介质阻挡等离子体放电与催化联用技术分解苯

采用介质阻挡等离子体放电与催化剂MnO₂联用技术对苯去除进行了研究.结果表明,加入MnO₂可充分利用O₂和产生于介质阻挡等离子放电区的O₃,能够增加苯氧化分解为CO₂的程度,且苯去除的能量效率是不用催化剂时的2倍.催化剂MnO₂苯去除率有显著影响.当能量密度低于564J/L时,MnO₂离放电区的距离越近,苯的去除效果越好;当能量密度高于1051J/L时,苯的去除效果与MnO₂离放电区的距离有关并有一个最佳值.阐述了苯在等离子体放电区以及MnO₂上的氧化机理.     

常压等离子体射流去除水中糖皮质激素污染物

搭建射流介质阻挡放电反应器,对常压等离子体射流技术降解水中代表性糖皮质激素氢化可的松（HC）进行了研究.考察了放电功率、空气流量、溶液初始pH值、放电时间等因素对HC降解效果的影响.结果表明,HC的去除率随放电功率增大和放电时间延长而增加;溶液初始pH值、通入空气流量等因素对HC处理效果也有很大影响.在初始浓度为0.138mmol/L,放电功率为49.7W,气流量为4L/min的实验条件下,在本反应器中放电处理120min后HC的去除率可达98%.本文使用了不同自由基抑制剂研究了活性氧自由基（ROS）在HC降解过程中的作用,并通过发射光谱（OES）观测了放电过程中产生的自由基种类.研究结果对常压等离子技术去除有机污染物的发展有一定的参考价值.     

低温等离子体处理VOCs事故案例分析

结合电晕放电和介质阻挡放电低温等离子体处理VOCs爆炸事故的分析,从低温等离子体处理VOCs的工程设计要求、设备运行、安全防护措施等方面深入分析燃烧爆炸事故,提出改进措施。     

DBD降解CF2ClBr过程中自由基与电子能量

利用介质阻挡放电方法对环境污染物CF2ClBr进行了等离子体降解的研究.在前人对该体系的降解产物分析及活性粒子推测的基础上,采用动态反应装置得到了等离子体的发射光谱,进一步确证了等离子体系中出现的CF2、CFCl、F、Cl、Br等主要自由基,并从中推出了等离子态气体可能发生的自由基反应.同时通过发射光谱的分析,近似得到该体系的平均电子能量约为2.42eV.     

用于碳烟燃烧的Cu0.05Ce0.95O催化剂活性氧物种的研究 ——等离子体的强化效应

研究等离子体对柠檬酸络合法制备的Cu0.05Ce0.95-CA催化剂表面结构和物种的强化效应. TPO、H2-TPR、O2-TPD、XRD、BET和XPS等测试结果表明,催化剂处于等离子放电区时,其氧化碳烟燃烧的活性显著增强.在介质阻挡放电电压为9kV时,起燃温度为243.1℃,比无等离子的情况降低了65.1℃;燃烧峰值温度为302.8℃,降低92.7℃.在等离子体存在下,Cu0.05Ce0.95-CA催化剂有着更大的比表面积和更小的晶粒粒径;等离子体可以提高催化剂表面游离态的CuO的分散度,并使得更多的Cu2+进入CeO2晶格,形成更多的Cuy2+Ce1-y4+O2-y2-□y固熔体,催化剂储氧容量增大,在催化剂表面生成更多的活性氧物种,其流动、迁移和转化促进催化剂产生更多的氧空穴,如此循环,持续促进碳烟催化燃烧.     

介质阻挡放电脱除H2S影响因素研究

恶臭污染物的危害已引起世界各国的广泛关注.选取恶臭污染物的典型代表硫化氢(H2S)气体,采用介质阻挡放电低温等离子体反应器在常温常压下对H2S气体进行去除,考察了在高频放电条件下,H2S去除率与放电电压、频率、浓度、停留时阃、湿度、和放电间隙、占空比的关系.实验结果表明,较高的放电电压、较长的停留时间、较大的放电间隙有利于提高H2S去除,合适的湿度、放电频率、脉冲调制有利于提高反应器的效率.反应器参数与电源的有效匹配对于提高H2S去除率及节能降耗十分重要.     

大气压脉冲介质阻挡放电离子体研究进展

从脉冲等离子体电学特性和实际应用两个部分综述大气压脉冲介质阻挡放电的研究进展。关于脉冲等离子体电学特性,文中介绍了脉冲放电均匀性,并且对比了不同驱动电源的电气参数(包括电压、电流和电子密度等);关于脉冲等离子体实际应用,除了介绍在传统领域材料表面改性方面的应用进展,着重归纳了近十年来脉冲等离子体在环境VOCs治理领域的应用。总结了脉冲放电等离子体研究现状以及大气压脉冲气体放电等离子体应用存在的难点挑战和发展趋势。     

介质阻挡放电处理水中3,4-二氯苯胺机理研究

采用介质阻挡放电产生低温等离子体来处理水中3,4-二氯苯胺(3,4-DCA),考察了放电功率、空气流量、金属离子(Fe2+、Cu2+)浓度、光催化剂二氧化钛对3,4-DCA去除率的影响,并分析了降解产物及可能的降解机理.实验结果表明,介质阻挡放电方法对3,4-DCA有良好的去除效果,在3,4-DCA初始浓度为30mg·L-1,放电功率为80W,空气流量为1L·min-1时,放电处理6min后3,4-DCA的去除率可达92.5%.增加空气流量能显著地提高3,4-DCA的去除率,添加亚铁离子(Fe2+)浓度和光催化剂TiO2均能提高3,4-DCA的去除率,且存在最佳添加量值.介质阻挡放电方法对3,4-DCA的降解去除反应符合一级反应动力学.通过气质联用仪(GC-MS)分析检测发现,反应主要为脱氯、脱氨基和苯环开环反应,二氯乙烯为其主要的降解产物.     

重度滴滴涕污染土壤低温等离子体修复条件优化研究

采用介质阻挡放电产生的低温等离子体对重度滴滴涕(DDTs)污染土壤进行修复处理实验,主要研究了土壤性质参数(土壤粒径和土壤含水量)和设备工作参数(放电功率、处理时间和放电气氛)对DDTs去除的影响.结果表明,采用介质阻挡放电产生的低温等离子体对土壤中的DDTs具有较好的去除作用,去除率随着处理时间的增加而升高.当处理时间增加至20min时,DDTs的去除率为95.3%～99.9%.同时确定优化条件为:放电功率1 kW、处理时间20 min、空气放电气氛、土壤粒径0～0.9 mm以及土壤含水量4.5%～10.5%.研究结果还表明,o,p’-DDE可能是o,p’-DDT氧化脱氯脱氢的中间产物.     

低温等离子体分解脱除NO影响因素研究

为优化低温等离子体反应器设计、提高NO分解率,在低放电电压下通过改变介质阻挡放电参数(放电电压、介质材料、放电间隙等)考察其对分解NO的影响.研究结果表明:在低电压范围条件下(≤6.5 kV),放电电压对提高NO分解率的效果是非线性的,其影响随电压的升高而减弱;选择介电常数较大的介质材料更易获得较高的分解率;当反应器其它特征参数确定后,放电间隙并非越小越好,而是存在一个最佳值;实际应用中,应选用二次电子发射系数较大的电极材料;NTP反应器中加入填充材料不仅具有吸附和存储性能,还具有介质阻挡放电的功能,选择适合的填充材料能更大程度地提高能量利用率,提高NO分解率.     

Toxic effects of acetochlor, methamidophos and their combination on nifH gene in soil

Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis （DGGE） and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity （both in gene richness and diversity index values） and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor （50 mg/kg） recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos （150 mg/kg） caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos （250 mg/kg） produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes （bands） responded differently to the impact of agrochemicals： four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera.     

EDTA-enhanced phytoremediation of lead contaminated soil by Bidens maximowicziana

Phytoremediation is a potential cleanup technology for the removal of heavy metals from contaminated soils.Bidens maximowicziana is a new Pb hyperaccumulator,which not only has remarkable tolerance to Pb but also extraordinary accumulation capacity for Pb.The maximum Pb concentration was 1509.3 mg/kg in roots and 2164.7 mg/kg in overground tissues.The Pb distribution order in the B. maximowicziana was:leaf>stem>root.The effect of amendments on phytoremediation was also studied.The mobility of soil Pb and the Pb concentrations in plants were both increased by EDTA application.Compared with CK(control check),EDTA application promoted translocation of Pb to overground parts of the plant.The Pb concentrations in overground parts of plants was increased from 24.23-680.56 mg/kg to 29.07-1905.57 mg/kg.This research demonstrated that B.maximowicziana appeared to be suitable for phytoremediation of Pb contaminated soil,especially,combination with EDTA.     

Distribution and ecological effect of mercury in Laogang landfill, Shanghai, China

Laogang landfill near Shanghai is the largest landfill in China, and receives about 10000 t of daily garbage per day, Samples of topsoil and plants were analyzed to evaluate mercury pollution from the landfill. For topsoil samples, there were significant correlations among total mercury （HgT）, combinative mercury （Hgc） and gaseous mercury （HgG）, and content of total organic carbon （TOC）, but, no significantly relationship was found between Hg content and filling time. Hg content changes in vertical profiles with time showed that the average Hgv of profiles 1992, 1996, and 2000 was similar, but their average HgG was quite different. HgT was significantly correlated with Hgc in profile 1992 and 2000, and Hgv was significantly correlated with Hg6 in profile 1996. HgG/Hgv ratio in profile samples decreased in the order of （HgG,/HgT）1992〉（HgG/HgT）1996〉〉（HgG/HgT）2000. A simple outline of Hg release in landfill could be drawn： with increasing of filling time, degradation undergoes different biodegradation, accordingly, gaseous mercury goes through small, more, and small proportion to total mercury. Distribution of Hg in plants was inhomogeneous, following the order of leaf〉root〉stem. The highest value of leaf may be associated with higher atmospheric Hg from landfill. Ligneous plants （e.g. Phyllostachys glanca, Prunus salicina and Ligustrum lucidum） are capable of enriching more Hg than herbaceous plants.     

Arsenic uptake by arbuscular mycorrhizal maize （Zea mays L.） grown in an arsenic-contaminated soil with added phosphorus

The effects of arbuscular mycorrhizal (AM) fungus (Glomus mosseae) and phosphorus (P) addition (100 mg/kg soil) on arsenic (As) uptake by maize plants (Zea mays L.) from an As-contaminated soil were examined in a glasshouse experiment.Non-mycorrhizal and zero-P addition controls were included.Plant biomass and concentrations and uptake of As,P,and other nutrients,AM colonization,root lengths,and hyphal length densities were determined.The results indicated that addition of P significantly inhibited root colonization and development of extraradical mycelium.Root length and dry weight both increased markedly with mycorrhizal colonization under the zero-P treatments,but shoot and root biomass of AM plants was depressed by P application.AM fungal inoculation decreased shoot As concentrations when no P was added,and shoot and root As concentrations of AM plants increased 2.6 and 1.4 times with P addition,respectively.Shoot and root uptake of P,Mn,Cu,and Zn increased,but shoot Fe uptake decreased by 44.6%,with inoculation, when P was added.P addition reduced shoot P,Fe,Mn,Cu,and Zn uptake of AM plants,but increased root Fe and Mn uptake of the nonmycorrhizal ones.AM colonization therefore appeared to enhance plant tolerance to As in low P soil,and have some potential for the phytostabilization of As-contaminated soil,however,P application may introduce additional environmental risk by increasing soil As mobility.     

Enzymatic oxidation of aqueous pentachlorophenol

The influence of the nonionic surfactant Tween 80 on pentachlorophenol （PCP） oxidation catalyzed by horseradish peroxidase was studied. The surfactant was tested at concentrations below and above its critical micelle concentration （CMC）. Enhancement of PCP removal was observed at sub-CMCs. The presence of Tween 80 in the reaction mixture reduced enzyme inactivation which occurred through a combination of free radical attack and sorption by precipitated products. A simple first-order model was able to simulate time profiles for enzyme inactivation in the presence or absence of Tween 80. At supra-CMCs, the surfactant caused noticeable reductions in PCP removal, presumably through micelle partitioning of PCP which precluded the hydrophobic PCP molecule from interacting with the enzyme.     

Decomposition of alachlor by ozonation and its mechanism

Decomposition and corresponding mechanism of alachlor, an endocrine disruptor in water by ozonation were investigated. Results showed that alachlor could not be completely mineralized by ozone alone. Many intermediates and final products were formed during the process, including aromatic compounds, aliphatic carboxylic acids, and inorganic ions. In evoluting these products, some of them with weak polarity were qualitatively identified by GC-MS. The information of inorganic ions suggested that the dechlorination was the first and the fastest step in the ozonation of alachlor.     

Degradation of metabolites accumulated of benzo[a]pyrene by coupling Penicillium Chrysogenum with KMnO4

Several main metabolites of benzo[a]pyrene （BaP） formed by Penicillium chrysogenum, Benzo[a]pyrene-1,6-quinone （BP 1,6- quinone）, trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene （BP 7,8-diol）, 3-hydroxybenzo[a]pyrene （3-OHBP）, were identified by high-performance liquid chromatography （HPLC）. The three metabolites were liable to be accumulated and were hardly further metabolized because of their toxicity to microorganisms. However, their further degradation was essential for the complete degradation of BaP. To enhance their degradation, two methods, degradation by coupling Penicillium chrysogenum with KMnO4 and degradation only by Penicillium chrysogenum, were compared; Meanwhile, the parameters of degradation in the superior method were optimized. The results showed that （1） the method of coupling Penicillium chrysogenum with KMnO4 was better and was the first method to be used in the degradation of BaP and its metabolites; （2） the metabolite, BP 1,6-quinone was the most liable to be accumulated in pure cultures; （3） the effect of degradation was the best when the concentration of KMnO4 in the cultures was 0.01% （w/v）, concentration of the three compounds was 5 mg/L and pH was 6.2. Based on the experimental results, a novel concept with regard to the bioremediation of BaP-contaminated environment was discussed, considering the influence on environmental toxicity of the accumulated metabolites.     

Impact of atrazine and nitrogen fertilizers on the sorption of chlorotoluron in soil and model sorbents

Sorption of chlorotoluron in ammonium sulfate, urea and atrazine multi-solutes system was investigated by batch experiments. The results showed application of nitrogen fertilizers to the soil could affect the behavior of chlorotoluron. At the same concentration of N, sorption of chlorotoluron decreased as the concentration of atrazine increased on the day 0 and 6 in soil, respectively. The sorption of chlorotoluron increased from 0 to 6 d when soils were preincubated with deionized water, ammonium sulfate and urea solution for 6 d. That indicated incubation time was one of the most important factors for the sorption of chlorotoluron in nitrogen fertilizers treatments. The individual sorption isotherms of chlorotoluron in rubbery polymer and silica were strictly linear in single solute system, but there were competition sorption between pesticides or between pesticides and nitrogen fertilizers. That indicated the sorption taken place by concurrent solid-phase dissolution mechanism and sorption on the interface of water-organic matter or water-mineral matter.     

基于综合水质标识指数和对应分析法的校园河道水质评价

以三峡大学的校园河道求索溪为研究对象,利用综合水质标识指数法确定求索溪水质类别,分析其水质时空变化规律,并利用对应分析法得出求索溪中不同监测点的主要污染因子.研究结果表明:求索溪整体的综合水质标识指数为7.423,整体水质为劣V类(地表水环境质量标准GB 3838-2002)且黑臭.从时间变化来看,求索溪4月份的水质最差,5月份次之,4、5月份所有监测点的水质都劣于V类且黑臭;8月份水质最好,水质为Ⅳ类;从空间分布来看,8个监测点综合水质标识指数均超过6.0,水质为劣V类,其中6号监测点的水质相对最好,监测点3号的水质相对最差;对应分析法得出求索溪的整体水体污染程度受总氮因子的影响最大,其次为总磷.该研究拟为求索溪及类似校园河道的水环境治理研究提供基础依据和参考.     

Potential of plant polyphenol oxidases in the decolorization and removal of textile and non-textile dyes

In this study an effort has been made to use plant polyphenol oxidases; potato （Solanum tuberosum） and brinjal （Solanum melongena）, for the treatment of various important dyes used in textile and other industries. The ammonium sulphate fractionated enzyme preparations were used to treat a number of dyes under various experimental conditions. Majority of the treated dyes were maximally decolorized at pH 3.0. Some of the dyes were quickly decolorized whereas others were marginally decolorized. The initial first hour was sufficient for the maximum decolorization of dyes. The rate of decolorization was quite slow on long treatment of dyes. Enhancement in the dye decolorization was noticed on increasing the concentration of enzymes. The complex mixtures of dyes were treated with both preparations of polyphenol oxidases in the buffers of varying pH values. Potato polyphenol oxidase was significantly more effective in decolorizing the dyes to higher extent as compared to the enzyme obtained from brinjal polyphenol oxidase. Decolorization of dyes and their mixtures, followed by the formation of an insoluble precipitate, which could be easily removed simply by centrifugation.