulted in the increase of membrane gas flux. When 276.09m3 m-2 h-1 is reached, the most significant change is the increase of contact angle to 131.43 擄, which has strong hydrophobicity. Secondly, the superhydrophobic modification of PVDF substrate was carried out by surface coating. By measuring pore size, porosity, gas flux and contact angle, the dispersant, the type and amount of inorganic nanoparticles and the amount of polydimethylsiloxane (PDMS) were studied. The effect of the amount of silane coupling agent (KH-550) on the properties of superhydrophobic PVDF films was investigated. The excellent PVDF superhydrophobic films were prepared by optimizing the coating process. The results showed that the coating solution was prepared by using isopropanol as dispersant, nano-scale CaCO3 was 1.5wt.and KH-550 was 1wt.5. the contact angle was increased from 131.43 擄to 147.06 擄, and the hydrophobicity was improved significantly. The gas flux is 264.12m3 m ~ (-2) h ~ (-1), the membrane pore size is 0.959 渭 m, the porosity is 74.88, and the air flux, pore size and porosity are lower than those before modification. Finally, the experimental study on the removal of CO_2 from simulated flue gas by membrane absorption method was carried out, and the matching between the absorbent and the membrane was investigated, and the effects of the type, concentration and flow rate of the absorbent on the removal rate of CO_2 were studied. The results showed that the potassium aminoacetate (PG) absorbent had the best match with the modified PVDF membrane, the CO_2 removal rate of the same concentration PG and MEA absorbent was higher than that of the latter, the optimum concentration of the absorbent was 2mol L-1, and the removal rate of CO_2 decreased with the increase of flue gas flow. When the concentration of PG absorbent is 2mol L-1 and the flue gas flow rate is 0.06m3 h-1, the removal rate of CO2 is 81.43.
【學(xué)位授予單位】：東北電力大學(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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