多孔镁铝复合氧化物对水溶液中Cr（VI）的吸附性能

摘要以镁盐、铝盐、纯碱和烧碱为原料制备了一种多孔镁铝复合氧化物（P—Mg3.1AlO4.6）,其比表面积、平均孔径和总孔容分别为206．3m2／g、8．961nm和0．4208cm3／g。研究了这种多孑L材料对水溶液中cr（VI）的吸附性能,在25～45qC时,静态吸附量为82．32～141．7mg／g;当初始浓度100mg／L、流速5mL／min、床层高度10cm和pH=6时,半穿透时间、半穿透吸附量和饱和吸附量分别为406rain、49．28ing／g和51．30Ing／g;拟合参数及误差分析表明,cr（Ⅵ）在P—M敬。AIO4.6上的静态吸附过程符合Freundlich等温方程式和伪二级动力学方程,Yoon·Nelson模型能很好地预测cr（Ⅵ）在P—Mg3.1A104.6上的动态穿透曲线。     

可旋转径向式微粒捕集器消声特性影响因素灰色关联分析

为降低可旋转径向式微粒捕集器中的排气噪声,采用有限元法建立可旋转径向式微粒捕集器声学特性模型,分析得到了其消声特性和传递损失曲线,并采用灰色关联分析方法研究可旋转径向式微粒捕集器结构参数对消声特性的影响程度。结果表明,可旋转径向式微粒捕集器具有降噪能力,且对高频噪声消声效果明显好于低频噪声,平均消声量为20 dB左右;直径比和扩张管锥角是影响可旋转径向式微粒捕集器消声特性的2个主要因素,适当选用小的直径比和扩张管锥角,有利于提高可旋转径向式微粒捕集器的消声性能。     

北京市人口老龄化的时空变化特征

人口老龄化现已成为当今主要的人口问题之一,并引起越来越多的关注,人口老龄化进程与老年人口空间分布特征研究是未来人口问题研究的一个重要分支.本文基于ESDA全局和局部空间自相关分析,利用北京市第四次和第五次人口普查数据以及1995和2005年1％人口抽样调查数据,对北京市县域尺度老龄人口分布总体和局部空间差异的变化趋势、特征进行了初步探索.结果表明,北京市老龄人口空间分布各区县差异较大,且呈现出明显的圈层结构特征,中心四城区老龄人口比重较高,近郊区老龄人口比重较全市平均水平低,远郊区老年人口比重又有所回升;同时,北京地区老年人口各区县的空间分布差异随着时间的推移而不断扩大,中心老城区呈现不断增强的集聚趋势,而远郊区的老年人口扩散效应明显大于集聚效应.     

Comprehensive Assessment and Promotion Policy of Producer Services’ Competitiveness in Beijing City:A Comparative Analysis among Beijing,Tianjin,Shanghai,Guangzhou and Shenzhen

The five central cities-Beijing,Tianjin,Shanghai,Guangzhou and Shenzhen-of the three most important strategic regions in China,namely Beijing-Tianjin-Hebei metropolitan region,the Yangtze River Delta and the Pearl River Delta,are taken as a comparative analysis on urban producer services’ competitiveness,especially focusing on the comparative advantages and disadvantages of producer services in Beijing.Firstly,based on an integrated indicator system including one objective hierarchy,four standard hierarchies and 35 indicator hierarchies,the study applies factor analysis model and analytic hierarchy process model reformed by entropy technology to measure the comprehensive competitiveness of producer services in the above five cities.Secondly,Beijing has comparative advantages of capital resource,industrial base,scientific research resource and market scale,since it takes the first place of the five cities in the comprehensive competitiveness of producer services,the competitiveness of industrial development,business environment and living environment,only inferior to Shanghai in the competitiveness of talent capital.Thirdly,Beijing has comparative disadvantages in the level of producer services development,urban innovation capability and living environment.Finally,five proposals are put forth to enhance the competitiveness of producer services in Beijing,namely perfecting the system of laws and statutes,supporting the development of industry association,implementing scientific development planning,introducing preferential fiscal and taxation policies and strengthening human capital reserve.     

周口店地质遗迹保护现状分析及对策建议

周口店地区地质遗迹丰富,在考古界和地质界都拥有极高的地位.通过实地考察,发现目前的保护中存在很多问题,如开山采石破坏了有价值的地质遗迹、众多水泥厂排放的烟尘污染了空气等,笔者针对存在的问题,提出了加强立法、严格执法、保护第一、积极开发、充分发挥其旅游文化价值等一系列方案措施;对比较典型突出的问题,提出了具体解决方案,希望以此唤起社会的进一步重视,以更好保护这一人类共有的财富.     

北京地区PM10与秸秆燃烧排放单颗粒对比分析

采用场发射带能谱扫描电镜(FESEM/EDS)法分析北京怀柔地区PM10与秸秆燃烧排放颗粒的形貌特征和成分差异.结果显示:秸秆燃烧后排放颗粒物多为大粒径颗粒,成分上都含S、Cl和K元素.含有生物质燃烧标志元素K的PM10颗粒物多为含Si、Al和Na元素的燃煤飞灰和矿物颗粒,与秸秆燃烧排放颗粒组成化学元素差异明显.据此推...     

Improved performance of a biomaterial-based cation exchanger for the adsorption of uranium(VI) from water and nuclear industry wastewater

The amine-modified polyhydroxyethylmethacrylate (poly(HEMA))-grafted biomaterial (tamarind fruit shell, TFS) carrying carboxyl functional groups at the chain end (PGTFS-COOH) was prepared and used as an adsorbent for the removal of uranium(VI) from water and nuclear industry wastewater. FTIR spectral analysis revealed that U(VI) ions and PGTFS-COOH formed a chelate complex. The adsorption process was relatively fast, requiring only 120 min to attain equilibrium. The adsorption kinetic data were best described by the pseudo-second-order equation. The equilibrium adsorption data were correlated with the Sips isotherm model. The maximum U(VI) ions uptake with PGTFS-COOH was estimated to be 100.79 mg/g. The complete removal of 10 mg/L U(VI) from simulated nuclear industry wastewater was achieved by 3.5 g/L PGTFS-COOH. The reusability of the adsorbent was demonstrated over 4 cycles using NaCl (1.0 M) + HCl (0.5 M) solution mixture to de-extract the U(VI). The results show that the PGTFS-COOH tested is very promising for the recovery of U(VI) from water and wastewater.     

废塑料生产汽柴油技术分析与应用中的误区

从废塑料生产汽柴油技术的工艺流程入手，对该项技术中存在的一些问题进行了分析，内容涉及原料来源及范围，裂化反应条件，传热与除焦，油品质量及收率，新形成的污染和经济效益评估等；指出了此项技术在应用中存在的误区。     

The Characterisation of Settled Dust by Scanning Electron Microscopy and Energy Dispersive X-ray Analysis

Settled dust has been collected inside the main foyers ofthree University buildings in Wolverhampton City Centre,U.K. Two of the three buildings are located in a streetcanyon used almost exclusively by heavy duty dieselvehicles. The dust was collected on adhesive carbonspectro-tabs to be in a form suitable for analysis byscanning electron microscope and energy dispersive X-rayanalysis. Using these analytical techniques, individualparticle analysis was undertaken for morphology andchemistry. Seasonal variations and variations due tolocation were observed in both the morphologicalmeasurements and chemical analysis. Many of the differencesappear attributable to the influence of road traffic, inparticular, the heavy duty diesel vehicles, travellingalong the street canyon.