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891.
892.
Preparation and Properties of Thermoplastic Starch/Montmorillonite Nanocomposite Using N-(2-Hydroxyethyl)formamide as a New Additive 总被引:1,自引:0,他引:1
Hongguang Dai Peter R. Chang Fengying Geng Jiugao Yu Xiaofei Ma 《Journal of Polymers and the Environment》2009,17(4):225-232
N-(2-Hydroxyethyl)formamide (HF) was synthesized efficiently and used as a new additive to prepare thermoplastic starch/montmorillonite
nanocomposite (TPS/MMT). Here, HF acted as both plasticizer for TPS and swelling agent for MMT. The hydrogen bond interaction
among HF, starch and MMT was proven by Fourier-transform infrared (FT-IR) spectroscopy. By scanning electron microscope (SEM),
starch granules were completely disrupted. Atomic force microscopy demonstrated that partially exfoliated TPS/MMT nanocomposite
was formed. The crystallinity of corn starch, MMT, HF-plasticized TPS (HTPS) and TPS/MMT nanocomposite was characterized by
X-ray diffraction (XRD). Thermal stability of HTPS and TPS/MMT was determined by thermogravimetric analysis (TGA). The water
resistance of TPS/MMT nanocomposite increased compared with that of pure HTPS. Tensile strengths of TPS/MMT nanocomposites
were higher than those of HTPS, but just the reverse for elongations at break. 相似文献
893.
Phosphorus (P) pollution in the sediments of seven artificial landscape lakes was studied via fractionation and phosphorus-31 nuclear magnetic resonance ((31)P NMR) spectroscopy. The lake sediments accumulated significant amounts of P from supplementation with reclaimed water and from runoff from the golf course lawns. The differences in total sediment P among lakes were correlated to the varied pollution extent from the lawns. One striking feature of the artificial lake sediments was the insufficiency of NaOH-extracted Al, which plays an important role in avoiding internal P release during anoxia. Another characteristic was the dominance of orthophosphate in the NaOH-EDTA extractants of the sediments, due to the heavy external P pollution. Phytate, considered prevalent in many soils and lake sediments, as well as polyphosphates and phosphonates which have appeared in some natural lake sediments, was not detected. The rank order of present biogenic P species was monoester-P>DNA-P>pyrophosphate>lipid-P. 相似文献
894.
Distribution of polybrominated diphenyl ethers in breast milk from North China: Implication of exposure pathways 总被引:1,自引:0,他引:1
The breast milk concentrations of polybrominated diphenyl ethers (PBDEs; sum of eight congeners: BDE-28, 47, 99, 100, 153, 154, 183 and 209) were determined (by high resolution gas chromatographic high resolution mass spectrometry) in samples from primiparous women collected in 2006 in Tianjin, China. Dietary and lifestyle habits of the participants were obtained by questionnaires. The median total PBDE concentration (including BDE-28, 47, 99, 100, 153, 154, 183) was 2500 pg g−1 lipid weight, ranging from 1700 to 4500 pg g−1 lipid weight. These levels were in the same range as those from Europe and Japan but much lower than those from North America. The congener profile in China was also different from other countries. The contribution of BDE-28 was around 15%, much higher than any other country, implying that a different Penta-BDE formulation might be used in the Chinese market. The lower ratio of the sum of BDE-47, 99, and 100 to the sum of BDE-153 and 154 suggested that Octa-products were in more demand in China. A significant correlation was found between a woman’s PBDE concentration and the time she used electronic appliances (h/d). This implies that electronics are a potential source of PBDEs to people. Inhalation or ingestion of particulate matter (such as dust) may also be an important exposure pathway. There was no significant correlation between the PBDE concentration and the consumption of meat, fish, and milk. Further research is needed to determine the specific contribution of each exposure route and their health effects. 相似文献
895.
896.
897.
油田采油污泥的热解动力学及其热解效果研究 总被引:3,自引:1,他引:2
以新疆克拉玛依油田采油污泥为对象,分别采用热重分析仪和小型流化床热解反应器研究了含油污泥的热解过程及其热解效果。结果表明,油泥热解主要经历了失水、轻质组分挥发、重组分快速热解失重和缓慢失重4个阶段,热解过程基本符合一级动力学方程,提高热解的升温速率,可使油泥的最大失重速率Dmax、失重速率峰值温度θmax、升温终点的最大失重率都随之增加,表现在动力学上,反映出表观活化能和碰撞频率因子的同时升高,即提高油泥热解转化率的同时也影响了热解效率。失水油泥用流化床热解,在热解温度600℃、反应时间3 min时,油泥回收率可达到87%。 相似文献
898.
水泥旋窑并行处理城市污水厂污泥的污染物排放研究 总被引:5,自引:1,他引:4
通过重庆某水泥厂的工业试验,测定了水泥旋窑并行处理城市污水厂污泥的烟气参数及污染物排放指标,分析了并行处理污泥对旋窑烟气的影响程度及各项指标之间的相关性。结果表明:①在污泥添加速率增大时,烟气流速、排气量、含氧量、空气过剩系数、HF和SO2等排放浓度均随之增加,粉尘、NOx排放浓度基本保持不变,HCl排放浓度下降,CO排放浓度先剧增后缓慢下降,而总烃排放浓度无明显规律;②污泥添加速率与SO2排放浓度、烟气流速与排气量、含氧量与空气过剩系数、总烃浓度与SO2排放浓度、烟气流速与总烃浓度呈显著正相关,污泥添加速率与HCl浓度、SO2浓度与HCl浓度、NOx与总烃浓度呈显著负相关;③烟气排放的污染物主要来自煤的燃烧,各指标之间的相关性主要表现为煤耗量增加而引起的连锁效应,但污泥本身在高温条件下燃烧产生的污染物较少,由污泥燃烧产生的污染物之间的相关性较小;④污泥添加速率达到2.4 t/h时,水泥旋窑并行处理城市污水处理厂污泥过程中所有指标均满足国家及相应的控制标准,但其参数优化及污染物控制极为复杂,该方法处理污泥需要进行深入研究才能在工业上应用。 相似文献
899.
Huizheng Che Zhifeng Yang Xiaoye Zhang Chize Zhu Qiangli Ma Huaigang Zhou Peng Wang 《Atmospheric environment (Oxford, England : 1994)》2009,43(5):1093-1099
The special and temporal characteristics of aerosol optical depth (AOD) and Angstrom wavelength exponent (Alpha) and their relationship with aerosol chemical compositions were analyzed by using the data of CE318 sun-photometer and aerosol sampling instruments at Lin'an, Shangdianzi and Longfengshan regional atmospheric background stations. Having the highest AOD among the three stations, Lin'an shows two peaks in a year. The AOD at Shangdianzi station shows a single annual peak with an obvious seasonal variation. The AOD at Longfengshan station has obvious seasonal variation which peaks in spring. The Alpha analysis suggests that the aerosol sizes in Lin'an, Longfengshan and Shangdianzi change from fine to coarse categories. The relationship between the aerosol optical depths of the Lin'an and Longfengshan stations and their chemical compositions is not significant, which suggests that there is not a simple linear relationship between column aerosol optical depth and the near surface chemical compositions of atmospheric aerosols. The aerosol optical depth may be affected by the chemical composition, the particle size and the shape of aerosol as well as the water vapor in the atmosphere. 相似文献
900.
Stream-riparian ecosystems are dynamic and complex entities that can support high levels of bird assemblage abundance and
diversity. The myriad patches (e.g., aquatic, floodplain, riparian) found in the riverscape habitat mosaic attract a unique
mixture of aquatic, semiaquatic, riparian, and upland birds, each uniquely utilizing the river corridor. Whereas standard
morning bird surveys are widely used across ecosystems, the variety of bird guilds and the temporal habitat partitioning that
likely occur in stream-riparian ecosystems argue for the inclusion of evening surveys. At 41 stream reaches in Vermont and
Idaho, USA, we surveyed bird assemblages using a combination of morning and evening fixed-width transect counts. Student’s
paired t-tests showed that while bird abundance was not significantly different between morning and evening surveys, bird assemblage
diversity (as measured by species richness, Shannon-Weiner’s index, and Simpson’s index) was significantly higher in the morning
than in the evening. NMS ordinations of bird species and time (i.e., morning, evening) indicated that the structure of morning
bird assemblages was different from that of evening assemblages. NMS further showed that a set of species was only found in
evening surveys. The inclusion of evening counts in surveying bird assemblages in stream-riparian ecosystems has important
experimental and ecological implications. Experimentally, the sole use of morning bird surveys may significantly underestimate
the diversity and misrepresent the community composition of bird assemblages in these ecosystems. Ecologically, many of the
birds detected in evening surveys were water-associated species that occupy high trophic levels and aerial insectivores that
represent unique aquatic-terrestrial energy transfers. 相似文献