Effect of Reaction Parameters on CO 2 Absorption from Biogas Using CaO Sorbent Prepared from Waste Chicken Eggshell.

This study provides an efficient and straightforward approach to eliminate carbon dioxide (CO 2 ) by absorption using a calcium oxide (CaO) sorbent derived from chicken eggshells. The sorbent concentration, stirring speed, and contact time were varied. The optimal condition for CO 2 removal was a 10% calcium hydroxide (Ca(OH) 2 ) suspension at 600 rpm with 20 min interaction. This optimum condition conferred the ever-highest absorption (98.71%) of CO 2 through Ca(OH) 2 suspensions from eggshell-derived CaO. X-ray diffraction was used to identify crystallographic phases and optimum conditions revealed calcium carbonate (CaCO 3 ) formation with the highest intensity, Fourier transform infrared spectroscopy revealed peaks for the carbonate (CO 3 2- ) group, field emission scanning electron microscopy was used to investigate the morphological and structural properties of the sorbent before and after CO 2 absorption, and thermogravimetric analysis was performed to understand the reaction mechanism. According to the kinetic analysis, the sorbent can be fully decomposed with a minimum activation energy ( E a ) of 89.09 kJ/mol.