以覆膜光纖結合光催化技術整治受含氯有機物污染之地下水

The Use of Coated Optical Fiber Combined with Photocatalytic Technology to Treat Groundwater Contaminated by Chlorinated Organic Matter.

陳慶榮(Chen Ching-Jung)

指導教授 ： 陳冠中

國立屏東科技大學/工學院/環境工程與科學系所/博士(2022年)

https://doi.org/10.6346/NPUST202200444

摘要

本研究利用新型處理技術-光纖光催化技術應用於受含氯有機物污染之地下水整治作業。在傳統整治技術方面，以化學方法進行現場處理為例，常添加化學藥劑之方式去除地下水中之有機污染物或無機污染物，但是在實際應用上可能有最佳加藥劑量不易控制的問題；劑量使用太低恐使污染物之去除效果不佳，無法達到預期處理成果；倘若添加過量，又有發生二次污染之虞。而離場處理主要是指將受污染之地下水抽出後，運送至廢水場處理，利用專業的廢水處理技術和設備去除污染物質，但是，相對地其處理成本較現場處理昂貴。因此，在不需要大規模開挖和盡量降低化學藥劑使用量之前提下，研發處理效果穩定和高效率之新穎地下水現地處理技術，有其必要性。研究所使用之光纖材料具有高光傳導能力、高光利用效率和增加光催化劑激發接觸距離等優點，可有效將光源傳輸至難以進行光催化反應之污染位置。
本研究為改善光纖導光距離與表面光觸媒黏附性與耐久性等關鍵因子，因此探討光纖光催化之覆膜技術開發，以及透過噸級反應系統模擬現地研究後，再進一步將技術應用於現地進行試驗，最後再以亞甲基藍作為目標污染物，以動力學模式進行各項影響因子之模式探討。在覆膜液研發方面，本研究以3種覆膜液(聚乙烯醇、無機樹脂、氟樹脂)作為覆膜液基底，搭配不同稀釋比例(覆膜液/稀釋劑25：75及50：50)，並探討不同聚四氟乙烯(Polytetrafluoroethylene, PTFE)之添加量，進而作為光纖內芯之包覆層，主要目的為提升光源傳輸距離及觸媒附著力之強度，並且能提升觸媒覆鍍於光纖上之分佈均勻性及結構性，研究結果顯示，覆膜液與稀釋劑比例控制在25:75，並PTFE添加量20 mL PTFE/L為最佳配方條件。另一方面，在光纖光催化技術完成噸級系統現地模擬，以及後續直接將系統應用於現地試驗之研究結果顯示，本技術應用於現地處理可以有效地去除地下水中含氯有機物，並分解成最終產物(氯離子)。
本研究透過光纖光催化亞甲基藍動力學反應試驗結果顯示，若以商業化光觸媒P25 TiO2在不同之光源波長，光照強度、污染物初始濃度、光觸媒覆膜劑量，光纖支數影響因子條件下進行動力學試驗，求得各操作條件之反應速率(Kapp)，進而推導出反應模式。由試驗結果得知，紫外光之光催化效果皆優於可見光，這主要為觸媒能隙所造成，另一方面，當增加光照強度與光纖支數可提升反應速率，而污染物初始濃度卻反之，當濃度增加會降低反應速率，在光觸媒覆膜劑量方面，可以發現當提升至10 mg時為最佳，若繼續提升覆膜劑量，將會造成反應速率下降。

關鍵字

光纖光催化技術 ； 覆膜光纖 ； 地下水整治技術 ； 反應動力學 ； 含氯有機污染物

並列摘要

In this study, a new treatment technology-fiber photocatalytic technology was applied to groundwater remediation operations polluted by chlorinated organic compounds. In terms of traditional remediation techniques, chemical methods are used for on-site treatment as an example. Chemicals are often added to remove organic pollutants or inorganic pollutants in groundwater. However, in practical applications, it may be difficult to control the optimal dosage, if the dosage is too low, the removal effect of pollutants may be poor, and the expected treatment results cannot be achieved, if the dosage is excessive, there is a risk of secondary pollution. Off-site treatment mainly refers to pumping out the polluted groundwater and transporting it to the wastewater field for treatment. Professional wastewater treatment technology and equipment are used to remove pollutants, however, the treatment cost is relatively more expensive than on-site treatment, therefore, it is necessary to develop novel groundwater in-situ treatment technologies with stable treatment effects and high efficiency without the need for large-scale excavation and the reduction of chemical usage.
The optical fiber material used in the research has the advantages of high light transmission capacity, high light utilization efficiency, and increased contact distance of photocatalyst excitation, which can effectively transmit the light source to the polluted location where it is difficult to carry out the photocatalytic reaction, however, to improve the key factors such as the optical fiber light-guiding distance and the adhesion and durability of the surface photocatalyst, this research discusses the development of the coating technology for optical fiber photocatalysis, and after simulating on-site research through a ton-scale reaction system, the technology is further applied to on-site tests. And then, methylene blue was used as the target pollutant, and the model of various influencing factors was discussed in the kinetic model.
In the research and development of coating liquids, this study uses three kinds of coating liquids (polyvinyl alcohol, inorganic resin, and fluoro-resin) as the coating liquid base, with different dilution ratios (coating liquids/dilute solution 25:75 and 50:50), and explores different polytetrafluoroethylene(PTFE). The main purpose is to improve the transmission distance of the light source and the strength of the catalyst adhesion and to improve the distribution uniformity and structure of the catalyst coating on the optical fiber, the research results show that the optimal formula condition ratio of the coating liquid and diluent is controlled at 25:75, and then added 20 mL PTFE/L. On the other hand, the results of the field simulation of the ton-scale system in the fiber photocatalytic technology and the subsequent direct application of the system to the field test show that the application of this technology to on-site treatment can effectively remove chlorine organic substances in groundwater, and decompose them into final products (chloride ions).
The results of the optical fiber photocatalytic methylene blue kinetic reaction test in this study show that if the commercial photocatalyst P25 TiO2 is used under the conditions of different light source wavelengths, light intensity, initial concentration of pollutants, photocatalyst coating dose, and fiber count influence factors Kinetic tests are used to obtain the reaction rate (Kapp) of each operating condition, and then the reaction mode is deduced. From the results, it is known that the photocatalytic effect of ultraviolet light is better than that of visible light, which is mainly caused by the energy gap of the catalyst. Besides, when the light intensity and the number of fiber counts are increased, the reaction rate can be increased, while the initial concentration of pollutants is the opposite. When the concentration increases, the reaction rate will be reduced. In terms of the photocatalyst coating dose, it can be found that it is the best when it is increased to 10 mg. If the coating dosage continues to increase, the reaction rate will decrease.

並列關鍵字

optical fiber photocatalytic technology ； coated optical fiber ； groundwater remediation technology ； reaction kinetic model ； chlorinated organic compounds

參考文獻

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