<![CDATA[Biogas utilization from agricultural waste in Indonesia remains underdeveloped despite its significant potential as a renewable energy source. Biogas produced through anaerobic digestion contains a high concentration of carbon dioxide (CO₂), which lowers its calorific value and limits its direct use as a clean fuel. Therefore, biogas upgrading is necessary to increase methane (CH₄) concentration and improve fuel quality. This study evaluates the performance of banana fiber as a natural adsorbent for methane enhancement and carbon dioxide removal in biogas. Banana fiber was selected because of its lignocellulosic composition and porous structure, which provide potential adsorption sites for gas molecules. The experimental setup employed a fixed-bed filtration system in which raw biogas from an anaerobic digester was passed through a column packed with untreated banana fiber. Gas samples were collected before and after filtration and analyzed using Gas Chromatography–Mass Spectrometry (GC–MS) to determine changes in CH₄ and CO₂ concentrations. The results showed that methane concentration increased from 51.37% to 60.84%, corresponding to an enhancement of 9.47%, while carbon dioxide concentration decreased from 48.63% to 39.15%, representing a reduction of 9.48%. These findings indicate that banana fiber effectively improves biogas quality by selectively adsorbing CO₂ and enriching methane content. The adsorption performance is attributed to the presence of hydroxyl (–OH) and carboxyl (–COOH) functional groups in the lignocellulosic structure of banana fiber, which facilitate physical adsorption and enhance gas–solid interactions. In addition, the porous structure of the fiber increases surface area and supports adsorption efficiency. This study demonstrates the effectiveness of untreated banana fiber as a low-cost and environmentally friendly adsorbent for biogas upgrading using GC–MS analysis. The findings highlight its potential application in small-scale and decentralized renewable energy systems, particularly in rural and agricultural areas. Furthermore, the study provides important implications for laboratory-scale biogas purification systems and future industrial biogas upgrading applications.]]>
