Modification of Waste-derived CaO Using Organic Acids for CO2 Capture

Calcium looping is a widely used CO2 capture technology, where calcium oxide (CaO) is used as a sorbent. However, it has many drawbacks such as expensive raw material and reduction in sorbent capacity over multiple cycles. This study is aimed at developing economic as well as environment friendly sorbents for CO2 capturing. For this purpose, chicken eggshells were collected from household municipal waste as a CaO sorbent for CO2 capture. The eggshell sorbent was characterized using different techniques such as SEM-EDS, XRD and TGA. Three different organic acids were used to improve the conversion of eggshell sorbents i.e., lactic, oxalic and tartaric acid. The results showed that one out of three acids i.e., lactic acid (ES LA-10%) showed improved conversion and stability over a period of 20 cycles as compared to other acids. In terms of CaO conversion ES LA-10% displayed the maximum performance of 47.8% and had improved cyclic stability during 20 cycles. Hence, this study showed that modifying sorbent (eggshells) by using acid is a better sorbent in comparison with other natural and synthetic sorbent, therefore reducing waste and cost simultaneously.