Plasma-modified lignin sorbents for enhanced CO₂ adsorption : a sustainable approach to synthesize CO₂ capture materials using plasma technology

Abstract

As CO₂ in the atmosphere rises exponentially, it significantly affects the Earth’s climate. Among other greenhouse gases, CO₂ is the major source of global warming. To address this, methods to capture CO₂ and store or utilize it in value-added resources are currently in demand. Current research trends on carbon capture methods from air or flue gas have been driven towards sustainable approaches. They are focused solely on the utilization of biomaterials as CO₂ adsorbents. Lignin has been developed as a sustainable biomaterial for CO₂ capture. The current lignin functionalization techniques are based on chemical methods, which produce waste and require harsh chemicals and are energy-intensive. This creates a clear opportunity to develop efficient and environmentally sustainable CO₂ capture materials. This study is focused on synthesizing plasma-modified lignin sorbents for efficient CO₂ capture to address the demanding evolution of bio-based CO₂ capture materials. To evaluate the effect of plasma parameters on the CO₂ capture performance of plasma-modified lignin, samples were synthesized with different distances between the plasma gun and the sample and different exposure times. The study reveals that, under plasma conditions, lignin has been successfully functionalized with carbonyl groups. The data from CO₂ capture capacities suggested that upon plasma treatment, the CO₂ capture capacity has been increased by more than double the amount of CO₂ captured by unmodified lignin. Plasma treatment with the highest exposure time achieved the highest CO₂ capture performance. The adsorption isotherms modelling done for the composite with the highest CO₂ adsorption capacity was in correlation with the Freundlich isotherm. Overall, this study demonstrated that lignin can be transformed into high-performance CO₂ adsorbents using atmospheric plasma in climate mitigation efforts and sustainable material development.