Edokpayi

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.

With Nigeria generating over 42 million tonnes of waste annually, improper disposal poses significant risks to soil health, groundwater, and public health. This study examines the contamination levels of heavy metals and the physicochemical properties of soil at a solid waste disposal site in Ovia Northeast, Edo State, Nigeria. Soil samples were collected at varying depths (10, 20, 30, and 40 cm) from a dumpsite and a control site, focusing on lead (Pb), iron (Fe), copper (Cu), and manganese (Mn), alongside properties such as pH, bulk density, porosity, organic matter, and electrical conductivity (EC). Results revealed elevated levels of heavy metals at the dumpsite compared to the control site, particularly in the top 10 cm of soil. For example, Pb concentrations reached 12.31 mg/kg at the dumpsite, nearly three times higher than the 4.24 mg/kg observed at the control. Similarly, copper (Cu) levels at the dumpsite peaked at 74.22 mg/kg, significantly higher than the control site’s 57.47 mg/kg. Physicochemical properties demonstrated a strong influence on metal mobility: soil pH at the dumpsite ranged from 7.12 to 7.62, slightly higher than the control’s 6.86 to 6.12. Organic matter content decreased with depth, from 8.74% at the surface to 3.15% at 40 cm in the dumpsite, compared to 9.07% to 2.54% in the control. EC values were markedly higher at the dumpsite (252–290 µS/cm) compared to the control (144–168 µS/cm), reflecting leachate infiltration and ion enrichment. The findings underscore the environmental risks posed by heavy metal contamination, including soil degradation, reduced fertility, and potential bioaccumulation in the food chain. Elevated metal concentrations exceeded WHO permissible limits, necessitating immediate remediation actions. Recommendations include the implementation of sustainable waste management practices, soil remediation techniques such as phytoremediation, and ongoing monitoring to mitigate long-term environmental impacts.

With Nigeria generating over 42 million tonnes of waste annually, improper disposal poses significant risks to soil health, groundwater, and public health. This study examines the contamination levels of heavy metals and the physicochemical properties of soil at a solid waste disposal site in Ovia Northeast, Edo State, Nigeria. Soil samples were collected at varying depths (10, 20, 30, and 40 cm) from a dumpsite and a control site, focusing on lead (Pb), iron (Fe), copper (Cu), and manganese (Mn), alongside properties such as pH, bulk density, porosity, organic matter, and electrical conductivity (EC). Results revealed elevated levels of heavy metals at the dumpsite compared to the control site, particularly in the top 10 cm of soil. For example, Pb concentrations reached 12.31 mg/kg at the dumpsite, nearly three times higher than the 4.24 mg/kg observed at the control. Similarly, copper (Cu) levels at the dumpsite peaked at 74.22 mg/kg, significantly higher than the control site’s 57.47 mg/kg. Physicochemical properties demonstrated a strong influence on metal mobility: soil pH at the dumpsite ranged from 7.12 to 7.62, slightly higher than the control’s 6.86 to 6.12. Organic matter content decreased with depth, from 8.74% at the surface to 3.15% at 40 cm in the dumpsite, compared to 9.07% to 2.54% in the control. EC values were markedly higher
at the dumpsite (252–290 µS/cm) compared to the control (144–168 µS/cm), reflecting leachate infiltration and ion enrichment. The findings underscore the environmental risks posed by heavy metal contamination, including soil degradation, reduced fertility, and potential bioaccumulation in the food chain. Elevated
metal concentrations exceeded WHO permissible limits, necessitating immediate remediation actions. Recommendations include the implementation of sustainable waste management
practices, soil remediation techniques such as phytoremediation, and ongoing monitoring to mitigate long-term environmental impacts.

Climate change driven by increasing atmospheric CO₂ concentrations calls for urgent implementation of atmospheric CO2 reduction. However, adsorbents are mostly expensive and energy-intensive, especially for developing nations. Agricultural wastes, especially corn cobs, are a sustainable alternative due to their lignocellulosic composition, natural porosity,
and abundance as underutilized biomass. This study investigated the CO₂ adsorption potential of chemically activated corn cob-derived adsorbent through packed bed column experiments. Corn cobs were collected, processed, and activated using potassium hydroxide (KOH) at temperatures between 400-600°C. CO₂ gas was generated in-situ via CaCO₃-HCl reaction and
passed through glass columns (2.1 cm diameter, 5 cm bed height) at flow rates of 0.5-2.0 L/min. Four particle size ranges (100, 250, 500, and above 500 μm) were evaluated over 60- minute contact periods at ambient temperature (29±2°C).
Characterization via SEM-EDS revealed highly porous morphology with 90.05% carbon content and oxygen-containing functional groups favorable for CO₂ binding. The 100 μm particle size achieved the highest equilibrium adsorption capacity of 5,459 ppm·L/g, while 250 μm particles demonstrated optimal removal efficiency of 48.0%. Breakthrough analysis indicated that smaller particles delayed saturation, with 100 μm maintaining effectiveness beyond 45 minutes compared to 25 minutes for above 500 μm particles. Flow rate influenced performance, with reduced rates (0.5 L/min) compensating for larger particle sizes by increasing contact time. These findings reveal that corn bobs are a viable solution for carbon capture.

Climate change driven by increasing atmospheric CO₂ concentrations calls for urgent implementation of atmospheric CO2 reduction. However, adsorbents are mostly expensive and energy-intensive, especially for developing nations. Agricultural wastes, especially corn cobs, are a sustainable alternative due to their lignocellulosic composition, natural porosity, and abundance as underutilized biomass. This study investigated the CO₂ adsorption potential of chemically activated corn cob-derived adsorbent through packed bed column experiments. Corn cobs were collected, processed, and activated using potassium hydroxide (KOH) at temperatures between 400-600°C. CO₂ gas was generated in-situ via CaCO₃-HCl reaction and passed through glass columns (2.1 cm diameter, 5 cm bed height) at flow rates of 0.5-2.0 L/min. Four particle size ranges (100, 250, 500, and above 500 µm) were evaluated over 60- minute contact periods at ambient temperature (29±2°C). Characterization via SEM-EDS revealed highly porous morphology with 90.05% carbon content and oxygen-containing functional groups favorable for CO₂ binding. The 100 µm particle size achieved the highest equilibrium adsorption capacity of 5,459 ppm·L/g, while 250 µm particles demonstrated optimal removal efficiency of 48.0%. Breakthrough analysis indicated that smaller particles delayed saturation, with 100 µm maintaining effectiveness beyond 45 minutes compared to 25 minutes for above 500 µm particles. Flow rate influenced performance, with reduced rates (0.5 L/min) compensating for larger particle sizes by increasing contact time. These findings reveal that corn bobs are a viable solution for carbon capture