剛果紅染料廢水以 UV/O3 程序脫色及礦化之研究

Decolorization and Mineralization of Congo Red Dyeing Wastewater by UV/O3 Process

剛果紅（Congo red, C32H22N6Na2O6S2）為一種透過人工合成之聯苯胺類直接偶氮染料，染料可藉由皮膚滲入體內，長時間暴露除了會對人體造成健康上之疑慮，排放於環境中也會造成水體之污染，因此，本研究分別利用紫外光（ultraviolet, UV）、臭氧（O3）以及UV/O3程序對剛果紅染料廢水進行脫色及礦化反應，並探討不同參數之影響，期能有效的分解剛果紅廢水。實驗結果顯示，單獨UV對剛果紅水樣脫色率僅12.4%，O3反應則較UV為佳，同時隨曝入之O3流量越高，達到最佳去除率所需時間越短；O3流量在100 mL/min以上即可達到100%之脫色效率，當流量持續升高至2,500 mL/min時，僅需30秒即可達95.4%去除率，若與單獨O3相比，UV程序的加入可提高約10%之脫色率，但以總有機碳（total organic carbon, TOC）的去除率來看，礦化率介於16.6% - 41.5%，較單獨UV或O3程序高出許多，顯示兩種反應之結合確實具有加成的效應。反應之pH仍以酸性條件下為佳，溫度的上升對於去除率並無正面的幫助，剛果紅初始濃度越低，礦化效果越好，最佳可達80%以上。

Congo Red is the sodium salt with the formula of C32H22N6Na2O6S2 which is generally used in many dyeing industries all over the world. It is an artificially manufactured secondary diazo dye and has been proven as a toxic compound because it can permeate into the body from the skin leading to the healthy problem when the human beings are exposure with Congo Red for long time. In addition, as the high concentration Congo Red presents in wastewater, a profitable degradation process is necessary to reduce the harmful effect to environment and human beings. Therefore, the ultraviolet (UV), ozone (O3) and their combination, UV/O3 process, were used in this study to decolorize and mineralize the Congo Red wastewater and the effect of experimental parameters were investigated. The results shown in this study indicate that the sole UV process was worthless to decolorize the Congo Red where the maximum decolorization efficiency was 12.4% only with 60 min reaction. Ozonation showed better performance of Congo Red decolorization and mineralization than UV and it was found that the necessary treatment duration by ozonation decreased with increasing introducing ozone gas flow rates. As the ozone gas flow rate was greater than 100 mL/min, decolorization of Congo Red reached 100% within 60 min reaction; if the flow rate increased to 2,500 mL/min, 95.4% of decolorization was achieved in by 30 sec. Comparing to the results obtained by sole ozonation, combination of UV and ozone was effective on the increment of Congo Red decolorization. Also, the mineralization, based on the removal of total organic carbon (TOC), was as high as 41.5%, which was much higher than sole UV or ozonation; this result indicated that the synergetic effect took place as the UV and ozone was combined. An acidic solution and low initial Congo Red concentration were profitable to increase the decolorization and mineralization of Congo Red where the maximum TOC removal was as high as 80%. However, increase of reaction temperature was worthless to the decolorization.