以銅鐵氧化物催化過硫酸移除水中三氯乙烯之研究

Abstract

本文主要係探討使用新式複合材料：銅鐵氧化物催化劑以活化過硫酸鹽，產生自由基以去除水中三氯乙烯的成效。三氯乙烯是已被禁用的工業溶劑，曾造成多處地下水汙染。過硫酸是近年來常用的除汙工具，有強氧化能力，且平時化學性質穩定，不易造成危害。 本次研究首先製備催化劑材料和特定溶液，兩者混合後按時取樣，分析殘餘的三氯乙烯含量以評估去除效果。 對於催化劑材料，本文亦有成分和元素分析。催化劑含有氧化銅和氧化鐵，若以元素敘述，則有氧、銅和鐵，各約占總重 20%、40%和 40%。 根據實驗結果，增加催化劑用量和降低溶液 pH 值可提高三氯乙烯被去除比例，而調整三氯乙烯濃度對去除率無顯著影響。若採用過一硫酸鹽，配合添加催化劑，可使三氯乙烯於 10 分鐘內完全去除。因此催化劑搭配過硫酸去除三氯乙烯絕對可行，有進一步研討之潛力。 本實驗也有探討主要的反應自由基。過硫酸被催化後，可能生成氫氧、硫酸和超氧自由基。根據自由基消除實驗結果，添加甲醇或異丁醇，皆顯著減少三氯乙烯的去除比率；若添加苯醌，於 60 分鐘內之去除率降低，反之則上升。因異丁醇易消除氫氧自由基、甲醇易結合硫酸自由基、苯醌可移除超氧自由基，而氫氧自由基較少自過硫酸直接產出，故主要反應自由基依序為硫酸、氫氧、超氧自由基。

The project is mainly talking about the results of using novel composite material: Copper-Iron oxide catalyst to activate persulfate, producing radical to remove TCE (Trichloroethylene) in water. TCE is banned industrial solvent, making many places of underground water polluted. Persulfate is frequently used chemical to degrade contaminant in recent years, possessing strong oxidizing ability and being stable with no harm in usual. To accomplish the research, we need to prepare catalyst and essential solution first, then sampling after mixing to analyze remaining content of TCE. The result is to evaluate extent of degradation. Lower remaining content, better removing effect. There are some analysis of component and element for catalyst. Referring to the analysis, catalyst consists of Copper (II) Oxide and Iron (III) Oxide, or includes Oxygen, Copper and Iron in elements, containing total weight of about 20%, 40% and 40%, respectively. According to results of experiments, increasing dose of catalyst and descending pH of solution would elevate removal percentage of TCE, however, there is no significant difference in changing initial TCE concentration. If replace PMS (Peroxomonosulfate) of PDS (Peroxydisulfate), TCE can removed in 10 minutes with catalyst added. Thus, degrading TCE by catalyst and persulfate is favorable. The project also discussed mainly reacting radical. Persulfate can produce hydroxyl, sulfate and superoxide radical after activated. Referring to radical scavenging test, adding methanol or TBA (tert-butanol) can both largely lower removal percentage of TCE, yet dosing benzoquinone would slightly decrease removal portion of TCE before 60 minutes and increase otherwise. TBA is active with hydroxyl radical, methanol is favorable with sulfate radical and benzoquinone is active with superoxide radical. Hydroxyl radical seldom produced from persulfate directly, thus, reactive radical in sequence with importance is sulfate, hydroxyl and superoxide, respectively.