臭氧結合活性碳增進2-氯酚水溶液之處理效能

Abstract

臭氧對2-氯酚有良好的分解作用，但其分解後的有毒中間產物及低礦化效果一直是臭氧實際應用的瓶頸。應用活性碳作為異相觸媒，其強大的吸附能力可增加被吸附的臭氧與其反應的機會，同時能去除臭氧化後有毒的中間產物。本研究以一套臭氧與顆粒狀活性碳結合之程序（O3╱GAC）來處理實驗室所合成的目標污染物2-氯酚水溶液，藉由系統中異相活性碳的同時作用，探討臭氧、污染物及活性碳的三相反應，並評估污染物氧化及礦化的效能，依此建立臭氧與活性碳結合的反應動力式，最後以連續流式的操作來檢驗系統的長時效性與模式可信度。再者，以不同前處理之活性碳及成分相近的石墨比較其處理效能之差異。 實驗結果顯示，在臭氧系統中加入活性碳觸媒，發現活性碳會與臭氧反應造成其表面官能基及元素的改變，同時加速臭氧分解的速率，此反應系統可以增進去除污染物及礦化的效果。其次在活性碳加入劑量為1 g/L時，無論pH值為何，TOC去除率皆大幅增加，尤以低pH值時去除率由8.9％增加到47.6％，增進效率有四倍餘。在臭氧消耗率方面，一樣是在低pH值的環境下臭氧節省率最佳，每去除一單位的TOC可節省2.75倍的臭氧劑量。在有機物的去除率及生物毒性降低方面，效果皆隨著活性碳劑量的增加而增加，但在劑量超過2 g/L時，臭氧與污染物競爭吸附越顯著，反而使臭氧大量消耗。 在連續流的實驗中得知，臭氧結合活性碳比單獨使用活性碳（1 g/L）時，活性碳使用時效增長50﹪以上，臭氧有對活性碳現場再生的功能。最後由半批次實驗所建立的動力方程式應用於連續流的模擬，發現模擬值與實驗值的誤差小於3％，顯示模擬效果佳。

Ozone exhibits a high competence on 2-Chlorophenol degradation , but the toxic intermediates after decompotion and low efficiency of mineralization are the bottleneck of practical ozone application. Applying granular activated carbon (GAC) that has powerful adsorbability to be a heterogeneous catalyst can increase the probability of the reaction between absorbed ozone and itself , and meantime this process can remove the toxic intermediates . This study use the Ozone/GAC combination （O3/GAC）to treat our pollutant 2-Chlorophenol aqueous solution . With the heterogeneous GAC reacting simultaneously , we discuss the tri-phases reaction of ozone , pollutant and GAC . Furthermore , the efficiency of pollutants’ oxidization and mineralization will be estimated . Thus , we can establish the Kinetics . Finally , the efficacy and reliability of model can be checked by continuous flow operation . Moreover , the difference of efficiency from other pretreatment GAC and graphite similar to GAC can be compared . The experiments employing GAC as a catalyst show that GAC has reactions with ozone that makes changes of surface functional group and elements , and meanwhile it speeds up the rate of ozone decomposition . The system can improve the effect of pollutant removal and mineralization . Moreover , no mater what the pH value is , the TOC removal rate raises considerably with GAC 1 g/L dosage . Particularly in the low pH value environment , the TOC removal rate increases from 8.9％ to 47.6％ , the efficiency increases more than four times , and ozone consumption also decreases more obviously at a low pH value . 2.75 times Ozone dosage can be saved while one unit of TOC is removed , the organic matter removal rate and the reduction of toxicity increase with GAC dosage , but the competition of adsorption among ozone and pollutants becomes critical , thus , making the ozone consumed enormously . In the continuous flow system , it shows the effective lifetime of GAC increased over 50% by combining Ozone/GAC than GAC only . Besides , ozone has the ability to regenerate GAC on the spot . The model value and the experimental value is compared by applying the models established from semi-batch in the continuous flow system , the inaccuracy between the model value and experimental value is less than 3% . It shows the accuracy of the model .