A facile approach in activated carbon synthesis from wild sugarcane for carbon dioxide capture and recovery: isotherm and kinetic studies

Carbon dioxide (CO₂) concentrations are rising in the atmosphere as a result of the industrial revolution. CO₂ emissions are a major contributor to climate change. In recent years, low-cost waste biomass material–based adsorbents have been used to adsorb CO₂. In this work, using phosphoric acid as a chemical activator, extremely porous activated carbon was effectively generated from Saccharum spontaneum, i.e., wild sugarcane (WS), and it is employed for the CO₂ capture. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopies (FTIR), and energy dispersive X-ray spectroscopy (EDAX) are used to analyze the prepared activated carbon characteristics. Enthalpy value of − 44.56 kJ/moles obtained from thermodynamic study confirms it as a chemisorption process. Langmuir, Freundlich, Dubinin-Radushkevich, Temkin, and Sips adsorption isotherms were used to characterize the experimental isotherm data of activated carbon from WS. The Brunauer Emmett Teller (BET) surface area of 1010 m²/g and the iodine value of 980 m²/g were more reliable indicators of the adsorption process. The R² value of 0.988 and adsorption capacity of 3.223 × 10^–3 mol/g/min for the Langmuir model indicates that it is the best fit for CO₂ adsorption. The Freundlich constant n value of 1.0811 indicates favorable adsorption of CO₂ on WS. The actual and estimated q_e values from pseudo-second-order kinetics are almost same, and a high R² value (0.9888) confirms that the system follows pseudo-second-order kinetics. At 90 min, the equilibrium point was reached. Three cycles of desorption investigations were carried out, and an efficiency of 80% was achieved.