Effect of humidity and nanocellulose content on Polyvinylamine-nanocellulose hybrid membranes for CO2 capture.

In order to address the need for more efficient technologies for carbon capture applications, a novel type of nanocellulose based hybrid membrane has been successfully prepared by blending the commercial Polyvinylamine solution Lupamin® 9095 (BASF) with Nano Fibrillated Cellulose (NFC) to improve its mechanical and separation capabilities. Self-standing films with different nanocellulose loading (from 30 to 70 wt%) have been prepared and characterized at 35 °C through water vapor sorption experiments and humid gas permeation tests. As expected, membrane permeability consistently increased with increasing water vapor and a higher presence of Lupamin in the film resulted in an increment of both gas permeability and selectivity. In particular blends with a NFC content of 70 wt% Lupamin reached an ideal selectivity of 135 for the separation of CO 2 /CH 4 and 218 for CO 2 /N 2 , at 60 RH%, while the maximum permeability in the order of 187 Barrer was instead reached at 80% RH. Water vapor solubility was also measured and modeled through Park Model to correlate the gas separation properties with the effective content of water present in the membrane matrix. As expected, a higher content of the hydrophilic polymer resulted in a larger water uptake, which at medium to high humidity appeared to trigger a water clustering phenomenon in the matrix. This fact was accompanied by a substantial relaxation of the polymer network, causing a marked reduction of selectivity, which dropped, at the highest RH investigated, to values in the order of 30 and 80 towards CH 4 and N 2 respectively. Despite this loss in performance, most materials tested still showed very interesting properties, well above Robeson's 2008 Upper Bound, making them an interesting alternative for traditional gas separation processes. [ABSTRACT FROM AUTHOR]