共查询到20条相似文献,搜索用时 15 毫秒
1.
建立了氯体系电子活度(pε)和pH优势区域图(pε-pH)图,从酸化、氧化和还原的角度,探讨了标准状态下pε和pH对二氧化氯制备和稳定性的影响。实际生产不可能制备绝对纯净的二氧化氯。对于不同的水体,由于其pε和pH值不同,因而可能使二氧化氯表现出不同的稳定性特征。如果水溶液中二氧化氯不歧化为氯酸根,二氧化氯相对稳定,并与亚氯酸根、氯分子或氯离子稳定共存。当氯体系实现最终平衡时,二氧化氯仅在强酸介质中优势存在,随着酸度降低,二氧化氯歧化为氯酸根和氯气,水溶性和二氧化氯在常规pH条件下不稳定。 相似文献
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The proposed work describes a simple spectrophotmetric as well as a titrimetric method to determine sulfur dioxide. The spectrophotometric method is based on a redox reaction between sulfur dioxide and iodine monochloride obtained from iodine with chloramine-T in acetic acid. The reagent iodine monochloride oxidizes sulfur dioxide to sulfate, thereby reducing itself to iodine. Thus liberated iodine will also oxidize sulfur dioxide and reduce itself to iodide. The obtained iodide is expected to combine with iodine to form a brown-colored homoatomictriiodide anion (460 nm), which forms an ion-pair with the sulfonamide cation, providing exceptional color stability to the system under an acidic condition, and is quantitatively relatd to sulfur dioxide. The system obeys Beer's law in the range 5 - 100 microg of sulfur dioxide in a final volume of 10 ml. The molar absorptivity is 5.03 x 10(3) l mol(-1)cm(-1), with a relative standard deviation of 3.2% for 50 microg of sulfur dioxide (n = 10). In the titrimetric method, the reagent iodine monochloride was reduced with potassium iodide (10%) to iodine, which oxidized sulfur dioxide to sulfate, and excess iodine was determined with a thiosulfate solution. The volume difference of thiosulfate with the reagent and with the sulfur dioxide determined the sulfur dioxide. Reproducible and accurate results were obtained in the range of 0.1 - 1.5 mg of sulfur dioxide with a relative standard deviation of 1.2% for 0.8 mg of sulfur dioxide (n = 10). 相似文献
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Infrared spectra of nitrogen and argon matrices containing ammonia and carbon dioxide have been recorded. A 1:1 ammonia carbon dioxide complex has been observed. The geometry of the complex has been deduced from its infrared spectrum. Carbon dioxide disturbs the rotation of ammonia in argon. 相似文献
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S. V. Makarov А. А. Kuznetsova D. S. Salnikov А. G. Kiseleva 《Russian Journal of General Chemistry》2018,88(4):646-649
The effect of glycine and monoethanolamine on the stability and reductive activity of thiourea dioxide in the reaction with acid orange II dye was studied. It was found that, in contrast to glycine, introduction of additives of monoethanolamine into aqueous solution of thiourea dioxide substantially increases its reductive activity in alkaline solutions, although the stability of the thiourea dioxide monoethanol amine derivative in alkaline solutions is much lower than that of thiourea dioxide and the product of its reaction with glycine. 相似文献
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The reactions of titanium monoxide and dioxide molecules with carbon dioxide were investigated by matrix isolation infrared spectroscopy. It was found that the titanium monoxide molecule is able to activate carbon dioxide to form the titanium dioxide-carbon monoxide complex upon visible light excitation via a weakly bound TiO(η(1)-OCO) intermediate in solid neon. In contrast, the titanium dioxide molecule reacted with carbon dioxide to form the titanium monoxide-carbonate complex spontaneously on annealing. Theoretical calculations predicted that both activation processes are thermodynamically exothermic and kinetically facile. 相似文献
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Zhou M Zhou Z Zhuang J Li ZH Fan K Zhao Y Zheng X 《The journal of physical chemistry. A》2011,115(50):14361-14369
Carbon dioxide coordination and activation by niobium oxide molecules were studied by matrix isolation infrared spectroscopy. It was found that the niobium monoxide molecule reacted with carbon dioxide to form the niobium dioxide carbonyl complex NbO(2)(η(1)-CO) spontaneously on annealing in solid neon. The observation of the spontaneous reaction is consistent with theoretical predictions that this carbon dioxide activation process is both thermodynamically exothermic and kinetically facile. In contrast, four niobium dioxide-carbon dioxide complexes exhibiting three different coordination modes of CO(2) were formed from the reactions between niobium dioxide and carbon dioxide, which proceeded with the initial formation of the η(1)-O bound NbO(2)(η(1)-OCO) and NbO(2)(η(1)-OCO)(2) complexes on annealing. The NbO(2)(η(1)-OCO) complex rearranged to the η(2)-O,O bound NbO(2)(η(2)-O(2)C) isomer under visible light irradiation, while the NbO(2)(η(1)-OCO)(2) complex isomerized to the NbO(2)(η(1)-OCO)(η(2)-OC)O structure involving an η(2)-C,O ligand under IR excitation. In these niobium dioxide carbon dioxide complexes, the η(1)-O coordinated CO(2) ligand serves as an electron donor, whereas both the η(2)-C,O and η(2)-O,O coordinated CO(2) ligands act as electron acceptors. 相似文献
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Minoru Matsuda Masashi Iino Shun-Ichi Numata 《Journal of polymer science. Part A, Polymer chemistry》1972,10(3):829-836
The radical terpolymerization of sulfur dioxide, styrene, and methyl methacrylate in o-dichlorobenzene with 2,2′-azobisisobutyronitrile was carried out in order to clarify the propagation mechanism of the radical copolymerization of sulfur dioxide and styrene, especially as a function of total concentration of sulfur dioxide and styrene. From the analysis of the trigonal composition diagrams it has been definitely shown that the radical copolymerization of sulfur dioxide and styrene proceeds by the propagation of two monomers, but the usual type of copolymerization mechanism, explicable in terms of the Lewis-Mayo equation, is not applicable to this copolymerization. The participation in the propagation of a monomer charge-transfer complex consisting of sulfur dioxide and styrene was also ruled out. 相似文献
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O. G. Tsiklauri T. A. Marsagishvili G. S. Tsurtsumiya S. A. Kirillov D. I. Dzanashvili 《Russian Journal of Electrochemistry》2008,44(10):1166-1170
Corrosion and adsorption properties of manganese dioxide, which was anodically deposited on platinum, its powder, and compacted tablets of manganese dioxide in the solutions with various pH values are studied using various experimental methods. It is shown that the corrosion rate of manganese dioxide decreases with increasing pH of solution, and the process proceeds by the electrochemical mechanism with conjugate chemical reactions of the formation and decomposition of the product of transition stage. The adsorption properties of manganese dioxide powder with respect to copper ions increase with increasing pH of solution, whereas the amount of manganese ions passing to the solution almost vanishes at pH 9. 相似文献
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Yingwu Yao Naichuan Yu Limiao Jiao Chunmei Zhao 《Russian Journal of Electrochemistry》2016,52(2):163-168
Lead dioxide electrodes were prepared by pulse electrodeposition in the lead nitrate solution with different pulse current density. The effects of pulse current density on the morphology and structure of lead dioxide electrodes were studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The SEM and XRD results show that the increase of pulse current density can make the morphology more fine, and the crystal size of lead dioxide decreases with the increase of pulse current density. The anodic polarization curves demonstrate that the oxygen evolution overpotentials of lead dioxide electrodes also enhance with the increase of pulse current density. The stability of lead dioxide electrodes enhances with the increase of pulse current density until 15 mA cm–2, then the stability decreases. The electrocatalytic property of lead dioxide electrodes was examined for the electrochemical oxidation of rhodamine B (RhB). The results show that the RhB removal efficiency on the lead dioxide electrodes increases with the increase of pulse current density, which can be attributed to the increase of oxygen evolution overpotential. 相似文献
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Billemont P Coasne B De Weireld G 《Langmuir : the ACS journal of surfaces and colloids》2011,27(3):1015-1024
The adsorption of carbon dioxide and methane in nanoporous carbons in the presence of water is studied using experiments and molecular simulations. For all amounts of adsorbed water molecules, the adsorption isotherms for carbon dioxide and methane resemble those obtained for pure fluids. The pore filling mechanism does not seem to be affected by the presence of the water molecules. Moreover, the pressure at which the maximum adsorbed amount of methane or carbon dioxide is reached is nearly insensitive to the loading of preadsorbed water molecules. In contrast, the adsorbed amount of methane or carbon dioxide decreases linearly with the number of guest water molecules. Typical molecular configurations obtained using molecular simulation indicate that the water molecules form isolated clusters within the host porous carbon due to the nonfavorable interaction between carbon dioxide or methane and water. 相似文献
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Tellurium dioxide, trimethylchorosilane, acetyl chloride, or acetyl bromide in glacial acetic acid generated a homogeneous solution. Addition of cyclohexene produced trans-2-halocyclohexyl tellurium trihalides of excellent purity in 70% yield. With dichloromethane or ethanol-free chloroform the same compounds were obtained from heterogeneous reaction mixtures. trans-2-Methoxycyclohexyl tellurium trichloride was obtained quantitatively from tellurium dioxide, trimethylchlorosilane, and cyclohexene in absolute methanol. In the absence of cyclohexene, tellurium tetrachloride was obtained in 91% yield from tellurium dioxide and trimethylchlorosilane in chloroform, and tellurium tetrabromide in 98% yield from tellurium dioxide and acetyl bromide in glacial acetic acid. 相似文献
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Rapid methods for the identification of chlorine and chlorine dioxide in air by a sensor are proposed. The methods are based on the different sensitivity of the sensor to chlorine and chlorine dioxide, depending on the temperature of its surface and the capability of chlorine dioxide to decompose readily under photolysis and thermolysis. 相似文献
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以实验数据为依据, 结合双Langmuir模型研究了用高比表面活性碳微球材料分离H2中少量CO2的行为. 在实验中, 用高精度的IGA-003重力吸附仪测定了温度为298、273 和268 K, 压力在0-1.8 MPa范围内CO2、H2及n(CO2):n(H2)=1:9混合物在活性碳微球中的吸附等温线. 比较不同吸附模型的计算结果与实验数据, 结果表明, 双Langmuir模型与实验结果拟合得较好; 而且通过结合理想吸附溶液理论, 该模型可以准确地计算不同的混合物体系(包括H2-CO2体系)的吸附量和吸附选择性. 利用该模型求解了不同温度下各组分的分吸附量, 得到了CO2的吸附选择性;在268 K和1.7 MPa下, CO2的吸附选择性可达到73.4, 表明活性碳微球是一种优秀的吸附H2中少量CO2的材料. 相似文献
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《Analytical letters》2012,45(7):1237-1243
Abstract This research deals with the quantitative formation of carbon dioxide in electrolytic oxidation reactions. The electrolytic reactions were run with barium peroxide to generate the superoxide anion at the anode. With the organic compounds used in these electrolytic studies we needed to develop a method where we could determine the amount of carbon dioxide liberated from these compounds with the superoxide anion. This method degasses an acidified solution with dry nitrogen, which carries the carbon dioxide to a standard solution of sodium hydroxide. Titration of the sodium hydroxide solution with standardized hydrochloric acid revealed the amount of carbon dioxide formed in the reaction after precipitation of the carbonate ions with barium chloride. Blank runs with the apparatus using anhydrous sodium carbonate produced 99% plus results of recovered carbon dioxide from the sodium carbonate. 相似文献
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二氧化碳和甲醇合成碳酸二甲酯研究进展 总被引:10,自引:0,他引:10
本文综述了以二氧化碳和甲醇为起始原料合成碳酸二甲酯(DMC)的研究状况。提出以CO2和甲醇直接合成DMC,不仅对合成化学,碳资源利用和环境保护具有重大意义,而且可使生产成本显著降低,它是发展DMC生产的一个具有很大潜力的方面。 相似文献
20.
P. Colombo J. Fontana M. Steinberg 《Journal of polymer science. Part A, Polymer chemistry》1968,6(12):3201-3215
The radiation-induced copolymerization of ethylene and sulfur dioxide has been studied in the liquid and gas phases. In the liquid phase, the copolymer composition remained equimolar over a temperature range of 20–160°C. and ethylene pressures of 50–680 atm. The rate of copolymerization in the liquid phase at 680 atm. increased with temperature to a maximum value at ~80°C. Above this temperature the rate steadily decreased to zero at 157°C. because of temperature-dependent depropagation reactions. In the gas phase, copolymers were formed that contained from 9 to 46 mole-% sulfur dioxide. Under constant conditions of temperature, pressure, and radiation intensity, the copolymerization rate in the gas phase increased with increasing sulfur dioxide in the initial gas mixture. The propagating species for the liquid-phase experiments is considered to consist of an equimolar complex molecule of ethylene and sulfur dioxide. For gas mixtures containing an excess molar concentration of ethylene, the propagating species are ethylene and the complex molecule. Infrared spectra show polysulfone structures. Calorimetric and x-ray diffraction analyses indicate crystalline structures for copolymers in the range 9–50 mole-% sulfur dioxide, although a melt transition temperature could not be observed for copolymer containing >31 mole-% sulfur dioxide. Clear uniform film was obtained with copolymers containing up to 31 mole-% SO2. 相似文献