Highly scalable honeycomb-like aminated PVDF-g-PEI hollow fiber membranes for direct air capture of CO2

Abstract

The rising level of CO₂ in the atmosphere requires highly scalable and efficient sorbents for direct air capture. In this study, a scalable aminated polyvinylidene fluoride grafted polyethyleneimine (PVDF-g-PEI) hollow fiber (HF) membrane was fabricated with stable and accessible amine groups. The aminated PVDF-g-PEI HF membrane was characterized using different techniques to verify the number of grafted amines, and the effect of amine content on the membrane structure and CO₂ adsorption performance were thoroughly examined. The results showed that the aminated PVDF-g-PEI HF membrane had a highly porous, honeycomb-like structure when the PEI loading was 6.6 wt%. This structure provided the best access to the grafted amine groups and resulted in the highest CO₂ adsorption capacity of 0.5 mmol-CO₂ per gram of membrane under the atmospheric conditions. The aminated PVDF-g-PEI membrane demonstrated a 96.7 % regeneration capability in 20 continuous long-term cyclic CO₂ adsorption–desorption experiments. Compared to the conventional amine-functionalized powdered sorbents for direct air capture of CO₂, the aminated PVDF-g-PEI HF membranes shows higher scalability for large scale applications.