金屬離子對臭氧化分解2-氯酚效能增進之探討與研究

Abstract

本研究主要目的在探討有機物質在各種不同金屬離子的環境中，在液相臭氧化反應系統中的氧化分解情況，藉著溶液中之金屬離子催化的效果，降低臭氧分解反應的活化能，以促進水溶液中有機物質的礦化。本實驗中以2-氯酚為目標污染物，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、臭氧消耗率等，評估對此臭氧化系統的效能增進情形。 另外，並推估其反應機制，於反應動力探討中，加入金屬離子對臭氧自解的影響因子，進行理論值與實驗值之比較。 本研究的包括有下列幾項： 1. 各金屬離子（分別為Pb、Cu、Zn、Fe、Ti及Mn）在水溶液中催化臭氧氧化分解2-氯酚之分解速率常數與臭氧自解係數成高度相關。也就是說，水中臭氧自解速率的增加，往往伴隨著氫氧自由基（OH•）的形成，因而增加了整體的氧化能力，以致促進了2-氯酚的分解。 2. 就所探討的各種離子中，對2-氯酚同相催化性臭氧化的效能增進上，以錳離子為最佳，鐵及鈦離子次之。其中，在pH=3、各離子濃度均為1ppm時，反應速率可提昇至2∼3倍，而反應60分鐘後TOC去除率可從12.6%（未添加金屬離子）增至20.4%（添加鐵離子）、20.8%（鈦離子）與29.9%（錳離子）。 3. 在低pH值的條件下（pH=3），添加微量（∼1.5ｐｐｍ以下）之錳離子可提升反應速率、ＴＯＣ（Total Organic Carbon，總有機碳）去除率並減低臭氧消耗率。其反應速率與ＴＯＣ去除率之增益約略與錳離子添加量成正比。 4. 當pH值提升（pH=7、9）時，於反應系統中添加錳離子仍有其催化效果。但反應增進至一定程度時，造成溶液中臭氧濃度下降，使催化效果較不明顯，推測原因應為質傳瓶頸使臭氧本身供應不足所造成。 5. 經由實驗數據探討，與反應機制之推估，求得臭氧在錳離子溶液中的自解行為模式，以及錳離子對臭氧化分解2-氯酚效能增進之動力模式。

In this study, Ozonation of 2- Chlorophenol catalyzed by several different metal ion was investigated to realize the performance of the system. The influence of catalyst dosages, catalyst species and pH values were considered as the operative factors to processed the experiment. The analysis of reaction rate, mineralization efficiency and ozone consumption were carried out during the whole experiment in order to evaluate the enhancement of the performance of this system. Further, Considering the ozone decomposition caused by metal ions, the kinetics of the system could be available. The results of this research are as follows: 1. The reaction constant of ozonation 2-Chlorophenol catalyzed by each metal ion ( comprises Pb, Cu, Zn, Fe, Ti and Mn ) is highly correlative with the ozone decomposition constant. It also means that the increase of the rate of ozone decomposition usually accompanies forming the OH-radicals. Thus, it could raise the whole oxidative ability and promote the degradation of 2-chlorophenol. 2. It was observed that ozonation catalyzed by manganese ion is most effective, iron and titanium ions are minor. Under pH=3, and the concentration of each metal ion is 1ppm, the reaction rate could be raised 2 to 3 times. The TOC (total organic carbon) removal efficiency increases from 12.6%(ozone alone) to 20.4%( iron ion added), 20.8%( titanium ion added) and 29.9%( manganese ion added) after reaction of 60 minutes. 3. Under low pH value (pH=3) situation, adding a trace of manganese ion(below 1.5ppm) could decrease ozone consumption; enhance the reaction rate and TOC removal efficiency. The enhancement of the reaction rate and TOC removal efficiency was approximately proportioned to the addition of manganese ion. 4. However, as the reaction rate raised, the concentration of ozone in the solution was must lower down. As the pH value raised (pH=7, 9), Adding manganese ion in the system still could catalyze this reaction, but only alittle enhancement was found. 5. The models of the ozone decomposition in the manganese ion solution and the kinetics of the ozonation of 2-Chlorophenol catalyzed by manganese ion were carried out during the whole experiment and data analysing.