二氧化氯對染料廢水降解及其反應機制之研究

Degradation and Reaction Mechanisms of Dyes Wastewaters by Chloride Dioxide

劉家興(Chia-Hsing Liu)

指導教授 ： 林錕松

元智大學/工程學院/化學工程與材料科學學系/碩士(2012年)

https://doi.org/10.6838/YZU.2012.00183

摘要

於染整工業製程中，包括尼龍、毛織品、棉與蠶絲等製程，每年約可產生70萬噸廢水，並且含有高濃度的污染物質，其色度與化學需氧量(Chemical oxygen demand, COD)皆高，需要處理後排放，才可符合環保規定。在染整業中在染整程序中必須使用染料來將所需的物品染色，但是其廢水所產生色度值卻是超過法令之放流水標準，為符合放流水標準大部分的染整廠都是將次氯酸鈉溶液加入到廢水池內，而添加量都是憑著經驗法則來添加，因此添加不足則會造成放流水色度增加，故本研究即是利用不同之氧化劑二氧化氯來處理染料廢水，使用二氧化氯處理的水被證實不會産生通常用氯氣消毒時易形成的致誘變和致癌的三鹵甲烷（THMs），不會與有機化合物反應而產生溴二氯甲烷(CHCl2Br)、二溴一氯甲(CHClBr2)及三氯甲烷(CHCl3)等形態的有毒致癌物質。
本實驗使用目前市售的二氧化氯溶液，處理染料污染水體的效果，在不同的溫度下反應，藉由紫外光可見光光譜儀和總有機分析儀，來探討二氧化氯的氧化程序與脫色效率，實驗中發現當濃度達到200 ppm與溫度達到40℃時，對染料有最佳之降解效果，去除率依序為Acid Orange 7 > Acid Red 1 > Methylene Orange > Acid Blue 9 > Basic Violet 10，當溫度到達50℃時，則處理效果不佳是因為二氧化氯被破壞而失去其高氧化能力。再經由氣相層析質譜儀、傅立葉轉換紅外光譜儀，鑑定分析處理後之中間產物，並從氣相層析儀分析圖譜中發現二氧化氯與有機物反應都是自由基氧化反應，先將染料共軛雙鍵的斷裂轉化成單鍵，其發色團被破壞而呈現脫色情況，進而將其裂解染料結構，最初特徵ClO2先將苯環與萘環上之-N=N-轉化成單鍵，進而將其裂解染料結構，其中間產物首先是被分解成鈉磺胺與芳香族之中間體與1-氨基,2-萘酚，再進一步氧化，則1-氨基,2-萘酚變成1,2萘酚，繼續降解形成雜環化合物，其中間產物是由苯分解成酸或是乙醛，萘則是分解成苯最後變成醇類，在最初的步驟先降解含氮類的鍵Ar-N=N-Ar，先失去不飽和特性轉換成氫氧根結構，然後再進一步的氧化成-N-N-鍵並與單一苯環或是多環類分開，隨著氧化繼續而將芳香烴破壞使其開環使其轉變成醇類、醛類、含碳類，最後因礦化作用而轉變成二氧化碳與水。為了建立合理的反應機制及反應動力式，故探討在不同濃度染料降解實驗下，發現濃度愈高分解速率愈慢，濃度愈低速率愈快，動力模式則使用簡化的擬一階反應（Pseudo-first-order rate）動力學模式ln(C/Co)=kt，並探討其活化能變化反應，依序為Acid Red 1 > Acid Orange 7 > Methylene Orange > Acid Blue 9 > Basic Violet 10。

關鍵字

染料 ； 二氧化氯 ； 降解 ； 脫色效率 ； 反應機制 ； 氧化劑

並列摘要

Manufacturing industries including nylon, wool, cotton and silk manufacturing process, produce 700,000 tons of wastewaters annually. They need to be properly addressed before discharge in order to conform with environmental requirements. In the dyeing and finishing procedures, dyes must be used to stain the required items and wastewaters with colors are more than effluent standards. To comply with effluent standards, most of the dyeing and finishing plant added sodium hypochlorite solution to the wastewater tanks, and the amount added were all from experience, any less may cause an increase in effluent chroma. In this study, oxidant of chlorine dioxide was used to treat five dye wastewaters. By using chloride dioxide to treat dye wastewaters will not produce chlorine disinfection, mutagenic, and carcinogenic trihalomethanes (THMs). Moreover, chlorine dioxide does not react with organic compounds bromodichloromethane (CHCl2Br), dibromochloromethane (CHClBr2), chloroform (CHCl3), and other forms of toxic carcinogens.
Experimentally, the currently commercially available chlorine dioxide solutions with the effects of five dye-contaminated wastewaters were conducted at different temperatures. By using UV-visible spectroscopy and total organic analyzer (TOCs), the chlorine dioxide oxidation processes and decolorization efficiency were investigated. Based on the dye concentration of 200 ppm and the temperature reaches 40℃, It was found that the best degradation effect and removal rate order is Acid Orange 7 > Acid Red 1 > Methylene Orange > Acid Blue 9 > Basic Violet 10. When the temperature reaches 50℃, the degradation efficiency is lower because dioxide chlorine is destroyed and lost its high oxidation ability. By using gas chromatograph with mass spectrometers (GC/MS), Fourier transform infrared spectrometer (FTIR), the processing intermediates were identified and observed. From GC/MS data, chlorine dioxide and organic reactions are a free radical oxidation reaction. Postunatedly, the fracture of the dye-conjugated double bonds were changed into single bonds, the chromophore is destroyed with decolorization and further decomposed of the structure of dyes. The initial characteristics of ClO2 on the first benzene ring and naphthalene ring-N=N-into a single bond were further decomposed the structure of dyes. The intermediates were firstly broken down into sodium sulfa aromatic intermediates of 1-amino-2-naphthol, further oxidation of 1-amino-2-naphthol into 1,2-naphthol, and continued degradation of the formation of heterocyclic compounds. The intermediate products are the decomposition of benzene into acid or acetaldehyde. Naphthalene is decomposed into benzene and finally turned into alcohol. In the first step for the degradation of azo bond Ar-N=N-Ar, the first loss of unsaturated feature was converte to the hydroxyl structure, then further oxidized to the -N=N- bond. They were also separated with a single benzene ring or polycyclic compounds with the oxidation. The aromatic hydrocarbons were continuely destroyed to the open-loop that may make it into alcohols, aldehydes, carbon species, and were finally mineralized into carbon dioxide and water.
In order to establish a rational reaction mechanism and kinetics parameters, the exploration of different concentrations of dye degradation experiments were performed. It was found that the higher dye concentration has the slower decomposition rate. The lower dye concentration has the faster the decomposition rate. The dynamic model is used to simplify the proposed first-order reaction (Pseudo-first-order rate) and dynamic model of ln (C/Co) = kt. In addition, the investigation of the activation energy of reaction order are Acid Red 1 > Acid Orange 7 > Methylene Orange > Acid Blue 9 > Basic Violet 10 in series.

並列關鍵字

Decolorization efficiency ； Reaction mechanisms ； Oxidant. ； Dyes ； Chlorine dioxide ； Degradation

參考文獻

1. Tsai L.S., Wilson R., and Randall V., Mutagenicity of poultry chiller water treated with either chlorine dioxide or chlorine, J. Agric. Food Chem., 45, 2267-2272 (1997).

2. Belluati M., Danesi E., Petrucci G., and Rosellini M.C., Chlorine dioxide disinfection technology to avoid bromated formation in desalinated seawater in potable waterworks, Desalination, 203, 312-318 (2007).

3. Akin E.W., Hoff J.C., and Lippy E.C., Waterborne outbreak control: Which disinfectant, Environ. Health Perspect., 46, 7-12 (2006).

4. Velasco G.L., Alejandro T.C., Adrian S., Francisco A.H., and Suslowa T.V., Chlorine dioxide dose, water quality and temperature affect the oxidative status of tomato processing water and its ability to inactivate Salmonella, Food Control, 26(1), 28-435 (2012).

5. Ayyildiz. O., Serdar S., and Burcu I., Effect of ultrasonic pretreatment on chlorine dioxide disinfection efficiency, Ultrason. Sonochem., 18(2), 683-688 (2011).