Preparation Of CMCS/PEI Blend Membrane And Its CO₂Permeability

Separation and capture of CO₂from flue gas and other sources haveattracted global attention for greenhouse gas emission control. CO₂isbelieved to be the most important greenhouse gas, accounting for about60%greenhouse gas effects. While membrane technology for CO₂separation is considered to be an option, the current generation of gasseparation membranes is not permselective enough to compete with otherprocesses for commercial applications. The utilization of reactive carriersto facilitate the transport of CO₂in membranes offer an attractive meansto attain a high permeation rate selectivity. In this work, carboxymethylchitosan （CMCS）/poly ethylenimine （PEI） blend membranes wereprepared for the facilitated transport of CO₂.The FIIR spectrum demonstrated that hydrogen bond formed betweenCMCS and PEI. And the DSC thermograms presented that there areattracted forces between CMCS and PEI. It can been seen that themembrane coated on the PS support was homogeneous via SEM viewers.The results of DSC, FTIR and SEM indicated that CMCS and PEI are miscible.The CMCS/PEI membrane was prepared and tested. The separationprocess without water was inefficient. Acid treatment was used tocrosslink the CMCS/PEI=90/10blends and perfect membranes withoutdefects were prepared. The permeation rate of CO₂through the acidtreated CMCS/PEI=90/10membrane containing water is1.0í10^-4cm³cm^-2s^-1cmHg^-1and the separation factor for the CO₂/N₂mixture is44.09at the pressure as15.2cmHg. The CO₂permeation rate andseparation factor are up to6.3í10^-4cm³cm^-2s^-1cmHg^-1and325.4at15.2cmHg when the content of PEI is30%in the blends.The CMCS/PEI membrane was prepared by dip-coating also. Athinner membrane, of which permeation rate was higher but theseparation was lower, was obtained, which is about3.5μm. PEG wasadded to the CMCS/PEI and a heterogeneous phase membrane wasobtained. However, the addition of PEG has not brought the desiredresults.