等离子体—电化学耦合处理难降解废水的应用研究

发布时间：2018-01-03 05:24

本文关键词：等离子体—电化学耦合处理难降解废水的应用研究　出处：《苏州大学》2015年硕士论文　论文类型：学位论文

【摘要】：环境污染问题日益得到广泛关注。难降解有机污废水的处理是目前环境工程界研究的焦点之一。氯酚是一种广泛使用的化工原料,具有稳定的化学性质、结构及较强的生物毒性,是一类优先监控的难降解有机污染物。因此,开展氯酚废水处理的研究在工业应用方面有着重要的理论与实际意义。本文提出一种新型的大气压放电等离子体-电化学耦合技术,有效的实现了4-氯酚废水及实际难降解有机废水的氧化处理,并通过降解效果测定、气泡影像采集、Danckwerts绘标法及活性物种分析等多种技术途径系统探讨了主要影响因素对反应体系的影响规律,并对相关机理进行了研究。主要的研究内容和结论如下:(1)通过对耦合系统电源电压的优化,得到4-氯酚(4-CP)降解最优耦合电压为:电氧化电压8.0 V,等离子体峰值电压14.2 kV。经对比发现,在相同的放电时间内,耦合系统内4-氯酚降解率远大于单独电化学氧化和单独等离子体放电系统。(2)通过研究耦合系统电解池溶液中盐含量与4-氯酚降解率的变化关系,得到溶液的最佳盐含量为80 mg/L NaCl。(3)溶液初始pH对4-氯酚降解率、溶液COD和TOC去除率的影响规律:初始pH为9.23时,相同时间下,4-氯酚去除率达到88.28%(4-氯酚降解的平均能量效率为0.72 g/kWh),远高于pH为6.50和3.65时的81.32%和79.99%。COD去除率在碱性条件下最高,达到61.10%(COD去除的平均能量效率为1.35 g/kWh),而中性为59.44%,酸性为49.29%。TOC去除率碱性条件最高,酸性次之,中性最差。(4)利用靛兰三磺酸钾分光光度法、草酸钛钾比色法和对羟基苯甲酸捕获法分别测定了耦合系统放电过程中产生的活性物质O3、H2O2和?OH。在pH为3.65和9.23时,O3的生成速率最快,且碱性大于酸性中的产率。酸性条件下,H2O2在90 min放电时间内的产量最大,为0.0507 mmol/L,中性次之,碱性最少。碱性条件下,?OH生成速率达到了2.67×10-5 mmol/(L s),能量产率高达1.16×10-7 mol/J。由此说明,在碱性条下促进4-氯酚降解的主要活性物质是O3和?OH,而在酸性和中性条件下为?OH和H2O2。(5)利用照相技术获取了放电等离子体系统内的瞬间气泡影像,统计并计算了不同实验条件下的气泡分布和特征参数。利用Danckwerts绘标法,测定了相同体系中的气-液传质系数,发现理论计算与气泡影像的统计结果基本一致,共同解释了等离子体放电反应器在不同条件下的传质反应过程。(6)采用HPLC和IC对4-氯酚芳香类中间产物和小分子有机酸进行测定。结合活性物质和中间产物的分析可推断4-氯酚在不同pH下的降解历程:在酸性和中性溶液中,主要是由?OH和H2O2诱导的羟基邻、对位上的亲电取代反应,分别生成了4-氯邻苯二酚和对苯二酚。在碱性溶液中,4-氯酚更易发生由臭氧化引发的亲电取代反应,并伴随着少量?OH引发的亲电取代反应。O3分子易攻击羟基的邻、对位碳原子,引起氯原子从4-氯酚苯环上脱去形成对苯二酚和苯酚,而羟基邻位上的氢原子被?OH取代分别生成了4-氯邻苯二酚。(7)利用耦合体系对实际难降解废水进行了应用实验研究,结果发现在没加催化剂的条件下,耦合系统处理难降解实际废水的效果比加入催化剂更佳,COD的去除率较高,但随着等离子体峰值电压的增大,COD的去除率呈现下降的趋势。在峰值电压为14.2 kV时,COD去除率高达67.68%。此时,整体耗能又是最少的。同时经过电氧化电压和等离子体峰值电压的交叉优化,得到的最优耦合电压条件为:电氧化电压5.0 V,等离子体峰值电压16.6 kV。此时,废水COD的去除率为43.33%,能量效率为0.48 g/k Wh。
[Abstract]:The problem of environmental pollution has been widely concerned. To deal with the degradation of organic wastewater is one of the focus of research in the field of environmental engineering at present. Chlorophenol is a widely used chemical raw materials, has stable chemical properties, structure and strong biological toxicity, is a kind of priority organic pollutants monitoring. Therefore, to carry out research on chlorophenols wastewater treatment has important theoretical and practical significance in industrial application. This paper presents a novel atmospheric pressure plasma electrochemical coupling technology, the effective implementation of the 4- oxidation treatment of chlorophenol wastewater and actual refractory organic wastewater, and the degradation effect of determination of bubble image acquisition, effect of the main influence the factors on the reaction system of Danckwerts plotting method and active species analysis and other technical approach system, and the related mechanism was studied. The main research The contents and conclusions are as follows: (1) through the optimization of the coupling system of the power supply voltage, 4- chlorophenol (4-CP) degradation of optimal coupling voltage: electro oxidation voltage of 8 V, the plasma peak voltage of 14.2 kV. by comparison, at the same time of discharge, coupled system 4- chloro phenol degradation rate is far greater than the single electrochemical oxidation and a separate plasma discharge system. (2) through the study of the relationship between the coupling system of electrolysis pool solution and the salt content changes 4- chlorophenol degradation rate, the optimal solution of the salt content is 80 mg/L NaCl. (3) initial solution pH on 4- chlorophenol degradation rate, influence of solution COD and TOC removal rate: initial pH 9.23 at the same time, by 4-, the removal rate reached 88.28% (the average energy efficiency of 4- chlorophenol degradation is 0.72 g/kWh), far higher than the pH 6.50 and 3.65 was 81.32% and the highest rate of 79.99%.COD removal under alkaline conditions, COD removal reached 61.10% ( The average energy efficiency of 1.35 g/kWh), and neutral acid is 59.44%, the removal rate of 49.29%.TOC alkaline conditions the highest acidity of neutral, the worst. (4) using indigo three sulfonic acid potassium spectrophotometry, potassium titanyl oxalate colorimetry and p-hydroxybenzoic acid capture were measured by the method of discharge process coupling in the system of active material O3 and H2O2? OH. at pH 3.65 and 9.23, the rate of O3 formation is the fastest, and greater than the yield of alkaline acid. Under acidic conditions, H2O2 in the 90 min discharge time maximum yield was 0.0507 mmol/L, neutral second, the less alkaline alkaline conditions. Next, the formation rate reached 2.67? OH * 10-5 mmol/ (L s), the energy yield of 1.16 * 10-7 mol/J.. This indicates that in alkaline under promote the main active substances 4- chlorophenol degradation are O3 and OH?, and in acidic and neutral conditions for OH and H2O2.? (5) the use of photography the discharge plasma technology The moment the bubble image system, calculated bubble distribution and characteristic parameters under different experimental conditions. Using Danckwerts plotting method, the same system in the determination of gas - liquid mass transfer coefficient, theoretical calculation and statistics found that the bubble image results are basically the same, the common interpretation of mass transfer reaction process of plasma discharge reactor under the different conditions. (6) using HPLC and IC to 4- by aromatic intermediates and small molecular organic acids were determined. Combined with the analysis of degradation process of active substances and the intermediate products can be inferred 4- chlorophenol in different pH: in acidic and neutral solutions, is mainly composed of OH H2O2 and the adjacent hydroxyl? The induction of the para position of the electrophilic substitution reaction, were generated 4- chloride of catechol and hydroquinone. In alkaline solution, 4- chlorophenol occurred more often caused by ozonation of electrophilic substitution, and accompanied by a small amount of OH caused? The electrophilic substitution reaction of.O3 molecules to attack the hydroxyl o para carbon atoms caused by chlorine atoms from 4- chlorophenol benzene off formation of hydroquinone and phenol, and the hydrogen atoms on the ortho hydroxyl? 4- chloride catechol formation of OH substituted respectively. (7) the actual wastewater was applied to experimental study using coupling the results found in the system, without catalyst under the condition of coupling system in treatment of refractory wastewater is better than adding catalyst is better, the removal rate of COD is higher, but with the increase of plasma peak voltage, the removal rate of COD decreased. The peak voltage is 14.2 kV, the removal rate of COD is up to 67.68%. at this time again, the overall energy consumption is minimal. At the same time through the cross optimization electro oxidation voltage and peak voltage of plasma, the optimal coupling voltage conditions are obtained: electro oxidation voltage of 5 V, the plasma peak voltage of 16.6 At this time, the removal rate of COD in the wastewater is 43.33% and the energy efficiency is 0.48 g/k Wh.

【学位授予单位】：苏州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X703

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