Preparation of polydimethylsiloxane-SiO2/PVDF-HFP mixed matrix membrane of enhanced wetting resistance for membrane gas absorption

• Published in: Separation and purification technology 2020-08, Vol.244, p.116543, Article 116543
• Main Authors: Toh, Moau Jian, Oh, Pei Ching, Chew, Thiam Leng, Ahmad, Abdul Latif
• Format: Article
• Language: English
• Subjects: CO2 removal; Hydrophobic SiO2; Mixed matrix membrane; Solvent additive; Wetting resistance
• ISSN: 1383-5866; 1873-3794
• DOI: 10.1016/j.seppur.2020.116543

•The PVDF-HFP membrane was synthesized using hydrophobic nanoparticles as solvent additive.•The mixed matrix membrane exhibited hierarchical structure and low surface free energy.•The mixed matrix membrane achieved the highest water contact angle of 150°. Membrane gas absorption (MGA) has been widely used to separate CO2 from gas mixture attributed to its high interfacial area. In order to secure high absorption flux, the pores of the membrane need to be non-wetted. Currently, hydrophobic membrane suffers from severe pore wetting over prolonged periods of operation. This has called for the enhancement of membrane hydrophobicity to suppress the tendency of pore wetting. In this work, highly hydrophobic PVDF-HFP membrane was synthesized using solvent additive i.e. polydimethylsiloxane-grafted-silica (PGS) via non-solvent induced phase separation. Results showed that mixed matrix membranes (MMMs) exhibited hierarchical structure composed of polymer spherulites due to delayed phase inversion. The embedment of nanoparticles in membrane matrix also contributed to the reduction of membrane’s surface energy. As a result, MMMs achieved an improvement in wetting resistance with a water contact angle up to 149.87° at 3 wt% of PGS nanoparticles. The CO2 absorption test using MEA as liquid absorbent showed that MMMs exhibited an enhancement in gas absorption flux owing to higher hydrophobicity. The CO2 absorption flux of pristine and MMMs was declined about 37% and 22%, respectively during 150 h of operation.