adsorption

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.

This study investigates the potential of Dangara middle layer clay, an abundant natural resource in Nigeria, as a low-cost and sustainable adsorbent for the removal of Pb²⁺ ions from aqueous solutions. Batch adsorption experiments were conducted to evaluate the effects of initial lead concentration (10– 50 mg/L), adsorbent dosage (0.2–1.0 g), agitation time (5–120 min), and pH (4–9) on removal efficiency. The Adsorption process was evaluated by different kinetic models such as pseudo-first-order and pseudo-second-order kinetic models. The Adsorption mechanism was determined by the use of adsorption isotherm such as Langmuir and Freundlich isotherms. Results obtained showed that adsorption efficiency decreased with increasing initial Pb²⁺ concentration due to active site saturation with values ranging from 99.80±0.01% − 96.34 ± 0.80%. Increasing adsorbent dosage enchaned removal, producing adsorption efficiency from 97.00 ± 0.35% − 98.57 ± 0.31% . Agitation time markedly improved adsorption efficiency, yielding removal values from 94.00 ± 0.03% − 99.00 ± 0.02%, while pH had the strongest effect, with adsorption efficiency increasing from 94.97 ± 0.91 % to 99.93 ± 0.06 %, with the maximum removal obtained at pH 9. Isotherm modelling revealed that the Freundlich model best described the equilibrium adsorption behaviour than the Langmuir model, indicating a heterogeneous multilayer adsorption, while Kinetic data fitted the pseudo-second-order model, suggesting chemisorption-controlled uptake. Overall, the findings reveal that Dangara middle layer clay demonstrates strong potential as an efficient, ecofriendly, and locally available material for the removal of lead ions from contaminated water, contributing valuable insight into sustainable water purification and environmental remediation strategies.

Palm Oil Mill Effluent (POME) is a wastewater byproduct of palm oil production, characterized by its high organic content and potential pollutant to water bodies and capable of causing significant environmental damage. This study therefore seeks to evaluate the treatment methods by coagulation and adsorption processes to remove suspended solids and pollutants, thereby purifying the wastewater for safe discharge or reuse. These methods are essential for environmental protection, resource recovery, and economic sustainability. The POME sample was collected, diluted, and analyzed to determine its physicochemical properties before treatment. Its pH was adjusted to both acidic and alkaline conditions using hydrochloric acid and sodium hydroxide, monitored with pH indicator paper. Processed periwinkle shell powder served as a natural coagulant and adsorbent. Standard laboratory instruments were used to assess parameters such as pH, turbidity, total dissolved solids, electrical
conductivity, and salinity before and after treatment. The study evaluated the effects of coagulant dosage, contact time, and pH on the treatment of Palm Oil Mill Effluent (POME) using a periwinkle shell–chitosan composite. Significant reductions in total dissolved solids (TDS) and salinity were achieved at moderate dosages (0.55– 0.82 g/L), contact times of 105–150 minutes, and near-neutral pH (7–8.2), showing effective coagulation and adsorption. X-ray diffraction (XRD) analysis revealed crystalline peaks at 2θ values of 23.9°, 26.5°, 27.5°, 33.4°, 36.4°, 38.1°, 41.4°, 43.1°, 46.0°, 48.6°, 50.5°, and 53.1°, corresponding to aragonite, muscovite, quartz, and orthoclase phases. Crystallite sizes (111–702 Å) confirmed a fine heterogeneous structure with high surface activity, making the composite suitable for efficient and sustainable POME purification

This study utilized cellulose for the adsorption of Zn(II) from aqueous solution via batch adsorption process. The effect of the adsorption parameters: Adsorbent Dosage, Initial Concentrations, and Contact time were investigated. examined under various conditions using heavy metal ion (Zn 2+ ) as the adsorbate. The amounts of Zn(II) adsorbed were estimated by using flame atomic absorption spectrophotometer. It was found to obey the langmuir isotherm as it gave the best fit to the isotherm data. The result of kinetic studies revealed that the adsorption process obeyed pseudo-second order. After the completion of the adsorption process of Zn(II), the result obtained shows that cellulose can be used as an effective adsorbent for the removal of Zinc ion (Zn 2+ ) from aqueous solution