Investigation of cellulose acetate and ZIF-8 mixed matrix membrane for CO₂ separation from model biogas

ABSTRACT

The separation of CO₂ from the biogas mixtures (CH₄/CO₂) is essential for biogas upgradation. However, polymer membranes used for CO₂ separation exhibit low permeability. Mixed Matrix Membranes (MMMs) incorporating inorganic filler in the polymer enhance CO₂ separation. In this work, bio-degradable cellulose acetate (CA) based MMMs with varying filler weight percentages (2–20 wt.%) of ZIF-8 were studied for the separation of CO₂ from a model biogas (CH₄/CO₂) mixture. The MMMs were characterized by analysis of TGA and DSC for thermal stability and FTIR for alteration or formation of any new functional group. FESEM was done to evaluate the dispersion and interaction of ZIF-8 in the CA polymer matrix. Considering the economic aspect, the fabricated MMMs were tested for gas separation performance at reasonably lower feed pressure (1.5, 2 bar). MMM with 5 and 10 wt.% of ZIF-8/ CA MMMs showed the best performance with CO₂ permeability of 9.65 Barrer and 9.5 Barrer, approximately two folds as compared to pure CA, and CO₂/CH₄ selectivity was 10.37 and 15.3. The experimental results were compared with the predicted gas permeation results determined using MMM transport predictive models, and found that the permeabilities were higher than the model predictions.

GRAPHICAL ABSTRACT

KEYWORDS:

• Cellulose acetate membrane
• ZIF-8 mixed matrix membrane
• MMMs for CO₂ separation

CRediT authorship contribution statement

Priya Tanvidkar: Conceptualization, methodology, Investigation, data curation, writing-original draft; Aditya Jonnalagedda: Conceptualization, methodology, Investigation, data curation, writing-original draft, Bhanu Vardhan Reddy Kuncharam: Conceptualization, methodology, formal analysis, visualization, writing-review & editing, funding acquisition, Supervision.

Data availability statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Science and Engineering Research Board (SERB) [grant number SRG/2019/000336].