Optimizing the synthesis of nanoporous activated carbon from date-palm waste for enhanced CO2 capture

Optimizing process parameters is essential for developing high efficacy carbonaceous adsorbents. This study investigated carbon dioxide (CO₂) capture using activated carbon (AC) synthesized from date-palm leaflets. Key process parameters-pyrolysis temperature, residence time, and KOH-to-carbon (KOH/C) impregnation ratio-were systematically varied to synthesize highly nanoporous AC for enhanced CO₂ uptake. Instead of relying on an intuitive selection of process variables, the optimization process was implemented using Response Surface Methodology (RSM) protocol, which provided a structured and effective strategy for process optimization. Over twenty different AC samples were synthesized and evaluated for their CO₂ adsorption capacities. The optimal conditions, identified as 700 °C, 1.5 h, and a 3:1 (KOH/C) impregnation ratio, yielded AC with exceptional CO₂ uptake capacities of 6.71 mmol/g at 0 °C and 4.214 mmol/g at 25 °C, outperforming most previously reported biomass-derived ACs. This superior performance is attributed to the well-developed nanoporous structure and high nitrogen content of the optimized sample, as confirmed by N₂ adsorption isotherms, elemental analysis, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The optimized AC demonstrated excellent stability over multiple adsorption-desorption cycles. Additionally, a high isosteric enthalpy of adsorption (35 kJ/mol at 0.2 mmol/g) further confirmed preferential CO₂ adsorption at energetically favorable nanopore sites. This study underscores the potential of date-palm leaflets as a sustainable and abundant precursor for synthesizing high-efficacy AC for carbon capture.