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981.
Dechlorination of octachlorodibenzo-p-dioxin (OCDD) was carried out in ethanol-water (v/v=1:1) solution of NaOH in the presence of Pd/C catalysts with the use of H(2). The substrate was dechlorinated with Pd/C under mild conditions (atmospheric pressure and <100 degrees C) to give a chlorine-free product, dibenzo-p-dioxin (DD), in high yields. After reaction of 3h at 50 degrees C, 95.9% OCDD was degraded to low dechlorinated congeners and the yield of DD was 77.4%. We have also studied the dechlorination selectivity of chlorine atoms on the different substituted positions and postulated the dechlorination pathway of OCDD. For OCDD, the 2-position has higher reactivity than 1-position, but the difference is very small. From the distribution statistics of the intermediates during the reaction, we postulate that the steric effect plays an important role during the reaction and affect the dechlorination pathway of OCDD. 相似文献
982.
针对地下储库受限空间的特点和油气爆炸抑制的需要.在前期所完成的系统油气爆炸试验和理论研究的基础上,采用超细冷气溶胶抑爆新技术,建立地下受限空间油气爆炸及其抑爆模拟试验系统,研制出新型超细冷气溶胶粉体抑爆剂,并对其进行可行性与有效性研究.对地下受限空间油气爆炸抑制的影响因素进行研究,分析了抑爆剂作用机理.结果表明:超细冷气溶胶是一种高效的抑制地下储库油气爆炸的抑爆剂;在相同试验条件下,迎着火焰传播方向喷射抑爆剂的抑爆效果优于垂直火焰传播方向喷射抑爆剂;喷射压力存在临界值,较小较大都不利于油气爆炸抑制,在本文试验条件下.最佳抑爆效果的喷射压力临界值约为0.8 Mpa;抑爆剂用量不能低于临界抑爆浓度,实验得到的抑爆刑临界浓度为0.232 ks/m3;布置方式对抑爆效果具有明显的影响.分散布置比集中布置具有更好的抑爆效果.本文的研究对后续抑爆装置的研制提供了重要的理论参考和关键设计参数. 相似文献
983.
三维脚型测量技术及方法的研究 总被引:1,自引:0,他引:1
本文阐述了人体脚型的测量方法及特点,比较后得出人工测量与三维扫描测量技术之间的差别。以YETI三维脚型扫描仪为模型,详细分析了脚型扫描仪的结构原理,摸索并提出了简单实用的测量方法,讨论了YETI三维脚型扫描仪获得的原始数据、脚型横截面以及脚型投影图的特点。 相似文献
984.
985.
A rapid spectrophotometric determination of persulfate anion in ISCO 总被引:10,自引:0,他引:10
Due to a gradual increase in the use of persulfate as an in situ chemical oxidation (ISCO) oxidant, a simple measurement of persulfate concentration is desirable to analyze persulfate distribution at designated time intervals on/off a site. Such a distribution helps evaluate efficacy of ISCO treatment at a site. This work proposes a spectrophotometric determination of persulfate based on modification of the iodometric titration method. The analysis of absorption spectra of a yellow color solution resulting from the reaction of persulfate and iodide in the presence of sodium bicarbonate reveals an absorbance at 352 nm, without significant interferences from the reagent matrix. The calibration graph was linear in the range of persulfate solution concentration of 0-70 mM at 352 nm. The proposed method is validated by the iodometric titration method. The solution pH was at near neutral and the presence of iron activator does not interfere with the absorption measurement. Also, analysis of persulfate in a groundwater sample using the proposed method indicates a good agreement with measurements by the titration method. This proposed spectrophotometric quantification of persulfate provides a simple and rapid method for evaluation of ISCO effectiveness at a remediation site. 相似文献
986.
987.
988.
Mingming Lu Prabhat Lamichhane Fuyan Liang Eric Imerman Ming Chai 《Water, Air, & Soil Pollution: Focus》2008,8(3-4):359-367
The odorous air emissions from confined animal feeding operations (CAFOs), such as swine, poultry and dairy farms, are increasingly
raising community complaints. Odorous emissions can result in health damages, psychological discomforts and adverse aesthetic
effects in the community. However, these emissions are not well characterized up to now due to the lack of legislation, the
limitations in sampling and instrumentation techniques, and the complexity of the emissions themselves. This study is aimed
at the development of a high volume sampler and sorbent assembly to identify the odor causing compounds from a diary CAFO.
The sorbent was custom designed to target the potential compounds that may exist in a dairy farm and was validated in laboratory
with a synthetic odor from the swine manure. The actual samples at the diary farm were collected in spring and summer of 2005.
The sorbents were solvent extracted and individual odor compounds were identified using GC–MS (gas chromatography–mass spectroscopy).
The data obtained indicated that high volume sampling can shorten the sampling time from days to within 4 h. Both volatile
organic compounds (VOCs) and volatile fatty acids (VFAs) have been identified from the dairy farm, such as phenol, methylphenol,
4-ethyl phenol, indole, methyl indole, benzyl alcohol, hexanoic acid, valeric acid and iso-valeric acid, together with some nitrogen containing compounds that have not been reported before. 相似文献
989.
为去除化工生产等过程中产生的酸雾废气,首先用水作用法、微波法和传统湿法对粉煤灰进行改性试验,结果显示:传统湿法中的碱法效果最佳,改性后粉煤灰的BET比表面积是改性前的8.23倍.再用改性后的粉煤灰与廉价易得的天然矿物沸石和熟石灰作为活性组分,制得一种新型的复合吸附剂.常温常压下,动态吸附盐酸雾,实验结果表明:由改性粉煤灰制作的吸附剂G对盐酸雾的吸附性能比未经改性的吸附剂W有所提高,在文中所述条件下,饱和吸附量由改性前的331.4 mg/g提高到改性后的445.2 mg/g. 相似文献
990.