Biogas has been exploited as one of the alternative sources of renewable energy having the potential to replace fossil fuels. It contains impurities when raw, as it consists of 50–70% methane (CH 4 ), 30–50% carbon dioxide (CO 2 ) and trace gases such as hydrogen sulfide (H 2 S). Chemical absorption is often a preferred purification technique in industrial applications because it has high efficiencies, removes H 2 S completely, operates at low pressures, and has higher reaction rates. The focus of this study is on amines as they are widely used worldwide to purify biogas. A continuous system was used where 1?L digester was used for biogas production which was bubbled through an absorbent in 500?mL gas washing bottle. The gas exiting the absorption column was analyzed using Gas Chromatography. The methane yield obtained in this study was higher because MEA is a good absorbent. The biomethane potential was found to be 0.40?m 3 CH 4 /kg VS (volatile solids). An increase in concentration resulted in increased co 2 absorption capacity and rate, an average of 76%, 78%, and 84% vol from an initial concentration of 52% vol were achieved for the respective concentrations. The CH 4 content of the purified biogas improved with increasing temperature. The removal efficiency of carbon dioxide increased from 66% at room temperature to 77% at 40?°C. Temperature of the solvent increased the absorption capacity and carbon dioxide removal efficiency of the process. Highlights ? The study was conducted in a laboratory scale at the University of Johannesburg. Two kinds of pathways were followed; the Buchner flask setup and the biochemical methane potential test system using the Automated Methane Potential Test System (AMPTS) II. ? The results obtained showed that monoethanolamine (MEA) is effective in absorbing impurities in biogas. It is capable of removing CO 2 in biogas resulting in biomethane that is over 85% CH 4 . ? The temperature of the solvent affects the absorption process. Higher MEA concentration results in high absorption as 30% MEA solution had the cleanest gas. ? Temperature of the solvent also affected the absorption process because the rate of reaction is dependent on temperature. ? The removal efficiency increased with increasing temperature and was recorded to be 77% for 40?°C.
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