異相催化性臭氧化系統分解水溶液中2-氯酚之研究

Abstract

本研究以建立一個異相催化性臭氧化系統為目的，企圖在25℃下，藉著固相之金屬氧化物催化劑，結合吸附及氧化之特性於臭氧化系統中，促進水溶液中有機物之礦化。本實驗中以2-氯酚與草酸為目標污染物，探討催化劑種類、劑量、pH值等因子，藉由分析其反應速率、礦化程度、臭氧消耗率與生物毒性變化等，評估此異相催化性臭氧化系統的效能，並進行反應動力之探討。 本研究發現，以Al2O3為主之異相催化性臭氧化系統，在中性條件下礦化2-氯酚有最顯著之增強效果（從22%增加至43%），臭氧的消耗率為傳統系統之二分之一，同時經長效性試驗，發現該催化劑可重複使用，且對於毒性之去除亦相當穩定，去毒效果更佳。 以MnO2/Al2O3催化草酸之臭氧化反應在酸性條件下有非常良好之效果，推測反應中有不分錳離子參與反應，加速了反應之進行。

The objective of this study is to establish the Heterogeneous Catalytic Ozonation System. It is attempted to combine ozone with the adsorptive and oxidative properties of solid metal oxide catalysts to mineralize dissolved organics at 25℃. 2-Chlorophenol and oxalic acid were selected as the target organics. The influence of catalyst dosages, catalyst species and pH values had been examined. The analysis of reaction rate, mineralization efficiency, ozone consumption and toxicity were carried out during the whole experiment in order to evaluate the performance of this system. Under neutral condition, ozonation in the presence of alumina exhibited the greatest enhancement in mineralizing 2-chlorophenol(from 22% to 43% ). The consumption of ozone was half of the conventional system, and the reduction of toxicity was steadier. In addition, three consecutive runs with the catalyst revealed the log-term stability of the catalyst. Ozonation of oxalic acid aqueous solution in presence of MnO2 supported on alumina under acidic condition revealed the great mineralization efficiency. It is suggested that some of the manganate ions participated in this reaction resulting in the increase in reaction rate.