چكيده به لاتين
Nowadays, since membrane processes have many advantages, such as low start-up costs, less required space, safe for the environment, ease of operation, and low operating costs can be a good alternative to traditional separation processes.
This study focuses on selecting the primary membrane fabrication material that is a suitable polymer with acceptable functional properties (CO2 permeability and CO2/CH4 selectivity) (Pebax) and modifying such membranes by dispersing effective nanoparticles within their polymeric matrices. In this research, by examining the separation efficiency of different polymeric membranes, it was observed that among the available polymers, ether amide copolymers have the desired separation capability due to their optimal interaction with CO2; therefore, in this study, Pebax-1657 polymer was chosen for synthesizing the membranes.
Also, one of the methods that caused the remarkable changes in gas separation processes is the use of fillers having a positive interaction with CO2 molecules in the polymeric matrix of the membranes. Literature review shows that halloysite nanotubes (HNTs) and surface-modified halloysite have high abilities to absorb CO2 molecules. In this work, the solvent-evaporation solution casting method is used to fabricate the membranes, and after studying the separation properties of the membranes, they are characterized using SEM, FT-IR (ATR), XRD, and TGA analyses.
Finally, in order to evaluate the performance of the fabricated membranes, the permeability tests of pure CO2 and CH4 gases are performed. Gas permeability tests have shown promising results for CO2 permeability for both halloysite and amino halloysite membranes. For example, CO2 permeability in the case of neat, mixed halloysite and modified halloysite membranes with 1.5 wt % of nanoparticles at 25 °C temperature and 4 bar pressure are 76.50, 98.07 and 104.87 Barrer, respectively, while the ideal selectivity (CO2 / CH4) of the halloysite membrane decreases and the modified halloysite membrane increases. The selectivity results for these three membranes are 23.79, 20.65 and 29.49, respectively. The highest permeability and selectivity is related to the membrane made of modified halloysite nanoparticles. For example, carbon dioxide permeability and the ideal selectivity of this type of membrane with 1.5 wt % of nanoparticles at 25 °C temperature and 10 bar pressure are 126.85 and 33.21 bar, respectively.
