Fabrication of high-performance biochar incorporated Pebax®1657 membranes for CO2 separation

This study highlights the utilization of biobased material for developing high-performance membranes for gas separation applications. Biochar was synthesized by the pyrolysis of pine needles and further modified by silane functionalization. Thus obtained biochar was incorporated into a rubbery polymer, poly(ether-blockamide) (Pebax-1657), to synthesize mixed matrix membranes (MMMs). Morphologies of membranes and physiochemical interactions of the biochar and polymer were evaluated using SEM, FTIR, DSC, and XRD. MMMs exhibit higher gas adsorption properties compared to the neat Pebax-1657 membrane. The effect of biochar incorporation on gas permeation properties was conducted in an indigenously designed setup using pure CH4, CO2, and N2 gases in the pressure range of 5-30 kg/cm2. 20 wt% Biochar loaded MMM achieved a higher CO2 permeability of 114 Barrer, signifying 79% higher permeability over the pristine Pebax membrane. Correspondingly, the highest selectivity values for CO2/CH4 and CO2/N2 achieved were 32 and 94, respectively, with increasing pressure. A regression model was developed to estimate the relation between biochar loading and gas permeability. The data revealed a strong positive correlation (0.7-0.9) between gas permeability and the percentage of biochar loaded. The developed MMMs are stable and exhibit superior performance for CO2 removal from natural gas and power plant off-gases. Pine needles derived MMMs represent a promising new approach for developing high-performance and environmentally sustainable membranes for gas separation applications.