Knowledge Bank

The burning of fossil fuels leads to greenhouse gas (GHG) emissions, like carbon dioxide (CO2), which contribute to global warming. Current CO2 mitigation practices comprise of: [a] separation, [b] transportation, and [c] sequestration. Presently CO2 separation costs play a dominant role in the CO2 management scheme. The focus of this investigation is to effectively utilize chicken eggshells, a bio-composite material rich in calcium, as a sorbent for CO2 capture. The eggshells offer a unique combination of sorbent strength and reactivity while maintaining a low cost. The reaction mechanism consists of a series of carbonation-calcination reactions (CCR): calcium oxide (CaO) reacts with CO2 forming calcium carbonate (CaCO3), then calcining the shell forms a pure CO2 stream and regenerates CaO. Taking advantage of the eggshell's capacity to capture CO2, can also lead to enhanced hydrogen (H2) production at high temperatures in a coal gasification process.
Treating the eggshell with acetic acid at low concentrations not only facilitates membrane removal, but also shows an increase in the eggshell reactivity, which leads to increased CO2 capture as well as improved H2 production. In addition, the membrane contains collagen which is used in skin grafting, cornea repair, osteoporosis treatment, and other medical and surgical procedures. Overall, this study focuses on potential of treated eggshells as calcium-based sorbents for CO2 capture and H2 production and as source of collagen. Data shows that eggshells treated with acetic acid, not only enhances membrane removal from the shell but also leads to increased reactivity over multiple CCR cycles. The 2 molar 15 minute treated eggshell sample shows the highest capture capacity over time. Using eggshell as a sorbent for H2 production shows that 100% conversion of CO to H2 can be achieved.

Advisor: LS Fan

(Proprietary: Iyer M. V. and Fan. L-S “High Temperature CO2 Capture Using Engineered Eggshells” U.S. Patent Application No. 11/384,011 (March 2006))