Preparation and Characterization of Polycarbonate-Blend-Raw/Functionalized Multi-Walled Carbon Nano Tubes Mixed Matrix Membrane for CO2 Separation

Membrane composed of PC as base of polymer matrix with different ratio of multiwall carbon nano tubes (MWCNTs) as nanofillers and poly ethylene glycol (PEG) as second polymer was prepared by solution casting method. Both raw-MWCNTs (R-MWCNTs) and functionalized carboxyle-MWCNTs (C-MWCNTs) were used in membrane preparation. The MWCNTs loading ratio and pressure effects on the gas transport properties of membranes were examined in relation to pure He, N-2, CH4, and CO2 gases. Results showed that the use of C-MWCNT instead of R-MWCNTs in mixed matrix membranes (MMMs) fabrication with base of PC provides better performance and also it increases (CO2/CH4) and (CO2/N-2) selectivities to 27.38 and 25.42 from 25.45 and 19.24, respectively (at 5wt% of MWCNTs). PEG as the second rubbery polymer was utilized to improve the separation performance and mechanical properties. In blend MMMs, highest (CO2/CH4) selectivity at 2bar pressure increased to 35.64 for PC/PEG/C-MWCNT blend MMMs which was 27.28 for PC/MWCNTs MMMs at 10wt%. Increase of feed pressure led to gas permeability and gas pair selectivity improvement in approximately all of membranes. Analysis of mechanical properties showed improvement in tensile modules with the increase of MWCNTs loading ratio and use of PEG in prepared MMMs.