介质阻挡放电技术处理挥发性有机物的研究进展

介质阻挡放电技术在处理低浓度挥发性有机物（VOCs）过程中具有反应快速、工艺简单及适应范围广等优点而受到广泛关注。本文从介质阻挡放电单独使用和介质阻挡放电协同催化两方面进行了概括总结。首先，简述了介质阻挡放电处理VOCs所用的驱动电源和等离子体发生器的研究现状及气体性质对VOCs降解性能的影响；其次，介绍了介质阻挡放电协同催化的两种方式（内置式和后置式）及各自情况下采用不同催化剂强化VOCs去除性能、提高能量效率、抑制副产物生成的过程机理；最后，分析了介质阻挡放电技术处理低浓度VOCs过程中存在的关键问题，并提出了未来的重要研究方向为：等离子体催化体系中VOCs的界面反应机理；催化剂的抗积碳性能的提高；适用于多组分VOCs的高效催化剂的开发。     

介质阻挡放电降解VOCs的能效特性研究

挥发性有机物（VOCs）已经严重威胁了城市居民的生活环境,介质阻挡放电技术最高可使VOCs的降解率达到95%以上。本研究选择甲苯作为目标污染物,进行介质阻挡放电（DBD）降解VOCs的能效研究。考察放电电压、电源频率、气体流量和初始浓度对能量密度（SED）和能量效率的影响。研究结果表明：能量效率随放电电压的升高而降低,随电源频率的升高而升高。且能量效率随气体流量的增大先升高后降低,随甲苯初始浓度的增大而提高。     

TiO2-HNTs催化剂协同介质阻挡放电等离子体降解亚甲基蓝废水

为进一步提高介质阻挡放电等离子体（DBD）降解亚甲基蓝（MB）的效率,研究了采用介质阻挡放电等离子体和光催化剂协同技术。实验采用溶胶-凝胶法制备TiO₂-HNTs复合光催化材料,并利用XRD、FTIR、TGA方法对催化剂进行表征分析。考察了该材料的光催化性能,以及它与介质阻挡放电的联合降解过程中操作因素的影响,并对反应进行动力学研究。研究结果表明,TiO₂-HNTs复合光催化材料与介质阻挡放电产生协同作用,并能有效地提高MB的去除率,处理60min后,协同体系对MB的降解率为85.37%,MB的降解过程符合表观一级反应动力学方程。MB的去除率与MB的初始浓度,TiO₂-HNTs的投加量、煅烧温度、放电功率和通气量有关。当MB的初始浓度为100mg/L、TiO₂-HNTs的投加量为70mg/L、煅烧温度为300℃、放电功率为200W、通气量为200mL/min时,MB的去除效果较好。     

低温等离子体协同锰银催化剂降解甲苯

以挥发性有机化合物(VOCs)的代表物质——甲苯为去除对象,采用自制线管式介质阻挡放电反应器,考察低温等离子体与γ-Al2O3负载不同类型催化剂相结合去除空气中甲苯的性能。通过对负载活性组分的γ-Al2O3小球与未负载进行对比分析,考察放电对催化活性的影响。对不同类型反应器从能量密度、甲苯去除效率、能量效率和副产物臭氧的产生量进行测定比较。研究结果表明,负载活性组分后,催化剂的比表面积和孔径均减小。与仅填充γ-Al2O3相比,负载催化剂后的反应器能量密度有所降低,填充负载锰银催化剂的反应器对甲苯的降解有明显的促进作用,但不同催化剂的作用程度不同,在电压17 k V时,MnO2、Ag O、MnO2-Ag O、MnO2-Ag O-CeO2催化剂及无负载催化剂对甲苯去除效率分别为53.4%、64.4%,67.9%、74.0%和53.3%。因此,活性组分有助于提高催化活性,进而提高甲苯去除效率。甲苯降解的能量效率随电压升高而减小,引入催化剂后的能量效率高于仅填充γ-Al2O3时的能量效率。臭氧的产生量随电压的升高而升高,引入催化剂有利于减少副产物臭氧的生成。     

催化强化低温等离子体降解甲苯的研究

研究了介质阻挡放电反应器与MnOx/γ-Al2 O3催化剂强化去除甲苯的性能.探究负载含量、焙烧温度、焙烧时间等条件对降解甲苯的影响,采用均匀设计的方法来优化甲苯降解的制备参数,并对产生的尾气进行在线监测分析.结果表明,5％的负载含量、焙烧温度660℃、焙烧时间为195 min时甲苯的降解率最高可达92.48％,较空塔...     

基于BP网络的等离子体法去除VOC_s实验研究

低温等离子体技术处理VOCs是目前国内外的研究热点。本实验研究通过电晕放电和介质阻挡放电相结合的方法,将实验装置划分为电源系统、配气系统和等离子体反应系统三大组成部分,探讨的相关的六种工况参数对甲苯去除效率的影响。在数据处理中运用BP神经网络的数值逼近和MATLAB三维可视化技术,对实验结果作了理论分析。研究结果表明,电压的升高有利于甲苯污染物的去除;频率对甲苯去除效率的影响与反应器材质和电源变压器的漏感有关,频率处于系统谐振频率附近对甲苯的去除效果有利。气体流量与进口浓度对甲苯去除效果的影响相似,随着气体流量的增大与进口浓度的上升,甲苯的去除效率下降,但气体流量对去除效率的影响程度较大。实验还考察了反应器直径和内电极直径对甲苯去除效率的影响,结果表明,对于直径较大管径,细电极更有利于甲苯的去除;而对于直径较小管径,粗电极的效果较好。     

基于BP网络的等离子体法去除VOC_s实验研究

低温等离子体技术处理VOCs是目前国内外的研究热点。本实验研究通过电晕放电和介质阻挡放电相结合的方法,将实验装置划分为电源系统、配气系统和等离子体反应系统三大组成部分,探讨的相关的六种工况参数对甲苯去除效率的影响。在数据处理中运用BP神经网络的数值逼近和MATLAB三维可视化技术,对实验结果作了理论分析。研究结果表明,电压的升高有利于甲苯污染物的去除;频率对甲苯去除效率的影响与反应器材质和电源变压器的漏感有关,频率处于系统谐振频率附近对甲苯的去除效果有利。气体流量与进口浓度对甲苯去除效果的影响相似,随着气体流量的增大与进口浓度的上升,甲苯的去除效率下降,但气体流量对去除效率的影响程度较大。实验还考察了反应器直径和内电极直径对甲苯去除效率的影响,结果表明,对于直径较大管径,细电极更有利于甲苯的去除;而对于直径较小管径,粗电极的效果较好。     

介质阻挡放电等离子体处理C.I.活性黄145废水的研究

本文采用介质阻挡放电等离子体技术对模拟C.I.活性黄145废水进行降解实验,考察了峰值电压、放电频率、气体流量、作用时间等因素对该染料废水色度、COD等处理效果的影响,并初步探讨C.I.活性黄145降解的降解机理。结果表明,介质阻挡放电可有效去除废水色度(去除率95%),COD去除率虽不高(去除率30%~40%),但生化可行性有一定提高(B/C由0.04上升到0.32)。通过降解机理的探讨表明,介质阻挡放电可将染料大分子降解为小分子的酸。     

不同电源及放电形式下低温等离子体降解挥发性有机物的研究进展

介绍了低温等离子体的产生方式,并对几种降解挥发性有机物(VOCs)的工艺及其特点进行阐述。针对电晕放电与介质阻挡放电,重点围绕不同类型电源作用下VOCs的降解特性进行叙述。结合不同电源及放电形式下低温等离子体降解VOCs的表现,对该技术的未来发展进行了展望。     

强电离放电合成高浓度臭氧实验研究

采用α-Al2O3陶瓷作为介质阻挡放电的电介质进行了臭氧合成实验,并确定了外加电场激励电压、频率、电耗率等参数对臭氧合成浓度的影响规律,进行了装置设计参数的优化实验.通过采用高介电常数、高电阻率的α-Al2O3陶瓷电介质材料使介质阻挡强电离放电的折合电场强度达到300 Td以上,并实现了臭氧合成装置结构简单、紧凑小型化,模块叠加组合化.当臭氧浓度为114 g/m3时,臭氧合成效率达256 g/kWh.     

低温等离子体除苯过程中臭氧的演变与作用

大气污染物中,挥发性有机化合物(VOCs)已超越NOx和SO_2成为排放量最高的气态污染物,对人体健康和环境的影响已引起广泛关注。相比传统去除VOCs的技术,低温等离子体法具有高效率、低能耗、易操作等优势,但有产生臭氧(O_3)等副产物的问题。本研究选择苯作为VOCs的代表污染物,采用线管式介质阻挡放电反应器,考察电压、电流等放电参数对苯去除率、副产物臭氧浓度和CO_2选择性的影响,重点分析臭氧的演变、机理及其作用。结果表明,影响臭氧浓度的直接因素是输入功率:随着输入功率的上升,苯去除率逐渐上升,臭氧浓度先上升后下降。其原因在于高功率下生成更多低能电子,使得臭氧分解为氧气。等离子体产生的臭氧无法直接氧化苯,但可以氧化苯的中间产物CO完全转化为CO_2。     

Toluene removal by a DBD-type plasma combined with metal oxides catalysts supported by nickel foam

The performance on toluene removal in a dielectric barrier discharge (DBD) type plasma system under different background gases, including N₂, Ar, N₂/Ar, and N₂/O₂ was studied at room temperature and atmospheric pressure. For comparison, another laboratory-scale plasma-catalysis system was set up and four kinds of metal oxides, i.e., copper oxide, iron oxide, cobalt oxide, and manganese oxide supported on alumina/nickel foam (NF), were used as catalysts. The reaction mechanism and dynamics analysis on toluene removal were suggested. In addition, the characterization of the catalysts was performed by BET, XRD, SEM, FT-IR, and EDS. It has been found that adding argon in the background gas could improve the toluene removal efficiency significantly in the plasma system. Combining plasma with catalyst in situ could improve the toluene removal efficiency, increase the carbon dioxide selectivity and suppress byproducts formation. In addition, manganese oxide/alumina/NF was confirmed as the most effective catalyst for toluene removal. The XRD and SEM results showed that the proportion of metal oxide increased while aluminate decreased after plasma application. The granularity of the grain on the catalyst surface became smaller and the distribution became more uniform after discharge. The results of FT-IR and EDS suggested that some organic compounds deposited on the catalysts after plasma reaction.     

Effect of zeolite in surface discharge plasma on the decomposition of toluene

Toluene was decomposed in a surface discharge plasma reactor packed with various zeolites. The positioning effect of the zeolite bed was also investigated Reactor-B, in which the zeolite bed was located upstream, performed much better than Reactor-A, in which the zeolite bed was located downstream. Furthermore, the decomposition efficiency in Reactor-B increased with the capacity for toluene adsorption on zeolite, while that in Reactor-A did not. The toluene adsorbed in micropores was not decomposed effectively by direct electron impact, but was decomposed by active oxygen species generated in the plasma zone on the zeolite surface. A good correlation was also observed between toluene decomposition and ozone consumption in the downward-type reactor.     

高压脉冲介质阻挡放电协同臭氧溶气降解聚丙烯酰胺模拟废水

利用高压脉冲介质阻挡放电与臭氧联用的上流式反应器,考察了高压脉冲介质阻挡放电、臭氧和二者协同处理聚丙烯酰胺的降解情况以及COD和BOD5/COD的变化趋势;另外研究了反应器内加入TiO2催化剂对处理效果的影响,并探讨了其作用机理。结果表明,停留时间为10min时,放电协同臭氧溶气对聚丙烯酰胺的降解率可达51%,比单独放电和单独臭氧分别提高了27%和4%。加入TiO2催化剂后,COD去除率达到65%,BOD5/COD提高到0.37。     

流向变换等离子体反应系统降解甲苯性能

将流向变换技术应用于低温等离子体反应系统,针对单独低温等离子体系统(即空管)以及协同7.5%Mn/堇青石催化剂对低浓度甲苯降解展开研究。考察了空管-未换向、空管-换向、7.5%Mn/堇青石-未换向与7.5%Mn/堇青石-换向4种反应系统的甲苯降解率、去除量、放电能量密度、能量效率以及副产物O₃的生成情况。结果表明,对于空管和7.5%Mn/堇青石的反应系统,添加流向变换技术,可以有效地提高甲苯降解率、去除量和放电能量密度;在较低场强时,有助于提高反应系统的能量效率;并且有助于抑制副产物O₃的生成。     

Removal of particulate matter from an air stream by a packed dielectric barrier discharge

This study elucidates the feasibility of using a packed dielectric barrier discharge approach to remove particulate matter from an air stream. The experimental results reveal that the particle removal efficiency of the packed dielectric barrier discharge system rose to 92.2% for 0.3 μm particles as the discharge voltage was increased to 20 kV at an operating frequency of 60 Hz. Only when the discharge voltage was sufficiently high to remove particulate matter did the particle removal efficiency increase with the operating frequency. The power required to adjust the discharge voltage was less than that required to adjust the operating frequency at the particular removal efficiency. Accordingly, energy can be saved in a packed dielectric barrier discharge system by adjusting the discharge voltage rather than the operating frequency to remove particulate matter from the air stream.     

Continuous flow removal of acid fuchsine by dielectric barrier discharge plasma water bed enhanced by activated carbon adsorption

Continuous processes which allow for large amount of wastewater to be treated to meet drainage standards while reducing treatment time and energy consumption are urgently needed. In this study, a dielectric barrier discharge plasma water bed system was designed and then coupled with granular activated carbon (GAC) adsorption to rapidly remove acid fuchsine (AF) with high efficiency. Effects of feeding gases, treatment time and initial concentration of AF on removal efficiency were investigated. Results showed that compared to the N2 and air plasmas treatments, O2 plasma processing was most effective for AF degradation due to the strong oxidation ability of generated activated species, especially the OH radicals. The addition of GAC significantly enhanced the removal efficiency of AF in aqueous solution and shorten the required time by 50%. The effect was attributed to the ability of porous carbon to trap and concentrate the dye, increasing the time dye molecules were exposed to the plasma discharge zone, and to enhance the production of OH radicals on/in GAC to boost the degradation of dyes by plasma as well as in situ regenerate the exhausted GAC. The study offers a new opportunity for continuous effective remediation of wastewater contaminated with organic dyes using plasma technologies.     

低温等离子体协同催化降解甲苯生成副产物臭氧的影响因素

低温等离子体协同催化降解甲苯过程中，在降解污染物的同时活性氧原子聚合生成臭氧。本文研究比较了不同催化剂、放电能量水平、催化段长度和气速条件下的臭氧浓度变化和甲苯降解情况，探究了低温等离子体协同催化降解甲苯过程中臭氧的生成情况。研究表明，将7.5% Mn/堇青石催化剂置于放电区时能有效抑制臭氧生成，促进甲苯降解，提高系统能效，臭氧最高浓度相比无催化剂时降低63.32mg/m³；而0.2%Pd-0.3%Ce/堇青石催化剂对甲苯降解和抑制臭氧的性能较差。随着系统能量水平的提高，甲苯降解率和臭氧生成浓度逐渐升高。臭氧生成浓度与催化段长度呈正相关关系，与气速的关系则相反。在不同的外加电压条件下，臭氧生成浓度呈先上升后下降的趋势，当外加电压为13kV条件时臭氧浓度最高，当电压升高至16kV时臭氧浓度降为零。     

脉冲放电等离子体协同Mn/TiO2-分子筛、Fe/TiO2-分子筛、Cu/TiO2-分子筛催化剂降解甲醛

为进一步提高脉冲放电等离子降解甲醛的效率,增加CO₂选择性,降低O₃产生量,研究采用放电等离子体和催化剂协同技术。实验以分子筛为载体,分别制备了Mn/TiO₂-分子筛、Fe/TiO₂-分子筛和Cu/TiO₂-分子筛3种催化剂,并利用XRD、SEM、EDS、FT-IR方法对催化剂进行表征分析。进行了脉冲放电等离子体协同3种催化剂降解甲醛的研究,比较了不同催化剂协同等离子体对甲醛去除率、CO₂选择性、O₃产生量的影响。结果表明,3种催化剂与脉冲放电等离子体都存在协同作用,并能有效地提高甲醛去除率,增加CO₂选择性,降低O₃产生量。当脉冲电压为20kV、放电频率为40Hz、气体流量为0.5L/min时,Mn/TiO₂-分子筛催化剂协同效果最佳,甲醛去除率为94.4%,CO₂选择性为42.2%。催化剂表征结果显示Mn/TiO₂-分子筛的活性组分颗粒分布均匀,锐钛矿相的TiO₂和微晶状态的MnO_x的存在有效促进了甲醛的氧化分解。研究还对放电等离子体协同Mn/TiO₂-分子筛催化剂降解甲醛的机理进行了探讨。     

流向变换-等离子体-催化反应系统降解甲苯

研究流向变换-等离子体-催化反应系统在空管与协同催化剂的情况下降解甲苯,讨论了反应系统在不同外加电源频率条件下对甲苯去除性能、能耗和产物生成的影响,主要参数包括甲苯降解率、甲苯去除量、能量密度、能量效率以及副产物臭氧生成情况。结果表明,实验选用的流向变换-等离子体-催化反应系统有助于提升甲苯降解性能和系统的能量利用率,有利于抑制副产物臭氧的生成。