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Isothermal desorption technique with chromatographic detection for estimation of solubility coefficient of gas in polymersтезисы доклада
- Авторы: Nizhegorodova Yu, Belov N., Yampolskii Yu
- Сборник: Book of Abstracts The 10th International Congress on Membranes and Membrane Processes ICOM 2014
- Тезисы
- Год издания: 2014
- Место издания: Suzhou (China)
- Первая страница: 1046
- Аннотация: Because of a wide use of membrane gas separation it is important to have a simple and versatile method for the direct determination of the gas and vapour solubility coefficients S. Some of existing methods for determination of Srequire expensive and complex equipment. In this work we present a new technique for determination the solubility coefficients, method of isothermal desorption with chromatographic detection. This method is carried out in several stages. At the first stage the "empty" volume V ∑,G of the sorption chamber is determined Then a membrane material with the known mass m pol is placed in the loop and saturated by the tested gas with a known partial pressure p 1 at given temperature T. After this, the dissolved gas under investigation is desorbed by gas-carrier (He) into the chromatographic detector for determining the total amount of gas contained in the sorption volume (loop), including the amount of gas sorbed in the polymer: n 1 ∑ = n 1 G + n 1 pol , where is the amount of gas in the gas phase of the sorption volume. The sorbed gas amount is estimated at the last stage bearing in mind that gas phase volume is a difference between "empty" volume V ∑,G of sorption chamber and volume V pol of membrane material introduced and taking into account the equation of state of the gas. Thus, an amount of the gas in the polymer at given partial pressure and temperature can be found. According to this procedure, it is possible to draw the gas sorption isotherm and calculate the gas solubility coefficient in the membrane material. For the verification of the proposed methodology sorption isotherms of various gases at pressure up to 2.5 atm were obtained for polyvinyltrimethylsilane, the polymer with well-known sorption parameters. A good agreement was achieved between the measured and published solubility coefficients in this polymer. Then this technique was applied to novel polymers: poly(3,4-bis(trimethylsilyl)tricyclononen-7), OH-containing polyimide and polyhexafluoropropylene. The sorption isotherms of N 2 , O 2 , CO 2 , CH 4 , C 2 H 6 , C 3 H 8 at 25 ± 2 ºC in these polymers were obtained. In the studied range of pressures they are linear. The found solubility coefficients S are in agreement with the ratios P/D, where P and D are permeability and diffusion coefficients, respectively. The results of the comparisons and peculiarities of performing of the proposed technique will be discussed in the presentation. It should be noted again that significant advantages of the method proposed are the simplicity of setup, speed of analysis, the possibility of constructing sorption isotherms at low partial pressures of the gas and possibility to investigate membrane material in different forms (films, fibers, flakes and grains).
- Добавил в систему: Белов Николай Александрович