<![CDATA[The increasing global demand for renewable energy and the urgent need to reduce greenhouse gas emissions highlight the importance of developing sustainable technologies for biogas upgrading. Coconut pulp, a plentiful agro-industrial residue rich in cellulose, hemicellulose, and lignin, offers a promising precursor for activated carbon production while addressing agricultural waste challenges. This study aimed to synthesize and characterize coconut pulp–based activated carbon through a combined physicochemical activation process and to evaluate its theoretical potential for CO₂ and H₂S adsorption in biogas purification. The preparation involved carbonization at 400 °C, sequential chemical activation using 3 N H₃PO₄ and 3 N KOH, followed by physical activation at 600 °C under semi-closed conditions. Proximate analysis revealed a moisture content of 4.665%, ash content of 0.637%, and a final yield of 12.38%, all within the Indonesian National Standard (SNI 06-3730-1995) limits except for volatile matter, which remained high due to the soft lignocellulosic nature of coconut pulp. BET surface analysis demonstrated a specific surface area of 345.57 m² g⁻¹, total pore volume of 0.1595 cc g⁻¹, and a dominant micropore area of 282.80 m² g⁻¹, indicating strong potential for small-molecule adsorption. The iodine number of 161.973 mg g⁻¹ confirmed micropore prevalence. FTIR spectra showed a marked decrease in –OH and C=O groups and the emergence of a new band near 900 cm⁻¹ (=C–H aromatic), evidencing the formation of stable aromatic domains. SEM–EDX images revealed a hierarchical pore network (macro–meso–micro) with uniform distribution and high carbon purity (96.65%) and minimal mineral residues. These structural and chemical features suggest enhanced interaction with acidic (H₂S) and non-polar (CO₂) gases through physisorption mechanisms. Compared with single-stage activation methods, the dual chemical–physical strategy provided superior surface area, pore connectivity, and carbon purity, representing a novel approach for biomass-derived adsorbents. Overall, coconut pulp–derived activated carbon synthesized via integrated physicochemical activation exhibits favorable physicochemical properties for efficient CO₂ and H₂S removal, supporting its application as a sustainable and low-cost adsorbent for biogas upgrading. Future work should include dynamic adsorption studies under real biogas conditions to validate the theoretical predictions and to optimize activation parameters for large-scale deployment.]]>
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