Reaction kinetics of the reaction between carbon dioxide and glycidyl methacrylate using tetraoctylammonium chloride as catalyst

Carbon dioxide was absorbed in an organic solutions of glycidyl methacrylate (GMA) in a semi-batch stirred tank with a plane gas-liquid interface at 101.3 kPa to obtain the absorption rate of carbon dioxide, from which the reaction kinetics of the reaction between carbon dioxide and GMA as studied using tetraoctylammonium chloride as catalyst. The reaction rate constants were estimated from the mass transfer mechanism accompanied by the pseudo-first-order reaction with respect to the concentration of carbon dioxide. An empirical correlation formula between the reaction rate constants and the solubility parameters of solvents such as toluene, N-methyl-2-pyrrolidinone, and dimethyl sulfoxide is presented.     

Coulometric titration of acids in isopropanol-I A rapid direct method for the determination of carbon in steel

A new procedure is described for the direct coulometric titration of the carbon dioxide liberated in the high-temperature combustion of steel. The carbon dioxide is absorbed in isopropanol containing 3% of ethanolamine and titrated with 100% titration efficiency with a constant current of 50 mA and spectrophotometric detection of the end-point. The accuracy and precision of the method have been established by the analysis of a wide range of standard steel samples.     

Absorption and foaming of plastics using carbon dioxide

In this study, carbon dioxide was used as a foaming agent for common plastics, such as acrylonitrile–butadiene–styrene (ABS) polymer, polystyrene (PS), polypropylene (PP), high-density polyethylene (HDPE), and high impact polystyrene (HIPS). Carbon dioxide was first absorbed by the sample plastics placed within a pressure vessel at various pressure levels and absorption time intervals. The Henry’s constant of the absorbed carbon dioxide in the plastics was determined. The diffusion coefficient of carbon dioxide in polymer was also identified by curve-fitting with the relationship between the absorbed amount and time. The results showed that ABS, PS, and HIPS absorbed more gas than did PP and HDPE, because PP and HDPE exhibit higher crystallinity. Generally, a polymer can take up saturation absorption of gas under higher pressure. After absorption, the foaming process occurred at various temperatures and time intervals. The cell structure, density, and size of the plastic foams were then investigated using scanning electron microscopy. A longer foaming period and higher temperature increase the size of the cell and decrease the cell density (the number of bubbles per unit volume). A dense skin layer without bubbles appeared directly adjacent to the surface of the foamed plastics. Its thickness decreased if the foaming process took place at higher temperatures.     

Determination of Carbon Dioxide in Finely Dispersed Diopside Using IR Spectroscopy

It has been shown that carbon dioxide can be determined in finely dispersed diopside using IR spectroscopy. For the concentrations of absorbed CO₂ from 1 to 20 wt %, the ratio of the logarithms of corresponding absorption bands depends linearly on its concentration. This linear relationship can be used for the determination of carbon dioxide.     

The absorption of carbon dioxide in solutions of monoethanolamine

Infrared, thermogravimetric and analytical results are presented that establish that the ethanolamine salt of 2-hydroxyethylcarbamic acid is formed when carbon dioxide is absorbed in solutions of ethanolamine.     

Coulometric titration of carbon dioxide on the micro scale

A method is described for the coulometric titration of milligram and submilligram amounts of carbon dioxide. Carbon dioxide is absorbed and titrated in dry acetone containing about 0.5% of methanol and saturated with potassium iodide, in a two-compartment cell. Thymol Blue is used as visual indicator. Current integration is carried out by means of a low inertia motor or a solid-state integrator. The generation efficiency is 99-100%. The method has been applied to the determination of small amounts of carbon (0-1 mg) in organic and inorganic materials and in aqueous solution.     

Surface chemistry of polymers Adsorption and absorption of gases by polyvinylchloride

Nitrogen and carbon monoxide are physically adsorbed on polyvinylchloride between 78 and 86 K, without hysteresis. At higher temperatures, carbon dioxide (195 K), sulfur dioxide (273 and 293 K) and chloroethane (293 K) are strongly absorbed by the solid, with hysteresis. The possibility of trapping CO inside the solid indicates that PVC has an open structure at higher temperatures. The effect of heating on the polymer was also investigated.     

Reduction Characteristics of Carbon Dioxide Using a Plasmatron

To decompose carbon dioxide, which is a representative greenhouse gas, a 3-phase gliding arc plasmatron device was designed and manufactured to examine the decomposition of CO₂, either alone or in the presence of methane with and without water vapour. The changes in the amount of carbon dioxide feed rate, the methane to carbon dioxide ratio, the steam to carbon dioxide ratio, and the methane to steam ratio were used as the parameters. The carbon dioxide conversion rate, energy decomposition efficiency (EDE), carbon monoxide and hydrogen selectivity, and produced gas concentration were also investigated. The maximum values of the carbon dioxide conversion rate, which is a key indicator of carbon dioxide decomposition, in different cases were compared. The maximum carbon dioxide conversion rate was 12.3 % when pure carbon dioxide was supplied; 34.5 % when methane was injected as a reforming additive; 7.8 % when steam was injected as a reforming additive; and 43 % when methane and steam were injected together. Therefore, this could be explained that the methane-and-steam injection showed the highest carbon dioxide decomposition, showing low EDE as 0.01 L/min W. Furthermore, the plasma produced carbon-black was compared with commercial carbon-black chemicals through Raman spectroscopy, surface area measurement and scanning electron microscopy. It was found that the carbon-black that was produced in this study has the high conductivity and large specific surface area. Our product makes it suitable for special electric materials and secondary battery materials applications.     

Photo-oxidation of polymers—I: A quantitative study of the chemical reactions resulting from irradiation of polystyrene at 253.7 nm in the presence of oxygen

The photo-oxidation of polystyrene irradiated at 253.7 nm at a pressure of 600 Torr oxygen has been studied quantitatively. Quantum yields have been measured for most chemical reactions observed. It has thus been shown that only about 4% of the oxygen absorbed ultimately results in chain scissions. These occur with formation of an acetophenone-type end-group and an unsaturated chain-end simultaneously. Unsaturated chain-ends are then starting points for the building of sequences of conjugated double bonds (polyenes). About 30% of the absorbed oxygen is transformed into carbon dioxide without any permanent chain scission. Since energy is absorbed almost exclusively by the phenyl chromophores of the polymer, most of the observed reactions occur only because of energy transfer to photo-reactive products.     

New Device for Adding Polar Modifiers to Carbon Dioxide Mobile Phase for Supercritical Fluid Chromatography

Abstract

Adding additional components to supercritical carbon dioxide in supercritical fluid chromatography can extend or significantly alter the fluid solvating properties. Polar samples which are difficult to be analyzed with pure supercritical CO₂ because of their high polarity can be separated by adding polar modifiers to supercritical CO₂. In this paper, a new mixing device using a teflon high capacity filter for adding polar modifiers to carbon dioxide mobile phase is introduced. This new mixing device could keep the amount of modifier in the mobile phase constant for a much longer time than a saturator column. The amount of water or methanol dissolved in supercritical CO₂ was measured by amperometric microsensor which is made of thin film of perfluorosulfonate ionomer(PFSI).     

Notes on analytical procedures : Determination of carbon dioxide

For the determination of carbon dioxide, methods suitable for general applications are described. a. Macro-titration method. The CO2 is absorbed in sodium hydroxide in a bubble column filled with glass beads. The excess of NaOH is titrated after the addition of BaCI2. b. Scmi-micro-titration method. The CO2 is absorbed in barium hydroxide, the excess of which is determined by titration with 0.1 n hydrochloric acid on cresolphthalein as the indicator. The absorption and titration are performed in a special vessel in which the liquid is kept in circulation by the injected stream of air. c. Gravimetrical method.Method b. is specially recommended.     

The titrimetric determination of carbon dioxide with special reference to the determination of carbon in organic compounds

The titrimetric barium carbonate method for the determination of. carbon in organic compounds has been examined and the various sources of error are discussed. The carbon dioxide from the combustion of the sample is absorbed in excess baryta containing 20% (w/v) barium chloride and the excess is back-titrated with hydrochloric acid in the presence of o-cresolphthalein indicator.The value of this method in conjunction with the previously described determination of water with succinyl chloride, for the simultaneous determination of carbon and hydrogen is assessed     

Fundamentals and Environmental Applications of Non-thermal Plasmas: Multi-pollutants Emission Control from Coal-Fired Flue Gas

Simultaneous control of multi-pollutants emission from coal-fired flue gas is essential for environmental quality. Non-thermal plasma (NTP) technologies have made numerous successful applications of combined removal for sulfur dioxide (SO₂), nitrous oxide, particulate matter and mercury. Nitric oxide, elemental mercury can be oxidized in the gas phase, while fine particle gets agglomeration in the same NTP device. SO₂ gets absorbed after heterogeneous oxidation by discharge. All the gaseous pollutants and aerosols generated will be further oxidized and captured in wet NTP device. Applications of NTP and typical configurations are also summarized.     

Analytical interference effects on laser-induced fluorescence of ethylene by selected molecular species

The interference of numerous compounds on the laser-induced fluorescence of ethylene at 10.6-mm was studied. The compounds studied were methane, propane, hexane, heptane, propylene, 1-butene, acetylene, benzene, cyclohexane, acetone, chloroform, carbon tetrachloride, methanol, ethanol, sulfur dioxide, nitrogen dioxide, nitric oxide, carbon dioxide, water, argon, helium, nitrogen, and air. Only some of these, in low concentrations, interfered at atmospheric pressure, but most interfered in evacuated systems. Compounds which absorbed the excitation 10.6μm radiation enhanced the fluorescence signals of ethylene, while non-absorbing compounds generally did not interfere. The quenching efficiencies of helium, argon, nitrogen, and methane on excited ethylene molecules were determined, and compared to values calculated from published data; good agreement was found except for methane. Quenching experiments with higher concentrations of added compounds were also performed.     

Extraction of major alkaloids from poppy straw with near-critical mixtures of carbon dioxide and polar modifiers

Near-critical extraction of major alkaloids from poppy straw was performed successfully with a simple device consisting mainly of two chromatographic pumps and a pressure regulator. The optimum extractant, consisting of carbon dioxide, methanol and water, gave a quantitative extraction of thebaine, codeine and morphine in 20 min. The method was compared with a classical liquid-solid extraction procedure and carbon dioxide was shown to act as a transporting agent of the extraction solvent (methanol-water) into the vegetable matrix.     

Simultaneous microdetermination of carbon, hydrogen, chlorine, bromine, sulfur, and metals in organometallic compounds

A method for the simultaneous microdetermination of carbon, hydrogen, chlorine, bromine, sulfur, and metals which combines features of the known intermediate storage technique in organic microanalysis and formation of the metal-oxine complex, is described. Carbon and hydrogen are determined gravimetrically as usual. Sulfur and halogens are absorbed and stored on electrolytic silver. After completion of the combustion, the oxygen is replaced first by nitrogen and secondly by hydrogen which liberates the sulfur as sulfur dioxide and halogens as hydrogen halides and regenerates the silver layer. The liberated gases can be easily absorbed by dilute hydrogen peroxide and determined titrimetrically. The metal oxide, remaining in the platinum boat, is dissolved in a mixture of nitric-perchloric acids in a test tube and the metal content is determined gravimetrically and titrimetrically using 8-hydroxyquinoline.     

测定Cu—Al—O复合物催化剂表面酸碱性的微量热法

以NH3－CO2作探针分子,采用微量热法测定Cu-Al－O复合物催化剂的表面酸碱性,实验结果表明,样品的酸中心强度顺序是：0．5CAO＞CAO＞2CAO（0．5CAO,CAO,2CAO分别表示复合物中n(Cu)/n(Al)为0．5,1和2）,而碱中心强度顺序是,0．5CAO＜CAO＜2CAO。该法测定Cu-Al-O复合物表面酸碱中心的强度和密度,不受样品颜色限制,操作方便,准确度高,是用于测定固体催化剂表面酸碱性的一种较理想的定量方法。     

Conductometric determination of carbon in uranium carbide and its solution in nitric acid

A simple but accurate method has been developed for the determination of carbon in uranium carbide powders/pellets as well as in solutions of uranyl nitrates. The methodology involves quantitative conversion of carbon present in the sample to carbon dioxide that is subsequently absorbed in a dilute solution of barium hydroxide. The conductivity shift of the barium hydroxide solution is monitored on-line continuously using a laboratory-built PC-based conductivity measurement system that has been developed in-house based on the direct conversion of conductance to the digital pulse frequency. A new gas absorption cell has been designed to ensure quantitative absorption during the residence time of the gas in the cell. The method is sensitive, accurate and precise to 1-3% at 600-1000 mug of carbon in samples of uranium carbide.     

In Process Citation

A rapid simple method is described for the determination of carbon in organic compounds. The technique is based on a flash-combustion of the weighed sample (1-3 mg) in a hot empty combustion chamber at 950-1050 degrees and swept by a stream of oxygen at a rate of 80-100 ml min . Together with this flash and dynamic combustion in oxygen, a cupric oxide filling at 850 degrees is necessary. Halogens and sulphur oxidation products are retained by means of a silvered alumina filling at 750-800 degrees . Water and acidic oxides of nitrogen are absorbed at room temperature by means of magnesium perchlorate and manganese dioxide respectively. Carbon dioxide is absorbed in the cathodic compartment of an automatic coulometer and generates H(+) ions which are neutralized by OH(-) obtained by electrolysis. This method makes possible the determination of carbon in compounds containing halogens (including fluorine), phosphorus and metals. However, some metal compounds with polynuclear rings in their molecules give low results and require the addition of an oxidant to the sample in the boat for complete combustion. Vanadium pentoxide seems to be the best oxidant in the present working conditions. Solid samples are weighed and analysed in platinum or porcelain boats; liquid samples are weighed in Pyrex capillaries which are laid in platinum boats and covered with a small piece of platinum gauze. When normal liquid samples are analysed, one tip of the capillary is broken before its introduction into the combustion tube but in the case of volatile liquid samples the sealed capillary is introduced into the combustion chamber, where it explodes. The precision obtained is better than that of the classical methods.     

An effervescent reaction micropump for portable microfluidic systems

A water-activated, effervescent reaction was used to transport fluid in a controllable manner on a portable microfluidic device. The reaction between sodium bicarbonate and an organic acid, tartaric acid and/or benzoic acid, was modeled to analyze methods of controlling the generation of carbon-dioxide gas for the purposes of pumping fluids. Integration and testing of the effervescent reaction pump in a microfluidic device was made possible by using elastomeric polymers as both photopolymerizable septa and removable lids. These materials combined to enable facile access to otherwise gas-tight devices. Based on theoretical predictions for 0.33 mg of sodium bicarbonate and a stoichiometric amount of organic acid, the pumping flow rate could be varied from 0.01 microL s(-1) to 70 microL s(-1). The flow rate is controlled by adjusting any or all of the particle size of the least soluble reactant, the amount of reactants used, and the type of organic acid selected. The tartaric acid systems rapidly produce carbon dioxide; however, the gas generation rates dramatically decrease over the course of the reaction. In contrast, carbon dioxide production rate in the benzoic acid systems is lower and nearly constant for several minutes. Water activation and direct placement on a microfluidic device are key features of this micropump, which is therefore useful for portable microfluidic applications.