Task-specific polymeric membranes to achieve high gas-liquid mass transfer

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Efficient gas-liquid mass transfer (GL-MT) is crucial for biological processes, particularly in bubble column reactors (BCRs).
• Conventional sparging methods often face limitations in achieving high oxygen transfer rates, impacting process efficiency.
• Polymeric membranes offer a novel approach to enhance GL-MT by controlling bubble characteristics.

Purpose of the Study:

• To fabricate Polyimide (P84)-based polymeric membranes incorporated with polyvinyl pyrrolidone (PVP) and Zeolitic Imidazolate Framework-8 (ZIF-8).
• To evaluate the gas-liquid mass transfer (GL-MT) efficiency of these membranes as spargers in a BCR for oxygen transfer.
• To investigate the impact of ZIF-8 incorporation on membrane porosity, hydrophobicity, and overall GL-MT performance.

Main Methods:

• Fabrication of P84-based membranes with varying compositions of PVP (porogen) and ZIF-8.
• Evaluation of GL-MT efficiency by measuring the overall volumetric mass transfer coefficient (k_La) of oxygen in air.
• Characterization of membrane properties including porosity and hydrophobicity (contact angle).

Main Results:

• Incorporation of PVP and ZIF-8 increased membrane porosity compared to pure P84 membranes.
• The membrane with 3 wt% ZIF-8 exhibited the highest porosity (80%) and hydrophobicity (95° contact angle).
• This ZIF-8 based membrane achieved the highest k_La of oxygen (241.2 h^-1), reaching 78% saturation in 60 seconds.

Conclusions:

• ZIF-8 based polymeric membranes significantly enhance GL-MT in BCRs by reducing bubble size and increasing bubble number.
• These membranes demonstrate potential for improving dissolved oxygen levels, benefiting microbial syngas fermentation.
• This study presents the first application of polymeric membranes for GL-MT, highlighting their promise for biotechnological processes.