Pd/C气体扩散电极用于电生成H2O2降解苯酚的研究

采用自制的Pd/C气体扩散阴极和Ti/IrO2/RuO2阳极,在无隔膜电解槽中对苯酚模拟废水降解效果及机制进行了研究,采用电子自旋共振法(ESR)对电解体系中产生的羟自由基(·OH)进行了检测.结果表明,在Pd/C气体扩散体系中掺杂Pd催化剂可以促进H2 O2的生成(H2 O2的稳定浓度是7.5 mg/L),有利于·OH的产生.经电化学氧化处理120 min后,苯酚和COD的去除率分别达到97.2%和50%,表明在电催化氧化过程中苯酚被氧化生成了大量低分子量中间产物.废水的BOD5/COD值达到0.73是处理前的9.1倍,苯酚废水的可生化降解性通过电化学氧化处理后显著提高.在该电化学体系中苯酚的降解是在阳极直接、间接氧化及阴极产生的H2 O2、·OH的氧化共同作用下完成的.通过对紫外扫描光谱图的分析推断出苯酚在电解过程中有醌类物质生成;由GC-MS检测到了邻苯二酚、对苯二酚、苯醌等芳香族化合物和己二酸、顺丁烯二酸、反丁烯二酸、丁二酸、丙二酸、乙二酸等短链羧酸,据此提出了苯酚降解的可能历程.     

水钠锰矿的Mn（Ⅲ）分布及Na4P2O7溶液处理对其铅吸附性能的影响

以深入理解水钠锰矿结构中低价锰离子的含量及分布对其铅吸附性能的影响为目的,通过不同pH（pH为2、4、5）的焦磷酸钠溶液络合浸提酸性水钠锰矿结构中的Mn（Ⅱ）和Mn（Ⅲ）,研究了浸提锰离子的形态、含量、矿物的锰平均氧化度和Pb2＋的吸附量及其伴随Mn2＋、H＋释放量的变化.结果表明,锰平均氧化度为3.670的酸性水钠锰...     

江苏句容水库农业流域水塘和河流N_2O排放速率的研究

在句容水库农业流域的水塘和河流中,用密闭箱法于2007年8、11月和2008年2、5月采集水体表面排放的N2O气样,研究水塘和河流N2O排放速率的季节变化及其影响因素.结果显示,水塘N2O的排放速率范围在-0.42～16.76μg.m-.2h-1之间,河流N2O排放速率在0.29～8.41μg.m-.2h-1之间.由于...     

Mg/Al双金属氧化物对As(V)吸附性能的研究

研究了以镁铝水滑石为原料制备的Mg/Al双金属氧化物对溶液中As(V)的吸附作用及其影响因素.结果表明：Mg/Al双金属氧化物对As(V)具有较强的吸附能力,吸附规律符合Langmuir等温吸附方程,根据计算所得的理论最大吸附量为51.02 mg·g-1,与实验得出的最大吸附量50.53 mg·g-1基本一致;运用3种...     

应用分子生物学与同位素示踪技术研究厌氧氨氧化菌活性及功效

厌氧氨氧化是一个新发现的氮循环途径,与反硝化作用都产生氮气,但准确衡量厌氧氨氧化活性及功效的相关方法还是个难题.本研究联合应用分子生物学与同位索示踪技术,以北京某污水处理厂的活性污泥为实验样品,研究其中厌氧氨氧化菌的存在、活性和功效.厌氧氨氧化菌的分子生物学分析是通过16S rRNA进行,选择两步引物分别为pla46-...     

猪粪秸秆高温堆肥过程中碳氮转化特征与堆肥周期探讨

将猪粪与秸秆以7：1（质量比,以鲜重计）的比例,在自制的强制通风静态堆肥反应箱中进行高温堆肥试验,研究了堆肥过程中碳氮转化特征及其腐熟时间.同时,在堆制的23d中,根据堆温变化采样6次,分析了堆肥样品中各种氮素和碳素含量及其它性质的变化情况.结果表明：堆肥结束时,硝态氮含量增加了103.0%,铵态氮、有机氮、总氮含量分...     

粗粒子气溶胶远距离输送造成华南严重空气污染的分析

2009年4月末,发生了一次罕见的粗粒子气溶胶远距离输送造成华南地区出现严重的空气污染事件,其特征主要是气溶胶质量浓度超标,而能见度没有明显恶化,对这次空气污染事件进行分析的结果表明.在过程中,粗细粒子质量比(PM2.5/PM10)有明显的3次下降,最低达到0.3,即PM2.5仅占PM10的30%,这与珠江三角洲地区通常以细粒子为主的污染特征有很大不同,反映了外来粗粒子的侵入特征.长江流域浮尘天气的沙尘粒子变性后,长距离输送污染物叠加本地污染物,造成这次严重空气污染事件.     

A numerical study of summer ozone concentration over the Kanto area of Japan using the MM5/CMAQ model

We assessed the ability of the MM5/CMAQ model to predict ozone (O3) air quality over the Kanto area and to investigate the factors that a ect simulation of O3. We find that the coupled MM5/CMAQ model is a useful tool for the analysis of urban environmental problems. The simulation results were compared with observational data and were found to accurately replicate most of the important observed characteristics. The initial and boundary conditions were found to have a significant e ect on simulated O3 concentrations. The results show that on hot and dry days with high O3 concentration, the CMAQ model provides a poor simulation of O3 maxima when using initial and boundary conditions derived from the CMAQ default data. The simulation of peak O3 concentrations is improved with the JCAP initial and boundary conditions. On mild days, the default CMAQ initial and boundary conditions provide a more realistic simulation. Meteorological conditions also have a strong impact on the simulated distribution and accumulation of O3 concentrations in this area. Low O3 concentrations are simulated during mild weather conditions, and high concentrations are predicted during hot and dry weather. By investigating the e ects of di erent meteorological conditions on each model process, we find that advection and di usion di er the most between the two meteorological regimes. Thus, di erences in the winds that govern the transport of O3 and its precursors are likely the most important meteorological drivers of ozone concentration over the central Kanto area.     

Effect of manufacturing methods of AgCl/Al2O3 catalyst on selective catalytic reduction of NOx

The AgCl/Al2O3 catalyst has potential for use in the selective catalytic reduction (SCR) of NOx. A compound hydrocarbon, following oxygenation is used as a type of reducing agent. In this experiment, the AgCl/Al2O3 catalyst was produced by four different methods, and the differences among their reduction catalysis of NOx were compared. Ethanol was used as a type of reducing agent. X-ray diffraction analysis was performed to study the crystalline structure and scanning electron microscope and transmission electron microscope (TEM) were applied to determine the microindentation. The results indicated that, in the range of 350–400°C, there was no significant difference on the NOx reduction rate; however, there was dispersion at high and low temperature ranges. The size of the AgCl particles was about 20–100 nm.     

Identification of odorous compounds in reclaimed water using FPA combined with sensory GC-MS

Odorous compounds in the influent of a reclaimed water treatment plant (RWTP), consisting of coagulation, sedimentation, continuous micro-filtration (CMF), and chlorination in succession, in a north China city, were identified by combining flavor profile analysis (FPA) with sensory gas chromatograph-mass spectrometry (GC-MS). The sewery/swampy/septic odor with an odor intensity of 6.4 was found to be the major odor group in the RWTP influent, and the existence of well-known odorant including dimethyl disulfide, dimethyl trisulfide, indole and skatole were confirmed using GC-MS. The result of a spiking test showed that the intensity (3.6) of the sewery/swampy/septic odor caused by these four chemicals contributed to over 50% of the odor intensity of the influent. The FPA intensity for sewery/swampy/septic odor in the RWTP effluent was 3.8, showing that the treatment process was not efficient for the removal of odorants, particularly indole and skatole.