Title : Stimuli-responsive amine-functionalized PVA-based composite membranes for post-sombustion CO₂ sapture from simulated flue gas
Abstract:
The continuous rise in atmospheric CO₂ concentration, driven largely by fossil-fuel-based power generation, poses serious environmental and climatic challenges. Post-combustion CO₂ capture from flue gas is therefore essential for mitigating greenhouse gas emissions. Membrane-based separation offers a promising alternative to conventional absorption processes due to its lower energy demand, operational simplicity, and scalability.
In this study, mixed matrix membranes based on poly(vinyl alcohol) (PVA) and 2-(1-piperazinyl)ethylamine (PZEA) were developed to enhance CO₂/N₂ separation through a facilitated transport mechanism. PZEA, a multifunctional diamine containing both piperazine and primary amine groups, introduces a high density of CO₂-philic sites capable of strong, reversible interactions with CO₂ via hydrogen bonding and acid–base complexation. When blended with PVA, PZEA forms amine-rich microdomains interconnected through hydrogen-bonded PVA hydroxyl groups, resulting in enhanced hydrophilicity, polymer chain mobility, and effective free volume.
The resulting membranes exhibit pronounced stimuli-responsive behavior toward moisture and temperature, which is particularly advantageous for CO₂ capture from humid flue gas streams. Water acts as an activator and plasticizer, facilitating reversible CO₂–amine interactions and significantly enhancing CO₂ permeability without compromising selectivity. In contrast, the weakly interacting and non-polar N₂ molecules experience strongly hindered transport through the membrane matrix. Consequently, the PVA/PZEA composite membranes demonstrate highly selective CO₂ transport with negligible N₂ permeation.
Notably, the membranes exhibit CO₂ permeability and CO₂/N₂ selectivity values that surpass the Robeson upper bound, underscoring their strong commercial attractiveness for post-combustion CO₂ capture. The membranes also show good polymer–amine compatibility, uniform dispersion, and stable separation performance under humid operating conditions. Overall, the developed PVA/PZEA membranes represent a cost-effective, energy-efficient, and industrially viable platform for flue gas purification and large-scale CO₂ capture applications.
