Abstract

Negative emissions technologies target the removal of carbon dioxide from the atmosphere as a way of combating global warming. Enhanced rock weathering (ERW) is a vital negative emissions technology that applied globally could remove gigatons of carbon dioxide per year from the atmosphere. In ERW, silicate minerals exposed to the atmosphere trap CO2 via mineral carbonation as thermodynamically stable carbonates. To obtain an atomic scale understanding of the weathering process and to design more reactive silicates for enhanced rock weathering, carbon dioxide adsorption on low Miller index wollastonite (CaSiO3) surfaces was modeled using density functional theory. Atomic scale structure of (100), (010), and (001) surfaces of wollastonite was predicted and the thermodynamics of their interaction with carbon dioxide was modeled. Based on surface energy calculations, (001) and (010) surfaces of wollastonite exhibit similar stabilities, while (100) surface is found to be least stable. Depending on the surface structure and chemistry, different carbon dioxide adsorption geometries are possible. A common trend emerges, wherein carbon dioxide adsorbs molecularly and demonstrates proclivity to bond with surface layer calcium and oxygen binding sites. Mechanisms for electronic charge transfer between the adsorbate and the substrate were studied to shed light on the fundamental aspects of these interactions. The most favorable bent dioxide geometry was bridged between calcium atoms, revealing that the enhancement of the likelihood of this geometry and binding site could pave the way to designing reactive silicates for efficient carbon dioxide sequestration via ERW.

Library of Congress Subject Headings

Wollastonite--Environmental aspects; Silicates--Environmental aspects; Carbon sequestration

Publication Date

4-26-2022

Document Type

Thesis

Student Type

Graduate

Degree Name

Materials Science and Engineering (MS)

Department, Program, or Center

School of Chemistry and Materials Science (COS)

Advisor

Pratik Dholabhai

Advisor/Committee Member

Ke Xu

Advisor/Committee Member

Kalathur Santhanam

Campus

RIT – Main Campus

Plan Codes

MSENG-MS

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