Carbon nanotube enhanced PVA-mimic enzyme membrane for post-combustion CO2 capture

A carbon nanotube (CNT) enhanced polyvinyl alcohol (PVA)-mimic enzyme nanocomposite membrane was developed for CO2 separation from flue gas under humidified conditions. A thin layer of PVA membrane containing mimic enzyme with uniformly dispersed CNTs on a porous support was prepared by dip coating. The thicknesses of the membranes was controlled by adjusting the polymer concentrations in the casting solutions. The membranes with the optimal concentration of the mimic enzyme (Zn-cyclen, 0.005 mmol/g) and different loadings of CNTs (0, 0.5, 1.0 and 1.5 wt%) in PVA at pH 5, 9 and 12 were prepared and tested for CO2/N2 separation. The addition of the CNTs as nano-fillers increased the degree of water swelling in the membrane, thus also significantly improved the CO2/N2 separation performance. A membrane containing 1.0 wt% CNTs at pH 12 showed the highest CO2 permeance of 0.98 m3 (STP)/m2 h bar and a CO2/N2 selectivity of 120, which is 30% higher in CO2 permeance and 15% higher in CO2/N2 selectivity compared with that of the counterpart membranes without CNT addition.