Bubble column application on purification of biogas and production of nano-calcium carbonate in continuous process

Purification of biogas by removing carbon dioxide content has been developed to increase its calorific value. The CO2 contained in biogas was absorbed by contacting Ca(OH)2 solution and CO2 in the bubble column to produce high purity of biogas and generated precipitated calcium carbonate (PCC) simultaneously. Two sources of CO2 were used in this work, which were CO2 contained in biogas and pure CO2. Pure CO2 was used as a benchmark in this study to show the effect of the presence of methane contained in biogas on the absorption process. The investigation was done in a continuous process. The results showed that the highest absorption of CO2 was obtained in biogas at 79.34 %. PCC with calcite phases was successfully formed in 225-270 nm. Rhombohedral calcite phase was formed by the use of pure CO2 and biogas as a source of CO2. The use of CO2 contained in biogas and pure CO2 in the absorption process did not have an effect on the crystalline phase and morphology of calcite formed. Several factors that significantly affected the absorption of CO2 were gas flow rate, absorbent flow rate, CO2 concentration in the gas inlet, and the initial liquid level in the bubble column.