Carrier Gas Method Research Articles

Dissolution equilibrium of Bi vapor and activities of Bi in liquid Ni-Cr-Fe-Nb solutions

The vapor pressure and the activity coefficients of minor elements at infinite dilution in liquid Ni-Cr-Fe-Nb alloys are a necessary and important basic property that is required to analyze the behavior of trace elements during metallurgical production process. The carrier gas method has been applied in this study of the dissolution equilibrium of Bi vapor pressures over liquid Ni-Cr-Fe-Nb alloys from 1723 K to 1823K and then the activities as well as the activity coefficients of Bi in liquid Ni-Cr-Fe-Nb alloys were calculated from the results. It is found that Bi shows strong negative deviation from Henry's Law, and the relationship between the standard free energy of dissolution reaction Bi(g) = [Bi]Ni-Cr-Fe-Nb and temperature is ΔG0 = A + BT, where A is −163058 J/mol and B is 52.6 J/(mol⋅K). At 1773 K and 1873K, the activity coefficients γ of bismuth at infinite dilution is 0.442 and 0.253, respectively. Under the condition of conventional vacuum melting, the volatile lower limit of Bi can be up to 0.22 ppm, which was calculated by using thermodynamic data mentioned above.

Comparison of test methods for oxygen permeability: Optical method versus carrier gas method

The oxygen permeability of films is relevant for packaging related and technical applications. An increasingly used test method for the measurement of oxygen permeability is the optical test method, because it allows a simple and cost-efficient measurement setup. This method is based on optical chemical sensors. However, not much is known about its validity. Therefore, method validation is necessary which is subject of this study. The optical method is compared with the carrier gas method for a variety of film samples. In the tested permeability range of 0.5–2500 cm3 (STP)·(m2 d bar)−1 both methods deviated less than 20% for zero and 50% relative humidity.

Gas permeabilities of polyurethane films for fresh produce packaging: Response of O2 permeability to temperature and relative humidity

Thermoplastic shape memory polyurethane (SMPU) polymers were synthesized, cast to films, and their gas barrier properties were characterized. In addition, performance of an optical method was assessed by measuring oxygen permeability (PO2) of the films. PO2 of the SMPU film was at least two times higher than that of low density polyethylene (LDPE and increased at higher relative humidity. Permselectivity (PCO2/PO2) of the SMPU film was 15, which is approximately three times higher than for LDPE. The film absorbed circa 18% water vapor at 98% relative humidity. The optical method agreed very well (maximum 20% deviation) with a standard carrier gas method in PO2 measurement. Overall our results show that SMPU is an attractive polymer for fresh produce packaging.

Determination of Vapor Pressure of Liquid Copper by Carrier Gas Method

The relationship between the vapor pressure of liquid copper and the flow rate of carrier gas argon was discussed, when the carrier gas method was used to determine the vapor pressure of liquid copper at 1892 K. The proper argon flow rate range obtained was 150–500 mL/min and enough evidence was provided to verify the vapor pressure-flow rate of carrier gas relationship at the target temperature. Based on the proper flow rate range, the vapor pressure of liquid copper was measured at 1609–1892 K. The relationship of vapor pressure–temperature obtained by the method of regression analysis can be expressed as: ln(p/Pa) = (25.470 ± 0.903) − (39099.8 ± 1574.5)/T. Further, the thermodynamic properties including the heat of vaporization and the Gibbs free energy of the Cu (l) = Cu (g) reaction were calculated by the vapor pressure obtained over the temperature range covered.

Permeation mechanisms of pulsed microwave plasma deposited silicon oxide films for food packaging applications

Silicon oxide barrier layers are deposited on polyethylene terephthalate as permeation barriers for food packaging applications by means of a low pressure microwave plasma. Hexamethyldisiloxane (HMDSO) and oxygen are used as process gases to deposit SiOx coatings via pulsed low pressure plasmas. The layer composition of the coating is investigated by Fourier transform infrared spectroscopy and energy dispersive x-ray spectroscopy to show correlations with barrier properties of the films. The oxygen permeation barrier is determined by the carrier gas method using an electrochemical detector. The transition from low to high barrier films is mapped by the transition from organic SiOxCyHz layers to quartz-like SiO1.7 films containing silanol bound hydrogen. A residual permeation as low as J = 1 ± 0.3 cm3 m−2 day−1 bar−1 is achieved, which is a good value for food packaging applications. Additionally, the activation energy Ep of oxygen permeation is analysed and a strong increase from Ep = 31.5 kJ mol−1 for SiOx CyHz-like coatings to Ep = 53.7 kJ mol−1 for SiO1.7 films is observed by increasing the oxygen dilution of HMDSO:O2 plasma. The reason for the residual permeation of high barrier films is discussed and coating defects are visualized by capacitively coupled atomic oxygen plasma etching of coated substrates. A defect density of 3000 mm−2 is revealed.

Investigations of plasma polymerized barrier films on polymeric materials

The present paper mainly deals with the development and characterization of plasma polymerized SiOx barrier films on polyethyleneterephthalate (PET). Hexamethyldisiloxane (HMDSO) in mixture with oxygen (O2) are used as deposition gases. The chemical composition and the morphology of the films are characterized by infrared absorption measurements and by REM investigations. The oxygen permeability was measured as a function of time with the carrier gas method using a ceramic (ZrO2) detector.

Temperature dependence of an ammonia sensor in humid air based on a cryptophane-coated quartz microbalance

A cryptophane-coated sensor for ammonia based upon a quartz microbalance has been developed and the influence of the operating temperature and humidity have been evaluated. Whereas the time constant of the sensor reaction decreases at higher temperature, a lower temperature yields a higher sensor signal. To characterize the interference of relative humidity on the determination of the ammonia concentration, we have constructed a scheme of isotherms based upon measurements using pulses of a carrier gas (purge-pulse (PP) method). This scheme of isotherms enables us to explain and estimate the efficiency of the PP and of the alternate temperature-pulse (TP) method.

Energy-efficient ethanol-water fractionation by a carrier-gas method

On presente une methode utilisant, au cours du fractionnement, un gaz vecteur inerte pour l'evaporation (et non l'ebullition) de l'eau et de l'ethanol, suivie d'une condensation de ces deux composes.

Transport of ethylene oxide through polymer films

AbstractThe transport of gaseous ethylene oxide (EtO) in several polymer films is studied using the carrier gas method of measurement. Permeability, solubility, and diffusion coefficients describing ethylene oxide (EtO) transport in polypropylene, polyvinylchloride, Teflon‐FEP copolymer, and polyethylene films have been obtained over a 30 Celsius degree range at a low concentration of EtO using the carrier gas method of measurement. The results indicate that the diffusion of EtO in polyethylene is independent of penetrant concentration over the range of concentrations used. However, concentration‐independent diffusion could not be verified directly for the other films studied. Two different techniques of determining diffusion coefficients were used, and within the precision of the data both yield the same result. An excess enthalpy of solution for the solubility of EtO in Teflon‐FEP copolymer was calculated, an observation that suggests that dual‐mode sorption may be taking place.

Hydrogen Permeation in Metals During Exposure to a Process Gas Environment

Hydrogen permeation of nickel-base heat-resistant alloys in a process gas environment is investigated in a high-temperature range up to 1273 K. Time-dependent permeation behavior of candidate alloys (R, NSC-1, SZ, KSN, 113M, and Hastelloy XR-51) for intermediate heat exchangers of a high-temperature gas-cooled reactor is examined in a reducing gas of 80% H2 + 15% CO + 5% CO2. The result in the reducing gas is compared to that of the permeation in pure hydrogen. For both measurements, a helium carrier gas method is used, simulating the practical configuration of the heat exchangers. The permeation rate decreased proportionally to the inverse of the square root of time in the reducing gas and had a square root dependence on hydrogen pressure at a constant thickness of the oxide layer. These results are discussed on the basis of a two-layer diffusion model.

Rapid determination of hydrogen in lithium oxide by carbon monoxide carrier gas method

The chemical form of hydrogen in lithium oxide is mainly lithium hydroxide, which is formed from the oxide and atmospheric moisture during its storage. The reaction of the hydroxide with carbon monoxide afford hydrogen gas and carbonate, so that hydrogen content in lithium oxide can be easily determined by the following method : lithium oxide sample (100 to 500 mg) is placed on a reaction tube (test-tube type, 15 mm i.d. × 200 mm, glassware). Then, carbon monoxide gas is passed through the tube at 80 ml/min and the tube is heated at 390 °C for 15 min. The hydrogen evolved from the sample is determined by using thermal conductivity detector. The evolution profile of hydrogen gas with the reaction of lithium hydroxide and carbon monoxide was influenced by physical property (density of powder) of sample rather than its hydrogen content. Carbonate in sample did not interfere with the determination of hydrogen. The lower limit of determination was 0.002 % for 500 mg of sample. The required time for analysis was about 20 min after the sample was weighed under a dried atmosphere in gloved box. The standard deviations for the determination of 0.028 %, 0.18%, and 0.70 % of hydrogen were 0.004 %, 0.01 %, and 0.05 %, respectively.

Thermodynamic properties of binary alloys of platinum metals II: Ir-Pt system

The iridium activity a Ir for Ir-Pt alloys at 1383, 1468 and 1573 K was determined by means of a reactive carrier gas method in which dry oxygen was used as the carrier gas. The corresponding platinum activity a Pt , was calculated from the Gibbs-Duhem relations. Both activities and the relative partial molar quantities derived from them exhibit a composition-independent region (0.50 < N Ir < 0.90) in the temperature range investigated. There should be shortrange ordering in these alloy phases. On the basis of the present investigation, it is predicted that a miscibility gap exists in the solid solution phase at temperatures up to 1573 K in the Pt-Ir binary system.

Permeation of water vapor through cellulose triacetate membranes in hollow fiber form

AbstractA modification of the carrier gas method for measuring permeability of a hollow fiber to a vapor is described with particular application to water vapor permeation through asymmetric cellulose triacetate in hollow fiber from. Conventional methods are inadequate because the high flux of permeation vapor combined with its low pressure on the permeate side and the small diameter of the fiber lead to an excessive buildup of pressure in the permeate stream—in some cases so great as to render much of the fiber length ineffective. The method described in this paper involves the permeation from the outside to the inside of the fiber of a binary mixture consisting of the water vapor and a fairly highly permeable carrier (helium). There is a significant pressure drop along the fiber, but a theoretical treatment is presented to take this into account and to permit a determination of the vapor permeability. Experiments at 35°C over a range of water vapor pressures up to 1.7 cm Hg gave a water flux of 9 × 10−3 cc(S.T.P.)/cm2‐sec‐cm Hg, with an apparent slight decrease with increasing pressure. Over the same range of water vapor pressure the helium flux decreased from 2.3 × 10−4 to 1.85 × 10−4 cc(S.T.P.)/cm2‐sec‐cm Hg.

Determination of hydrogen in lithium hydroxide by carbon monoxide carrier gas method

Determination of hydrogen in lithium hydroxide by carbon monoxide carrier gas method

Determination of Oxygen in Zinc Compounds

Abstract Oxygen in zinc compounds was determined by a modification of the method of Schütze. Oxygen in some zinc compounds such as zinc oxide, zinc acetate and zinc oxalate could not be determined by the usual method. The carrier gas method of adding carbon was employed for the determination of total oxygen. Total oxygen could be determined by the addition of 5 mg of carbon to a sample boat and heating at 1000 °C. The determination was also carried out by the carrier gas method by addition of 2 mg naphthalene. As a result, total oxygen could be determined by the addition of 2 mg of naphthalene.

Measurement of gas permeability of polymers. II. Apparatus for determination of permeabilities of mixed gases and vapors

A gas permeability apparatus has been constructed to facilitate the study of permeation of mixtures of gases and vapors. The apparatus utilizes the carrier gas method with gas-chromatographic analysis to determine individual permeation values and in-line thermal conductivity detectors to provide simultaneous overall diffusion and permeability data. The effects of film type, structure, and morphology on permeability may be studied from atmospheric to 100 psi feed pressure and from ambient to 300°C. Feed stocks may be custom mixed, and a vaporizing bath permits introduction of vapors either as contaminants or as primary permeants in an inert carrier. The experiments which illustrate the use of the equipment suggest that the noninteracting gases H2 and CH4 permeate a number of polymer films independently over a wide concentration range and that water vapor retards their permeation in polyimide films.

Studies on oxygen determination by the carrier gas method. IX. Determination of oxygen in thallium and thallium compounds.

Oxygen determination in thallium and thallium compounds was investigated by a modification of the Schutze-Unterzaucher method. When oxygen in thallium compounds was determined by the conventional method for organic compounds, the oxygen content in almost all samples was 1-5% less than the calculated value. A silica tube that was used for heat decomposition was subjected to erosion by thallium (I) oxide produced by the pyrolysis of thallium compounds and cracks were caused. In order to prevent this, the inside wall of the silica tube was coated with carbon which had been produced by the pyrolysis of naphthalene. Carbon powder was also added into the sample boat to reduce thallium oxides formed by the decomposition of thallium compounds. All of the oxygen in thallium and thallium compounds was determined according to the proposed method, and quite favorable results could be obtained. About 40 min was required for one determination.

Determination of oxygen in nickel compounds

Oxygen in nickel compounds was determined by the Unterzaucher method.Nickel perchlorate, organic-acid salts of nickel, such as nickel formate, nickel acetate and nickel oxalate, and nickel complexes and organic nickel compound, Such as bis(2, 3-butanedione dioximato)nickel, bis (2, 4-pentane dionato) nickel, hexaammine nickel diperchlorate and tetraaquo (2, 2'-bipyridine) nickel sulfate were used as samples. Oxygen in these samples was determined precisely by the usual method.Oxygen in nickel chloride with crystal water was also determined precisely by the same method. On the other hand, the amount of oxygen in nickel oxide, nickel nitrate and nickel sulfate was(517)% less than the calculated value.For the compounds whose total oxygen could not be determined precisely with the usual method, the authors designed the carrier gas method using reaction agent. In this paper naphthalene was used as reaction agent. The results of oxygen determination in nickel oxide, nickel nitrate and nickel sulfate were in good agreement with those of their calculated values with this method. About 40 min was required for one determination.

Determination of hydrogen in metals by a combination of the so-called carrier gas method and the technique of frontal chromatography

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDetermination of hydrogen in metals by a combination of the so-called carrier gas method and the technique of frontal chromatographyVlastimil. Rezl, Bozena. Kaplanova, and Jaroslav. JanakCite this: Anal. Chem. 1975, 47, 1, 159–161Publication Date (Print):January 1, 1975Publication History Published online1 May 2002Published inissue 1 January 1975https://doi.org/10.1021/ac60351a044RIGHTS & PERMISSIONSArticle Views24Altmetric-Citations4LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (341 KB) Get e-Alerts Get e-Alerts

Recovery of Hydrating Agent by Carrier Gas Method

Recovery of Hydrating Agent by Carrier Gas Method