Our research focuses on the environmental aspects of combustion. Although combustion and industrial, thermal processes are essential to our everyday well being, they can produce a myriad of harmful pollutants. While the biomedical research community is hard at work understanding the health impacts of pollution and the engineering community is developing methods for pollution control, surprisingly little is known about the mechanisms of formation of combustion-generated pollutants. Our research places pollution prevention on a sound scientific basis and provides a critical interface between engineering and biomedical research.
The term, toxic combustion by-products, came into being as a result of research on the emissions from hazardous waste incinerators. Research on incineration revealed that toxic chlorinated hydrocarbons (CHCs) are formed in combustion processes when chlorine is present. Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F), or dibenzofurans for short, are particularly toxic, inducing tumors and birth defects in human populations. Methods for control of dioxins and related compounds is the subject of international treaties and research efforts.
Airborne fine particulate matter with a mass mean aerosol diameter of less than 2.5 microns (PM2.5) has been determined to be responsible for 50,000 deaths in the US each year. However, the mechanism of its toxicity is unknown. Once again, there is an international effort to understand the toxicty of PM2.5 and court battles over whether the US-EPA has the authority to regulate a pollutant whose health effects are so poorly understood.
We have several concurrent research projects and programs designed to address the health impact of combustion-generated pollution, identification of toxic combustion by-products, elementary reaction mechanisms of pollutant formation, and methods for their control.
Using EPR spectroscopy, we have discovered that persistent, combustion-generated radicals are present on samples of airborne PM2.5.. Using cellular assays, radical scavenging techniques, and metal chelators, we have demonstrated that, when inhaled, the radicals on these particles generated reactive oxygen species (ROS) that result in DNA strand breakage. These nicks to DNA can result in development of various cancers and cardiovascular disease. In collaboration with the biomedical and engineering communities, we are working to determine the actual mechanism of biological activity, the source of these radicals, and their atmospheric chemistry.
Using high-temperature flow reactors coupled to GC-MS, we are determining the identity and conditions of formation of toxic by-products from the combustion of a range of wastes and industrial materials. Using ab initio modeling and chemical kinetic codes (CHEMKIN), we are developing detailed mechanism of the formation of these pollutants.
Key elementary reactions have been identified in these pathways for which the kinetic parameters are poorly characterized. Using laser photolysis coupled to laser-induced fluorescence and photoionionzation time-of-flight mass spectrometry, we are determining the temperature dependent rates of these elementary reactions.
Research on the mechanism of dioxin formation has shown that surfaces can catalyze their formation. Using a temperature controlled dosing cell in conjunction with FTIR spectroscopy, we are determining how dioxin precursors adsorb on various surfaces and form dioxins. Using EXAFS and XANES spectroscopy techniques available at LSUâ€™s synchrotron source, we are studying the role of transition metals and oxidative cycling in formation of dioxins.
The formation of dioxin precursors through attack of carbonaceous particulate by combustion-generated radicals is also being studied using laser photolysis techniques. As an outgrowth of our research on the surface catalyzed formation of dioxins, we are actively engaged in the development of innovative catalysts for destruction of CHCs.
Che-Be Instrument Develop for Environmental, 2001
Charles A. Lindberg Foundation Certificate of Merit
Wohleben-Hochwalt Research Award
EPA Science Advisory Board
EPA STAR Award (3)
Engineering and Science Foundation Award
Ohio General Assembly Award for Professional Achievement
Cheri A. McFerrin, H. Barry Dellinger, and Randall W. Hall. Ab Initio Study of the Formation and Degradation Reactions of Semiquinone and Phenoxyl Radicals. Theochem, 2008, 848, 16-23
Barry Dellinger, Slawomir Lomnicki, Lavrent Khachatryan, Zofia Maskos, Randall W. Hall, Julien Adounkpe, Cheri McFerrin, Hieu Truong. Formation of stabilization of persistent free radicals. Proceedings of the Combustion Institute, 2007, 31, 521-528
G. Farquar, S.A. Alderman, E.D. Poliakoff, and B. Dellinger. X ray Spectroscopic Studies of the High Temperature Reduction of Cu(II)O by 2-Chlorophenol on a Simulated Fly-Ash Surface. Environ. Sci. Technol., 2003, 38, 931-935
G.L. Squadrito, R. Cueto, B. Dellinger and W.A. Pryor. Quinoid Redox Cycling as a Mechanism for Sustained Free Radical Generation by Inhaled Airborne Particulate Matter. Free Radic. Biol. Med., 2001, 31, 1132-1138
S. Sidhu, N. Kasti, P. Edwards and B. Dellinger. Hazardous Air Pollutants Formation from Reactions of Raw Meal Organics in Cement Kilns. Chemosphere, 2001, 42(5-7), 499-506
B. Dellinger, W.A. Pryor, R. Cueto, G.L. Squadrito and W.A. Deutsch. The Role of Free Radicals in the Toxicity of Fine Particulate Matter. Chem. Res. Toxicol., 2001, 14, 1371-1377
B. Dellinger, W.A. Pryor, R. Cueto, G.L. Squadrito and W.A. Deutsch. Combustion-Generated Radicals and Their Role in the Toxicity of Fine Particulate. Organohalogen Compounds, 2000, 46, 302-305
P.H. Taylor and B. Dellinger. Pyrolysis and Molecular Growth of Chlorinated Hydrocarbons. J. Anal. And Appl. Pyrolysis, 1999, 49, 9-29
P.H. Taylor and B. Dellinger. Pyrolysis and Molecular Growth of Chlorinated Hydrocarbons. J. Analytical and Applied Pyrolysis, 1999, 49, 9-29