The determination of accurate volatile organic compound (VOC) and greenhouse gas (GHG) partitioning coefficients for air-water interfaces is essential for pollution and global climate modeling. In the atmosphere, oceans, and groundwater the concentration of dissolved salts is high enough to significantly alter the air-water partitioning behavior of the VOC or GHG, prohibiting the use of literature data or predictive models that omit the salt effect. Despite the great need for air-water partitioning data of the VOCs and GHGs threatening the environment, there is a lack of air-water partitioning data in the presence of dissolved salt. Furthermore, there are large disagreements between reported data from different research groups, which hamper model development. Henry s constants of several VOCs with salts were measured with a new high-throughput headspace gas chromatography (HTHSGC) method to create a library of internally consistent air-water partition coefficients for modeling. The VOCs studied included a homologous series of 1-alkanols, 2-ketones, organic sulfides, and the principle components of gasoline including: toluene, ethylbenzene, o-xylene, methyl tertbutyl ether, and ethyl tertbutyl ether. A model with temperature-independent parameters based on dilute solution theory was developed using the library of data to resolve the disagreements between literature sources and perform a priori prediction of salt effects. The model correlated air-water partitioning data in the form of Henry s constants over temperature ranges as wide as 300 Kelvin, salt concentrations up to 4 molal, and pressures up to 1000 bar. Extrapolations of up to 50 K, and 1 molal salt and 100 bar pressure can also safely be performed to eliminate the need for additional experiments. The temperature-independent salt effect parameter was found to be directly proportional to the critical volume of the VOC and all homologous VOCs explored followed the same linear trend allowing a priori prediction of the salt effect for unexplored compounds.
| Identifer | oai:union.ndltd.org:GATECH/oai:smartech.gatech.edu:1853/16221 |
| Date | 10 May 2007 |
| Creators | Falabella, James Benjamin |
| Publisher | Georgia Institute of Technology |
| Source Sets | Georgia Tech Electronic Thesis and Dissertation Archive |
| Detected Language | English |
| Type | Dissertation |
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