Therefore, this membrane cannot be used for water filtration applications. The quasi-dense behavior of the carbon
membrane for low applied external pressure emboldens us to evaluate this material for gas separation. From the 1970s, carbon membranes have been extensively used for gas separation [6, 9, 28]. Different studies were conducted on membranes originating from different sources such as polymers and carbohydrates (glucose) and have demonstrated promising permeance values in the range of 10-8 to 10-9 mol·m-2·Pa-1·s-1, associated with high selleck selectivity. For instance, a carbon membrane elaborated by pyrolysis of commercial polymers and having a pore diameter between 3 and 5 Å has demonstrated a He/CO2 selectivity of 4, and a He/N2 selectivity between 20 and 40 [9]. In our case, the gas separation test was driven using three types of gases, namely helium (He, kinetic diameter = 2.6 Å), carbon dioxide (CO2, kinetic diameter = 3.3 Å), and nitrogen (N2, kinetic diameter = 3.64 Å). The permeances of these gases were recorded as a function
of the pressure at different temperatures of 25°C (T01), 100°C, and after cooling down again to 25°C (T02) (Figure 12). At 25°C, the membrane gave a 10-9 mol·m-2·Pa-1·s-1 permeance value for He, CO2, and N2, which is in good agreement with the values reported in the literature [6]. At 100°C, a stable flux was obtained exhibiting a permeance in the range of 10-7 mol·m-2·Pa-1·s-1. We also observed an increase buy GSK2126458 in the permeance while increasing the temperature up to 100°C Transferase inhibitor whatever the used gas and the applied pressure were [26]. We assume that this result may reflect a Knudsen diffusion mechanism for the gas separation. For CO2 and N2, these systems enter into an apparent stationary regime by varying the pressure, and their permeances appear to become almost constant whatever the applied pressure
was. In contrast, the permeance Ponatinib of helium increases with the applied pressure (lower kinetic diameter). As a consequence, the selectivity of helium versus the other gases increases with the pressure up to approximately 2 (Figure 13). This value is lower than the one reported in the literature [6]. Figure 12 Permeances of (a) helium, (b) nitrogen, (c) carbon dioxide as a function of the differential pressure. These were taken at different temperatures: 25°C (T01), 100°C, and 25°C after an exposure of up to 100°C (T02). Figure 13 He/CO 2 selectivity (a) and He/N 2 selectivity (b) as a function of the applied pressure at 100°C. After measurement at 100°C, the membrane was cooled down to 25°C, and its permeance was measured again for each gas (Figure 12). By comparing T01 and T02, we have observed a significant increase of the permeances (by a 102 factor) whatever the studied gas was. By considering this result, we underwent measurements at 200°C.
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