Polydimethylsiloxane based mixed matrix membranes with pretreated fumed silica for efficient CO2 separation
Murshid Jaman Chowdhury, Jianzhong Lou, Debasish Kuila, Debarati Mukherjee
Abstract
Polydimethylsiloxane (PDMS) membranes exhibit significant potential for use in CO 2 separation applications. However, the selectivity of CO 2 over N 2 and CH 4 in a pure PDMS membrane is relatively low. Herein, we developed mixed matrix membranes (MMMs) by incorporating a surface-treated fumed silica (FS) into a PDMS polymer matrix to enhance the CO 2 separation performance of PDMS membranes from N 2 , and CH 4 . The surface treatment of FS reduced its hydrophilicity, leading to more uniform dispersion within the PDMS matrix and increased fractional free volume by altering molecular packing, thereby enhancing CO 2 permeability as well as CO 2 /N 2 and CO 2 /CH 4 selectivity. Structural, morphological, and thermal stability analyses demonstrated that the PDMS matrix remained intact even with the incorporation of fillers at higher loadings. Single gas permeation tests revealed that the highest CO 2 /N 2 and CO 2 /CH 4 selectivity were achieved at FS loading of 7.5 wt%. The optimized MMM, containing 7.5 wt% fillers in PDMS, exhibited a 1.42-fold increase in CO 2 permeability and enhancements of 1.47-fold and 1.39-fold in CO 2 /N 2 and CO 2 /CH 4 selectivity, respectively, compared to neat PDMS. This study also indicates that feed pressure and time had no significant effect on CO 2 /N 2 and CO 2 /CH 4 separation performance.