金屬絡合染料製程廢水之螯合金屬特性 : 由螯合鐵量推估廢水中螯合官能基之去除率與處理方法探討

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Title:	金屬絡合染料製程廢水之螯合金屬特性 : 由螯合鐵量推估廢水中螯合官能基之去除率與處理方法探討
Other Titles:	Metal-chelating character of wastewater generated from metal-complex dye manufacturing processes : using chelated iron concentration to evaluate the removal efficiency of chelating functional group and treatment options
Authors:	張立瑋;Chang, Li-Wei
Contributors:	淡江大學水資源及環境工程學系碩士班李奇旺;Li, Chi-Wang
Keywords:	金屬絡合染料製程廢水;混凝;螯合;高級氧化法;勻相類Fenton法;wastewater generated from metal-complex dye manufacturing processes;Coagulation;AOP;chelate;homogeneous Fenton-like
Date:	2012
Issue Date:	2013-04-13 12:04:27 (UTC+8)
Abstract:	研究中所談之染料製程廢水，為染料製程廢水為在染料之製作過程中所排放，其中含有合成此種染料所必須加入之各種化學物質，以及經過調整酸鹼度或溫度等程序，因此製程廢水應含有許多合成染料之過程中所產生的過渡化合物，並且除了含有結構較完整之染料分子，還有一些還未完成染料分子之單體結構。混凝處理後，有機物去除效率不佳，且當pH值越低，其色度越高，測溶解鐵後發現廢水具有螯合金屬的能力。而後再以已形成之氫氧化鐵吸附有機物，有機物的去除效率也不佳。因此廢水混凝效果不佳的因應為廢水本身大部分為親水性較佳之有機物。螯合金屬則為屬絡合染料製程廢水之特性，以C/Fe3+顯示處理後螯合之官能基之破壞情形。原水之C/Fe3+=15，生物處理後C/Fe3+=29，過硫酸鹽加熱後C/Fe3+=13，由此可知經由生物處理後，能破壞大部分之螯合金屬的官能基，且TOC也去除一半以上，因此生物處理可作為廢水之前處理，再結合其他處理程序。本研究之處理方式為利用類似於Homogeneous Fenton-like，為亞鐵離子與廢水中螯合金屬之官能基螯合，亞鐵離子能因被螯合而呈溶解態，均勻地分布於廢水中，並能於中性時反應。因此實驗進行於pH7，並與進行於pH3比較。實驗結果為過氧化氫於pH3與pH7下，其隨時間之消耗量相同，但有機物與色度去除率於pH3時較佳，而於pH7時也能夠去除少部分之有機物(pH3之TOC去除率約20%，pH7約為5%；色度於pH3時去除率約70%，pH7時去除率約10%)。於pH7時，未被螯合之亞鐵離子逐漸氧化成三價鐵離子，一部分與過氧化氫形成錯合物 (Fe2O3．nH2O)沉澱，一部分則與氫氧根離子結合，形成氫氧化鐵沉澱，則無法再進入Fenton反應之循環中。因此要使用Homogeneous Fenton-like之方法處理時，應考慮能螯合亞鐵離子的量，使較多之亞鐵離子被螯合後，則不受到pH值之影響。 In this study, Dye manufacturing processes wastewater (DMPW) is the effluent generated from synthesizing process of dyes, consisting of intermediated compounds, monomer structure, and dyes molecules. Coagulation is found to be an inefficient process for removing organic matters. Color of treated water is increased with the decreasing coagulation pH. Measured dissolved iron after coagulation allowed one to evaluate the content of functional groups of organics which can chelate iron from coagulant. Organic removal efficiency is also not very well when pre-precipitated ferric hydroxide was used as adsorbent. It is concluded that DMPW contains hydrophilic functional groups as the result that coagulation is not able to remove the most of the organic matters. One feature of DMPW is its metal-chelating ability. The C/chelated-Fe3+ molar ratio is used to explore the destruction of chelating functional groups after various treatment processes. The C/chelated-Fe3+ molar ratios of raw DMPW, biologically- treated DMPW, and thermo-persulfate treated DMPW are 15, 29, and 13, respectively. Since chelating functional groups and TOC were reduced after biological treatment, biological treatment process can be employed as a pretreatment process to improve degradation efficiency of DMPW. In this study, the chelating characteristic of DMPW was exploited with Homogeneous Fenton-like process being tested. The potential of chelating functional groups to enhance oxidation efficient in the Fe(III)/H2O2 system under neutral pH condition was compared with the same process at pH 3. Our results show that the trend of residual hydrogen peroxide concentration in neutral and acidic pHs were the same during a 3-hr reaction. A higher degree of organic matters and colour removal were observed at pH3. The removal efficiencies of TOC are 20% and 5% under pH 3 and pH 7 conditions, respectively, while the removal efficiencies of color are 70% and 10%, respectively. Under pH 7 condition, unchelated ferrous ions are oxidized to ferric ions gradually, and ferric ions form complexes (Fe2O3．nH2O) and precipitate as ferric hydroxide. The precipitated ferric ions could not be used efficiently in Fenton cycle.
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