Preparation methods and thermal stability of Ba-Mn-Ce oxide catalyst for NOx-assisted soot oxidation

Manganese oxide-loaded and -doped ceria as well as the corresponding barium-modified oxide catalysts were prepared for soot oxidation in the presence of NOx, and were characterized by using X-ray diffraction, Brunauer-Emmett-Teller and NO temperatureprogrammed oxidation measurements. The activity of catalyst depended strongly on the NO2 production capacity, and the importance of surface nitrates was weakened without heat transfer limitations. The formation of perovskite-type oxides after the high-temperature calcination caused the loss of NOx storage capacity for the Ba-modified catalysts, but did not seem to affect the NO oxidation activity obviously. The addition of barium did not prevent the phase separation of MnOx-CeO2 solid solutions, whereas it inhibited the sintering of oxide crystallites effectively. This, as well as the relatively high surface area, resulted in a small increase in soot oxidation temperature for the thermally aged Ba/Mn-Ce catalyst.     

新型树脂NDA-66处理DBP生产废水及影响因素

采用新型超高交联树脂NDA-66处理增塑剂DBP生产废水,对比不同吸附剂对DBP生产废水中的邻苯二甲酸的吸附效果,考察了吸附时间、p H、温度、流速和不同初始溶液浓度对NDA-66静态吸附效果的影响。结果表明,NDA-66对邻苯二甲酸的最佳吸附条件为p H 2.0,温度30℃,最佳静态吸附时间为12 h。经过8批次连续吸附-脱附后,NDA-66树脂对邻苯二甲酸的去除率在94%以上,脱附率在90%以上,回收邻苯二甲酸晶体纯度高达95%,实现了废水有用物质的资源化。     

污泥堆肥及其应用研究

随着城市化进程的不断推进,城市污水厂所处理的污水量不断增大,由此产生了数量庞大的污泥,致使城市污水厂的污泥的合理处理处置成为研究热点.目前污泥的主要处理方法有卫生填埋、污泥堆肥以及焚烧等,其中污泥堆肥为诸多学者所赞同.文章探讨了污泥堆肥的基本原理与过程,介绍了条垛式堆肥系统、强制通风静态垛系统、反应器堆肥系统以及槽式堆肥系统的发展与污泥堆肥在农业以及绿化方面的应用情况,以期为污泥堆肥的发展与应用提供一定的参考.     

Effect of water vapor on NH3-NO/NO2 SCR performance of fresh and aged MnOx-NbOx-CeO2 catalysts

A MnOx–NbOx–CeO2 catalyst for low temperature selective catalytic reduction(SCR) of NOx with NH3 was prepared by a sol–gel method, and characterized by NH3–NO/NO2 SCR catalytic activity, NO/NH3 oxidation activity, NOx/NH3 TPD, XRD, BET, H2-TPR and in-situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy(DRIFTS). The results indicate that the Mn Ox–Nb Ox–CeO2 catalyst shows excellent low temperature NH3-SCR activity in the temperature range of 150–300℃. Water vapor inhibits the low temperature activity of the catalyst in standard SCR due to the inhibition of NOx adsorption. As the NO2 content increases in the feed, water vapor does not affect the activity in NO2 SCR. Meanwhile, water vapor significantly enhances the N2 selectivity of the fresh and the aged catalysts due to its inhibition of the decomposition of NH4NO3 into N2O.     

城市消防救援网络形态特征、抗毁性与鲁棒性研究*

为探讨城市消防规划系统救援能力的空间布局科学性,采用复杂网络理论构建某城市消防救援站现状与规划网络模型。首先从模型紧密度、性能效率、连通性等方面分析复杂网络基本网络特征;其次采用节点随机/蓄意攻击、边随机/蓄意攻击、混合随机/蓄意攻击研究网络结构的抗毁性;然后根据失效发生位置,探讨网络组织内部信息系统失活导致的合作中断的鲁棒性特征;最后针对不同的规划建设方案,讨论城市消防系统建设规划的中远期时序性。研究结果可为提高消防网络的救援能力提供理论支撑。     

PCDD/Fs in soil around a hospital waste incinerator: comparison after three years of operation

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) can be formed during the cooling of flue gases in waste incinerator. These pollutants are either in the gas phase or attached to the fine particles, escaping dust collection. After stack emission, they are slowly oxidized photochemically (gas phase), or eventually are deposited (dry and wet deposition of particulate) in earth surface. In 2007 and 2010, 11 soil samples were collected in the vicinity of a hospital waste incinerator (HWI), prior and after its startup. In order to find out any variation of PCDD/Fs in soil, in brief dioxins, their concentrations were analyzed by high-resolution gas chromatography with high-resolution mass spectrometry (HRGC/HRMS). Compared to the baseline survey (2007), PCDD/Fs in soil significantly increased, by average, +81.6% in total PCDD/Fs and +132.7% in international toxic equivalency (I-TEQ) unit. By principal component analysis (PCA), both the PCDD/Fs homologue and the HxCDF isomer profile in soil were found to become more similar with fly ash. Generally, this incinerator influences the soil only in a limited area. More comprehensive supervision, stricter management and more advanced technology should be implemented in this plant to reduce pollutants emission, even though the level of PCDD/Fs in soil is quite low at present.     

民用建筑噪声防治与通风净化系统设计初探——以一种智能通风器为例

近年来,智能通风器作为一种民用建筑物通风换气、净化室内空气,同时又能降低噪声污染(尤其是交通噪声污染)的家用设备正逐步被广泛采用。尤其是最近几年,由于人们生活水平的提高,空气、噪声环境污染严重,人们对居住的建筑室内环境提出了更高的要求,智能通风器就是在该大背景下构思设计出来的。智能通风器是一种具有智能控制的通风换气、空气净化和降低室内噪声污染的家用设备。本文主要从智能通风器的设计理念、设计内容和设计效果三方面进行简要的介绍,为民用建筑噪声防治与通风净化系统提供探索性的探讨。     

1928年甘肃旱灾的时空差异及气候背景

整理了1928年甘肃救灾档案资料《甘肃省民国十七年各县灾情一览表》,通过提取该档案中的被灾地域、灾民人口、灾情状况等数据,建立以县为基本单位的灾情指数的方法,复原了我国近代历史时期一次重大旱灾——1928年甘肃旱灾的受灾地区和受灾情况。复原结果表明,甘肃省此次旱灾灾情最严重地区为该省的中东部,而该省西部和北部地区受灾相对较轻。在成灾时间上,春季该省中东部地区就形成旱灾的中心,并且该中心在夏季和秋季一直存在,形成了罕见的春、夏、秋三季连旱连灾的特点。     

硫化氢浓度测定方法的比较和建议

本文研究了过滤式防毒面具滤毒罐防护硫化氢性能试验中,采用用碘量法和紫外光度法对硫化氢浓度测定的对比。通过试验证明了,碘量法测得的硫化氢的浓度均偏低。结果表明:紫外光度法具有良好的准确度和精确度,适用于长时间测定硫化氢混合气体浓度。     

厌氧－缺氧－好氧工艺去除废水中COD、氮和磷的研究

为了减少废水中营养盐的排放量,采用实验室规模的厌氧─缺氧─好氧工艺处理豆制品废水。结果表明,TCOD、SCOD、NH⁺₄-N、NO^-₃－N、TN、TP、SP（可溶性磷）、SS、细菌总数和大肠菌群数的去除率分别为96%、94％、93％、89％、82％、88％、78％、98.0％、99.9％以上。厌氧相产气率平均0.4L/L·d,上所产气体中平均甲烷含量69.8％,CO₂3.8％,N226.4%。缺氧相产气率平均为0.2L/L·d,平均甲烷含量59.5％,CO₂12％,N₂39.2％。好氧相中亚硝酸细菌含量为1.1×10⁵/mL,硝酸细菌含量为1.4×10³/mL。