脉冲放电等离子体—活性炭联合降解水体中有机污染物的研究

发布时间：2018-02-22 04:09

本文关键词： 脉冲放电等离子体活性炭联合体系降解发射光谱　出处：《江苏大学》2016年硕士论文　论文类型：学位论文

【摘要】：近年来,人口的增长及工业的迅速发展导致水体中有机污染物含量激增。针对水体中有机污染物的普遍性与危害性,本研究采用脉冲放电等离子体(Pulsed discharge plasma,PDP)与活性炭(Activated carbon,AC)相联合的体系降解水体中有机污染物,提高了有机物降解效率及PDP自身的能量利用效率。研究首先依据体系中H2O2的产生量为指标,通过变化参数确定有利于活性物质生成的PDP/AC联合体系操作参数;继而选取酸性橙II(Acid orange 7,AO7)及双酚A(Bisphenol A,BPA)两种典型的有机物来模拟有机污染废水,考察了不同参数下PDP/AC联合体系对两种污染物的降解效果,并分析有机物的降解机理;最后,通过光谱检测技术考察了联合体系中主要自由基(·OH及·O)的生成及变化规律,以验证PDP与AC的协同增效作用及自由基的氧化作用。具体研究结果如下:(1)建立了七针-板电极形式的PDP发生体系,根据不同参数(脉冲电压峰值、载气量、溶液初始pH值、AC的添加量)条件下体系中H2O2的生成量,优化PDP/AC联合体系的操作参数。在脉冲电压峰值为20 kV,载空气速率为4L/min,溶液初始pH值为6.9,AC添加量为4 g时,PDP/AC联合体系中H2O2的生成量最高,达到0.30573 mmol/L,相应的能量效率为0.022505 mmol/J。(2)以AO7为目标污染物,考察了PDP/AC联合体系中,AC添加及AC粒径、电极间距、溶液初始电导率、溶液初始pH值、载气种类及载气速率对AO7脱色率的影响并进行了相应的动力学分析,得出了联合体系用于AO7脱色的较优操作条件:4 g AC添加量、15 mm电极间距、3溶液初始pH值、2 L/min载氧气量;不同放电时间段AO7溶液的紫外-可见吸收光谱分析表明,随着放电时间的延长,AO7分子的各基团数量均呈下降趋势;较优操作条件下处理60 min后AO7溶液的TOC去除率为30.3%;GC-MS分析得出AO7降解产物主要为苯醌、邻苯二甲酸酐、苯并吡喃、对醛基苯甲酸、萘酚、奈二酮,并推测出了其降解路径;放电作用使得AC表面变得更加平滑,微孔和中孔数量减少,出现了大孔。(3)以BPA为目标污染物,考察了溶液初始浓度、自由基捕获剂及载气种类对BPA降解率的影响。结果表明,随溶液初始浓度的增加,BPA的降解率呈现先增加后减少的趋势;自由基捕获剂的添加不利于BPA的降解;相对于在空气和氮气,载氧气时BPA的降解效果达到了最佳。研究同时考察了BPA降解过程中,溶液pH值及电导率的变化,结果表明,随着放电时间的延长,溶液pH值出现了降低的趋势,溶液电导率却出现了增加的趋势。紫外-可见吸收光谱分析表明,BPA降解过程中有大量中间产物的存在。(4)通过光谱检测技术,考察了不同参数条件下·OH及·O的相对发射光谱强度,同时比较了单独PDP体系及PDP/AC联合体系在去离子水、AO7溶液及BPA溶液放电中·OH及·O的相对发射光谱强度。结果表明:随着AC添加量的增加,PDP/AC联合体系中·OH相对含量呈增加趋势,·O的相对含量基本不变;较高脉冲电压峰值及较小的电极间距有利于·OH及·O的产生;在各溶液相条件下,联合体系中·OH和·O的相对发射光谱强度均分别高于单独PDP体系中·OH和·O的相对发射光谱强度,说明了PDP/AC联合体系具有协同作用;无论是单独PDP体系还是PDP/AC联合体系,AO7溶液及BPA溶液中·OH和·O的相对发射光谱强度均低于去离子水中·OH和·O的相对发射光谱强度,证明了有机物对活性自由基的消耗。
[Abstract]:In recent years, the rapid development of industry and population growth led to the proliferation of organic pollutants in water. The organic pollutants in the water of universality and harmfulness, this study adopts pulsed discharge plasma (Pulsed discharge, plasma, PDP) and activated carbon (Activated carbon, AC) organic pollutants degradation in combination, improve the energy utilization efficiency of organic matter degradation efficiency and PDP. Its research is mainly based on the production of H2O2 in the system as the index, by changing the parameters of PDP/AC combined system operating parameters for the formation of active materials; then select the acid orange II (Acid Orange 7, AO7) and A (Bisphenol A, bisphenol BPA) two a typical organic matter to simulate organic wastewater, the combination of PDP/AC system with different parameters of two kinds of pollutants degradation was investigated, and the mechanism analysis of organic solution drop; finally, through the spectrum Detection of free radicals was investigated mainly in the combined system (OH and O) formation and change rules, to verify the PDP oxidation and AC synergistic effect and free radical. The main results are as follows: (1) established seven needle to plate PDP system, according to the different parameters (pulse peak voltage, the amount of gas, the initial pH value of solution, the addition of AC) production under the condition of H2O2 system, the optimization of operating parameters with PDP/AC system. The peak value of the pulse voltage is 20 kV, the air loading rate is 4L/min, the initial pH value of solution is 6.9, the dosage of AC was 4 g. The production of H2O2 PDP/AC combined system is the highest, reached 0.30573 mmol/L, the corresponding energy efficiency of 0.022505 mmol/J. (2) with AO7 as the target pollutants, the effects of PDP/AC combined with AC and AC system, adding particle size, electrode spacing, initial conductivity, initial pH value of solution, carrier gas and carrier gas velocity The rate of effect on the decolorization rate of AO7 and analyzed the corresponding dynamics, the combined system for optimum operation conditions of AO7 bleaching: 4 g amount of AC 15, mm 3 electrode spacing, initial pH value, the amount of oxygen contained 2 L/min; UV - different discharge time of AO7 solution absorption spectra the analysis showed that with the extension of the discharge time, the number of each group of AO7 molecules was decreased; the better operating conditions after 60 min AO7 solution TOC removal rate is 30.3%; GC-MS analysis shows that AO7 degradation products were mainly benzoquinone, two phthalic anhydride, benzopyran, naphthol of aldehyde benzoic acid two, Nye, ketone, and infer the degradation path; discharge makes the AC surface becomes more smooth, the number of micropores and mesopores decreased, there has been a large hole. (3) with BPA as the target pollutants, the effects of initial concentration of solution free radical trapping agent and the type of carrier gas on the degradation rate of BPA The effect. The results show that with the increase of initial solution concentration, the degradation rate of BPA increased firstly and then decreased; free radical trapping agent is not conducive to the degradation of BPA; compared with in air and nitrogen, the degradation efficiency of BPA carrying oxygen to achieve the best. At the same time BPA was investigated in the degradation process, changes the pH value of the solution, and the conductivity results show that with increasing the discharge time, the pH value of the solution has decreased, the conductivity of solution appeared increasing trend. The UV Vis absorption spectra show that there are a large number of products between the presence of BPA in the degradation process. (4) the relative spectrum detection technology the emission intensity was investigated under different parameters, OH and O, and compare the separate PDP system and the PDP/AC combined system in deionized water, the relative intensity of the emission spectrum of AO7 solution and BPA solution in the discharge - OH and O. The results showed that With increasing AC content, the PDP/AC combined system, the relative content of OH increased, and the relative content of O is basically unchanged; the electrode spacing high peak pulse voltage and smaller for OH and O; in the solution phase conditions, the relative emission intensity relative emission intensity of combined system in OH and O were higher than those in the PDP system in OH and O, the PDP/AC system has a synergistic effect; either alone or combined with PDP system PDP/AC system, AO7 solution and BPA solution, OH and O, the relative emission intensity was lower than that of deionized water and OH O, the relative emission intensity, that consume organic compounds on the activity of free radicals.

【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：X52

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