硝酸及氯离子对高温硝酸铵水溶液热危险性的影响研究

国内外学者对硝酸铵的危险性进行了大量的研究,而对其水溶液的危险性至今开展不多。笔者采用差示扫描量热仪(DSC)及全自动反应量热仪(RC1e)对高温状态下的硝酸铵水溶液的热分解危险性、杂质离子对其稳定性的影响进行了研究。纯硝酸铵和90%硝酸铵水溶液的DSC实验表明,90%硝酸铵溶液和分析纯硝酸铵具有相似的热爆炸危险;90%硝酸铵水溶液在140~180℃之间的RC1e试验表明:硝酸或氯离子单独存在时,对硝酸铵分解都有不同程度的抑制作用,而同时存在时则大大降低体系的热稳定性。该结果对保障硝酸铵在生产、使用过程中的安全具有重要的参考价值。     

Effects of shear force on formation and properties of anoxic granular sludge in SBR

This paper reports the effects of shear force on anoxic granular sludge in sequencing batch reactors （SBR）. The study was carried out in two SBRs （SBR1 and SBR2） in which sodium acetate （200mg COD·L^-1） was used as the sole substrate and sodium nitrate （40 mgNO3-N·L^-1） was employed as the electron acceptor. The preliminary objective of this study was to cultivate anoxic granules in the SBR in order to investigate the effects of shear force on the formation of anoxic granular sludge and to compare the properties of anoxic sludge in the SBR. This study reports new results for the values of average velocity gradient, a measure of the applied shear force, which was varied in the two SBRs （3.79 s^-1 and 9.76 s^-1 for SBR1 and SBR2 respectively）. The important findings of this research highlight the dual effects of shear force on anoxic granules. A low shear force can produce large anoxic granules with high activity and poor settling ability, whereas higher shear forces produce smaller granules with better settling ability and lower activity. The results of this study show that the anoxic granulation is closely related to the strength of the shear force. For high shear force, this research demonstrated that： 1） granules with smaller diameters, high density and good settling ability were formed in the reactor, and 2） granular sludge formed faster than it did in the low shear force reactor （41days versus 76 days）. Once a steady-state has been achieved, the nitrate and COD removal rates were found to be 98% and 80%, respectively. For low shear force, such as was applied in SBR1, this research demonstrated that： 1） the activity of anoxic granular sludge in low shear force was higher than that in high shear force, 2） higher amount of soluble microbial products （SMPs） were produced, and 3） large pores were observed inside the larger granules,which are beneficial for nitrogen gas diffusion. Electron microscopic examination of the anoxic granules in both reactors showed that the morphology of the granules was ellipsoidal with a clear outline. Coccus and rod-shaped bacteria were wrapped by filamentous bacteria on the surface of granule.     

环球扫描

皮特·扎赫勒：拯救阿富汗野生动物 阿富汗80％的野生动物是直接依靠自然资源生存的。如果没有可持续性的自然资源,它们就无法存活。因此自然保护是阿富汗重建的核心支柱。     

Morphology of single inhalable particle inside public transit biodiesel fueled bus

In an urban-transit bus,fueled by biodiesel in Toledo,Ohio,single inhalable particle samples in October 2008 were collected and detected by scanning electron microscopy and energy dispersive X-ray spectrometry(SEM/EDS).Particle size analysis found bimodal distribution at 0.2 and 0.5 μm.The particle morphology was characterized by 14 different shape clusters:square,pentagon,hexagon,heptagon,octagon,nonagon,decagon,agglomerate,sphere,triangle,oblong,strip,line or stick,and unknown,by quantitative order.The square particles were common in the samples.Round and triangle particles are more,and pentagon,hexagon,heptagon,octagon,nonagon,decagon,strip,line or sticks are less.Agglomerate particles were found in abundance.The surface of most particles was coarse with a fractal edge that can provide a suitable chemical reaction bed in the polluted atmospheric environment.The three sorts of surface patterns of squares were smooth,semi-smooth,and coarse.The three sorts of square surface patterns represented the morphological characteristics of single inhalable particles in the air inside the bus in Toledo.The size and shape distribution results were compared to those obtained for a bus using ultra low sulfur diesel.     

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环保总局局长呼吁给予江河湖海人文关怀,今年中秋香港的垃圾山终于减少了,人类逼近环境恶化“引爆点”,绿色生态消费是否真的有助于环保,中国2006环境公报：2567亿元治污历史最高,     

Rapid removal of bisphenol A on highly ordered mesoporous carbon

Bisphenol A (BPA) is of global concern due to its disruption of endocrine systems and ubiquity in the aquatic environment. It is important, therefore, that e orts are made to remove it from the aqueous phase. A novel adsorbent, mesoporous carbon CMK-3, prepared from hexagonal SBA-15 mesoporous silica was studied for BPA removal from aqueous phase, and compared with conventional powdered activated carbon (PAC). Characterization of CMK-3 by transmission electron microscopy (TEM), X-ray di raction, and nitrogen adsorption indicated that prepared CMK-3 had an ordered mesoporous structure with a high specific surface area of 920 m2/g and a pore-size of about 4.9 nm. The adsorption of BPA on CMK-3 followed a pseudo second-order kinetic model. The kinetic constant was 0.00049 g/(mg min), much higher than the adsorption of BPA on PAC. The adsorption isotherm fitted slightly better with the Freundlich model than the Langmuir model, and adsorption capacity decreased as temperature increased from 10 to 40°C. No significant influence of pH on adsorption was observed at pH 3 to 9; however, adsorption capacity decreased dramatically from pH 9 to 13.     

热脱附-稳定化工序对土壤镉稳定化效率的影响

热脱附-稳定化是修复重金属-有机物复合污染土壤的主要工艺。由于热脱附对土壤重金属有“活化”和“固化”的双重作用,因此,热脱附-稳定化工序会影响重金属的稳定化效率。以含镉(Cd)的复合污染土壤为研究对象,从浸出率、形态分布、微观形貌3个层面,分析热脱附-稳定化(T-S)和稳定化-热脱附(S-T)工艺对Cd稳定化效率的影响。结果表明：S-T工艺浸出率(42.26%)低于T-S工艺(52.11%);由于Cd“活化”“固化”与稳定化作用,S-T工艺处置的土壤Cd弱酸提取态和残渣态比例分别是T-S工艺的0.75,1.4倍,形态更趋于稳定分布;电镜扫描(SEM)显示,S-T工艺比T-S工艺处置后土壤颗粒结晶更为显著,说明土壤Cd的稳定化效果更好。     

微囊藻毒素的极谱测定法

建立了微囊藻毒素的一种新的测定方法.在Ni2 -硼砂为支持电解质的体系中,微囊藻毒素-RR在-1.55V产生一个极谱波.在此实验条件下,微囊藻毒素在1.50～8.00mg/L浓度范围内,极谱波高与微囊藻毒素浓度有良好的线性关系,线性相关系数为0.998,检测限为0.07mg/L.同时对测定条件进行了研究,并探讨了极谱电流的性质,认为该极谱波是一个催化氢波;常见无机物和有机物不干扰本法测定,具有良好的选择性.该方法用于实际水样测定,获得了满意结果.     

Graphene TiO2 nanocomposites with high photocatalytic activity for the degradation of sodium pentachlorophenol

A series of graphene–TiO2photocatalysts was synthesized by doping TiO2 with graphene oxide via hydrothermal treatment. The photocatalytic capability of the catalysts under ultraviolet irradiation was evaluated in terms of sodium pentachlorophenol（PCP-Na） decomposition and mineralization. The structural and physicochemical properties of these nanocomposites were characterized by X-ray diffraction, N2adsorption–desorption, transmission electron microscopy, scanning electron microscopy, Ultraviolet–visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, electron paramagnetic resonance spectra, and Fourier-transform infrared spectroscopy. The graphene–TiO2nanocomposites exhibited higher photocatalytic efficiency than commercial P25 for the degradation of PCP-Na, and 63.4% to 82.9% of the total organic carbon was fully mineralized. The improved photocatalytic activity may be attributed to the accelerated interfacial electron-transfer process and the significantly prolonged lifetime of electron-hole pairs imparted by graphene sheets in the nanocomposites. However,excessive graphene and the inhomogeneous aggregation of TiO2 nanoparticles may decrease photodegradation efficiency.     

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<正>《美国国家地理》2015年5月4日特斯拉助垃圾车电动化跑车、运输卡车,甚至连公共汽车都已经有自己的电动系列了,然而有一种特殊的汽车却一直未能摆脱对化石燃料的依赖—老式垃圾车。今年夏天,加州北部的17辆垃圾车将首次采用电力作为驱动力,该批垃圾车同时还会内置一个备用的柴油发电机。单从外观看来,