TY - JOUR
T1 - Permeation of supercritical CO2 through dense polymeric membranes
AU - Shamu, Andrew
AU - Dunnewold, Marije
AU - Miedema, Henk
AU - Borneman, Zandrie
AU - Nijmeijer, Kitty
PY - 2019/2/1
Y1 - 2019/2/1
N2 - Supercritical carbon dioxide (scCO2) is used in the food industry as a water-extracting drying agent. Once saturated with water, the scCO2 needs to be regenerated. A promising way of drying scCO2 is by using H2O permeable membranes. Ideally, these membranes demonstrate low CO2 permeability. Here, we investigated the CO2 permeability of three types of dense membranes, Nafion, Natural Rubber and PDMS, of which the latter in more detail because of its ease of handling. The experimental conditions, temperature and pressure, resulting in minimum CO2 permeability (=losses) were explored. Even though the absolute CO2 permeability depends on the intrinsic membrane material properties, its trend with increasing feed pressure is defined by the (supercritical) behavior of CO2, notably its density as a function of temperature and pressure. The data points to transitions within the supercritical regime, from the gaseous-like supercritical state to the liquid-like supercritical state, graphically visualized by the Widom line for CO2 density. Sorption measurements with PDMS membranes confirm this behavior that follows the diffusion-solution theory. In the gaseous state, the (normalized) permeability follows the (normalized) solubility, indicating a constant CO2 diffusivity. With increasing pressure and when entering the liquid-like (supercritical) regime, the diffusivity drops, resulting in a (normalized) permeability that starts to lag behind the (normalized) solubility.
AB - Supercritical carbon dioxide (scCO2) is used in the food industry as a water-extracting drying agent. Once saturated with water, the scCO2 needs to be regenerated. A promising way of drying scCO2 is by using H2O permeable membranes. Ideally, these membranes demonstrate low CO2 permeability. Here, we investigated the CO2 permeability of three types of dense membranes, Nafion, Natural Rubber and PDMS, of which the latter in more detail because of its ease of handling. The experimental conditions, temperature and pressure, resulting in minimum CO2 permeability (=losses) were explored. Even though the absolute CO2 permeability depends on the intrinsic membrane material properties, its trend with increasing feed pressure is defined by the (supercritical) behavior of CO2, notably its density as a function of temperature and pressure. The data points to transitions within the supercritical regime, from the gaseous-like supercritical state to the liquid-like supercritical state, graphically visualized by the Widom line for CO2 density. Sorption measurements with PDMS membranes confirm this behavior that follows the diffusion-solution theory. In the gaseous state, the (normalized) permeability follows the (normalized) solubility, indicating a constant CO2 diffusivity. With increasing pressure and when entering the liquid-like (supercritical) regime, the diffusivity drops, resulting in a (normalized) permeability that starts to lag behind the (normalized) solubility.
KW - Dense membranes
KW - Permeability
KW - Polydimethylsiloxane (PDMS)
KW - Sorption
KW - Supercritical carbon dioxide
KW - Widom line
UR - http://www.scopus.com/inward/record.url?scp=85055519092&partnerID=8YFLogxK
U2 - 10.1016/j.supflu.2018.10.009
DO - 10.1016/j.supflu.2018.10.009
M3 - Article
AN - SCOPUS:85055519092
VL - 144
SP - 63
EP - 70
JO - Journal of Supercritical Fluids
JF - Journal of Supercritical Fluids
SN - 0896-8446
ER -