CARBON CAPTURE

Escalating anthropogenic carbon dioxide (CO₂) emissions necessitate the development of sustainable and cost-effective capture technologies. This research investigates the valorization of corn cobs, an abundant agricultural waste, as a precursor for producing activated carbon (AC) for CO₂ capture via adsorption. The activated carbon was synthesized from corn cobs, sourced from Benin City, Nigeria, using a chemical activation method with potassium hydroxide (KOH). The resulting adsorbent was characterized using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), and Thermogravimetric Analysis (TGA). Adsorption experiments were conducted in a packed column to evaluate CO₂ capture performance. The study systematically assessed the effects of key operational parameters, including contact time, adsorbent dosage, gas flow rate (0.5 and 2.0 L/min), and particle size (100, 250, 500, and >500 µm). Characterization confirmed the synthesis of a porous, carbon-rich material. SEM revealed a rough, heterogeneous surface with significant porosity ideal for adsorption, while EDS confirmed carbon as the predominant element (90.05% atomic concentration). TGA demonstrated high thermal stability, indicating suitability for regeneration cycles. Adsorption studies showed rapid CO₂ uptake, reaching equilibrium in approximately 50-60 minutes. Particle size was identified as a critical factor influencing performance. The 250 µm particle size achieved the highest CO₂ removal efficiency at 48.0%. However, the 100 µm particles exhibited the highest equilibrium adsorption capacity (qₑ) of 2,939 ppm·L/g, attributed to their greater specific surface area. Breakthrough analysis further confirmed that smaller particle sizes (<100 µm) significantly prolonged bed saturation time (approx. 45 minutes) compared to larger particles.This study concludes that corn cob-derived activated carbon is an effective, low-cost, and sustainable adsorbent for CO₂ capture. The 250 µm particle size offers an optimal balance between removal efficiency and practical operational handling. This wasteto-value approach supports circular economy principles and presents a viable pathway for mitigating CO₂ emissions using locally available agricultural residues.