Synthesis of a Low Cost, Natural Base Solution for CO2 Scrubbing from Biogas and its Comparison with KOH

Abstract

AbstractBiogas produced from anaerobic digestion of organic waste is composed of methane (CH4) and carbon dioxide (CO2) as the major constituents with trace amounts of other components like water vapor, hydrogen sulfide, ammonia, and nitrogen. Scrubbing of CO2 is essential for upgradation of biogas, which increases the calorific value of the treated gas and enhances its efficiency for power production and cooking. This study was conducted to investigate and compare the effects of different concentrations of KOH (0.1, 0.3, 0.5, 0.7, and 1.0 M) and natural base ash solutions prepared from different parts of banana plant, viz. banana pseudostem (BPS), Musa balbisiana Peel (MBP), and Musa acuminata Peel (MAP) for scrubbing of CO2 from biogas. The methane content of the untreated biogas analyzed in a gas chromatograph was found to be 56.9%. The scrubber with natural base solution from MBP could enrich the methane content in biogas from 56.9% to 86.3% followed by MAP (78.4%) and BPS (76.8%). The experiments revealed that banana peel ash base solutions have nearly equivalent potential as KOH for CO2 absorption from biogas. The highest CO2 absorption of ~ 68% was achieved with MBP with saturation time of 19 min approximately at a flow rate of 200 ml/min. The study also indicated that CO2 absorption by different natural as well as chemical base solvents is transient and has to be replenished after saturation. Natural bases have the added advantage of being easily available, cheap production method, environment friendly and require no treatment for disposal.KeywordBiogasCO2 scrubbingPotassium hydroxideNatural baseAbsorption