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1.
采用气液滑动弧放电非平衡等离子体进行降解高浓度苯酚模拟废水(初始浓度为872 mg/L)的研究。实验研究表明:由于液滴的存在改变了电极间的介电常数和局部电场,气液滑动弧放电的电压波形比纯气流滑动弧放电更加不规则,起弧电压更低;采用氧气作为载气能提高苯酚的降解效果,最后TOC值为44 mg/L;增大气液混合比,相应的加强了废水的雾化效果,增大水气接触表面积,进而提高了苯酚的降解效果;在尾气中检测到CO2的存在,最高浓度达到35357 mg/m3。  相似文献   

2.
研究了利用强电离放电产生等离子体方法制取羟基自由基氧化降解高浓度苯酚废水。当羟基自由基浓度达到1 037 mg.L-1时,初始浓度为1 215 mg.L-1的废水降解率达99.11%;初始浓度为8 853 mg.L-1的废水苯酚浓度下降到6 250 mg.L-1,1 mg羟基自由基可处理苯酚2.5 mg。在同样羟自由基浓度下,苯酚初始浓度越小,去除率越高;但初始浓度越高,处理的绝对量越大。阐述并解释了不同降解阶段废水pH值、电导率与羟基自由基浓度变化的关系。随着羟自由基浓度的增大,废水酸碱性由接近中性逐渐转为酸性,浓度越大,酸性越强;继续增大羟自由基浓度,变化渐趋平缓。随着羟自由基的通入,电导率有一个微小的降低阶段然后开始上升,说明苯酚不断的被氧化为有机酸。通过紫外图谱和色谱分析了降解中间产物,表明氧化初始阶段邻苯二酚、对苯二酚和苯醌是其中重要的化合物。  相似文献   

3.
采用光助Fenton氧化法处理间氨基苯酚模拟废水,考察了光强、Fenton试剂的用量、初始pH、反应时间对降解效果的影响,初步探讨了其降解动力学规律。结果表明:在不同光源下(闭光、高压汞灯照射以及较强太阳光照射),450W高压汞灯照射以及较强太阳光照射的条件均可以明显加快Fenton法催化氧化降解间氨基苯酚溶液的过程。选择1.5mL2.5g.L-1FeSO4.7H2O,1.0mL6%H2O2,初始pH=3.5,太阳光照射下降解间氨基苯酚效果较好,反应40min后降解率高达99%;降解过程符合准一级反应动力学方程。  相似文献   

4.
在柱-板式介质阻挡放电体系中投加铋酸钠催化剂,研究了该体系的放电光谱特性及对苯胺模拟废水的协同处理效果,考察了pH 值、苯胺初始质量浓度及催化剂投加量等因素对降解率的影响,探讨了铋酸钠协同介质阻挡放电(DBD)催化降解苯胺的机理。实验结果表明,柱-板式电极结构放电过程中辐射出了紫外光和可见光,300~450 nm之间出现高强度N2第二正带谱线。初始浓度100 mg/L苯胺废水被处理10 min后,投加0.2 g/L催化剂时溶液的TOC去除率最高,比单独DBD低温等离子体体系提高14.11%。在碱性条件下,苯胺和TOC的去除率均好于酸性和中性条件。XRD检测结果显示铋酸钠在反应前后峰值位置未发生明显改变。  相似文献   

5.
在静态条件下,研究了活性炭对间氨基苯酚废水的吸附效果,确定了处理废水的pH值、活性炭用量、振荡时间、温度、废水中间氨基苯酚浓度、振荡速率以及电解质对吸附效果的影响。实验表明:活性炭在pH值为6.0,用量3.5g,温度40℃,振荡2.5h的条件下,对100mL质量浓度为50mg/L的间氨基苯酚模拟废水处理效果最佳。  相似文献   

6.
气液两相滑动弧放电中自由基的光谱研究   总被引:1,自引:0,他引:1  
气液两相滑动弧放电是近年来出现的一种新型低温等离子体废水处理技术,对高浓度有机废水具有很好的降解效果.为了认识气液两相滑动弧放电降解有机废水的机理,用发射光谱法对气液两相滑动弧在空气中放电所产生的主要自由基进行了实验研究,分析了自由基持续再生的化学过程.通过对光谱线强度变化的分析,得到了OH和NO自由基谱线强度在放电反应空间的分布特点,以及输入电压和液相(水)流量因素对OH和NO自由基产生过程的影响.结果表明:OH是气液两相滑动弧放电的主导自由基,OH和NO自由基谱线强度沿着电极中轴均先增后减;在非平衡区域,自由基谱线强度随着输入电压的增大而增大;OH自由基谱线强度随水流量的增大而增大,NO自由基谱线强度则随着水流量的增大而减小.  相似文献   

7.
仇聪颖  管显涛  刘振  朱安娜  闫克平 《强激光与粒子束》2020,32(2):025010-1-025010-7
随着印染行业的快速发展,印染废水的排放与日俱增。由于废水中的有机物具有成分复杂、难以降解的特点,若未经有效处理直接排放,会对生态环境造成严重的污染和危害。试验设计了一种多针-网式反应器循环处理有机组分为酸性红73(AR73)的模拟废水,其采用自行设计的基于TLT(Transmission Line Transformer)的高压重频纳秒脉冲电源驱动。电源可以产生峰值电压为50 kV,脉宽40 ns,上升沿20 ns的纳秒脉冲信号,工作频率可达500 Hz。试验考察了峰值电压、放电频率、染料初始质量浓度及作用时间等因素对AR73降解效果的影响。为评价处理效果,采用紫外分光光度法分别测量了废水中剩余染料浓度、过氧化氢浓度等指标。结果表明,在初始浓度30 mg/L,循环流量3.4 L/min,放电间距30 mm,峰值电压44.26 kV,放电频率200 Hz条件下处理30 min,AR73降解率可以达到83.20%,单次脉冲注入能量为11.73 mJ,过氧化氢浓度为47.36μmol/L,反应器脱色能效(G50)可以达到31.07 g·kW^-1·h^-1。增大放电电压可以进一步提高AR73降解率,溶液中活性物质浓度提高,但是能量效率有所下降。  相似文献   

8.
文章用UV-Vis光谱和高效液相色谱(HPLC)研究了苯酚和苯胺溶液在Ti/SnO2-Sb2O5电极上的电氧化降解过程.研究结果表明,对苯二酚、苯醌、马来酸是苯胺和苯酚降解的共同产物,因而苯酚和苯胺可能具有相同的降解途径.由于苯胺发生电聚合反应,导致氧化降解历程的差异.  相似文献   

9.
电晕放电等离子体技术是近年发展起来的一种新型高级氧化工艺,因其处理效果好、操作简单、占地面积小的特点在印染废水处理领域得到了广泛应用。目前因大部分有机污染物的降解机理不详,该技术尚处于探索阶段。因此,为了尽早将电晕放电等离子体技术应用于工业印染废水的处理,不同污染物降解机理的研究对该技术的工业化和产业化应用具有重要意义。至今,电晕放电等离子体技术对研究较多的染料的降解效果均较好,然而,是否适合所有染料的降解有待进一步研究。采用电晕放电等离子体技术处理三苯甲烷类染料甲基蓝,研究了溶液的初始浓度对甲基蓝紫外-可见光谱中芳香环的降解率、发色基团吸光度变化的影响,测定了溶液的浓度、总有机碳(TOC)、总氮(TN)、pH值等指标随着放电时间的变化,并对其相关性进行了分析。结合紫外-可见光谱(UV-Vis)、三维荧光光谱(3D-fluorescence)和傅里叶变换红外光谱(FTIR)三种光谱学手段分析了电晕放电降解甲基蓝过程溶液的颜色、荧光物质和官能团变化,分析了电晕放电降解甲基蓝30 min后生成的中间产物。结果表明:电晕放电等离子体降解甲基蓝过程,溶液的浓度随着放电时间的延长逐渐减小,表明该技术对甲基蓝溶液有一定的降解能力;降解过程高压电极放电击穿含有大量氮气的空气产生N,NO·,N+2等含氮高活性粒子,这些粒子通过扩散作用迁移至液相,使得溶液中TN含量在整个降解过程逐渐升高;另有部分含氮高活性粒子与钨钢针电极溶出的C元素键合生成发色的CN双键,使得溶液中的总有机碳在放电5 min时有所升高。延长反应时间产生的高活性粒子与溶液中的有机物(甲基蓝及中间产物)继续作用,部分有机物矿化生成CO2,引起溶液中TOC含量的下降。电晕放电相同时间内产生的活性粒子数量相当,增大甲基蓝浓度,未被降解的甲基蓝分子越多,导致甲基蓝降解率的减小。电晕放电过程甲基蓝分子之间的聚合与发色CN双键的生成共同促使甲基蓝发色基团吸光度在放电5 min时达到最大;且甲基蓝溶液的初始浓度越高,吸光度(A5-A0)升高的越多。概括来说,甲基蓝结构中发色CN双键的存在是电晕放电等离子体降解甲基蓝过程溶液颜色加深再变浅的主要原因。反应过程羟基自由基的消耗导致放电5 min时溶液的pH值升高;随着反应的进行溶液中生成的硝酸及小分子酸增强了溶液的酸性,导致pH值降低。三维荧光光谱结果表明,甲基蓝降解过程出现了三类明显的荧光峰,位于EX/EM=310~320/430~450,EX/EM=240~250/320~340和EX/EM=280/340,分别代表腐殖酸类物质、芳香族蛋白质和溶解性微生物代谢副产物。甲基蓝溶液降解前的荧光物质主要为腐殖酸类,随着降解时间的延长,腐殖酸类物质首先降解生成了芳香族蛋白质,进一步降解产生可溶性微生物代谢副产物。比较电晕放电前后甲基蓝溶液的红外光谱图和红外分峰图发现,甲基蓝结构中N-H键3 432.8 cm-1处不对称伸缩振动峰红移了0.3 cm-1,烯烃和苯环上C-H键2 975.9 cm-1处的伸缩振动峰向高波数偏移了0.5 cm-1,1 638.7 cm-1处RCHCHR的双键伸缩振动位置蓝移了3.2 cm-1,芳仲胺的C-N伸缩振动峰1 341.6 cm-1向高波数偏移了1.3 cm-1,磺酸基SO的伸缩振动峰1 121.1和1 034.3 cm-1分别红移了3.8和13 cm-1,甲基蓝结构中的环外CC双键与CN双键吸收峰消失,在1 692.4和1 400.4 cm-1处分别出现了CO和NO的伸缩振动吸收峰,产生了2,5-环己二烯-1,4-二酮、对硝基苯磺酸钠和芳香酮类等中间产物。该结果对于利用电晕放电等离子体技术处理甲基蓝废水具有重要的理论意义和实用价值。  相似文献   

10.
给出不同空化状态下超声波降解苯酚溶液的实验结果,比较了相应的声压级频谱和合成声强。研究了苯酚溶液的浓度、二阶铁盐、超声辐照时间对苯酚降解率的影响,讨论了不同空化状态下的声压级频谱特征。  相似文献   

11.
Sonochemical and photochemical oxidation of organic matter   总被引:35,自引:0,他引:35  
Recent developments in sonochemistry have led us to study its use to treat water and wastewater. The effects of ultrasound wave in hydrophilic chemical oxidations are mainly due to hydroxyl radical production during the cavitation-induced water decomposition. Currently, the sonochemical destruction of aromatic compounds in water solution is obtained with low rates. The aim of this work is to evaluate the efficiency of the sonochemical effect in conjunction with a photochemical irradiation. Taking phenol as an example, the combined action of sonochemistry and photochemistry has been considered in a ‘sonuv’ reactor. An important enhancement of the degradation rate of phenol has been observed. It may be the result of three different oxidative processes: direct photochemical action, high frequency sonochemistry and reaction with ozone (produced by UV irradiation of air). The process has been successfully tested to lower the chemical oxygen demand of a municipal wastewater.  相似文献   

12.
Phenol degradation was carried out in acidic aqueous solution on different crystal structures of PbO2 surfaces at room temperature. Phenol, benzoquinone and maleic acid concentrations were monitored during the electrolysis process. It was determined that β surfaces have higher performance than surfaces on phenol degradation. Then, the effect of crystallinities of pure β-PbO2 surfaces was investigated and found that higher crystallinity increased the efficiency of the phenol degradation process.  相似文献   

13.
Sonochemical (SC) processes can be increased with the application of fluid flow due to changes in bubble characteristics. In this work, a novel flow through set-up was applied to an ultrasonic horn system to investigate the effects of flow on the degradation of phenol. KI dosimetry and sonochemiluminescence (SCL) were also analysed, under the same conditions, to provide comparison of degradation to other SC processes. Further, sonoluminescence (SL) in water and different concentrations of potassium iodide (KI) and phenol solutions was studied to determine the effect of flow on processes inside the bubble that result in SL. The degradation of 0.1 mM phenol solutions, KI dosimetry and SL from phenol (0.1, 20 and 60 mM) and KI (0.1, 1 and 2 M) solutions were analysed under flow rates of 0, 24, 228 and 626 mL/min. For an ultrasonic horn system, all flow rates could augment phenol degradation beyond that of the systems without flow. At the lowest applied power, the amount of degradation was significantly increased with flow, becoming greater than degradation observed at the highest power. A strong correlation between phenol degradation and SC processes indicated that degradation followed an oxidative process. SL intensity from water, KI, and phenol solutions could also be increased with flow beyond the no flow system. For water this occurred most readily at higher powers, then for the solutes there was varied behaviour dependent upon the solute concentration. It was theorised that flow may increase the transfer of radical species to solution to enhance SC processes. An increase in SL, with flow, indicates that flow is acting to change the properties of the bubbles and/or the bubble field such that the active bubbles present collapse with greater total intensity.  相似文献   

14.
A novel method of laser cavitation (LC) was proposed for degrading organic dye wastewater. Rhodamine B (RhB) aqueous solution was employed as the simulated organic dye wastewater, and a LC system was designed to conduct the experiments of degrading RhB. The effects of laser energy, initial concentration and cavitation time on the degradation were investigated. Moreover, the degradation kinetics, degradation mechanism and energy efficiency were analyzed. The experimental results indicate that RhB aqueous solution can be degraded effectively by LC and the degradation follows the pseudo-first-order kinetics. The extent of degradation increases by 27.6% with the rise of laser energy (50–100 mJ) while it decreases by 7.8% with increasing the initial concentration from (20–40 mg/L), but RhB can not be degraded when exceeding 100 mg/L. The degradation extent of RhB at 100 mJ and 20 mg/L for 3 h is 81.11%, and the RhB solution is almost completely degraded at 150 mJ (98.4%). The degradation velocity of RhB rises firstly and then decreases as the cavitation time increases. The degradation of RhB by LC can be attributed to the N-de-ethylation and chromophore cleavage caused by oxidation of hydroxyl (OH) radical and thermal decomposition. LC has a higher energy efficiency compared with other methods and is more energy efficient at lower laser energy.  相似文献   

15.
Current literature shows a direct correlation between the sonochemical (SC) process of iodide oxidation and the degradation of phenol solution. This implies phenol degradation occurs primarily via oxidisation at the bubble surface. There is no work at present which considers the effect of fluid flow on the degradation process. In this work, parametric analysis of the degradation of 0.1 mM phenol solution and iodide dosimetry under flow conditions was undertaken to determine the effect of flow. Frequencies of 44, 300 and 1000 kHz and flow rates of 0, 24, 228 and 626 mL/min were applied with variation of power input, air concentration, and surface stabilisation. Phenol degradation was analysed using the 4-aminoantipyrine (4-AAP) method, and sonoluminescence (SL) images were evaluated for 0.1, 20 and 60 mM phenol solutions. Flow, at all frequencies under certain conditions, could augment phenol degradation. At 300 kHz there was excellent correlation between phenol degradation and dosimetry indicating a SC process, here flow acted to increase bubble transience, fragmentation and radical transfer to solution. At 300 kHz, although oxidation is the primary phenol degradation mechanism, it is limited, attributed to degradation intermediates which reduce OH radical availability and bubble collapse intensity. For 44 and 1000 kHz there was poor correlation between the two SC processes. At 44 kHz (0.01 mM), there was little to suggest high levels of intermediate production, therefore it was theorised that under more transient bubble conditions additional pyrolytic degradation occurs inside the bubbles via diffusion/nanodroplet injection mechanisms. At 1000 kHz, phenol degradation was maximised above all other systems attributed to increased numbers of active bubbles combined with the nature of the ultrasonic field. SL quenching, by phenol, was reduced in flow systems for the 20 and 60 mM phenol solutions. Here, where the standing wave field was reinforced, and bubble localisation increased, flow and the intrinsic properties of phenol acted to reduce coalescence/clustering. Further, at these higher concentrations, and in flow conditions, the accumulation of volatile phenol degradation products inside the bubbles are likely reduced leading to an increase SL.  相似文献   

16.
Organic compounds in aqueous solution submitted to an ultrasonic irradiation behave differently according to their physical and chemical properties. In this work, hydrogen peroxide formation and the degradation rate of phenol and carbon tetrachloride have been studied at different frequencies: 20, 200, 500 and 800 kHz. Whatever the frequency, it is easier to decompose CCl4 than phenol by means of ultrasonic wave. It is shown that the rates of reactions involving hydroxyl radicals (hydrogen peroxide formation and phenol degradation) have a maximum value at 200 kHz. The best yield observed at 200 kHz for the phenol degradation may be the result of better HO radicals availability outside of the bubble of cavitation. The degradation rate for carbon tetrachloride which decomposes into the bubble of cavitation increases with frequency. Calculating the reaction rate for one ultrasonic period shows that the efficiency of one ultrasonic cycle decreases as frequency increases.  相似文献   

17.
The chemical effect of swirling jet-induced cavitation was investigated with the decomposing reaction of rhodamine B in aqueous solution. It was found that rhodamine B in aqueous solution can be degraded with swirling jet-induced cavitation and the degradation can be described by a pseudo-first-order kinetics. The effects of operating conditions such as pressure, temperature, initial concentration of rhodamine B, pH of water on the degradation rate of rhodamine B were discussed. It was found that the degradation rate of rhodamine B increased with increasing pressure and decreased with increasing initial concentration. It was also found that the degradation of rhodamine B was strongly dependent of temperature and pH of aqueous solution. The oxidation efficiency of swirling jet-induced cavitation for rhodamine B degradation was discussed and compared with ultrasonic cavitation. The result indicated that the swirling jet-induced cavitation is more energy efficient as compared to sonochemical cavitation.  相似文献   

18.
Sonochemical degradation of phenol was found to be enhanced in the presence of the volatile hydrogen atom scavengers CCl4 and perfluorohexane. The non-volatile hydrogen atom scavenger iodate did not enhance phenol degradation. The first order rate constant for aqueous phenol degradation in separate experiments using different sonochemical probes increased in the presence of 150 microM CCl4 from 0.014 to 0.031 min(-1) (probe 1) and from 0.022 to 0.061 min(-1) (probe 2). In the presence of <1.5 microM C6H14, the first order rate constant increased from 0.014 to 0.032 min(-1) (probe 1). Hydroquinone was the major observed reaction intermediate both in the presence and absence of hydrogen atom scavengers. Hydroquinone yields were substantially higher in the presence of hydrogen atom scavengers, suggesting that hydroxyl radical pathways for phenol degradation were enhanced by the hydrogen atom scavengers. These additives may be useful in improving pollutant degradation efficiency or improving synthetic processes that rely on hydroxyl radical as a key intermediate.  相似文献   

19.
Ultrasonic degradation of polyvinyl alcohol (PVA) was carried out in aqueous solution at 25 degrees C. In this experiment, the effect of solution concentration on the rate of degradation was investigated. Kinetics of degradation was studied by viscometry method. The calculated rate constants indicate that degradation rate of PVA solutions decreases with increasing of solution concentration (C= g lit(-1)). The calculated rate constants correlated in terms of reverse concentration and relative viscosity of PVA solutions. This behavior in the rate of degradation was interpreted in terms of viscosity and concentration of polymer solution. With increasing solution concentration, viscosity increases and it causes a reduction in the cavitation efficiency thus, the rate of degradation will be decreased.  相似文献   

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