亞臨界水系統的組裝及廢棄物處理的應用

Construction of Subcritical Water System and Application to Waste Management

周哲宇(Che-Yu Chou)

指導教授 ： 陳力騏

國立臺灣大學/生物資源暨農學院/生物產業機電工程學研究所/碩士(2017年)

https://doi.org/10.6342/NTU201704006

摘要

當水處在一高溫高壓狀態時，其介電常數會下降且其反應性會上升，因此亞臨界水在綠色萃取製程中逐漸受到重視。本研究使用動態式亞臨界水系統萃取檸檬桉葉中的香茅醛防蚊成分，以對抗日益嚴重之登革熱疫情；使用批次式亞臨界水系統對於廚餘進行脫水處理，以達到公共衛生及節省其儲運成本之目標。
動態式亞臨界水系統其最前端為HPLC高壓幫浦，功用為輸送流體及調整流速參數；而後接上內徑20 mm，長度100 mm，材質為316不鏽鋼之空管柱；空管柱後端則設置背壓閥以調控壓力參數使之能呈現亞臨界狀態；空管柱內部溫度則由纏繞其外之加熱帶控制。由氣相層析系統檢測後，只有檸檬桉之樹葉內部含有較多的香茅醛成分。動態式亞臨界水系統雖成功萃取出香茅醛成分，但其萃取效率0.12%仍遠低於有機溶劑萃取法之1.45%，推測原因為香茅醛在高溫時產生了熱降解。
批次式亞臨界水系統則由材質316鋼的反應器、pt 1000溫度感測器、壓力表、溫度控制器以及鐵氟龍杯所組成。本研究將飯類廚餘經由批次式亞臨界水系統處理後不僅將含水率降至10%以下，亦達成殺菌目的。唯其能量利用效率低落，未來若能找出更節電之方法，將增加此套系統之實用性。

關鍵字

亞臨界水 ； 萃取 ； 驅蟲劑 ； 檸檬桉 ； 廢棄物處理

並列摘要

Subcritical water has drawn much attention to several eco-friendly extraction and green reaction processes due to the lower dielectric constant and higher reactivity of water under elevated temperature and pressure. For extracting the insect repellent, citronellal, from the leaves of lemon scented gum（Eucalyptus Citriodora）, we constructed a flow-through subcritical water extraction system; and a batch subcritical water reactor was also developed to evaporate the water from kitchen waste for hygiene and transportation cost reduction.
The flow-through subcritical water system was assembled with HPLC devices. Water was driven with a high pressure HPLC pump and then introduced to the flow-through extraction chamber（20mm i.d.  10 cm, a 316 stainless steel HPLC column） with a back pressure regulating valve to raise the pressure to subcritical status. The temperature of the extraction chamber was controlled by heating tape. As measured by gas chromatography, only the leaves from lemon scented gum contain more citronellal. However, citronellal was successfully extracted but decomposed at elevated temperature. The extraction efficiency of subcritical water is 0.12%, lower than organic solvent extraction which extraction efficiency is 1.45%. Therefore, a more efficient subcritical extraction system with a cooling manifold is demanded.
The batch subcritical water reactor was constructed with a bomb reactor made of 316 stainless steel, a pt1000 temperature sensor, a pressure gauge, a heating controller and a 300 ml Teflon sample cup. Kitchen waste such as rice can be sterilized and dehydrated to less than 10% in water content. A more power-saving protocol is under investigation.

並列關鍵字

Subcritical water ； Extraction ； Insect repellent ； Lemon scented gum ； Waste management

參考文獻

36. Su, Y. C., Ho, C. L., Wang, E. I., & Chang, S. T. 2006. Antifungal activities and chemical compositions of essential oils from leaves of four eucalypts. Taiwan J For Sci, 21（1）, 49-61.

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