Helen Onyeaka

By Abarasi Hart and Helen Onyeaka

This review aims to explore the application of natural and renewable bioceramics such as eggshell and seashells in carbon dioxide (CO2) capture from power plant flue gas. CO2 capture, utilisation and storage (CCUS) is considered a means to deliver low carbon energy, decarbonising industries, power plants and facilitates the net removal of CO2 from the atmosphere. The stages involved include CO2 capture, transport of the captured CO2, utilisation and secure storage of the captured CO2. This chapter reports the use of eggshell and seashells biomaterials as an adsorbent to separate CO2 from other gases generated by power plants and industrial processes. The capture of carbon dioxide by adsorption is based on the ability of a material to preferentially adsorb or carbonate CO2 over other gases. In light of this, calcined eggshell and seashells biomaterial rich in calcium carbonate from which calcium oxide (94%) can be obtained have demonstrated a strong affinity for CO2. These biomaterials are abundant and low-cost alternative to zeolite, activated carbon and molecular sieve carbon. The mechanism of CO2 capture by eggshell and seashells derived CaO adsorbent comprises of a series of carbonation-calcination reactions (CCR): calcium oxide (CaO) reacts with CO2 resulting in calcium carbonate (CaCO3), which releases pure CO2 stream upon calcinations for sequestration or utilisation, and as a consequence, the biomaterial is regenerated. Findings reveal that these biomaterials can hold up to eight times its own weight of CO2 from flue gas stream. It was also found that the combination of 2 M acetic acid and water pretreatment improved the reactivity and capture capacity of the biomaterial for successive regeneration over four cycle’s usage. Unlike activated carbon, these biomaterials are considered stable for high-temperature adsorption through carbonation.

Part of the book: Carbon Capture