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Liu Zhengchao Pan Xunxi Dong Wenbo Hou Huiqi Zhang Zhenman Hou Jian Yu Yong Li Changlin 《环境科学学报(英文版)》1997,9(1):95-99
In this paper pulsed corona discharge is shown to be effective for the decomposition of CF3Cl(Freon-13).The pressure of CF3Cl was 2.67×103Pa,after discharged for 2 min,39.5% of CF3Cl was decomposed.The products were mainly CF4,Cl2 and CF2Cl2.The yield increased by adding O2 or air.Under the same conditions,more than 94% decomposition yield was obtained if 5.32×103Pa O2 or air was added.The composition of products became CF2O,Cl2 and CF4.While the partial pressure of O2 or air reached 1 arm,the decomposition yield decreased to 54.5% and 48. 5% respectively. 相似文献
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1IntroductionSincethe1970s,theCFCsandHalonsemitedbyhumanhavebeenwidelythoughtassubstanceswhichmaycauseozonedepletioninstrato... 相似文献
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采用线-筒式脉冲电晕反应器对四氯乙烯去除效果进行了研究.结果表明,四氯乙烯去除率随电压的增大而增大.在氮气中加入氧气,四氯乙烯降解效果低于纯氮气下的降解效果.四氯乙烯在氮气下的主要气相产物为Cl_2和少量的CCl_4.当氧气加入后,四氯乙烯主要降解为CO_2、CO、COCl_2、O_3和C_2Cl_4O.为了去除有害中间产物,在反应器中加入Ca(OH)_2固体吸收剂,这明显提高了有害中间产物的去除,存在水汽及含Ca(OH)_2固体吸收剂时并未检测到COCl_2、O_3和有害中间产物C_2Cl_4O,但水汽不利于四氯乙烯去除. 相似文献
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全氟辛酸(PFOA)具有环境持久性及内分泌干扰性,传统的生物降解及高级氧化法对PFOA的去除效果微弱.本研究采用电化学氧化法降解PFOA,选取BDD(掺硼金刚石电极)、Pt、Ti、Ti/RuO2、Ti/RuO2-IrO2、Ti/In2O3、Ti/SnO2-Sb2O5-IrO2、Ti/SnO2-Sb2O5-RhO2、Ti/SnO2-Sb2O5、Ti/SnO2-Sb2O5-CeO2和Ti/SnO2-Sb2O5-Bi2O3这11种阳极材料为备选电极.采用线性扫描伏安法测试析氧电位(OEP),评价11种电极对PFOA的降解效果和脱氟效果,并采用超声-电化学协同方法间接证明PFOA分子在电极表面的直接电子转移是降解反应的第一步.Ti/SnO2-Sb2O5-Bi2O3、Ti/SnO2-Sb2O5-CeO2、Ti/SnO2-Sb2O5和BDD对PFOA有较好的电氧化效果,降解率分别是89.8%、89.8%、93.3%和98.0%.Pt、Ti/SnO2-Sb2O5-RhO2、Ti/SnO2-Sb2O5-IrO2和Ti/In2O3对PFOA的电氧化效果微弱,降解率分别是2.1%、2.3%、12.5%和3.1%.而Ti、Ti/RuO2和Ti/RuO2-IrO2对PFOA没有电氧化能力.PFOA分子经过电极表面的直接电化学氧化发生脱羧反应,后经过逐步脱掉CF2单元的循环生成短链的全氟羧酸类化合物C6F13COO-、C5F11COO-、C4F9COO-和C3F7COO-. 相似文献
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SF5CF3是近年被发现的具有强红外辐射强迫、长寿命的新温室气体.本文利用火花放电技术模拟研究了放电条件下SF5CF3的去除机理.结果表明,SF5CF3在放电过程中将被分解并生成多种含硫、氟、氧和碳的化合物.H2O的存在能够降低SF5CF3的分解速率,但降低的量与H2O的分压无关. 在有H2O存在的条件下,当体系总压约为31kPa时,闪电过程中SF5CF3的分解速率常数分别为0.011s-.同时,SF5CF3的分解率随着体系的总压上升而呈指数下降.基于实验结果,对SF5CF3在放电过程中的反应途径作了探讨,并估算实际大气中放电的一种形式--闪电所引起的SF5CF3的分解量为53.6 kg·a-. 相似文献
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采用线-筒式脉冲电晕反应器对二硫化碳(CS2)模拟废气的去除效果进行了实验研究.实验以氩气为载气,考察了氧气和氢气对CS2去除效果的影响.结果表明CS2的去除率随脉冲电压升高而增大;氧气能够促进CS2的氧化分解,CS2去除率可达97%;有氧气存在时,CS2的最终氧化分解产物为CO、CO2、COS和SO2;当添加氢气时,反应产物主要为H2S和CH4.当反应器内筒表面加Ca(OH)2吸收剂时,CS2去除率有小幅度提高,同时气体产物中未检测到SO2和H2S,表明CS2的分解产物SO2和H2S气体被反应器中的Ca(OH)2吸收.实验还发现水汽的存在不利于CS2的氧化分解 相似文献
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Decomposition of trifluoromethane in a dielectric barrier discharge non-thermal plasma reactor 总被引:1,自引:0,他引:1
The decomposition of trifluoromethane (CHF3) was carried out using non-thermal plasma generated in a dielectric barrier discharge (DBD) reactor. The effects of reactor temperature, electric power, initial concentration and oxygen content were examined. The DBD reactor was able to completely destroy CHF3 with alumina beads as a packing material. The decomposition efficiency increased with increasing electric power and reactor temperature. The destruction of CHF3 gradually increased with the addition of O2 up to 2%, but further increase in the oxygen content led to a decrease in the decomposition efficiency. The degradation pathways were explained with the identified by-products. The main by-products from CHF3 were found to be COF2, CF4, CO2 and CO although the COF2 and CF4 disappeared when the plasma were combined with alumina catalyst. 相似文献
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利用水热法制备了3种不同形貌(纳米棒、纳米颗粒、纳米立方体)的CeO_2催化剂,并通过比表面积测试(BET)、扫描电子显微镜(SEM)、拉曼光谱分析(Raman)、O_2程序升温脱附(O_2-TPD)手段表征其物理化学性质,结果发现,CeO_2纳米棒的表面氧空位和氧物种最多.等离子体与催化协同降解甲醇性能评价实验结果显示,CeO_2纳米棒展现出最好的催化性能.进一步设计实验(甲醇-TPD、不同气氛常温催化、催化剂内后置比较、O_3催化氧化)推测在等离子体场内CeO_2表面活性氧物种来源及其作用.结果表明:①在等离子体场内参与CeO_2表面催化反应的活性氧物种有两个来源,一是催化剂本身存在的表面氧物种,二是等离子体区域产生的短寿命物种及长寿命物种(主要是O_3),其中,O_3分解产生的活性氧物种是提高催化性能的主要因素.②不同形貌CeO_2由于表面氧空位含量不同,导致O_3在催化剂上分解产生的活性氧物种的量不同,最终影响等离子体催化性能. 相似文献
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Xinbo Zhu Chenghang Zheng Xiang Gao Xu Shen Zhihua Wang Zhongyang Luo Kefa Cen 《环境科学学报(英文版)》2014,26(11):2249-2256
Non-thermal plasma technology has been regarded as a promising alternative technology for NOx removal. The understanding of NO2 reduction characteristics is extremely important since NO2 reduction could lower the total NO oxidation rate in the plasma atmosphere. In this study, NO2 reduction was experimentally investigated using a non-thermal plasma reactor driven by a pulsed power supply for different simulated gas compositions and operating parameters. The NO2 reduction was promoted by increasing the specific energy density (SED), and the highest conversion rates were 33.7%, 42.1% and 25.7% for Ar, N2/Ar and O2/Ar, respectively. For a given SED, the NO2 conversion rate had the order N2/Ar 〉 Ar 〉 02/Ar. The highest energy yield of 3.31 g/kWh was obtained in N2/Ar plasma and decreased with increasing SED; the same trends were also found in the other two gas compositions. The conversion rate decreased with increasing initial NO2 concentration. Furthermore, the presence of N2 or O2 led to different reaction pathways for NO2 conversion due to the formation of different dominating reactive radicals. 相似文献
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We herein used Fe3O4 nanoparticles(NPs) as an adsorption interface for the concurrent removal of gaseous benzene, toluene, ethylbenzene and m-xylene(BTEX) and sulfur dioxide(SO2), at different relative humidities(RH). X-ray diffraction, Brunauer–Emmett–Teller, and transmission electron microscopy were deployed for nanoparticle surface characterization.Mono-dispersed Fe3O4(Fe2O3·Fe O) NPs synthesized with oleic acid(OA) as surfactant, and uncoated poly-dispersed Fe3O4 NPs demonstrated comparable removal efficiencies.Adsorption experiments of BTEX on NPs were measured using gas chromatography equipped with flame ionization detection, which indicated high removal efficiencies(up to(95 ± 2)%) under dry conditions. The humidity effect and competitive adsorption were investigated using toluene as a model compound. It was observed that the removal efficiencies decreased as a function of the increase in RH, yet, under our experimental conditions, we observed(40 ± 4)% toluene removal at supersaturation for Fe3O4 NPs, and toluene removal of(83 ± 4)% to(59 ± 6)%, for OA-Fe3O4 NPs. In the presence of SO2, the toluene uptake was reduced under dry conditions to(89 ± 2)% and(75 ± 1)% for the uncoated and coated NPs, respectively, depicting competitive adsorption. At RH 100%,competitive adsorption reduced the removal efficiency to(27 ± 1)% for uncoated NPs whereas OA-Fe3O4 NPs exhibited moderate efficiency loss of(55 ± 2)% at supersaturation.Results point to heterogeneous water coverage on the NP surface. The magnetic property of magnetite facilitated the recovery of both types of NPs, without the loss in efficiency when recycled and reused. 相似文献
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Numerical evaluation of the effectiveness of NO2 and N2O5 generation during the NO ozonation process
Haiqiang Wang Zhuokai Zhuang Chenglang Sun Nan Zhao Yue Liu Zhongbiao Wu 《环境科学学报(英文版)》2016,28(3):51-58
Wet scrubbing combined with ozone oxidation has become a promising technology for simultaneous removal of SO2 and NOx in exhaust gas. In this paper, a new 20-species, 76-step detailed kinetic mechanism was proposed between O3 and NOx. The concentration of N2O5 was measured using an in-situ IR spectrometer. The numerical evaluation results kept good pace with both the public experiment results and our experiment results. Key reaction parameters for the generation of NO2 and N2O5 during the NO ozonation process were investigated by a numerical simulation method. The effect of temperature on producing NO2 was found to be negligible. To produce NO2, the optimal residence time was 1.25 sec and the molar ratio of O3/NO about 1. For the generation of N2O5, the residence time should be about 8 sec while the temperature of the exhaust gas should be strictly controlled and the molar ratio of O3/NO about 1.75. This study provided detailed investigations on the reaction parameters of ozonation of NOx by a numerical simulation method, and the results obtained should be helpful for the design and optimization of ozone oxidation combined with the wet flue gas desulfurization methods (WFGD) method for the removal of NOx. 相似文献
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纳米Fe3 O4-H2 O2 非均相Fenton反应催化氧化邻苯二酚 总被引:4,自引:3,他引:1
由四氧化三铁(Fe3O4)-过氧化氢(H2O2)构成的非均相Fenton体系主要利用H2O2分解产生的羟基自由基氧化去除难降解有机污染物.研究了邻苯二酚在纳米Fe3O4-H2O2构成的非均相Fenton体系中的催化氧化特征,同时对实验室制备的纳米级Fe3O4和商品微米级Fe3O4两种催化剂的催化活性进行比较,并考察了H2O2初始浓度对邻苯二酚的催化氧化的影响.结果表明,自制纳米Fe3O4-H2O2体系较商品Fe3O4-H2O2体系,能更快速地去除溶液中的邻苯二酚和总有机碳(TOC),邻苯二酚的去除率接近100%,同时能迅速催化H2O2分解.邻苯二酚的催化氧化反应遵循准一级反应动力学方程,H2O2的分解反应能用三级反应动力学方程较好拟合.此外,反应过程中铁释放低于0.3 mg.L-1,不足以启动均相Fenton反应,反应机制为由界面反应控制的非均相反应机制. 相似文献