Highly Efficient Multisubstrate Agricultural Waste-Derived Activated Carbon for Enhanced CO₂ Capture

Activated carbon (AC) made of single-substrate agricultural wastes is considered to be a suitable raw material for the production of low-cost adsorbents; however, the large-scale application of these materials is highly limited by their low efficiency, seasonal scarcity, poor stability, low surface area, and limited CO₂ adsorption performance. In this study, composite activated carbon (CAC) was prepared via controlled carbonization followed by chemical activation of four wastes (i.e., peanut shell, coffee husk, corn cob, and banana peel) at an appropriate weight ratio. The Na₂CO₃-activated CAC showed a higher surface area and valuable textural properties for CO₂ adsorption as compared with KOH- and NaOH-activated CAC. The CAC production parameters, including impregnation ratio, impregnation time, carbonization temperature, and time, were optimized in detail. The as-prepared CACs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Raman spectroscopy, N₂ adsorption-desorption isotherm, and iodine number analysis. The CAC produced at optimal conditions exhibited the highest CO₂ removal efficiency and adsorption capacity of 96.2% and 8.86 wt %, respectively, compared with the single-biomass-derived activated carbon. The enhanced CO₂ adsorption performance is due to the large surface area, a considerable extent of mesopores, and suitable pore width. The adsorbent in this study reveals a promising strategy for mitigating the CO₂ emission problems instead of more expensive and ineffective materials.