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目錄
1 在濕空氣中氧化的可降解的印染廢水 1
1.1 概述 1
1.2 理論 1
1.3 實驗 2
1.4 結(jié)果及討論 3
1.5 結(jié)論 5
1 ON THE DEGRADABILITY OF PRINTING AND DYEING
WASTEWATER BY WET AIR OXIDATION 6
1.1 INTRODUCTION 6
1.2 THEORY 7
1.3 EXPERIMENTAL 8
1.4 RESULTS AND DISCUSSION 8
1.5 CONCLUSIONS 11
2 鎂氯化物使顏料及工業(yè)顏料廢物的轉(zhuǎn)移 13
2.1 概述 13
2.2 材料及方法 15
2.3 結(jié)果及討論 16
2.4 結(jié)論 19
2 REMOVAL OF DYES AND INDUSTRIAL DYE WASTES BY
MAGNESIUM CHLORIDE 21
2.1 INTRODUCTION 21
2.2 MATERIALS AND METHODS 23
2.3 RESULTS AND DISCUSSION 25
2.4 CONCLUSION 30
31
1 在濕空氣中氧化的可降解的印染廢水
摘要——用第一次序的動力學(xué)模型來修正濕空氣氧化中的印染廢水的模擬與實驗的數(shù)據(jù)吻合，結(jié)果指出印染廢水的一個有機(jī)污染物質(zhì)的特定分?jǐn)?shù)是無法離開甚至是提高了溫度而且延長了反應(yīng)時間的，發(fā)現(xiàn)能不依賴溫度和使用改良催化劑的可以降解的有機(jī)物質(zhì)。
關(guān)鍵字：濕氣氧化，廢水治療, 催化劑
1.1 概述
紡織廢水從印刷和染色程序后放出，具有高化學(xué)需氧量 (COD) 、低的生物化學(xué)的需氧量 (BOD) 和深色度的特點。 它是紡織工業(yè)中污染物質(zhì)的主要來源之一。在個別項目中，廢水的COD和色度用傳統(tǒng)的廢水處理是很難達(dá)到預(yù)期效果的。 濕空氣氧化法 (WAO) 已經(jīng)被實驗證實是一個能在提高的溫度和壓力把有機(jī)污染物質(zhì)轉(zhuǎn)換成水和二氧化碳的方法 (蘭德爾和 knopp,1980; Skaates et al,1981; Dietrich al,1985; Levec,1990; Mantzavinos et al。,1996)。 因為它能達(dá)到非常高的轉(zhuǎn)變率,濕空氣氧化程序比傳統(tǒng)的方法典型地需要少很多的空間。此外，在運用生物學(xué)程序的情況之下，沒有多于的泥或廢物生產(chǎn)。 WAO 已經(jīng)用實驗證明是處理來自紡織工業(yè)的廢水的退漿、漂白、染色和印刷工藝的一個可行的程序 (lei et al，1997， 1998,2000). WAO 需要高溫 (大約 3000C) 和高壓 (超過 10 MPa), 在一個合理的時間段里達(dá)到高化學(xué)需氧量的需求。 而采用一個適當(dāng)?shù)拇呋瘎┠芨淖兎磻?yīng)溫度和壓力 (Chu et al,1998; 匈牙利，1999)。
因為染料的結(jié)構(gòu)非常穩(wěn)定, 所以在一般的文學(xué)中都用了第一次序反應(yīng)動力學(xué)模型來模擬，而不用那個印染廢水的經(jīng)驗數(shù)據(jù)(Mishra et al,1995; Ingale et al,1996; Lei et al.,2000)在這一個運用中, 第一次序反應(yīng)動力學(xué)模型增加一個非可氧化性的分?jǐn)?shù)來修正過去一直研究的有機(jī)的印染廢水的 WAO。
1.2 理論
在印染工藝中產(chǎn)生許多不同的有機(jī)化合物包括各種不同的染料的廢水。 在這一項研究中，總有機(jī)碳 (TOC) 用來表示印染廢水有機(jī)濃度的綜合指標(biāo)。Mantzavinos (1996)和lei et al (2000)證明，由于氧是過量的，則大量的轉(zhuǎn)移干擾是可以忽略的。由WAO法和假定的第一次序反應(yīng), 我們有
（1）
前提條件是
t=0; Y=Y0; （2）
Y 和 Y0是可氧化有機(jī)濃度，對應(yīng)的反應(yīng)時間是 t 和0；k 是比率常數(shù), 遵循阿倫尼烏斯公式
（3）
k0為指前因子（也稱頻率因子）, E為表觀活化能， R 為摩爾氣體常量和，T為熱力學(xué)溫度。
求得（1）的微分方程解為：
（4）
在印染廢水中含有一些非可氧化性的WAO成份。假設(shè)α是可氧化有機(jī)物中TOC的分?jǐn)?shù), 則有：
(5)
TOC0 是反應(yīng)時間為0時的TOC值。
TOC 價值隨時間變化的：
（6）
在任意時間轉(zhuǎn)移的TOC量為：
(7)
TOCi不同于廢水的開始 TOC值TOC0，是因為在加熱期間廢水的熱分解不同(lei et al,2000)。
1.3 實驗
WAO實驗是在一個有冷卻裝備盤繞和一個有活潑磁性的2-l的高壓鍋系統(tǒng)中實行的。該設(shè)備功能和它的操作程序在我們的早先工作中是得到預(yù)期效果 (lei et al ,1997)。樣本廢水是直接從香港的一家紡織公司印染程序收集來。它有11100mg/l 的COD值， 3204mg/l 的 TOC值,BOD5為440mg/l 和pH值為6.6。
1.4 結(jié)果及討論
圖 1 為在四個不同的溫度下表示的印染廢水中 WAO與TOC轉(zhuǎn)移關(guān)系,分別為1500C、2000C、2500C 和 3000C。 需氧部分壓力是2.65MPa(以2000C 為參考溫度), 是理論總需氧量的兩倍。
實驗的數(shù)據(jù)體現(xiàn)出當(dāng)符號和樣板的配件為使用最少的正方形方法時當(dāng)做標(biāo)準(zhǔn)線。TOC 的轉(zhuǎn)移在 t 0 時有非零值。這是因為在程序上的熱解過程中有一些廢水進(jìn)行了熱分解 (lei et al,2000)。 熱的分解在較高的溫度中表現(xiàn)得更重要。圖1中模型和實驗的數(shù)據(jù)反映得很好。 要選取的參數(shù)在表 1 中清楚的列出。 可氧化的有機(jī)印染廢水的分?jǐn)?shù)α，大約為0.35時幾乎不受溫度的影響。這意味著只有大約 35% 的有機(jī)物在熱分解之后才能被氧化。 增加溫度能加速氧化速度但是不能夠增加有機(jī)物被氧化的分?jǐn)?shù)。
反應(yīng)率常數(shù)在各種不同的溫度下獲得氧化反應(yīng)的活化能的理論值是 43.7 kJ/mol (圖 2) 。 活化能比 25 kJ/mol大很多, 其值對于轉(zhuǎn)移阻能可被忽略 (Satterfield,1991; Shende 和 Mahajani,1994).。在動力學(xué)控制之下假定的印染廢水WAO，是包括完全被供應(yīng)的過度氧量的模擬值。
因為有機(jī)印染廢水轉(zhuǎn)換率不能夠由增加溫度 (常數(shù)α)以及嘗試使用一些催化劑而提高或改善氧化率。 圖 3表示在2000C接觸反應(yīng)的 WAO和2.65 MPa 的需氧部分壓力下的印染廢水的實驗數(shù)據(jù) (符號)。
催化劑是濃度為200mg/l 的Cu(NO3)2 和 CuO，Cu2+。兩種催化劑能明顯地提高氧化率而且達(dá)成較好的 TOC 轉(zhuǎn)移率。相應(yīng)的模型如圖3，而且模型與實驗數(shù)據(jù)表現(xiàn)得極一致。動力學(xué)參數(shù)α和k,對于Cu(NO3)2是 0.434 和 0.0559/min, 對于CuO是 0.435 和 0.0492/min。當(dāng)沒有催化劑作用的時候，CuO 的參數(shù)值最小，分別的相對值為 0.34 和 0.0066/min。 催化劑能同時提高可氧化有機(jī)的分?jǐn)?shù)和反應(yīng)率。
1.5 結(jié)論
用第一次序的動力學(xué)模型來修正濕空氣氧化中的印染廢水的模擬與實驗的數(shù)據(jù)吻合。 因為一些顏料的高的穩(wěn)定結(jié)構(gòu), 特定的部分有機(jī)物質(zhì)在廢水中不能分離，甚至在提高溫度時也不能被氧化，而且延長反應(yīng)時間。 雖然增加溫度能加速它的氧化速度，但不能夠增加而且有可能降低有機(jī)物質(zhì)的比。 然而，氧化有機(jī)廢水的分?jǐn)?shù)能因增加一個催化劑而得到改良。
1 ON THE DEGRADABILITY OF PRINTING AND DYEING
WASTEWATER BY WET AIR OXIDATION
XIJUN HU*, LECHENGLEI, GUOHUA CHEN and PO LOCK YUE
Department of Chemical Engineering, Hong Kong University of Science and Technology,
Clear Water Bay, Kowloon, Hong Kong
(First received 13 January 2000; accepted in revised form 6 September 2000)
Abstract——A modified first-order kinetics model was used to study the wet air oxidation of printing and dyeing wastewater. The model simulations are in good agreement with experimental data. The results indicate that a certain fraction of organic pollutants in the printing and dyeing wastewater could not be removed even at elevated temperature and prolonged reaction time. The ratio of degradable organic matter is found independent of temperature and can be improved by using a catalyst. # 2001 Elsevier Science Ltd. All rights reserved
Key words——wet oxidation, wastewater treatment, catalyst
1.1 INTRODUCTION
The textile wastewater discharged from printing and dyeing processes is characterized by high chemical oxygen demand (COD), low biochemical oxygen demand (BOD), and heavy colour. It is one of the major sources of pollutants in the textile industry. In particular, the COD and colour of the wastewater are resistant to conventional wastewater treatment. Wet air oxidation (WAO) has been shown to be a feasible method to convert the organic pollutants into water and carbon dioxide at elevated temperatures and pressures (Randall and knopp, 1980; Skaates et al., 1981; Dietrich et al., 1985; Levec, 1990; Mantzavinos et al., 1996). Since it can achieve very high conversion rates, the wet air oxidation process typically requires much less space. Furthermore, no additional sludge or concentrated waste is produced as in the case of biological processes. WAO has been demonstrated to be a viable process for the treatment of desizing, scouring, dyeing and printing wastewater from the textile industry (Lei et al., 1997, 1998, 2000). WAO requires high temperatures (about 3008C) and high pressures (over 10 MPa), to achieve a high COD removal within a reasonable time scale. A suitable catalyst can be added to reduce the reaction temperature and pressure (Chu et al., 1998; Hu et al., 1999).
Because of the very stable structure of dyes, the first-order reaction kinetics model commonly used in the literature (Mishra et al., 1995; Ingale et al., 1996; Lei et al., 2000) does not fit our experimental data with the printing and dyeing wastewater. In this note, the first-order reaction kinetics model is modified by adding a fraction of non-oxidizable organics and used to study the WAO of printing and dyeing wastewater.
1.2 THEORY
There are many different organic compounds in the printing and dyeing wastewater including various dyestuffs. In this study, the total organic carbon (TOC) is used to represent the organic concentration in the printing and dyeing wastewater. The mass transfer resistance is negligible because oxygen is in excess, as demonstrated by Mantzavinos et al. (1996) and Lei et al. (2000). By assuming that the WAO follows the first-order reaction, we have
（1）
with the initial condition as
t=0; Y=Y0; （2）
where Y and Y0 are the oxidizable organic concentrations at reaction time t and zero, t is reaction time and k is the rate constant, which follows the Arrhenius equation:
（3）
with k0 being the pre-exponential factor, E the activated energy, R the gas constant and T the temperature.
The solution for equation (1) is
（4）
There are some components in the printing and dyeing wastewater which are non-oxidizable by WAO. Let a be the fraction of oxidizable organic among TOC, we have
(5)
where TOC0 is the TOC value at reaction time zero.
The TOC value at any time is
（6）
The total removal of TOC at any time is
（7）
where the initial TOC value of the wastewater, TOCi, is different from TOC0 because of the thermal decomposition of wastewater during the heating up period (Lei et al., 2000).
1.3 EXPERIMENTAL
WAO experiments were carried out in a 2-l autoclave equipped with a cooling coil and a magnetic stirring system. The equipment description and its operation procedures were available in our previous work (Lei et al., 1997). The wastewater was collected directly from the printing and dyeing process of one textile company in Hong Kong. It has a COD value of 11100 mg/l, TOC of 3204 mg/l, BOD5 of 440 mg/l and pH of 6.6.
1.4 RESULTS AND DISCUSSION
Figure 1 shows the TOC removal of printing and dyeing wastewater by WAO at four different temperatures, 150, 200, 250, and 3008C. The oxygen partial pressure is 2.65MPa (at a reference temperature of 2008C), which is twice the theoretical amount
of oxygen required to completely oxidize the organics in the wastewater. The experimental data are presented as symbols and the model fitting using the least-square method as solid lines. The TOC removal has a non-zero value at t