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51.
Karel Ciahotný Lenka Melenová Hana Jirglová Olga Pachtová Milan Kočiřík Mladen Eić 《Adsorption》2006,12(3):219-226
Natural and impregnated clinoptilolite tuffs were studied to assess their potential to remove ammonia from air and, in a subsequent
application, to use the spent adsorbent as a fertilizer. H2SO4, H3PO4 and HNO3, as agents containing important plant nutrients compatible with soil, were selected for impregnation to enhance sorption
capacity of the natural clinoptilolite tuffs for ammonia removal. Sorbents were characterized using N2 adsorption isotherms at 77 K, X-ray analysis and high pressure mercury porosimetry. Ammonia breakthrough curves on fixed
beds of sorbent were determined using appropriate NH3 and H2O input concentrations, flow rates and temperatures similar to the conditions in animal breeding farms. Impregnated clinoptilolite
tuffs showed adsorption capacities comparable to SSP-4, an activated carbon that is commercially used for NH3 removal. Impregnations with H2SO4 and HNO3 are particularly important, since such modified adsorbents exhibit relatively high breakthrough capacities, thus rendering
them potentially useful for practical applications in controlling ammonia emissions. The main contribution to the sorption
capacity enhancement on impregnated clinoptilolite tuff samples seems to be due to the chemical reaction of ammonia with acids
remaining in the macro- and mesopores. 相似文献
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Vinh-Thang H Huang Q Eić M Trong-On D Kaliaguine S 《Langmuir : the ACS journal of surfaces and colloids》2005,21(11):5094-5101
In our recent studies (Vinh-Thang, H.; Huang, Q.; Eic, M.; Trong-On, D.; Kaliaguine, S. Langmuir 2005, 21, 2051-2057; Vinh-Thang, H.; Huang, Q.; Eic, M.; Trong-On, D.; Kaliaguine, S. Stud. Surf. Sci. Catal. 2005, in press), a series of synthesized SBA-15 materials were characterized using nitrogen adsorption/desorption isotherms at 77 K and SEM images. In the present paper, four of them (MMS-1-RT, MMS-1-60, MMS-1-80, and MMS-5-80) were further investigated with regard to their equilibrium characteristics using n-heptane and toluene as sorbates by the standard gravimetric technique. SBA-15 materials proved to have a broad pore size distribution within the micropore/small-mesopore range in the walls of their main mesoporous channels. The adsorption capacities for toluene were found to be higher than for n-heptane. The isosteric heats of adsorption, estimated by the Clausius-Clapeyron equation, are also higher for toluene compared to n-heptane. They were found to depend on framework microporosity of the relevant SBA-15 samples. The isosteric heats of adsorption for all sorbates decrease with increased loading and approach the heats of evaporation of the respective sorbate. The adsorption capacities of SBA-15 samples are significantly higher than those of silicalite, i.e., the MFI zeolite silica analogue. In contrast to that, the isosteric heats of adsorption in the mesopore channels of SBA-15 were found to be much smaller. This result also suggests that SBA-15 can potentially be a good candidate for separation of C(7) hydrocarbons. 相似文献
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Shouquan Huo Ji‐cheng Shi Ei‐ichi Negishi 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2002,114(12):2245-2247
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Alemayehu H. Bedane Mladen Eić Madjid Farmahini-Farahani Huining Xiao 《Cellulose (London, England)》2016,23(3):1537-1552
The theory of mass transport in porous media is of fundamental importance for different applications such as food, paper packaging, textiles, and wood for building materials. In this study, a theoretical water vapor transport model has been developed for cellulose-based materials, such as paper and regenerated cellulose film. Pore diffusivities were determined from the dynamic moisture breakthrough experiments comprising a stack of paper sheets and regenerated cellulose films in a configuration similar to a packed adsorption column. Other mass transfer parameters were determined from transient moisture uptake rate measurements. The model incorporates pore and surface diffusion as a lump parameter into a variable effective diffusion coefficient. The mass transport, involving both pore and surface diffusions, is evaluated independently. The theoretical water vapor transmission rates (WVTRs) obtained from the model were compared with experimentally determined WVTRs measured under steady-state conditions. The theoretical model, based on intrinsic diffusion, stipulates higher WVTR values compared to the experimental results. However, the theoretical water vapor transfer rates agree well with the experimental results when external mass transfer resistance is incorporated in the model. 相似文献
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Equilibrium data and diffusion characteristics of propane and propylene were determined on mesoporous adsorbents modified
with an organic molecule (APTES) and/or impregnated with AgNO3, in order to obtain a separation by adsorption via π-complexation.
Adsorption capacities were determined by a gravimetric technique, while diffusion characteristics were evaluated by the ZLC
technique. The equilibrium isotherms data showed that the modification with an organic molecule will weaken the π-interaction between Ag+ and double C=C bond. On the other hand slightly higher adsorption capacities for propylene (about 1.5 mol/kg) were obtained
for the sample prepared by a direct impregnation with larger amounts of AgNO3 (M4 sample).
Diffusion runs confirmed that the propane desorption rate on M4 sample was much higher compared to propylene. This evidence
leads to a potential application of that adsorbent material for a kinetic separation. 相似文献
59.
Ultrasensitive method to quantify intracellular zidovudine mono‐, di‐ and triphosphate concentrations in peripheral blood mononuclear cells by liquid chromatography–tandem mass spectrometry 下载免费PDF全文
Ei Kinai Hiroyuki Gatanaga Yoshimi Kikuchi Shinichi Oka Shingo Kato 《Journal of mass spectrometry : JMS》2015,50(6):ii-ii
Although zidovudine (AZT) is not the preferred antiretroviral drug for adult HIV‐infected patients, it is still widely used in infants for both prevention of mother‐to‐infant HIV‐1 transmission and treatment of HIV‐infected children. However, it is difficult to measure intracellular concentrations of AZT metabolites in small blood samples due to their extremely low concentrations in peripheral blood mononuclear cells and interference by endogenous nucleotide triphosphates, residual plasma phosphates and electrolytes. We developed an ultrasensitive assay using liquid chromatography–tandem mass spectrometry (LC–MS/MS) for measurement of intracellular concentrations of zidovudine (AZT)‐monophosphate (AZT‐MP), ‐diphosphate (AZT‐DP) and ‐triphosphate (AZT‐TP). The high sensitivity was due to the improvement of peripheral blood mononuclear cells extraction for complete removal of plasma and electrolytes, alkalization of LC buffer and use of alkaline‐stable high performance liquid chromatography column and tetrabutylammonium hydroxide as the ion pair. Using this method, the lower limits of quantification of AZT, AZT‐MP, ‐DP and ‐TP were 6, 6, 10 and 10 fmol per sample, respectively. Accuracy ranged 89–115% and precision was lower than 15% in the quantification range of 6–6000 fmol/sample for plasma AZT and intracellular AZT‐MP and 10–10 000 fmol/sample for AZT‐DP and ‐TP. The validation parameters met the international requirements. Among nine AZT‐treated HIV‐infected adult patients, five had low AZT‐TP levels (<10 fmol/106 cells). Our assay has high sensitivity and is advantageous for evaluation of AZT phosphates in children and infants based on minimum blood sampling requirement. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
60.
Dr. W. Eißner 《Analytical and bioanalytical chemistry》1933,91(5-6):172-173