排序方式: 共有35条查询结果,搜索用时 890 毫秒
11.
采用甲醇提取-吹扫捕集的前处理方法并结合气相色谱-质谱仪来测定土壤样品中的8种苯系物。实验结果表明,8种苯系物在前处理过程中被有效提取出来并被准确定性和定量,对于低浓度样品也具有良好的实验效果。此方法的检出限为0.3~0.8μg/kg,测定下限为1.2~3.2μg/kg。加标低、中、高3种不同质量比的标准物质,经实验分析土壤中8种苯系物相对标准偏差(RSD)为2.1%~6.8%,加标回收率为91.0%~105%,与相关行业标准相比具有一定的优势。 相似文献
12.
C.S. Cheung Lei Zhu Zhen Huang 《Atmospheric environment (Oxford, England : 1994)》2009,43(32):4865-4872
Experiments were carried out on a diesel engine operating on Euro V diesel fuel, pure biodiesel and biodiesel blended with methanol. The blended fuels contain 5%, 10% and 15% by volume of methanol. Experiments were conducted under five engine loads at a steady speed of 1800 rev min−1 to assess the performance and the emissions of the engine associated with the application of the different fuels. The results indicate an increase of brake specific fuel consumption and brake thermal efficiency when the diesel engine was operated with biodiesel and the blended fuels, compared with the diesel fuel. The blended fuels could lead to higher CO and HC emissions than biodiesel, higher CO emission but lower HC emission than the diesel fuel. There are simultaneous reductions of NOx and PM to a level below those of the diesel fuel. Regarding the unregulated emissions, compared with the diesel fuel, the blended fuels generate higher formaldehyde, acetaldehyde and unburned methanol emissions, lower 1,3-butadiene and benzene emissions, while the toluene and xylene emissions not significantly different. 相似文献
13.
The high-temperature and high-pressure methanol one-step oxidation has been the primary process for the mass production of dimethoxymethane. However, the risk of explosion for this process is still not properly defined. This paper presents new results from the experimental study on the explosion characteristics, including the explosion pressure and the explosion limits for methanol/air mixtures with a variable oxygen level, under an initial pressure between 0.3 MPa and 0.75 MPa and at the initial temperature of 423 K. The upper explosive limits were found to increase along with the initial pressure. If the limits for normal air are known, the oxygen effect on flammability is predictable from the thermal balance method. With a correlation for the pressure effect and a method for the oxygen effect, we can have the flammable range predictable. 相似文献
14.
Methanol is the most widely used natural gas hydrate inhibitor and it is only effective as a hydrate inhibitor in the aqueous phase. Methanol is not regenerated in natural gas inhibition process due to its intermittent application in most cases. However, a significant cost is associated with the process because of methanol loss while utilizing this inhibitor. In this work, several intelligent models along with a new mathematical correlation are presented in terms of methanol concentration in aqueous phase and temperature to precisely forecast the methanol loss in the saturated hydrocarbons phase. An excellent match was noticed between the calculated results and literature data. 相似文献
15.
Kevin J. McGraw Elizabeth A. Tourville Michael W. Butler 《Behavioral ecology and sociobiology》2008,62(12):1991-2002
Interest in animal carotenoids, especially in birds, has exploded in recent years, and so too have the methods employed to
investigate the nature and function of these pigments. Perhaps the most easily and commonly performed procedure in this work
has been the determination of carotenoid concentration from avian plasma. Over the past 20 years of research on avian carotenoids,
numerous methods have been used to extract carotenoids from bird plasma, all of which have differed in several important parameters
(e.g., number and types of solvents used, degree of mixing/centrifugation). However, to date, no study has systematically
compared these methods to determine if any of them are more effective than others for recovering any or all types of carotenoids
present. We undertook such an investigation on plasma samples from two bird species (house finch, Carpodacus mexicanus, and mallard, Anas platyrhynchos) using five of the most commonly employed methods for extracting carotenoids from avian plasma: (1) acetone-only, (2) methanol-only,
(3) ethanol-only, (4) ethanol + hexane, and (5) ethanol + tert butyl methyl ether. We also manipulated the amount of time that extracts were centrifuged, which has varied tremendously
in previous studies, to evaluate its importance on carotenoid recovery. We found that all methods equally recovered the polar
xanthophylls (lutein and zeaxanthin), but that the methanol-only procedure poorly recovered non-polar carotenoids (less β-carotene
in both species and less β-cryptoxanthin in house finches) compared to the other methods. These results suggest that the data
accumulated to date on xanthophyll plasma carotenoids in birds should be comparable across studies and species despite the
different chemical extraction methods used. However, care should be taken to use relatively strong organic solvents for fully
recovering non-polar carotenoids. We also found no effect of centrifugation duration (1 vs. 10 min at 10,000 rpm) on carotenoid
recoveries, demonstrating that researchers can save considerable time by centrifuging for a much shorter time period than
is typically used. 相似文献
16.
17.
Chung Song Ho Jianfei Peng UnHyok Yun Qijun Zhang Hongjun Mao 《Frontiers of Environmental Science & Engineering》2022,16(9):121
18.
This study investigated the removal of hydrophobic trichloroethylene (TCE) in the presence of methanol (co-metabolite) in a biotrickling filter, which was seeded with fungi at pH 4. Starvation was chosen as the biomass control strategy. Two systems, Biofilter I (methanol:TCE 70:30) and Biofilter II (methanol:TCE 80:20) were run in parallel, each with varying composition ratios. The TCE loading rates for both biofilters ranged from 3.22 to 12.88 g/m3/hr. Depending on the ratio, methanol concentrations varied from 4.08 to 27.95 g/m3/hr. The performance of the systems was evaluated and compared by calculating removal kinetics, carbon mass balance, efficiencies and elimination capacities. Methanol was observed to enhance TCE removal during the initial loading rate. However, methanol later inhibited TCE degradation above 6.44 g TCE/m3/hr (Biofilter I) and 3.22 g TCE/m3/hr (Biofilter II). Conversely, TCE did not impede methanol removal because over 95% methanol elimination was consistently achieved. Overall, Biofilter I was able to outperform Biofilter II due to its greater resistance towards methanol competition. 相似文献
19.
吕后鲁 《石油化工环境保护》2004,27(1):61-64
对甲醇装置“三废”及噪声污染源现状进行调查和分析,提出并采取了相应的控制对策。对目前存在的环保问题,提出了改进措施。 相似文献
20.
测定空气中甲醇的毛细管气相色谱方法研究 总被引:3,自引:0,他引:3
使用HP—Wax毛细管柱进行水样分析,甲醇和乙醇分离效果好,该方法的精密度和准确度高,每0.2μL的最低检出限为0.7ng。此法利用了化学工作站,使得分析更简单、方便。 相似文献