A Method to Obtain Gas-PDMS Membrane Interaction Parameters for UNIQUAC Model

Abstract

The recovery or capture of one or more components from gas mixture by membrane separation has become a research focus in recent years. This study investigates the gas-membrane solution equilibrium, for which Henry's law is not applicable if the gas phase is a mixture. This problem can be solved by using UNIQUAC model to calculate the activity coefficient of gas dissolved in the membrane. A method was proposed in this study to obtain the gas-membrane interaction parameter for UNIQUAC model. By the experiments of gas permeation through polydimethylsiloxane PDMS membrane, the solubility coefficients of some gases (N 2 , CO 2 , CH 4) were measured. Through non-linear fitting UNIQUAC model to the experimental results from this study and in literature (H 2 , O 2 , C 3 H 8), the gas-membrane interaction parameters for these gases were obtained. Based on these parameters, the activity coefficients of the dissolved gas were calculated by UNIQUAC model, and their values agree well with the experimental data. These results confirm the feasibility and effectiveness of the proposed method, which makes it possible to better predict gas-membrane solution equilibrium.

A Fiber-Integrated CRDS Sensor for In-Situ Measurement of Dissolved Carbon Dioxide in Seawater

“…The diffusion flux on the side of the gas chamber can be expressed by Fick’s first law [ 24 , 26 , 27 ]: where (cm 3 ·cm 2 (cm 2 polymer) −1 ·s −1 ) is the diffusion flux of gas component G per unit time, (cm 2 ·s −1 ) is the diffusion coefficient of gas component G in the membrane, (cm 3 ·(cm 2 polymer) −1 ·Pa −1 ) is the solubility coefficient of gas component G in the membrane, (Pa) is the partial pressure of seawater dissolved gas G , (Pa) is the partial pressure of gas component G in the gas chamber, A (cm 2 ) is the film area, l (cm) is the film thickness. While gas diffusion flux can be expressed by Fick’s second law in the case of unstable situation [ 25 , 26 ]: where, is the gas flux at time t , is the gas flux in the stable situation.…”

“…is the solubility coefficient of gas component G in the membrane, P G1 (Pa) is the partial pressure of seawater dissolved gas G, P G2 (Pa) is the partial pressure of gas component G in the gas chamber, A (cm 2 ) is the film area, l (cm) is the film thickness. While gas diffusion flux can be expressed by Fick's second law in the case of unstable situation [25,26]:…”

“…A fast exponential regression model is proposed to retrieve the concentration of dissolved gas in seawater. In the implementation, we design high-pressure assembling and use polydimethylsiloxane (PDMS) membrane for water/gas separation and enrichment [ 24 , 25 ]. A long-time in-situ observation near the coast is carried out to prove the feasibility of in-situ separation, enrichment and measurement of dissolved CO 2 in seawater.…”