ABSTRACT

CAREER: On the Prevention of Selenium and Arsenic Release into the Atmosphere

The goal of the proposed work is to aid in the prevention of the release of the volatile metals, selenium and arsenic, from the flue gases of coal combustion. There have been extensive research efforts aimed at capturing mercury and understanding its speciation in flue gases, but not as much is known of selenium and arsenic in the chemically complex flue gas environment. The proposed research will also examine novel sorbent technologies for the capture of these trace elements, and a mechanism responsible for their retention will be determined. Model development will take place through high level ab initio energetics calculations. The research activities proposed will advance discovery through the development of two kinetic models that will elucidate, for the first time ever, the mechanism of retention of selenium and arsenic on calcium based sorbents. In addition, the proposed plan includes the development of a high school outreach program, which will involve undergraduate students training high school teachers on the incorporation of computational chemistry and molecular modeling techniques into their science courses. The research and educational activities combined will advance understanding through the incorporation of molecular computational applications in the classroom, which will provide both college and high school students the opportunity to gain a deeper understanding of chemical interactions using multimedia-based approaches for effective teaching.

Understanding the speciation of selenium and arsenic in the flue gas environment is essential for developing effective technologies to control their emissions. Homogeneous reactions involving these species will be examined through the theoretical prediction of rate constants obtained from quantum mechanical derived potential energy surfaces. Effective core potentials that include relativistic effects will be incorporated into the basis sets, and this will be carried out for all calculations using both Quadratic Configuration Interaction (QCI) and Coupled Cluster (CC) techniques. Heterogeneous reaction investigations will also take place to elucidate the mechanisms responsible for the retention of arsenic and selenium on calcium-based sorbents. Heterogeneous rate constant predictions will be experimentally validated through the analysis of the reacted sorbent material using an Inductively Coupled Plasma Mass Spectrometer (ICP-MS). In total, this research will benefit the scientific community in that there will be a greater understanding of the speciation of these trace elements in the flue gases of combustion processes and also further understanding on methods involving their capture. The impact that the proposed research could have on society is the possible prevention of the release of these toxic elements into the atmosphere.

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