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排序方式: 共有1275条查询结果,搜索用时 15 毫秒
1.
M. V. Veselovskaya S. V. Shilin M. M. Garazd V. P. Khilya 《Chemistry of Natural Compounds》2003,39(2):177-181
Furocoumarins modified by amino acids were prepared by condensation of the N-hydroxysuccinimide ester of 3-(2,3,5-trimethyl-7-oxofuro[3,2-g]chromen-6-yl)propanoic acid with amino acids. 相似文献
2.
Marco Sangermano Mehmet Atilla Tasdelen Yusuf Yagci 《Journal of polymer science. Part A, Polymer chemistry》2007,45(21):4914-4920
Photoinitiated cationic polymerization of mono‐ and bifunctional epoxy monomers, namely cyclohexeneoxide (CHO), 4‐epoxycyclohexylmethyl‐3′,4′‐epoxycyclohexanecarboxylate (EEC), respectively by using sulphonium salts in the presence of hydroxylbutyl vinyl ether (HBVE) was studied. The real‐time FTIR spectroscopic, gel content determination, and thermal characterization studies revealed that both hydroxyl and vinyl ether functionalities of HBVE take part in the polymerization. During the polymerization, HBVE has the ability to react via both active chain end (ACE) and activated monomer mechanisms through its hydroxyl and vinyl ether functionalities, respectively. Thus, more efficient curing was observed with the addition of HBVE into EEC‐containing formulations. It was also demonstrated that HBVE is effective in facilitating the photoinduced crosslinking of monofunctional epoxy monomer, CHO in the absence of a conventional crosslinker. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4914–4920, 2007 相似文献
3.
4.
缓慢炭化部分氧化对制备煤质活性炭的影响 总被引:5,自引:0,他引:5
研究了炭化升温速度、炭化低温区引入空气部分氧化对活性炭制备过程中炭化阶段、炭化物结构、活性炭性能等的影响。结果表明,炭化时低温部分氧化可提高炭化物得率,使炭化物微晶的d002值升高和Lc值减小;而较慢的炭化升温速度有利于制备优质活性炭。缓慢炭化、部分氧化可以在一定程度上控制炭化路径,使炭化向生成取向性差、难石墨化、各向同性、呒定形炭多的炭化物的方向进行;并讨论了它们控制炭化的作用机理。以此为指导, 相似文献
5.
与轻质油品(汽油、柴油等)燃烧特性不同,重质燃料油在燃烧时,首先发生燃料的热分解,分解的产物扩散到气相空间发生着火、燃烧,最后剩下固体残炭,然后残炭再着火、燃烧,由于残炭的燃烧属于异相反应,比燃料气与空气的同相反应慢,导致其燃尽时间明显变长,文献[1]给出了沥青和十二烷单滴的燃烧过程温度变化曲线,从曲线可以看出,残炭的燃烧阶段明显比气体的燃尽时间长,而残炭的质量只为沥青质量的10%~20%[2,3]。虽然残炭含量低,但它在整个燃烧过程中占有十分重要的地位;文献[4]利用热重系统研究了渣油热加工的副产物石油焦的燃烧特性,主要从… 相似文献
6.
A new branched-pore adsorption model has been developed using an external mass transfer coefficient, K
f, an effective diffusivity, D
eff, a lumped micropore diffusion rate parameter, K
b, and the fraction of macropores, f, to describe sorption kinetic data from initial adsorbent-adsorbate contact to the long-term adsorption phase. This model has been applied to an environmental pollution problem—the removal of two dyes, Acid Blue 80 (AB80) and Acid Red 114 (AR114), by sorption on activated carbon. A computer program has been used to generate theoretical concentration-time curves and the four mass transfer kinetic parameters adjusted so that the model achieves a close fit to the experimental data. The best fit values of the parameters have been determined for different initial dye concentrations and carbon masses. Since the model is specifically applicable to fixed constant values of these four parameters, a further and key application of this project is to see if single constant values of these parameters can be used to describe all the experimental concentration-time decay curves for one dye-carbon system.The error analysis and best fit approach to modeling the decay curves for both dye systems show that the correlation between experimental and theoretical data is good for the fixed values of the four fitted parameters. A significantly better fit of the model predictions is obtained when K
f, K
b and f are maintained constant but D
eff is varied. This indicates that the surface diffusivity may vary as a function of surface coverage. 相似文献
7.
Gun'ko V. M. Mikhalovskii S. V. Melillo M. Voronin E. F. Nosach L. V. Pakhlov E. M. 《Theoretical and Experimental Chemistry》2004,40(3):137-143
The interaction of ibuprofen [2-(4-isobutylphenyl)propionic acid] with the surface of carbon and oxide adsorbents was investigated. The significant role of wide pores during the adsorption of ibuprofen on carbon adsorbents in the presence of protein molecules was demonstrated. At low concentrations ibuprofen is adsorbed on the surface of hydrophilic and hydrophobic adsorbents in the form of a monomer, but the contribution from the adsorbed dimer increases with increase in its concentration. 相似文献
8.
Svetlana B. Lyubchik Irene I. Perepichka Olga L. Galushko Andrey I. Lyubchik Elena S. Lygina Isabel M. Fonseca 《Adsorption》2005,11(5-6):581-593
In order to understand the patterns of the adsorption equilibrium of Cr (III) on activated carbon, the adsorption process
was studied by two different ways: classical batch experiments on commercial Norit and Merck activated carbons and their oxidized
forms in a wide range of pHs; and extended time-based tests at the same pH values on the same adsorbents. This approach allowed
us to understand the role of texture, chemical carbon surface functionality and experimental conditions (initial pH of the
solution, contact time and adsorbate/adsorbent ratio) on the effectiveness of Cr (III) removal. The adsorption process of
Cr (III) at (24 ± 1∘C) on Merck and Norit activated carbons and their oxidized forms were studied at pH values between 1.5 and 5 (either adjusted
or buffered). Chromium concentration was fixed at 200 ppm. The carbon loading ranged from 1.2 to 20 g/l. The carbon/Cr (III)
solution contact time was varied from 0.5–1 month to 5 months, to ensure that the saturation of the carbon level was reached.
According to the data obtained, the presence of carboxylic groups on carbon surface seems to enhance Cr (III) uptake at initial
pH of the solution in the range between 2 and 4. Depending on the nature of the adsorbent surface chemistry, the contact time
to reach equilibrium may range from 3 to 5 months. There is an optimum carbon loading which limits the Cr (III) uptake/removal
at given pH value. In order to understand the adsorption process, an ion exchange, surface complex and surface precipitation
were considered.
This paper was presented in the 5th Brazilian Meeting on Adsorption, held at Natal, Brazil, 18-21 July, 2004. 相似文献
9.
杂多酸在活性炭上的固载化Ⅲ.活性炭在酸性介质中对钨硅杂多酸(SiW_(12))的吸附 总被引:1,自引:0,他引:1
在氢离子浓度均为3mol/L的硫酸,盐酸,磷酸,醋酸水溶液中和冰醋酸中研究了具有Keggin结构的硅钨杂多酸(SiW_(12))在不同来源活性炭上的吸附作用。各活性炭对SiW_(12)吸附等温线的形式是不相同的,吸附剂载体的微孔结构以及杂多酸的溶剂化起着重要的作用。并且在无机酸介质中,杂多酸的吸附量比在水溶液中成规律性地增加,且与酸强度成正比关系。在有机酸介质中,吸附作用比较复杂。根据所得结果,提出了在酸性介质中杂多酸在活性炭表面的吸附模型。 相似文献
10.
合成异丙苯二次失活FX-01催化剂烧炭再生研究 总被引:4,自引:3,他引:4
以工业合成异丙苯二次失活催化剂为研究对象,考察了二次失活催化剂在不同温度下再生前后酸种类及其比例、酸含量、晶相、孔结构等性能,并分析了失活催化剂结炭性质及不同温度烧炭再生情况。结果表明:温度大于450℃才能烧炭,500℃可将炭烧除78%,600℃方可将炭烧净。500~600℃烧炭后催化剂酸种类及其比例可完全恢复,酸量可恢复80~99%,晶相、孔结构基本未改变,本征活性恢复66~85%。与一次轻度结炭FX01催化剂相比,要提高烧炭温度。 相似文献