Introduction

The unprecedented rise in atmospheric carbon dioxide (CO₂) concentration represents one of the most critical challenges for modern energy systems, directly impacting climate stability and energy sustainability [1, 2]. Carbon capture and storage (CCS) technologies are therefore indispensable for enabling low-carbon energy transitions. Among emerging solutions, porous carbons derived from biomass have attracted increasing attention due to their low environmental footprint, scalability, and structural tunability [3]. Grape seeds, a major waste stream of the wine industry, constitute an abundant lignocellulosic resource with untapped potential for advanced energy and environmental applications [4]. Despite growing interest in biomass-derived carbons, a fundamental understanding of how activation strategies govern pore architecture and CO₂ adsorption efficiency remains insufficient.

Methods

In this work, grape seed-derived activated carbons were synthesized via chemical and physical activation routes at temperatures between 600 and 800 °C to systematically evaluate structure–performance relationships. The materials were comprehensively characterized using XRD, Raman spectroscopy, XRF, SEM, and N₂ adsorption–desorption analyses to determine their crystallinity, chemical purity, morphology, and pore structure. To bridge macroscopic performance with microscopic mechanisms, Grand Canonical Monte Carlo (GCMC) simulations were employed to investigate CO₂ adsorption behavior [5], interaction energies, and isosteric heats of adsorption at the molecular level.

Results

Chemical activation yielded a highly developed porous carbon (AC-GC-C-800) with an exceptional specific surface area of 1968 m² g⁻¹ and a total pore volume of 1.22 cm³ g⁻¹. In contrast, physically activated carbons exhibited progressively reduced porosity and larger particle sizes with decreasing activation temperature. Structural analyses revealed that AC-GC-C-800 possessed the highest degree of structural disorder (I_D/I_G = 0.75), which strongly correlated with enhanced microporosity and superior CO₂ uptake. As a result, AC-GC-C-800 achieved a CO₂ adsorption capacity of 6.5 mmol g⁻¹ at 273 K and 4.8 mmol g⁻¹ at 298 K under 1 bar, outperforming physically activated counterparts by up to ~40%. Elemental analysis confirmed that KOH activation effectively removed inorganic impurities, resulting in a carbon purity of 92.5 wt%. GCMC simulations demonstrated that while surface area dominates adsorption at elevated pressures, CO₂ capture under low-pressure, post-combustion conditions is governed by the presence of narrowly distributed ultra-micropores [6, 7]. Simulation snapshots and energy analyses clearly showed stronger host–guest interactions in chemically activated carbons.

Conclusions

This study reveals that precise control of pore geometry, rather than surface area alone, is the decisive factor governing CO₂ capture efficiency in biomass-derived carbons. By combining advanced characterization with molecular-level simulations, this work provides a mechanistic framework for designing high-performance, sustainable adsorbents for CCS applications. The results highlight grape seed waste as a viable feedstock for advanced energy materials and contribute to the rational development of carbon capture technologies aligned with circular economy and low-carbon energy strategies

Acknowledgments

This research was funded by the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan (grant no. AP19679878—Conversion of plant biomass waste into microporous activated carbons to successfully capture and separate CO₂, N₂ and CH₄.)

References

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