以芬頓程序同時去除水中異丙醇及過氧化氫

Abstract

過氧化氫普遍應用於不同行業，如作為食品業中的消毒劑、造紙業及紡織業中的漂白劑，而在半導體產業中，過氧化氫的使用在晶圓清洗過程中尤為重要，因此過氧化氫容易出現於上述行業之廢水。異丙醇(Isopropyl alcohol, IPA)作為半導體製程中常用之有機溶劑，為一種無色且易揮發之液體，主要應用於晶圓清洗及濕式蝕刻製程中之乾燥用溶劑。 本研究以國內某半導體廠廢水中同時存在之過氧化氫及異丙醇濃度作為目標濃度，利用芬頓法、電芬頓法、光芬頓法處理模擬廢水，利用水中原有之高濃度過氧化氫與額外添加之亞鐵離子形成芬頓反應以去除異丙醇且同時消耗水中過氧化氫。芬頓法從較低濃度之初始過氧化氫濃度(750 ppm)進行實驗探討初始pH值、[H2O2]/[Fe2+]比例之影響，得到最佳條件後再提升初始過氧化氫濃度至所設定之實廠濃度(3000 ppm)，觀察降解之結果。電芬頓法與芬頓法相同，先在低濃度之初始過氧化氫濃度(750 ppm)，探討初始pH、電解質濃度、電流強度、[H2O2]/[Fe2+]比例對於降解效果之影響，得到最佳條件後再提升至實廠初始過氧化氫濃度(3000 ppm)觀察降解之效果。光芬頓法則直接以實廠初始過氧化氫濃度進行實驗，探討[H2O2]/[Fe2+]比例對於降解效果之影響。 比較芬頓、電芬頓、光芬頓之降解效果，在實廠濃度條件下([IPA]0= 250 ppm, [H2O2]= 3000 ppm)三項系統對於IPA皆可達到大於99 %之去除率，而IPA降解產物丙酮之殘餘濃度在電芬頓系統中為最低，且電芬頓系統中之鐵鹽用量為另外兩系統的五分之一，因此以電芬頓系統作為本次實驗最佳系統並進行後續之副產物及COD分析，在電芬頓最佳條件下([IPA]0= 250 ppm, [H2O2]= 3000 ppm, [H2O2]/[Fe2+]= 5, pH= 2, I= 1.5A)，反應時間120分鐘COD去除率達到76 %，亦有觀察到甲酸及乙酸等副產物產生。

Hydrogen peroxide is commonly used in different industries, such as disinfectant in the food industry, bleaching agent in the paper industry and textile industry, and in the semiconductor industry. The use of hydrogen peroxide is particularly important in the wafer cleaning process, so hydrogen peroxide is apt to appear in the wastewater of the above industries. Isopropyl alcohol (IPA) is a commonly used organic solvent in semiconductor manufacturing processes. It is a colorless and volatile liquid, which is mainly used as a drying solvent in wafer cleaning and wet etching processes. In this study, the concentration of hydrogen peroxide and isopropyl alcohol in the wastewater of a semiconductor factory in Taiwan was used as the target concentration. The Fenton method, the electro-Fenton method, and the photo Fenton method were used to treat synthetic wastewater. The original high concentration of hydrogen peroxide and additional ferrous ions form a Fenton reaction to remove isopropanol and consume hydrogen peroxide in the water at the same time. The Fenton method first conducts experiments from a lower initial hydrogen peroxide concentration (750 ppm) to explore the initial pH value, [H2O2]/[Fe2+] ratio, and then increases the initial hydrogen peroxide concentration to the real water value (3000 ppm) after obtaining the optimal conditions. The operating parameters of electro-Fenton method is the same as the Fenton method except electrolyte concentration and current intensity. Photo Fenton only explore the [H2O2]/[Fe2+] ratio based on the initial hydrogen peroxide concentration of the real water(3000 ppm). Comparing the degradation efficiency of Fenton, electro-Fenton and photo Fenton under the real water concentration conditions ([IPA]0 = 250 ppm, [H2O2] = 3000 ppm), the three systems can achieve greater than 99% removal of IPA. The residual concentration of acetone, which is the degradation product of IPA, is the lowest in the electro- Fenton system, and the amount of iron salt used in the electro-Fenton system is one-fifth of the other two systems, so the electro-Fenton system is the most effective method in this experiment. By-product and COD analysis were conducted under the best conditions of electro-Fenton ([IPA] 0 = 250 ppm, [H2O2] = 3000 ppm, [H2O2]/[Fe2+] = 5, pH = 2, I = 1.5A), and the COD removal rate reached 76% at a reaction time of 120 minutes, and by-products such as formic acid and acetic acid were also observed.