以超音波搭配臭氧及過氧化氫程序降解水中異丙醇

Abstract

台灣的半導體產業發達，半導體製造過程中產生的廢水可能含有酸、鹼、鹽和其他有機化合物，而異丙醇 (Isopropanol Alcohol, IPA) 是一種無色、易揮發的有機溶劑，具有強烈的酒精氣味，廣泛應用於半導體產業的晶圓表面清洗和其它清洗過程，當排放大量含有異丙醇的廢水，可能透過生物的接觸、吸入或吸收而產生危害，還會對人體健康造成威脅。 超音波對污染物的降解有兩種反應機制，一種是污染物在空蝕氣泡內被熱裂解，另一種是在空蝕氣泡中產生氫氧自由基氧化極性的污染物。超音波和臭氧結合的系統具有許多優勢，超音波的空蝕作用增加了臭氧的傳質和分解，加上局部高溫和高壓，產生更多的氫氧自由基，可進一步氧化有機污染物。本研究探討在異丙醇濃度固定的條件下，調整超音波強度及頻率、初始pH值、臭氧曝氣流量、超音波探頭浸入水深及過氧化氫添加濃度，觀察不同操作條件下異丙醇去除率的變化。 以超音波頻率40 kHz、功率500 W、超音波探頭浸入水深5 cm、臭氧曝氣流量300 mg/hr、初始pH 10、過氧化氫添加濃度為1 mM之系統中，初始濃度250 ppm之異丙醇經120分鐘反應後可達到81.4 %的去除率。利用高效液相層析儀 (HPLC, High Performance Liquid Chromatography) 觀察到超音波搭配臭氧系統中異丙醇降解後產生副產物丙酮、甲酸及乙酸。 透過本研究所使用之降解異丙醇方法可提供未來實廠應用之參考，並期望能降低異丙醇對環境的危害。

With the development of semiconductor industries in Taiwan, the wastewater contains acids, alkalis, salts, and other organic compounds. Isopropanol (IPA) is a colorless, volatile organic solvent with a strong alcohol odor. It is widely used in the semiconductor industry as a cleaning agent. When the IPA-containing wastewater is discharged, it may pose a threat to human health and our environment. Ultrasound (US) has been used to treat wastewater in many studies. It has two reaction mechanisms for the degradation of pollutants. One is that the pollutants are thermally cracked in the cavitation bubbles, and the other is the pollutants that produce hydroxyl radical in the cavitation bubbles. The system combining ultrasound and ozone (US/O3) has many advantages. The cavitation of ultrasound increases the mass transfer and decomposition of ozone. Coupled with high temperature and high pressure, it generates more hydroxyl radicals, which can further oxidize organic pollutants. In order to understand the effects of different operating parameters, the degradation efficiency of IPA was studied and discussed by ultrasonic frequency and power, initial pH, ozone flow rate, ultrasonic probe immersion depth, and hydrogen peroxide addition concentration. The results show that 40 kHz / 500 W of ultrasonic frequency and power, 5 cm of ultrasonic probe immersion depth, 300 mg/hr of ozone flow rate, initial pH 10, 1 mM of hydrogen peroxide concentration can reach about 81.4 % of 250 ppm IPA decomposition in 120 minutes. The degradation of IPA was investigated by using gas chromatography (GC) with flame ionization detection (FID), and high-performance liquid chromatography (HPLC) was used to observe the byproducts including acetone, formic acid and acetic acid in the ultrasonic system. The method of degrading isopropanol used in this study can provide a reference for future applications, and it is expected to reduce the harm of isopropanol to the environment.