結合碳氣凝膠與過硫酸鹽系統降解全氟辛酸之研究

Decompositions of Perfluorooctanoic Acid (PFOA) by Persulfate and Carbon Aerogel

李仲豪(Jhong-Hao Li)

指導教授 ： 駱尚廉

國立臺灣大學/工學院/環境工程學研究所/碩士(2019年)

https://doi.org/10.6342/NTU201901303

摘要

本研究是以結合碳氣凝膠與過硫酸鹽系統來降解全氟辛酸，利用溶液中被催化產生的自由基，針對降解全氟辛酸之降解進行探討。碳氣凝膠有許多優秀的特性，包含低電阻、優良電導率、高比表面積等，此外，碳氣凝膠密度非常低，約只有空氣的六分之一，是人類創造過最輕質材料之一，有望能成為保溫材料、吸音材料以及本研究所著重的催化載體。
本研究利用甲醛及間苯二酚作為前驅物、碳酸鈉作為催化劑來製備碳氣凝膠。製備完碳氣凝膠之後，將碳氣凝膠以X射線繞射儀、掃描式電子顯微鏡、比表面積與孔徑分析儀、界達電位儀和X射線光電子光譜儀進行特性分析，能更進一步了解所製備之碳氣凝膠，並利用電子順磁共振光譜來測定自由基，確定碳氣凝膠確實能催化過硫酸鹽產生更多自由基，藉由上述之特性分析以及結合現有文獻內容，探討碳氣凝膠催化過硫酸鹽之可能途徑。
在碳氣凝膠結合過硫酸鹽系統中，結合系統明顯對全氟辛酸的降解率高於單純添加過硫酸鹽系統，經由添加碳氣凝膠可提升催化過硫酸鹽的效率並增加全氟辛酸的降解，實驗操作選定多種參數進行探討，包含碳氣凝膠添加劑量、溫度、過硫酸鹽濃度、pH值以及添加自由基抑制實驗，利用HPIC和IC測出其去除率、脫氟率以及中間產物，探討可能之反應途徑，並利用擬一階反應動力模式對不同系統之全氟辛酸降解率數據進行模擬。

關鍵字

全氟辛酸 ； 碳氣凝膠 ； 過硫酸鹽 ； 催化 ； 自由基

並列摘要

In this study, a treatment to decompose perfluorooctanoic acid (PFOA) by persulfate when adding carbon aerogel. The purpose of the research is to identify the degradation of PFOA by free radicals activated in the solution. There are many excellent properties in the carbon aerogels, including low electrical resistance, excellent electrical conductivity, high specific surface area, etc. In addition, the density of the carbon aerogel is very low, about one-sixth of the air. It is one of the lightest materials which human ever created. It is expected to become a thermal insulation material, a sound absorbing material, and a catalytic carrier which is important in this study.
In this study, formaldehyde and resorcinol were used as precursors and sodium carbonate was used as a catalyst to synthesize carbon aerogels. After the preparation, carbon aerogels can be further characterized by X-ray diffractometer, scanning electron microscope, specific surface area and porosimetry analyzer, zeta potential analyzer, and X-ray photoelectron spectroscopy. The electron paramagnetic resonance spectrometer was used to determine the free radicals, and it was confirmed that carbon aerogels can activate the persulfate to generate more free radicals. Based on the above characteristics analyses and the existing literature, we can discuss the possible ways of carbon aerogels activate persulfate.
In the PS/CA system, the degradation rate of PFOA was significantly higher in the combined system than in the persulfate-only system. The addition of carbon aerogels can improve the efficiency of activating persulfate and increase the degradation of PFOA. In order to explore the different factors influence the performances, experiments were designed for the effect of carbon aerogels dosage, temperature, persulfate concentration, pH values, and the radical inhibitors. The removal rate, defluorination rate and intermediate products of the degradation of PFOA were measured by high performance ion-chromatography and ion-chromatography to explore the possible reaction pathways. The pseudo-first-order kinetic was used to model the decomposition of PFOA.

並列關鍵字

perfluorooctanoic acid ； carbon aerogel ； persulfate ； activation ； free radical

參考文獻

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