SO2对CoH-ZSM-5催化CH4还原NO催化性能的影响

研究了富氧条件下SO₂对CoH-ZSM-5上CH₄选择还原NO(CH₄-SCR)的影响,应用SO₂-TPSR,NO+(O₂)-TPD等方法研究了产生中毒的原因并定量研究了被毒化的活性位.反应在773 K进行时,加入体积分数78×10^-6SO₂,NO的转化率由72%逐渐降低并稳定在58%,提高反应温度至823 K,NO稳定转化率上升至62%.同时加入2.5     

壳-核结构Fe3O4/MnO2磁性吸附剂的制备、表征及铅吸附去除研究

采用共沉淀法制备了具有壳-核结构的磁性吸附剂Fe₃O₄/MnO₂,对其性质进行了系统表征,并对其铅吸附行为进行了初步研究.透射电镜(TEM)结果表明,Fe₃O₄/MnO₂为大小不规则的纳米级细小颗粒.X-射线衍射仪(XRD)表征结果表明,Fe₃O₄/MnO₂具有尖晶石的结构.振动样品磁强计(VSM)测得比饱和磁化强度为54.7 A·m²·kg^-1, 吸附剂磁性较强,易于磁分离;BET比表面积为76.5 m²·g^-1.吸附试验结果表明,Fe₃O₄/MnO₂对铅具有良好的去除效果(特别是在低平衡浓度情况下),最大吸附量为142.0 mg·g^-1(pH=5.0);Langmuir等温线能更好地拟合Fe₃O₄/MnO₂对溶液中铅的吸附(R²=0.852);吸附速率较快,在初始30 min内可达到平衡吸附量的80%,准二级动力学模型(R²=0.959)能较好地描述吸附过程;溶液pH对Fe₃O₄/MnO₂吸附铅的影响较为明显,随pH升高,吸附量增大,但离子强度变化对吸附影响不大.     

钒和钨负载量对V2O5-WO3/TiO2表面形态及催化性能的影响

采用浸渍法制备了一系列不同钒和钨负载量的V₂O₅-WO₃/TiO₂催化剂样品,对样品NH₃选择性催化还原NO性能进行了评价,并用BET、XRD、XPS等手段对催化剂样品的表面形态进行了表征.研究发现,钒的负载量对催化剂的比表面积和催化活性有显著影响,当钒负载量从1％升高到8％时,催化剂比表面积下降了16 m²/g,最高活性温度降低了约100℃.钨起到稳定剂和助剂的双重作用,当钒负载量为1％时,钨负载量从0升高到6％,催化剂比表面积仅下降了3 m²/g,而活性温度窗口向高温和低温各拓宽了约50℃.研究表明钒和钨负载量都能影响催化剂表面的VO_x物种,但对催化剂的表面晶型没有明显影响.     

Ni2+改性的Cu-ZSM-5催化分解NO的性能

研究 Ni²⁺改性的 Cu^- ZSM-5催化剂在无氧和有氧气氛下的 NO分解反应性能 ,考察 Ni²⁺的加入量及加入方式对 Cu-ZSM-5催化剂 NO分解活性的影响 .结果表明 ,先交换适量 Ni²⁺再交换 Cu²⁺的 Ni-Cu-ZSM-5催化剂较单组分 Cu-ZSM-5催化剂有较高的高温 (500℃～600℃) NO分解活性 .在含 5.5% O₂ 的反应气氛中 ,Ni-Cu-ZSM-5在 500℃下的 NO分解率较之 Cu-ZSM-5高出约 20% ,Ni²⁺的引入显著提高了催化剂的抗氧活性 .就 Ni²⁺对 Cu-ZSM-5催化剂的可能改性机制进行了讨论 .     

上海市PM2.5的物理化学特征及其生物活性研究

采集了上海市区和郊区春季和夏季的大气PM_2.5样品,分析了市区和郊区春夏2季PM_2.5质量浓度变化的规律,使用PIXE(Proton Induced X-ray Emission)分析技术获得S、K、Ca、Ti、Cr、Mn、Fe、Ni、Cu、Zn、As、Se、Br、Sr、Pb等15种元素的质量浓度.结果表明,上海PM_2.5中化学元素的质量浓度在春季　(5?038.6 ng·m^-3) 比在夏季 (3?810.6 ng·m^-3) 高,春季郊区(2?528.9 ng·m^-3) 和市区(2?509.7 ng·m^-3) PM_2.5中化学元素的质量浓度相当,夏季市区样品 (1?674.2 ng·m^-3) 中化学元素质量浓度的总量比郊区(2?136.3 ng·m^-3) 的低,但来自人为污染的化学元素 (Cr、Mn、Ti、Ni、Cu、Zn、As、Br、Sr、Pb) 在市区PM_2.5中的含量较高;场发射扫描电镜 (FESEM) 分析显示,上海PM_2.5主要由烟尘集合体、燃煤飞灰、矿物颗粒、生物质颗粒和不明物质组成,质粒DNA评价揭示上海市区PM_2.5比郊区的具有更强的生物活性,主要原因可能在于市区样品中含有较高的重金属元素和较多的烟尘集合体．     

UV/H2O2液相氧化净化烟气中NO的实验研究

采用UV/H₂O₂液相氧化技术净化气体中的NO,通过正交实验和单因素实验,研究了H₂O₂浓度、温度、初始pH值、NO浓度、光照条件、O₂含量和气体流量等因素对NO去除率的影响.结果表明,UV/H₂O₂液相氧化体系对NO有良好的净化效果,可以获得80%左右的NO去除率, 温度、H₂O₂浓度和初始pH值对NO去除率具有不同程度的影响,温度和H₂O₂浓度对NO去除率影响较大.单因素实验结果表明, 当H₂O₂浓度为0.2 mol/L、初始pH值为6～7时NO去除率较高;溶液中H₂O₂浓度过高或过低、溶液过酸或过碱均会抑制·OH的产生而不利于NO的去除;净化NO的最佳反应温度为40 ℃,低于一般湿法脱硝温度(50 ℃);NO的去除率随紫外光辐射强度和O₂含量的增加而升高;同时,NO的去除也受气液传质面积和气液传质系数的控制.     

大气臭氧浓度升高对丛枝菌根(AM)及其功能的影响

通过模拟大气O₃浓度(0.02μL·L^-1、0.1μL·L^-1和0.2μL·L^-1)升高,观察其对丛枝菌根(AM)及功能的影响.结果表明,大气O₃浓度升高对菌根侵染率影响较小,但对孢子和外生菌丝影响显著,高浓度O₃时的孢子数比自然O₃浓度时增加1倍,低、高浓度O₃分别使AM外生菌丝量比自然浓度时下降48.7%和85.6%.随着O相似文献   

Fe2O3/PC功能化复合多孔炭材料的制备及除磷机理

采用热活化法辅以加压超声浸渍技术将硅酸盐水泥颗粒（PC）和Fe₂O₃负载于稻壳生物炭（RHC）的表面,得到了具有优异除磷效能和高选择性吸附性能的Fe₂O₃/PC功能化复合多孔炭材料（Fe-PC/RHC）.基于磷吸附容量和磷去除率,对PC和Fe³⁺负载进行量的优化;选取优化炭进行比表面积、孔径分布、物相结构、表面结构、微观形貌和零电位点表征测定.结果表明：复合炭材料表面均匀分散着硅酸钙盐、硅酸铁盐和Fe₂O₃等矿物活性颗粒,对其比表面积、孔结构和吸附性能具有增强作用;当RHC：PC=0.8：1（质量比）,Fe³⁺：RHC=2：1（2 mmol·g^-1）时制备的炭材料Fe₂-PC/RHC,投加0.2 g,处理100 mg·L^-1的磷酸盐溶液,在pH=6~8的条件下表现出了优异的吸附性能;铁盐的掺杂能有效调控介质pH值从11.09降低至7.71,zeta电位从2.82提高到7.57;准二级动力学模型和Langmiur模型更适用于描述Fe₂-PC/RHC吸附磷酸盐的过程,吸附4 h后逐渐趋于平衡,饱和吸附量为69.92 mg·g^-1;在几种常见阴离子和阳离子共存的情况下,Fe₂-PC/RHC对磷酸盐仍然表现出了优异的选择性吸附;结合吸附前后材料的表征结果,化学吸附是主要的除磷机理,此外还可能存在配体交换和静电吸引.     

温和条件下磁性Pd-MgFe2O4/MgAl(O)催化4-氯苯酚高效加氢脱氯

以镁铁尖晶石MgFe₂O₄为磁核,在磁核表层包覆MgAl水滑石后经高温焙烧形成MgAl （O）复合氧化物包覆的磁性载体MgFe₂O₄/MgAl （O）,进而负载纳米金属Pd制成磁性催化剂Pd-MgFe₂O₄/MgAl （O）.通过X射线衍射（XRD）、X射线光电子能谱分析（XPS）、傅里叶红外光谱（FT-IR）、透射电镜（TEM）、扫描电子显微镜（SEM）、选区电子衍射（SAED）、比表面积（S_BET）和振动样品磁强计（VSM）等手段对催化材料进行表征.结果表明,MgFe₂O₄-LDH转化为磁性MgFe₂O₄/MgAl （O）载体有利于催化材料比表面积的增加、结构稳定性的提升及相应催化活性位点的增加,进而有利于提升4-氯苯酚高效加氢脱氯效率.研究进一步考察了催化剂负载量、催化剂用量、底物浓度、反应温度、反应溶剂等条件对4-氯苯酚降解效率的影响.结果发现,在优化反应条件下催化反应的转换频率TOF （0.04 s^-1）可媲美常温、常压、无碱性添加剂等温和条件下4-氯苯酚高效加氢脱氯反应的最佳文献报道水平.磁性催化剂Pd-MgFe₂O₄/MgAl （O）循环使用4次后仍保持很好的催化活性.     

氨氧化菌混培物在O2/微量NO2下的氨氧化动力学

运用序批式试验,在无分子氧条件下,确定了好氧氨氧化菌的NO₂型氨氧化动力学方程,得到了最大氨氧化速率［q_NO2,max=0.144　mg·(mg·h)^-1］、二氧化氮半饱和常数(k_NO2=0.821 μmol·L^-1）和二氧化氮抑制性常数（k_i=1.721 μmol·L^-1）.在微量NO₂气体中添加2% O₂氧气后,氨氧化速率明显提高,最大氨氧化速率发生在体积分数2% O₂和50×10^-6 NO₂的条件下,达到0.198 　mg·(mg·h)^-1.在21%　O₂和微量NO₂条件下,氨氧化速率继续大幅度提高;在21%　O₂和100×10^-6　NO₂时氨氧化速率达到0.477 　mg·(mg·h)^-1,比无NO₂空气曝气条件下氨氧化速率高3倍.提出了NO₂表观强化氨氧化函数的概念,建立了在O₂和微量NO₂混合气体下的氨氧化动力学方程,利用2%　O₂和微量NO₂条件下的实验结果验证了动力学方程,讨论了NO₂强化氨氧化的机理.     

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.     

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.     

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.     

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.     

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.     

Effects of chitosan on growth of an aquatic plant (Hydrilla verticillata) in polluted waters with different chemical oxygen demands

Effects of chitosan on a submersed plant, Hydrilla verticillata, were investigated. Results indicated that H. venicillata could prevent ultrastructure phytotoxicities and oxidativereaction from polluted water with high chemical oxygen demand (COD). Superoxide dismutase (SOD) activity and malondialdehyde (MDA) contents in H. verticillata treated with 0.1% chitosan in wastewater increased with high COD (980 mg/L) and decreased with low COD (63 mg/L), respectively. Ultrastructural analysis showed that the stroma and grana of chloroplast basically remained normal. However, plant cells from the control experiment (untreated with chitosan) were vacuolated and the cell interval increased. The relict of protoplast moved to the center, with cells tending to disjoint. Our findings indicate that wastewater with high COD concentration can cause a substantial damage to submersed plant, nevertheless, chitosan probably could alleviate the membrane lipid peroxidization and ultrastructure phytotoxicities, and protect plant cells from stress of high COD concentration polluted water.     

Removal of cadmium using MnO2 loaded D301 resin

MnO2 loaded weak basic anion exchange resin D301 （Anion exchange resin, macroreticular weak basic styrene） as adsorbent has been prepared and applied to the removal of cadmium. The adsorption characteristics have been investigated with respect to effect of pH, equilibrium isotherms, removal kinetic data, and interference of the coexisting ions. The results indicated that the Cd^2＋ could be efficiently removed using MnO2 loaded D301 resin in the pH range of 3-8 from aqueous solutions with the co-existence of high concentration of alkali and alkaline-earth metals ions. The saturate adsorption capacity of the Cd^2＋ was 77.88 mg/g. The adsorption process followed the pseudo first-order kinetics. The equilibrium data obtained in this study accorded excellently with the Langmuir adsorption isotherm.     

Evaluation of phytoextracting cadmium and lead by sunflower, ricinus, alfalfa and mustard in hydroponic culture

Soil contaminated with heavy metals cadmium(Cd)and lead(Pb)is hard to be remediated.Phytoremediation may be a feasible method to remove toxic metals from soil,but there are few suitable plants which can hyperaccumulate metals.In this study,Cd and Pb accumulation by four plants including sunflower(Helianthus annuus L.),mustard(Brassica juncea L.),alfalfa(Medicago sativa L.), ricinus(Ricinus communis L.)in hydroponic cultures was compared.Results showed that these plants could phytocxtract heavy metals, the ability of accumulation differed with species,concentrations and categories of heavy metals.Values of BCF(bioconcentration factor)and TF(translocation factor)indicated that four species had dissimilar abilities of phytoextraction and transportation of heavy metals.Changes on the biomass of plants,pH and Eh at different treatments revealed that these four plants had distinct responses to Cd and Pb in cultures.Measurements should be taken to improve the phytoremediation of sites contaminated with heavy metals,such as pH and Eh regulations,and so forth.     

Effect of coagulation pretreatment on the fouling of ultrafiltration membrane

The purpose of this study is to understand the effect and mechanism of preventing membrane fouling, by coagulation pretreatment, in terms of fractional component and molecular weight of natural organic matter （NOM）. A relatively higher molecular weight （MW） of hydrophobic compounds was responsible for a rapid decline in the ultrafiltration flux. Coagulation could effectively remove the hydrophobic organics, resulting in the increase of flux. It was found that a lower MW of neutral hydrophilic compounds, which could remove inadequately by coagulation, was responsible for the slow declining flux. The fluxes in the filtration of coagulated water and supernatant water were compared and the results showed that a lower MW of neutral hydrophilic compounds remained in the supernatant water after coagulation could be rejected by a membrane, resulting in fouling. It was also found that the coagulated flocs could absorb neutral hydrophilic compounds effectively. Therefore, with the coagulated flocs formed on the membrane surface, the flux decline could be improved.     

Penetration analysis of elements and bioleaching treatment of spent refractory for recycling

Acidithiobacillus ferrooxidans ATCC23270 and Acidithiobacillus thiooxidans TM-32 were used for bioleaching of spent refractories of aluminium and copper melting furnaces for their recycling.Firstly,penetration of elements into aluminium melting furnace refractory was investigated and it was found that up to 7 cm from surface was contaminated.Comparison on leaching efficiency by the strains ATCC23270 and TM-32 found that the strain ATCC23270 could treat larger amount of the refractories than the strain TM-32 could do.In the experiment of bioleaching of spent refractory aluminium melting furnace by the strain ATCC23270,high leaching efficiency were obtained on Al,Si,and Ca,and extremely low leaching performance was,however,shown on the rest of elements i.e.,Na,Mn,and Zn.Under the strain TM-32 use,relatively high leaching performance was recognized on Al,Si,Ca,Na,Mn,and Zn.In the experiment of bioleaching for spent refractory copper melting furnace,almost the same leaching trends were shown on Cu,Zn,Al,and Si under the strains ACTT23270 and TM-32 uses.