電漿改質聚丙烯中空纖維膜接觸器於二氧化碳吸收應用之研究

Plasma Modified Polypropylene Hollow Fiber Membrane Contactor for Carbon Dioxide Absorption

陳偉杰(Wei-Jie Chen)

指導教授 ： 童國倫

中原大學/工學院/化學工程研究所/碩士(2009年)

https://doi.org/10.6840/cycu200900223

摘要

本研究主要為探討中空纖維薄膜表面不同親疏水性對於二氧化碳吸收之影響，利用CF4氣體電漿改質聚丙烯(Polypropylene, PP)中空纖維薄膜表面之方式，以達到中空纖維薄膜表面疏水化之效果，並自行組裝成一薄膜接觸器與商業化之薄膜接觸器加以比較，探討二氧化碳通量、質傳係數與質傳阻力之變化。
研究中發現，薄膜表面經過電漿改質後之聚丙烯(PP)薄膜接觸器之二氧化碳通量較商業化之聚二氟乙烯(Polyvinylidenefluoride, PVDF)來的高，使用吸收劑AMP (2-Amino-2-methyl-1-propanol)吸收二氧化碳，固定液體流速於200 cm3/min，且於氣體流速為200 cm3/min時，電漿改質後之聚丙烯(PP)薄膜接觸器二氧化碳通量高出聚二氟乙烯(PVDF)薄膜接觸器3 %，相同條件下操作於氣體流速為500 cm3/min時，其二氧化碳通量高出8 %；而在長時間的操作下，電漿改質後之聚丙烯(PP)薄膜接觸器操作十四天後，其二氧化碳通量僅有些微下降2.7 %，而聚二氟乙烯(PVDF)與尚未改質之聚丙烯(PP)薄膜接觸器則是在經過四至七天後之操作後，二氧化碳通量則分別下降了22.1 %與48.3 %，由此可知經過電漿改質後之聚丙烯中空纖維因表面疏水性之增加，使得二氧化碳之通量與操作使用時間上都有一定程度上的提升。
此外，針對不同吸收速率之醇胺吸收劑探討，不同吸收劑對於二氧化碳吸收速率不同，造成薄膜潤濕之情形也不盡相同。本研究中選用二胺基二甲基丙醇(AMP)與甲基二乙醇胺(MDEA)作為二氧化碳吸收劑，並添加無水二次乙亞胺(PZ)作為促進劑。結果中發現，掺合PZ之吸收劑其單位體積吸收速率都有明顯之提升，但同時對於薄膜孔洞潤濕也會有相對的增加，直到PZ濃度增加至0.3 M之後其薄膜潤濕才有趨於平緩之現象，發現其原因為掺合吸收劑濃度增加時，其吸收劑之粘度也隨之提升，使得薄膜孔洞潤濕之情形較不嚴重，由此可以得知吸收劑粘度之效應不可被忽略。

關鍵字

聚丙烯中空纖維薄膜 ； 電漿改質 ； 二氧化碳

並列摘要

The objective of study is to investigate the effect of surface hydrophobicity of hollow fiber membrane on absorption of carbon dioxide. The tetrafluoromethane (CF4) plasma was adopted to modify the polypropylene (PP) hollow fiber membrane surface characteristic to improve the surface hydrophobicity of hollow fiber membrane. A membrane contactor module was fabricated using the modified PP hollow fiber to compare the performance with the commercial polyvinylidenefluoride (PVDF) hollow fiber membrane contactor by analyzing the flux of carbon dioxide, mass transfer coefficient and mass transfer resistance.
The results showed that the flux of carbon dioxide of the plasma modified polypropylene hollow fiber membrane contactor was higher than the commercial polyvinylidenefluoride hollow fiber membrane contactor. When the 2-Amino-2-methyl-1-propanol (AMP) was used as an absorbent, the CO2 flux of modified PP membrane contactor is 3 % higher than polyvinylidenefluoride membrane contactor with a fixed liquid and gas flow rate, where the gas flow rate is 200 cm3/min. While the gas flow rate was increased to 500 cm3/min and the liquid flow rate was maintained, it is found that the CO2 flux was improved about 8 %. By long-term operation test, the CO2 flux of modified PP membrane contactor had a small decrease about 2.7 % (14 days operation) while the un-modified PP and PVDF membrane contactor revealed apparent decay about 48.3 % and 22.1 % after 7 days operation, respectively. It is considered that the membrane durability was improved resulted from the higher hydrophobicity after the plasma modification which is benefit for CO2 permeation and long-term operation.
Moreover, the influence of various absorption rate of absorbent was also discussed. In the study, the 2-Amino-2-methyl-1-propanol (AMP) and N-methyldiethanolamine (MDEA) were adopted as absorbent. In addition, the Piperazine (PZ) was chosen as an accelerant for the CO2 adsorption. The result showed that the better absorption rate was revealed by adding the PZ. However, it also makes the membrane wetting obviously and this phenomenon was mitigated till the concentration of PZ was raised to 0.3 M. It is because that the viscosity of absorbent was promoted in the higher PZ concentration that reduced the membrane wettability. Thus, the viscosity of absorbent was also regarded as an important factor that controls the contactor performance.

並列關鍵字

polypropylene hollow fiber membrane contactor ； plasma modification ； CO2

參考文獻

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