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Full-Text Articles in Physical Sciences and Mathematics
Effect Of Metal Speciation In Fly Ash On Environmentally Persistent Free Radical Formation, Elisabeth Eileen Cook
Effect Of Metal Speciation In Fly Ash On Environmentally Persistent Free Radical Formation, Elisabeth Eileen Cook
LSU Doctoral Dissertations
Waste incineration and Superfund sites lead to the formation of pollutants harmful to both the environment and human health. Environmentally Persistent Free Radicals (EPFRs) are a class of newly discovered radical pollutants known to form on combustion by-products such as fly ash and particulate matter. EPFRs are rapidly gaining attention for their harmful effects on the environment and human health. Previous research has shown the formation of EPFRs through surface-mediated reactions with transition metal-oxides on particulates. The work presented in this dissertation explores the relationship between fly ash composition and EPFR formation. Fly ash production occurs from combustion systems, namely …
An Investigation Of Environmentally Persistent Free Radical (Epfr) Formation In Contaminated Soils Using Surrogate-Based Model Systems, Ugwumsinachi Godwin Nwosu
An Investigation Of Environmentally Persistent Free Radical (Epfr) Formation In Contaminated Soils Using Surrogate-Based Model Systems, Ugwumsinachi Godwin Nwosu
LSU Doctoral Dissertations
Environmentally persistent free radicals (EPFRs) have recently attracted attention due to their properties that detrimental to the health of living organisms. Earlier studies devoted to the formation of combustion generated particulate matter (PM) showed that EPFRs formed as a result of the association of aromatic chlorinated hydrocarbons with transition metal centers. Based on our previous studies, the amounts of EPFRs formed at Superfund soil sites contaminated with pentachlorophenol (PCP) are ~30 times higher compared to those formed at the neighboring uncontaminated soil sites, showing that EPFR formation is not confined to combustion generated particle. In order to design viable remediation …
Environmentally Persistent Free Radicals (Epfrs) In Pm₂.₅ : Their Contribution To Hydroxyl Radical Formation And Atmospheric Transformation, William Micheal Gehling, Jr.
Environmentally Persistent Free Radicals (Epfrs) In Pm₂.₅ : Their Contribution To Hydroxyl Radical Formation And Atmospheric Transformation, William Micheal Gehling, Jr.
LSU Doctoral Dissertations
Previous research demonstrated environmentally persistent free radicals (EPFRs) will form on particulate surfaces under combustion conditions (temperature range of 150-400 °C) from reactions of organic precursors with redox-active transition metals. With an understanding of how these EPFRs form, it is necessary to determine how they behave in a natural environment after emission. To better understand this, the nature of EPFRs in ambient PM2.5 under simulated atmospheric conditions was investigated. Ambient PM2.5 samples were collected at a roadside ambient monitoring site near heavy interstate traffic and major industrial activity. The EPFR concentration and general radical structure were determined with EPR spectroscopy. …
Experimental And Computational Studies Of Environmentally Persistent Free Radicals (Epfrs) Formation, Lucy W. Kiruri
Experimental And Computational Studies Of Environmentally Persistent Free Radicals (Epfrs) Formation, Lucy W. Kiruri
LSU Doctoral Dissertations
The first part of the thesis investigates the use of theoretical quantum calculations for the study of EPFRs as the initial and fundamental step in the formation of polychlorinated dibenzo-p-dioxin and dibenzofuran. The computational model comprised of density functionals (B3LYP, PBE1PBE, and M06) and two types of basis set namely: LANL2DZ for all atoms and GEN (LANL2DZ for metals and aug-cc-pVDZ for non-metals). Full mechanisms of EPFRs formation over (CuO)1-8, and aluminum oxide clusters were studied. The most stable intermediates and products have been determined and compared to available experimental data. In case of (CuO)1-8 clusters, the small clusters are …
Detection And Characterization Of Environmentally Persistent Free Radicals (Epfrs) In Soils And Sediments From Superfund Sites, Albert Leo N. Dela Cruz
Detection And Characterization Of Environmentally Persistent Free Radicals (Epfrs) In Soils And Sediments From Superfund Sites, Albert Leo N. Dela Cruz
LSU Doctoral Dissertations
Environmentally persistent free radicals (EPFRs) from combustion-generated PM have been demonstrated to form via reactions of molecular precursors with redox-active transition metals at 150-500C thermal reactions in a few seconds reaction times. While ambient temperatures are much lower, soils/sediments contain similar transition metals, and reaction times of contaminants in soils/sediments are years, rather than seconds. This questions whether EPFRs could be formed at ambient temperatures in soils/sediments from Superfund sites that are contaminated with hazardous materials. Superfund soils contaminated with PCP from Georgia and Montana, and sediments contaminated with PAHs from Washington. Using EPR spectroscopy, EPFR concentrations and structural assignments …
Formation And Stabilization Of Combustion-Generated Environmentally Persistent Free Radicals On Transition Metal Oxides Supported On Silica, Eric Warren Pimentel Vejerano
Formation And Stabilization Of Combustion-Generated Environmentally Persistent Free Radicals On Transition Metal Oxides Supported On Silica, Eric Warren Pimentel Vejerano
LSU Doctoral Dissertations
The formation of environmentally persistent free radicals in combustion system was investigated from chemisorptions of chlorine- and hydroxy-substituted benzenes on transition metal oxide surface under post-combustion conditions. This manuscript reports the formation of EPFRs on silica particles containing 5% Fe(III)2O3, Ni(II)O, and Zn(II)O. The EPFRs are formed by the chemisorption of substituted aromatic molecular adsorbates on the metal cation center followed by electron transfer from the adsorbate to the metal ion at temperatures from 150 to 400 oC. Depending on the nature of the adsorbate and the temperature, two organic EPFRs were formed: a phenoxyl-type radical, which has a lower …