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Catalytic Behavior of K-doped Fe/MgO Catalysts for Ammonia Synthesis Under Mild Reaction Conditions. CHEMSUSCHEM 2023; 16:e202300942. [PMID: 37877342 DOI: 10.1002/cssc.202300942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 10/13/2023] [Accepted: 10/23/2023] [Indexed: 10/26/2023]
Abstract
An important part of realizing a carbon-neutral society using ammonia will be the development of an inexpensive yet efficient catalyst for ammonia synthesis under mild reaction conditions (<400 °C, <10 MPa). Here, we report Fe/K(3)/MgO, fabricated via an impregnation method, as a highly active catalyst for ammonia synthesis under mild reaction conditions (350 °C, 1.0 MPa). At the mentioned conditions, the activity of Fe/K(3)/MgO (17.5 mmol h-1 gcat -1 ) was greater than that of a commercial fused iron catalyst (8.6 mmol h-1 gcat -1 ) currently used in the Haber-Bosch process. K doping was found to increase the ratio of Fe0 on the surface and turnover frequency of Fe in our Fe/K(3)/MgO catalyst. In addition, increasing the pressure to 3.0 MPa at the same temperature led to a significant improvement of the ammonia synthesis rate to 29.6 mmol h-1 gcat -1 , which was higher than that of two more expensive, benchmark Ru-based catalysts, which are also potential alternative catalysts. A kinetics analysis revealed that the addition of K enhanced the ammonia synthesis activity at ≥300 °C by changing the main adsorbed species from NH to N which can accelerate dissociative adsorption of nitrogen as the rate limiting step in ammonia synthesis.
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Co Nanoparticle Catalysts Encapsulated by BaO-La 2O 3 Nanofractions for Efficient Ammonia Synthesis Under Mild Reaction Conditions. ACS OMEGA 2022; 7:24452-24460. [PMID: 35874216 PMCID: PMC9301956 DOI: 10.1021/acsomega.2c01973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Ruthenium catalysts may allow for realization of renewable energy-based ammonia synthesis processes using mild reaction conditions (<400 °C, <10 MPa). However, ruthenium is relatively rare and therefore expensive. Here, we report a Co nanoparticle catalyst loaded on a basic Ba/La2O3 support and prereduced at 700 °C (Co/Ba/La2O3_700red) that showed higher ammonia synthesis activity at 350 °C and 1.0-3.0 MPa than two benchmark Ru catalysts, Cs+/Ru/MgO and Ru/CeO2. The synthesis rate of the catalyst at 350 °C and 1.0 MPa (19.3 mmol h-1 g-1) was 8.0 times that of Co/Ba/La2O3_500red and 6.9 times that of Co/La2O3_700red. The catalyst showed ammonia synthesis activity at temperatures down to 200 °C. Reduction at the high temperature induced the formation of BaO-La2O3 nanofractions around the Co nanoparticles by decomposition of BaCO3, which increased turnover frequency, inhibited the sintering of Co nanoparticles, and suppressed ammonia poisoning. These strategies may also be applicable to other non-noble metal catalysts, such as nickel.
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Effects of changes in polycyclic aromatic hydrocarbons (PAHs) emissions and degradation on their concentrations in Tokyo from 2007 and 2016. Sci Rep 2022; 12:4249. [PMID: 35277564 PMCID: PMC8917142 DOI: 10.1038/s41598-022-08138-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Accepted: 02/22/2022] [Indexed: 11/15/2022] Open
Abstract
The concentrations of polycyclic aromatic hydrocarbons (PAHs) in aerosol were measured in Shinjuku, which is central Tokyo, Japan, for 10 years from 2007 to 2016. The effects of changes in emission sources and their degradation by reaction with ozone were assessed in this study. There was no significant increasing or decreasing trend of the PAH concentrations during 10 years (P > 0.05). The average selected seven the PAH concentrations (0.88 ng m−3) during 10 years was lower than those in New York and Paris. However, the trend of ozone concentrations is increasing in central Tokyo. This inconsistency raises a question. Did the fact that the ozone concentration was higher than the PAH concentrations promote PAH degradation? To apportion the PAH sources, we used PAH concentration profiles and positive matrix factorization analysis. The contribution of vehicle emissions to the PAHs ranged from 40 to 80%. Ozone concentrations increased by 3.70%/year during 10 years. The theoretical degradation rates of PAHs by ozone, which were calculated using a pseudo-first-order rate equation, suggested that the lifetimes of benzo[a]pyrene (BaP) decreased by 1 min from 2007 to 2016. We investigated the aging of BaP using the profile of the isomer ratios. We found that the aging of BaP at the urban and roadside sites were nearly identical indicating aging regardless of the season. Although the decomposition of BaP is promoted by the photochemical oxidation reaction, this result suggests that a certain threshold value exists as the degree of the decomposition. This degradation of PAH can improve chemical loss processes in air quality model.
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Barium Oxide Encapsulating Cobalt Nanoparticles Supported on Magnesium Oxide: Active Non-Noble Metal Catalysts for Ammonia Synthesis under Mild Reaction Conditions. ACS Catal 2021. [DOI: 10.1021/acscatal.1c02887] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Multifunctional Catalytic Surface Design for Concerted Acceleration of One-Pot Hydrosilylation-CO 2 Cycloaddition. Org Lett 2019; 21:9372-9376. [PMID: 31741391 DOI: 10.1021/acs.orglett.9b03602] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Silica-supported Rh-ammonium iodide catalyst showed high performance for hydrosilylation-CO2 cycloaddition reaction sequences. The catalyst was prepared by surface grafting of Rh and the silane-coupling reaction of the ammonium iodide moiety. The acceleration of each catalytic reaction was realized due to the concerted catalysis between Rh species, immobilized organic functions, and surface Si-OH groups. As a result, good to excellent yields of silyl carbonates were obtained from epoxyolefins, hydrosilanes, and CO2 under mild reaction conditions.
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Prediction of rate constants for the gas phase reactions of triphenylene with OH and NO3 radicals using a relative rate method in CCl4 liquid phase-system. CHEMOSPHERE 2013; 90:766-771. [PMID: 23084261 DOI: 10.1016/j.chemosphere.2012.09.071] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Revised: 09/11/2012] [Accepted: 09/20/2012] [Indexed: 06/01/2023]
Abstract
The kinetics of CCl(4) liquid-phase reactions of ten kinds of polycyclic aromatic compounds (PACs) including triphenylene (TP) with NO(3) radicals have been investigated at 273K by a relative rate method using naphthalene (NA) as a reference compound. The obtained relative reaction rates of the tested PACs to NA in CCl(4) were as follows: 2.57±0.24 (acenaphthene), 2.11±0.30 (2,3-dimethylnaphthalene), 1.21±0.13 (fluoranthene), 0.56±0.07 (fluorene), 1.85±0.19 (1-methylnaphthalene), 1.77±0.12 (2-methylnaphthalene), 0.11±0.03 (1-nitronaphthalene), 1.59±0.23 (phenanthrene), 2.40±0.29 (pyrene), 0.22±0.04 (TP). TP is a semi-volatile PAC with four aromatic rings and it is chemically changed into mutagenic 2-nitrotriphenylene (2-NTP) via the gas-phase OH or NO(3) radical-initiated reactions. On the basis of the relative reactivity of the PACs in the CCl(4) liquid phase-system, the rate constants of the gas-phase reactions of TP with OH and NO(3) radicals at 298 K were predicted to be (8.6±1.2)×10(-12) cm(3) molecule(-1) s(-1) and (6.6±1.5)×10(-29)[NO(2)] cm(3) molecule(-1) s(-1), respectively. Based on the ambient concentrations of TP and 2-NTP and the obtained rate constant for the reaction of TP with OH radicals, the atmospheric loss rate of 2-NTP was also evaluated.
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COMPARISON OF PAHS, NITRO-PAHS AND OXY-PAHS ASSOCIATED WITH AIRBORNE PARTICULATE MATTER AT ROADSIDE AND URBAN BACKGROUND SITES IN DOWNTOWN TOKYO, JAPAN. Polycycl Aromat Compd 2010. [DOI: 10.1080/10406638.2010.525164] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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8
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Application of a simple kinetic model for the oxidative coupling of methane to the design of effective catalysts. Catal Today 2009. [DOI: 10.1016/j.cattod.2008.07.036] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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ATMOSPHERIC OCCURRENCE OF 2-NITROBENZANTHRONE ASSOCIATED WITH AIRBORNE PARTICLES IN CENTRAL TOKYO. Polycycl Aromat Compd 2008. [DOI: 10.1080/10406630802374457] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Reaction Kinetics of Methanol Carbonylation to Methyl Formate Catalyzed by CH3O− Exchange Resin. Catal Letters 2007. [DOI: 10.1007/s10562-007-9171-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Dichlorodifluoromethane decomposition to CO2 with simultaneous halogen fixation by calcium oxide based materials. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2006; 40:823-9. [PMID: 16509324 DOI: 10.1021/es050139f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The decomposition of CCl2F2 to CO2 and accompanying halogen fixation by a CaO based material was studied. To improve the low reactivity of CaO, a consequence of its low surface acidity, transition metal oxides were added. Impregnation of metal acetylacetonate followed by removal of the ligand under vacuum was found to be an effective method. This method resulted in the formation of carbonaceous species and the reduction of metal oxide to metal, both of which were thought to initiate the decomposition reaction. The reactivity of these materials (MOx(a)/CaO-vac) was found to be in the following order: M = Ni > Cu > V = Fe > Mn > Co > Ca. In particular, nickel supported on CaO was most effective for the decomposition of CCl2F2. During the preparation, nickel oxide was reduced to the metal phase. CCl2F2 was decomposed to CO2 with a small amount of CO, and halogens were fixed as CaFCl, without significant deactivation at 723 K.
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Heterolytic Dissociation of C–H Bond of Methane over Ag+-exchanged Zeolites and Conversion of Methane into Higher Hydrocarbons in the Presence of Ethene or Benzene. CHEM LETT 2006. [DOI: 10.1246/cl.2006.142] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Decomposition of Dichlorodifluoromethane with Simultaneous Halogen Fixation by Vanadium Oxide Supported on Magnesium Oxide. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2005. [DOI: 10.1246/bcsj.78.1565] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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14
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A Novel Technique to Determine the Rate Constants for the Gas-phase Reactions of Low-volatile Compounds with OH Radical Using a Relative-rate Method in CCl4Liquid Phase-system. CHEM LETT 2005. [DOI: 10.1246/cl.2005.758] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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15
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Barium Hexaaluminate as a Novel Promising Support for Ruthenium-based Ammonia Synthesis Catalysts. CHEM LETT 2005. [DOI: 10.1246/cl.2005.692] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Catalytic Transformation of Methane over In-Loaded ZSM-5 Zeolite in the Presence of Ethene. J Phys Chem B 2005; 109:4263-8. [PMID: 16851490 DOI: 10.1021/jp045640t] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Methane is shown to react with ethene over In-loaded ZSM-5 to higher hydrocarbons such as propene and toluene at around 673 K. Such methane conversion is not catalyzed by proton-exchanged ZSM-5 (H-ZSM-5) under the same conditions, only C2H4 being converted to higher hydrocarbons. By using 13C-labeled methane (13CH4) as a reactant, the reaction paths for the formation of propene, benzene and toluene were examined. 13C-labeled propene (13CC2H6) is formed by the reaction of 13CH4 with C2H4. The lack of 13C-labeled benzene revealed that propene is not transformed to benzene, which instead originates entirely from C2H4. The 13C atom is inserted both into the methyl group and benzene ring in the toluene formed. This indicates that toluene is formed by two reaction paths; the reaction of 13CC2H6 with butenes formed by the dimerization of C2H4 and the reaction of benzene with 13CH4. The existence of the latter path was proved by the direct reaction of 13CH4 with benzene. The reaction of methane with benzene was also carried out in a continuous flow system over In-loaded ZSM-5. The reaction afforded 7.6% and 0.9% yields of toluene and xylenes, respectively, at 623 K.
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Novel Anion Exchange Resin-based Catalyst for Liquid-phase Methanol Synthesis at 373–393 K. CHEM LETT 2004. [DOI: 10.1246/cl.2004.1252] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Enhanced Dichlorodifluoromethane Decomposition with Selective Fluorine Absorption by Acidic Fluorinated Magnesium Oxide. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2004. [DOI: 10.1246/bcsj.77.1239] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Selective wet-air oxidation of diluted aqueous ammonia solutions over supported Ni catalysts. WATER RESEARCH 2004; 38:778-782. [PMID: 14723948 DOI: 10.1016/j.watres.2003.10.025] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2003] [Revised: 10/01/2003] [Accepted: 10/22/2003] [Indexed: 05/24/2023]
Abstract
Wet-air oxidation (WAO) of diluted aqueous ammonia solutions over Ni supported on Al(2)O(3) catalysts was investigated. A nitrogen selectivity of approximately 90% was achieved by the WAO of ammonia over the 20-wt% Ni/Al(2)O(3) catalyst at 503K, a reaction time of 2h and air-feed pressure of 2.0MPa without the dissolution of Ni during the reaction. Ni/Al(2)O(3) pretreated by calcinations in air at 1173K for 4h showed high stability due to the formation of a NiAl(2)O(4) phase.
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DETERMINATION OF ATMOSPHERIC NITRO-POLYCYCLIC AROMATIC HYDROCARBONS AND THEIR PRECURSORS AT A HEAVY TRAFFIC ROADSIDE AND AT A RESIDENTIAL AREA IN OSAKA, JAPAN. Polycycl Aromat Compd 2004. [DOI: 10.1080/10406630490471708] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Decomposition of Dichlorodifluoromethane with Simultaneous Halogen Fixation by Transition Metal Oxides Supported on Magnesium Oxide. CHEM LETT 2003. [DOI: 10.1246/cl.2003.436] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Abstract
We describe two related methods for preparing arrays of nanowires composed of molybdenum, copper, nickel, gold, and palladium. Nanowires were obtained by selectively electrodepositing either a metal oxide or a metal at the step edges present on the basal plane of highly oriented pyrolytic graphite (HOPG) electrodes. If a metal oxide was electrodeposited, then nanowires of the parent metal were obtained by reduction at elevated temperature in hydrogen. The resulting nanowires were organized in parallel arrays of 100-1000 wires. These nanowires were long (some > 500 microns), polycrystalline, and approximately hemicylindrical in cross-section. The nanowire arrays prepared by electrodeposition were also "portable": After embedding the nanowires in a polymer or cyanoacrylate film, arrays of nanowires could be lifted off the graphite surface thereby facilitating the incorporation of metal nanowire arrays into devices such as sensors.
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Selective wet air oxidation of diluted aqueous ammonia solutions over co-precipitated transition metal-aluminium catalysts. RESEARCH ON CHEMICAL INTERMEDIATES 2002. [DOI: 10.1163/156856702760346888] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Environmental occurrence of nitrotriphenylene observed in airborne particulate matter. CHEMOSPHERE 2001; 44:681-690. [PMID: 11482656 DOI: 10.1016/s0045-6535(00)00516-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
1- and 2-Nitrotriphenylenes were found in the airborne particulate matter extracts collected in central Tokyo between the winter of 1998 and the winter of 1999. In particular, we have identified and quantified nitrotriphenylenes in the airborne particulate matter extracts collected over four consecutive 6-h periods on 2 December 1999. The concentrations of 1- and 2-nitrotriphenylene ranged from 0.04 to 0.44 and from 0.02 to 0.47 ng/m3, respectively, and the concentrations in the airborne particulate matter extracts collected during the 18:00-24:00 h time period were the highest of the four collection periods. 1-Nitropyrene and 2-nitrofluoranthene were also identified and quantified in the four 6-h samples. Although the concentrations of 1- and 2-nitrotriphenylenes were not higher than that of 2-nitrofluoranthene except during the 18:00-24:00 h time period, the concentrations were much higher than that of 1-nitropyrene during the four collection periods. The higher concentrations of 1- and 2-nitrotriphenylenes during the 18:00-24:00 h time period are presumably responsible for the high reactivity of parent triphenylene with NO2/NO3/N2O5, and high stability of 1- and 2-nitrotriphenylenes toward O3 + O2. In addition, the observed isomer distribution of nitrotriphenylenes suggested that direct emission of nitrotriphenylenes is also a source as well as their atmospheric formation.
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SO2-Enhanced Nitration of Fluoranthene and Pyrene Adsorbed on Particulate Matter in the Heterogeneous Reaction in the Presence of NO2. Polycycl Aromat Compd 2000. [DOI: 10.1080/10406630008034785] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Mutagenic nitrated benzo[a]pyrene derivatives in the reaction product of benzo[a]pyrene in NO2-air in the presence of O3 or under photoirradiation. CHEMOSPHERE 2000; 41:1809-1819. [PMID: 11057622 DOI: 10.1016/s0045-6535(00)00029-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In order to clarify the contribution of nitrated products to the direct-mutagenic activity of products of the reactions of benzo[a]pyrene in NO2-air under various conditions, heterogeneous reactions of BaP deposited on filter in the air containing 10 ppm of NO2 have been conducted in dark or under photoirradiation. The reaction products have been analyzed by gas chromatography and mutagenicity of the products fractionated by preparative HPLC was assayed for Salmonella typhimurium strains TA98 and YG1024 in the absence of S9 mix. 3,6-dinitrobenzo[a]pyrene and 1,3-dinitrobenzo[a]pyrene, which are strong direct-acting mutagens, largely contributed to the total direct-acting mutagenicity of the dark reaction products in NO2-air. On the other hand, both the dark reaction in the presence of O3 and the photoreaction in NO2-air resulted in the formation of much smaller amounts of nitrobenzo[a]pyrenes than that observed in the dark reaction in the absence of O3. These results show that the contribution of other direct-acting mutagens to the total direct-acting mutagenicity of the products in these reactions should be considered. Benzo[a]pyrene lactones were identified in a highly mutagenic fraction of the products of the dark reaction in the presence of O3 and photoreaction and a nitrobenzo[a]pyrene lactone was also identified in a highly mutagenic fraction of the dark reaction products in the presence of O3. Nitrated oxygenated benzo[a]pyrene derivatives such as nitrobenzo[a]pyrene lactone were considered to largely contribute to direct-acting mutagenicity of the products of the dark reaction in the presence of O3 and photoreaction.
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Hydrogen-Treated Active Carbon Supported Palladium Catalysts for Wet Air Oxidation of Ammonia. CHEM LETT 1999. [DOI: 10.1246/cl.1999.377] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Formation of Mutagenic Nitrofluoranthenes in the Gas-Solid Heterogeneous Reaction of Particle-associated Fluoranthene in NO2-O3-O2System. CHEM LETT 1996. [DOI: 10.1246/cl.1996.1105] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Freeze-drying of cephalothin sodium: granularly agglomerated crystallization during freezing. II. Biol Pharm Bull 1993; 16:407-13. [PMID: 8358392 DOI: 10.1248/bpb.16.407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The mechanism of granularly agglomerated crystallization during freezing of cephalothin sodium (CET-Na) in aqueous solution has been discussed. Our previous report noted that strict control of the following is important in order to obtain crystalline granular agglomerates of CET-Na: (1) thermal history of the solution before receiving freezing, (2) cooling rate in freezing, and (3) aging temperature level in the crystal growth step. In order to clarify the physico/chemical meanings of the individual controls, further investigations have been made: 1) with varying thermal history, aqueous 30-% CET-Na solutions were prepared for storage, first at 0 degrees C with its supersaturation and secondly at 25 degrees C, in an unsaturated state for observing any structural changes by viscosimetry, refractometry, and surface tensiometry; 2) morphological changes in ice crystals during freezing at varying cooling rates, as well as those during the crystal growth step, were observed by polarized-light cryomicroscopy and scanning electron microscopy; 3) melting, as well as crystal growth, at several aging temperature levels were observed by electrical conductometry and also by the above-mentioned techniques.(ABSTRACT TRUNCATED AT 250 WORDS)
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Freeze-drying of cephalothin sodium: granularly agglomerated crystallization during freezing. I. Biol Pharm Bull 1993; 16:402-6. [PMID: 8358391 DOI: 10.1248/bpb.16.402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Optimal conditions for the crystallization and subsequent freeze-drying of an aqueous cephalothin sodium (CET-Na) solution of supersaturated concentrations to obtain granular crystalline CET-Na have been discussed, as have the qualities of the product thus obtained. In general, CET-Na in supersaturated aqueous solution is barely recrystallized, even when in its frozen stage. Our previous report revealed that when the solution is kept at low temperatures for a long duration, the molecules begin to change structurally to as condensed a state as that of liquid crystals, and such change facilitates a spontaneous nucleation and seed-independent crystal growth in the frozen solution. These findings prompted the authors to investigate optimal CET-Na concentrations and thermal histories during the crystallization and subsequent freeze-drying process without seeding. It has subsequently been found out that optimization of the latter conditions gives granular agglomerated crystalline CET-Na contaminated with neither the amorphous nor the quasi-crystalline form. The optimized conditions are: 25-28% CET-Na concentrations; storage before the freezing process at 0 degrees C for 2 h, and subsequent storage at 20-25 degrees C for 1 h; cooling in the freezing process at a rate not faster than 0.5 degrees C/min; warming of the solution for facilitating crystallization prior to vacuum application for drying at -4 degrees C. Under these conditions, the freeze-dried product of CET-Na in granular form has been successfully obtained in a shorter freeze-drying cycle, exhibiting a faster reconstitution time than those of CET-Na prepared according to seeded crystallization followed by a conventional freeze-drying.
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Decomposition of Chlorinated Hydrocarbons in Aqueous Solutions by Ultrasonic Irradiation. CHEM LETT 1993. [DOI: 10.1246/cl.1993.57] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Synthesis and Characterization of 10-Se-3 Type Selenatetraazapentalene Derivatives with A Hypervalent Selenium. PHOSPHORUS SULFUR 1992. [DOI: 10.1080/10426509208045829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Synthesis of Novel Tetraazapentalenes with Fused Cyclic Systems: Reaction of Tetraazapentalene Derivatives with 2-Bromoethyl and 3-Bromopropyl Isothiocyanates. SYNTHESIS-STUTTGART 1991. [DOI: 10.1055/s-1991-26492] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Abstract
Cephalothin sodium (CET-Na) in crystals can be obtained by freezing the aqueous solution and subsequent warming at a fixed temperature for facilitating crystallization prior to vacuum application for drying. The product has, however, been found to unavoidably contain traces of the amorphous CET-Na, which causes a rapid color development during storage. By using thermal analysis, differential scanning calorimetry (DSC), electric conductometry, and polarized light cryomicrographic techniques, the solubilities in water, freezing point, eutectic point, and melting behavior of CET-Na in aqueous solution were investigated. The investigation demonstrated that CET-Na in supersaturated aqueous solution is very stable, and that seeding with microcrystalline CET-Na to the supersaturated solution and subsequent cooling of the mixture till its freezing point gives neither any evidence for crystallization nor for growth of the seed crystals. The freeze-drying of CET-Na in the supersaturated solution after seeding has been demonstrated to give crystalline CET-Na containing neither of amorphous nor of quasi-crystalline form.
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Abstract
Cephalothin sodium (CET-Na) prepared according to the conventional freeze-drying methods is known to easily develop color during storage. Since amorphous CET-Na has been reported to be markedly unstable, the color development is thought to be due to the presence of traces of CET-Na in an amorphous state observed with scanning electron microscopy. Quantitation by use of the powder X-ray diffractometry of such traces of amorphous CET-Na has proved to be of little use. Thermogravimetry (TG) and differential scanning calorimetry (DSC) have demonstrated that the freeze-dried CET-Na by the conventional methods contains three types of CET-Na: amorphous (unstable phase), quasi-crystalline (metastable phase) and crystalline (stable phase). Pyrolysis initiation temperatures of these three types of CET-Na have been demonstrated to become higher in this order. A new parameter for the evaluation of non-crystallinity of CET-Na has been introduced, in which the ratio is calculated from the data of the total weight loss observed through the pyrolysis of both amorphous and quasi-crystalline CET-Na against the total weight loss of all components during the pyrolysis of sample specimen. The ratio thus calculated is defined as "non-crystallinity". This new parameter has successfully been introduced to establish a good correlation to the degree of increasing color intensity with aging of freeze-dried CET-Na.
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Total organic carbon as an index for specification of water for injection. JOURNAL - ASSOCIATION OF OFFICIAL ANALYTICAL CHEMISTS 1987; 70:681-6. [PMID: 3624176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Determination of organic compounds present as contaminants in purified water is of great importance. Total organic carbon (TOC) may be a useful parameter for evaluating the purity of water. This paper describes and compares the analytical results for solutions of 12 model compounds obtained by 3 methods: total organic carbon (TOC) analysis, determination of potassium permanganate consumption, and UV spectroscopy. TOC analysis gave values corresponding to the expected amounts of organic carbon for all the model compounds, whereas the other 2 methods gave highly variable results.
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[Crystal growth of cephalothin sodium in a frozen solution. II. Effects of the amount of seed, concentration, and temperature]. YAKUGAKU ZASSHI 1984; 104:1268-74. [PMID: 6533287 DOI: 10.1248/yakushi1947.104.12_1268] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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[Changes in electrical conductivity of various drugs in aqueous frozen phase. II. The frozen state of aqueous solution of cephalothin sodium]. YAKUGAKU ZASSHI 1984; 104:981-5. [PMID: 6527227 DOI: 10.1248/yakushi1947.104.9_981] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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40
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[Changes in electrical conductivity of various drugs in an aqueous frozen phase. I. The measurement of eutectic temperature and collapse temperature at amorphous freezing]. YAKUGAKU ZASSHI 1984; 104:966-72. [PMID: 6527225 DOI: 10.1248/yakushi1947.104.9_966] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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41
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[Crystal growth of cephalothin sodium in frozen solution. I. Determination of crystallinity in frozen solution]. YAKUGAKU ZASSHI 1984; 104:973-80. [PMID: 6527226 DOI: 10.1248/yakushi1947.104.9_973] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Studies on the stabilities of thiamine and its modified compounds. XII. Stabilities of O-, S-, and O,S-bis(ethoxycarbonyl)thiamines in neutral aqueous solution. YAKUGAKU ZASSHI 1969; 89:331-5. [PMID: 5815792 DOI: 10.1248/yakushi1947.89.3_331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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44
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[Studies on the stabilities of thiamine and its modified compounds. X. Stabilities of S-alkoxycarbonylthiamines in acid aqueous solution]. YAKUGAKU ZASSHI 1969; 89:310-9. [PMID: 5815790 DOI: 10.1248/yakushi1947.89.3_310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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45
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Studies on the stabilities of thiamine and its modified compounds. XI. Stabilities of O,S-bis(alkoxycarbonyl)thiamines in acid aqueous solution. YAKUGAKU ZASSHI 1969; 89:320-30. [PMID: 5815791 DOI: 10.1248/yakushi1947.89.3_320] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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[Studies on the stability of thiamine and its modified compounds. IX. Stability of thiamine-O-esters in acid aqueous solutions]. YAKUGAKU ZASSHI 1968; 88:1552-8. [PMID: 5752578 DOI: 10.1248/yakushi1947.88.12_1552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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