ANALYSIS OF GASES DISSOLVED IN GLASS AND GASES PRESENT IN SEEDS*

A method of analysis for gases dissolved in glass has been developed which gives more reproducible results than those previously reported. The problem of the volatilization of alkali from the sample during the course of analysis appears to have been satisfactorily solved through the use of an auxiliary furnace. A number of commercial glasses have been analyzed for dissolved gases. Water vapor, sulfur dioxide, and oxygen are the principal gases found in flint glass. Water vapor seems to be the principal constituent of the gases found in amber glass. A method for the analysis of gases present in seeds in glass has been developed which gives fairly satisfactory quantitative results on samples containing more than 1 cu. mm. of gas. The results obtained on samples containing less than 1 cu. mm. of gas are qualitative only. The procedure consists (1) in the determination of the temperatures at which gases present in the seeds undergo a change of state and (2) in the microchemical analysis of these same gases. Seeds have been found that contained entrapped air, sulfur dioxide, and also carbon dioxide. Some seeds, especially those in amber glass, appear to be vacuum seeds, and these frequently contain a deposit on the inside which has been identified as a sulfite or a sulfate.     

The electrochemical kinetics of sulfur dioxide reactions in molten bisulfates

Alkali-metal bisulfates are candidate electrolytes for use in electrochemical flue-gas desulfurization. The kinetics are explored of the electrochemical reactions of gases containing sulfur dioxide and oxygen on gold electrodes in alkali bisulfate at 205°C. The cathodic reaction is found to be strongly dependent upon gaseous sulfur dioxide content, but nearly independent of oxygen, within the range of the experiment. All evidence points to a scheme whereby dissolved sulfur dioxide reacts with an oxide layer on the electrode to form pyrosulfate. The anodic reaction also appears strongly dependent on sulfur dioxide concentration; however, the pathway remains unclear.     

Equilibrium and Transport Properties of Gases in E-Glass Melts

The solubility and diffusion coefficients of oxygen, sulfur dioxide, and water were determined (and those for nitrogen, carbon dioxide, and argon were estimated) in commercial E-glass melts as a function of melt temperature and atmosphere. Knowledge of these fundamental constants of gases in glass melts is required for the development of models for bubble growth and elimination within the melt. The effectiveness of fining agents can be traced to the production of those gases in the melt which possess the greatest variation in solubility and diffusion as a function of the temperature and atmosphere. Accordingly, oxygen through multivalent elements and sulfur are the best fining agents for glass production.     

Raman Microprobe Investigation of Oxygen and Carbon Dioxide Dissolution from Bubbles in Silicate Glasses Containing Arsenic Oxide

Raman microprobe analysis was used to investigate the changes in the relative concentrations of oxygen and carbon dioxide found in bubbles in silicate glasses containing different amounts of arsenic oxide, sodium nitrate, and/or sodium nitrite after various heat treatments. As expected, analysis of the spectral data clearly indicated that addition of arsenic oxide to the glass accelerates the relative rate of oxygen dissolution with respect to carbon dioxide. Addition of either sodium nitrate or sodium nitrite to the glass composition containing arsenic oxide generates a relative rate of oxygen dissolution that is intermediate between those for the glass containing no refining agent and the silicate glass containing only arsenic oxide. This relative rate of oxygen dissolution is closely related to the amount of As³⁺ that is present in the glass.     

Comparison of the sulfation rates of calcium,magnesium and zinc oxides with SO2 and SO3

The sulfation rates of reagent grade calcium and zinc oxides and technical grade magnesium oxide with sulfur trioxide and sulfur dioxide - oxygen mixtures have been measured thermogravimetrically. Experiments have been conducted to determine the rate of reaction for various particle radii (0.071-0.151 mm), temperatures (450-1100 K.) and concentrations of sulfur dioxide, sulfur trioxide (0.075-0.62 moles/m³), oxygen (0-1.5 moles/m³). Experimental results are presented which compare the sulfation rates of each basic oxide with sulfur dioxide and sulfur trioxide at different temperatures. The rate of sulfation of different oxides are compared under the same experimental conditions.     

淤浆反应器中SO_2的催化氧化

研究了常温常压下淤浆反应器中SO_2催化氧化反应,通过改变反应物的进口浓度和测定小颗粒床层平均氧化反应速率(此时传质阻力最小),间接验证了假定的反应机理:氧在活性炭活性位上的吸附为速率控制步骤,本征反应速率相对于颗粒表面的溶氧浓度为一级,而与此浓度范围内的SO_2浓度无关,通过改变催化剂的用量、粒径及反应温度,测定了各模型参数.     

DYNAMIC ADSORPTION OF S02 ON ZEOLITE MOLECULAR SIEVES†

Sulfur dioxide is one of the major pollutants resulting from fuel combustion. Numerous dry, semi-dry and wet processes have been developed for pollution control of sulfur dioxide. Solid carbonates, natural and synthetic zeolites, ion exchange resins and carbon based sorbents are the most commonly used dry sorbents for sulfur dioxide removal

In this study, measurements of the adsorption properties of sulfur dioxide on zeolites were investigated. The adsorbents used in this work are 5A, 4A and AW300 type molecular sieve zeolites. Adsorption equilibrium parameters were determined from the pulse chromatographic response to injections of low concentrations of sulfur dioxide. The method of moments were used to evaluate the adsorption equilibrium parameters from pulse chromatographic experiments. Data, such as adsorption equilibrium constants or reaction rate parameters are essential in the design of adsorption systems or reactors in which sulfur dioxide is removed

The experiments were conducted in a temperature range of 523-718 K. The relatively strong adsorption properties of sulfur dioxide on zeolites necessitated the use of high carrier gas flow rates and subsequently non-isobaric operation. Non-isobaric pulse chromatography theory was found to describe accurately the adsorption trends." printpubdate="Adsorption equilibrium constants of S0₂ were found to decrease considerably with increasing temperature. It was also found out that adsorption of SO₂ on the adsorbents investigated were found to decrease in the order of AW300 ≤ 4A ≤ 5A. The adsorption equilibrium parameter of S0₂ on 5A was found as 11.78 at 673 K, whereas it has a value of 157.11 at 523 K. The adsorption equilibrium parameter of S0₂ on 4A zeolite was determined to be 8.63 at 718 K and 213.78 at 523 K.     

CFD simulation of chemical reaction between sulfur dioxide and water in a venturi scrubber

ABSTRACT

The use of fossil fuel, i.e., coal, was first initiated in 1880s for electricity generation. It was used extensively worldwide due to its cheap rate. Consequently, there is an adverse effect on the environment that results in a climate change. Many industries were working on cleaning flue gases emitted from coal power plants according to Environmental Protection Agency (EPA) standards by using different scrubbing technologies and venturi scrubber is one of them having ability to remove particulates and toxic gases simultaneously. Industries were using computational fluid dynamics (CFD) techniques to fully understand the gases behavior inside scrubbing technologies prior employed in the project. This research represents CFD simulation to study abatement process of sulfur dioxide through chemical reaction with water in a venturi scrubber. Parameters such as mass concentration of sulfurous acid formation, sulfur dioxide and water mass content distribution inside venturi scrubber were analyzed. The sulfur dioxide removal efficiency was also investigated. The results show that water mass content distribution was greatly influenced by sulfur dioxide mass flow rates. Desulfurization efficiency depreciates with an increase in sulfur dioxide mass flow rate, whereas efficiency increases with accession in liquid to gas ratio. Maximum sulfur dioxide removal was observed at lower sulfur dioxide concentration comparatively to higher concentration of sulfur dioxide.     

Role of Amines in Adhesion of Polybutadiene to Glass Substrates. II. Reactions of Amines with Trimethoxysilanol and/or Fumed Silica

This paper is part of a larger investigation of the role of amines in the adhesion of polybutadiene to glass substrates. It describes near infrared, infrared and nuclear magnetic resonance spectroscopy studies of the interaction of amines with silanol groups usually under ambient conditions but sometimes when heated in air. Additional supporting evidence was obtained from gas liquid chromatography, mass spectrometry and elemental analyses. In order to assure a sufficiently high concentration of silanol groups, triethylsilanol and fused silica were used as models for the glass surface. The mechanism of interaction of aliphatic amines and of the aminosilane was different from that of aromatic amines. Most notably, reaction of aliphatic amines with carbon dioxide in the air and/or dissolved/adsorbed in/on the silanol occurred almost instantaneously, whereas the corresponding reaction of the aromatic amines with carbon dioxide was not observed under the experimental conditions used. The carbamates formed underwent further reactions much more rapidly than either the simple aromatic amines or the unmodified aliphatic amines.     

GASES IN GLASS*

An apparatus is described for extracting the gas from glass at glass-furnace temperature and determining its composition. Results are given for glasses of various compositions and various melting histories. All ordinary glasses were found to contain appreciable quantities of dissolved (or chemically combined) gas, the amount varying from a few hundredths to a few tenths per cent. Water is frequently the most abundant gas, the content being highest in borosilicate glasses. Carbon dioxide is also usually present, the amount depending on the basicity of the glass. Nitrogen, carbon monoxide, and hydrogen were never found present in appreciable quantities. All oxidized glasses contain some oxygen. Glasses containing arsenic give off a comparatively large volume of oxygen. The effect of this oxygen on fining is discussed. It has been found that remelting a glas has little effect on the gas content. The gas content is greatly influenced by the size of the melt, being the lowest in small experimental melts.     

Oxidation of aqueous sulfur dioxide catalyzed by poly-4-vinylpyridine–Cu(II) complex. Part 1: Homogeneous phase oxidation

The oxidation of aqueous sulfur dioxide in the presence of polymer-supported copper(II) catalyst is also accompanied by homogeneous oxidation of aqueous sulfur dioxide catalyzed by leached copper(II) ions. Aqueous phase oxidation of sulfur dioxide of low concentrations by oxygen in the presence of dissolved copper(II) has therefore been studied. The solubility of SO₂ in aqueous solutions is not affected by the concentration of copper(II) in the solution. In the oxidation reaction, only HSO is the reactive S(IV) species. Based on this observation a rate model which also incorporates the effect of sulfuric acid on the solubility of SO₂ is developed. The rate model includes a power-law type term for the rate of homogeneous phase reaction obtained from a proposed free-radical chain mechanism for the oxidation. Experiments are conducted at various levels of concentrations of SO₂ and O₂ in the gas phase and Cu(II) in the liquid phase. The observed orders are one in each of O₂, Cu(II) and HSO. This suggests a first-order termination of the free radicals of bisulfite ions.     

Equilibria in a Limestone Based FGD Process: A Pure System and with Chloride Addition

On the basis of physical and chemical equilibria conditions a model of gaseous sulfur dioxide solubility in the solutions applied in an FGD (flue‐gas desulfurization) process was developed. The dependencies of solution pH in the bulk liquid and in the limestone particle vicinity on the calcium carbonate and/or on the dissolved sulfur dioxide content are presented. The influence of the concentration of dissolved carbon dioxide on pH, sulfite to sulfate oxidation conditions, limestone and calcium sulfite solubility are also discussed. The mechanisms leading to a decrease in calcium carbonate solubility or limestone particle blinding are explained. The restrictions in calcium chloride concentration for the reliable operation of an FGD process are predicted.     

Grafting of vinyl monomers by the xanthate method

The removal of oxygen from swollen pulp is very difficult. At least 1–2 h of purging with oxygen-free nitrogen or argon is required as well as efficient mixing and a low concentration of pulp (not higher than 1%). During the grafting reaction, in which the xanthate cellulose is a part of the redox system, the concentration of oxygen falls to zero and stabilizes at this level even if air is purged through the system or a higher rate of stirring is applied. Primary sulfur radicals created in the reaction of the xanthated groups with H₂O₂ are further oxidized by H₂O₂ or by particles of oxygen dissolved in the reaction mixture. The observed increase in reaction caused by an increase in stirring speed is due to the higher rate of diffusion of hydrophobic monomers as well as the diffusion of oxygen to active centers at high stirring speed. The low rate of grafting at lower agitation speeds is caused by agglomeration of monomer molecules to bigger particles and, as a result, decreased diffusion of monomer to active centers. Above 300 rpm, the effect of monomer diffusion diminishes and further increase in conversion is caused only by a higher rate of oxygen diffusion to active centers from reaction mixture or passing gas. However, above a certain level of oxygen, the effect of termination by oxygen prevails and the rate of reaction decreases. Additives increase the conversion in the lower range of agitation speed only. The application of additives and agitation are two equivalent methods, both of which lead to an increase in conversion in the lower range of stirring speed.     

OXIDATION OF SULFUR DIOXIDE IN DIFFERENT TYPES OF THREE PHASE REACTORS

Five different types of three-phase reactors are compared with each other by using oxidation of sulfur dioxide on activated carbon. The kinetic measurements were carried out by changing concentrations of sulfur dioxide from 0.04 to 0.17% (volume) and those of oxygen from 2 to 21%. The reaction rate was 0.2 order with respect to sulfur dioxide and 0.5 order with respect to oxygen. The catalytic effectiveness factor and intraparticle diffusivity were evaluated by changing particle sizes of activated carbon from 0.03 to 1.6 mm. Resistances of gas-liquid, liquid-solid mass transfer and intraparticle diffusion were estimated for individual reactors. The optimum reactor was dependent on operating conditions such as gas flow rates, rotating speeds and particle sizes.     

Chemical transformations of sulfur compounds adsorbed onto activated carbon materials during thermal desorption

Four commercial activated carbon materials, including two fiber cloths, were studied as adsorbents for three organosulfurs in terms of adsorption and thermal regeneration, the organosulfurs being ethyl mercaptan, isopropyl mercaptan and tetrahydrothiophene. Their performance is interpreted using their inherent porosity and surface functional groups characteristics. The most porous granular carbon with acidic surface functional groups performed better than the other adsorbents at a high organosulfur concentration. However, at a low concentration the fiber cloths exhibit greater adsorption than granular materials, thereby confirming their potential to desulfurize various gases. Thermal desorption was performed in nitrogen and oxidizing atmosphere, the major role of oxygen in the degradation process of the organosulfurs has been pointed out. Mercaptans are oxidized to their respective sulfide, disulfide, sulfur dioxide, minor carbonyl compounds and elemental sulfur, whereas tetrahydrothiophene by-products are limited to thiophene, sulfur dioxide, elemental sulfur and traces of sulfone compound. Based on the various observed by-products, the oxidative degradation pathways for the three organosulfurs are presented in this study.     

FUNCTIONS OF MINOR CONSTITUENTS IN COMMERCIAL SELENIUM RUBY BATCH*

In addition to the chemicals essential to the formation of the colorant, the nature of which is well established, successful commercial selenium ruby batches commonly contain a number of characteristic minor ingredients. These are zinc oxide, cryolite or other fluorine compounds, bone ash, and minute amounts of copper or nickel oxide. Laboratory experiments are described which helped to establish the functions of these minor constituents. Owing to the extreme insolubility of copper and nickel sulfide in silicate melts, these compounds form at high temperatures and provide nuclei for the cadmium sulfoselenide which requires a lower temperature for its formation. Bone ash, especially in combination with fluoride, leads to a very insoluble phase, apatite, which enhances the striking of the selenium ruby. Formation of cadmium sulfoselenide will not take place at high temperatures. Introducing fluorine into a silicate glass facilitates molecular rearrangements because of the weaker forces exerted by this monovalent anion as compared with divalent oxygen ions. Fluorides increase the low-temperature mobility of the glass and speed up the striking process. The chief function of zinc oxide is to retain sulfur and selenium in the melt. Alkali sulfoferrite and selenoferrite produce a red-brown color, and their formation in glasses containing strong reducing agents, such as carbon, accounts for the deep color of some glasses containing only small amounts of cadmium sulfoselenide.     

Investigation of the energetics of methane-utilising bacteria in methane- and oxygen-limited chemostat cultures

A special apparatus was used to establish methane- and oxygen-limited chemostat cultures of a methane-utilising bacterium, at 30 °C, pH = 7.0, respectively. Although total growth yields with respect to methane and oxygen were hardly affected by dissolved oxygen concentration in the medium, provided dilution rate was kept nearly at 0.1 h^?1, these values appeared to increase slightly with the increase of dilution rate. Assuming that no metabolites other than carbon dioxide and water were produced during bacterial growth, maintenance coefficients and true growth yields were assessed from specific rates of methane uptake and respiration. These energetic constants, nearly independent of the limiting substrates, either methane or oxygen, were compared with those from published data on facultative and obligate aerobes, including a mixed culture of methane-utilising bacteria.     

High-voltage arc erosion behavior and mechanism of Ti3AlC2 under different ambient atmospheres

The arc erosion behavior of Ti₃AlC₂ in oxygen, air, nitrogen, carbon dioxide, argon, and sulfur hexafluoride atmospheres at 9 kV voltage was studied. The breakdown strength increased in the order of oxygen, air, carbon dioxide, nitrogen, argon, and sulfur hexafluoride, whereas the arc energy decreased. Cracks, pits, and bulges on the eroded surface were investigated using scanning electron microscopy and three-dimensional (3D) laser confocal scanning microscopy. Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to determine the composition of the eroded surface. The arc energy and electromagnetic force lead to the formation of erosion characteristics. The mechanism of erosion under the different atmospheres is discussed systematically, and is called the “decomposition-oxidation” process in oxygen, air, and carbon dioxide and the “decomposition-rereaction” process in nitrogen and sulfur hexafluoride. This study provides a reference for the application of MAX phase materials in high-voltage electrical appliances.     

旋转填充床中SO2与O2同时吸收的扩散-反应模型

引　言迄今为止 ,旋转填充床 (ＲａｔａｔｉｎｇＰａｃｋｅｄＢｅｄ ,ＲＰＢ)用于模拟烟气的脱硫吸收 (包括物理吸收和化学吸收 )已经有了较多的研究 ,ＲＰＢ中ＳＯ2 物理吸收的传质模型已有报道[1～ 3] ,但有关化学吸收的数学模型还属鲜见 .在数学上描述ＲＰＢ中ＳＯ2 化学吸收的传质 -反应特征 ,必须考虑物质传递和化学反应两个方面的影响因素以及这两种因素间的相互关系 .描述气 -液相之间的物质传递过程有不同的传质模型[4 ,5] ,如双膜理论、Ｈｉｇｂｉｅ渗透理论、Ｄａｎｃｋｗｅｒｔｓ表面更新理论和湍流传质理论等 ,但用之于处理具体…     

旋转填充床中SO2与O2同时吸收的扩散-反应模型

In this paper the rotating packed bed, a new type of absorber, which has high mass-transfer characteristic by means of centrifugal field instead of gravity field, is used to study on stimulated flue gas desulfurization. Based on experimental data,a model of mass-transfer and reaction of the sulfur dioxide chemical absorption in the rotating packed bed reactor is proposed according to the film-theory. It can be used to predict the performance of the total absorption rate and the enhancement factor of the sulfur dioxide and oxygen simultaneous absorption in the rotating packed bed reactor.The prediction of the model is consistent with the experimental result varying operating conditions, and the relative error between experimental result and predicted result is below 12%. Some interesting potential projects of simultaneous absorption of sulfur dioxide and oxygen in the rotating packed bed reactor are also discussed.