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The products and mechanisms of some photo-reactions of indenes and naphthalene with acrylonitrile have been studied. Indene reacts with acrylonitrile with the hydrocarbon absorbs light, or when a triplet sensitizer is absorbing. Photolysis under the former condition yields 2-(1-indenyl)- and 2-(3-indenyl)propionitrile, and 6-cyano-2,3-benzobicyclo[3,2,0]hep-2-ene. Base-catalyzed isomerizations of the substituted indenes are reported. On sensitization, cis- and trans-isomers of 7-cyano-2,3-benzobicyclo[3,2,0]hep-2-ene are formed; the known indene dimer is a minor product. Adducts 1,1-dimethyl- and 1,1-diphenylidene with acrylonitrile are also described. Naphthalene adds to acrylonitrile on photolysis to afford trans-8-cyano-2,3-benzobicyclo[4.2.0] octa-2,4-diene and 1- and 2-naphthyl-2-propionitriles. Sensitization gives no detectable products. Studies on fluorescence quenching, solvent effect and deuterium-labelling indicates that exciplexes are formed between acrylonitrile and the excited hydrocarbons. Inter- or intra-molecular protonation of the exciplexes with subsequent reaction of the carbonium ion formed, is suggested to produce indenes or naphthalenes. Possible mechanisms for the formation of other products are proposed. / Thesis / Doctor of Philosophy (PhD)

<p> It has been shown that the hydroxy compounds la-4a possess triplet states which are substantially shorter-lived than those of their methoxy analogs (lb-4b). In each case the efficient quenching of the excited carbonyl triplet state has been attributed to intramolecular phenolic hydrogen abstraction. Evidence for this is found in the detection of biradical species generated from triplet decay, primary hydrogen-deuterium kinetic isotope effects and thermodynamic parameters which support both atom transfer (enthalpy) and high degrees of order (entropy) in the transition state necessary for the proposed abstraction process. The difference in triplet lifetimes (16 ns to 1135 ns) is due almost exclusively to varying degrees of difficulty in obtaining a transition state geometry in which the phenoxy hydrogen is properly lined up for intramolecular hydrogen abstraction. </p> / Thesis / Master of Science (MSc)

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The kinetics of the pressure dependent O + SO2 + Ar reaction have been investigated using laser photolysis resonance fluorescence at temperatures of 289 K, 399 K, 581 K, 699 K, 842 K and 1040 K and at pressures from 30-665 torr. Falloff was observed for the first time in the pressure dependence. Application of Lindemann theory yielded an Arrhenius expression of k(T) = 3.3 x 10-32exp(-992/T) cm6 molecule-1 s-1 for the low pressure limit and k(T) = 8.47 x 10-14exp(-468/T) cm3 molecule-1 s-1 for the high pressure limit at temperatures between 289 and 842 K. The reaction is unusual as it possesses a positive activation energy at low temperature, yet at higher temperatures the activation energy is negative, illustrating a reaction barrier.

Due to their potential health impact on human beings and ecosystems, persistent trace organic compounds (TOrCs) have aroused concern from both the public and professionals. In particular, the discharge of pharmaceuticals, endocrine disrupters, disinfection byproducts and other TOrCs from wastewater treatment plants into the environment is an area of extensive current research. This work studies the fate and treatments of TOrCs, with emphases on advanced oxidation processes (AOPs). This work presents predicted removal efficiencies of a variety of engineered and natural processes for 55 frequently encountered TOrCs in treated wastewater, based on previously reported data and using existing predictive models. Correlations between physicochemical and biological properties of TOrCs and treatment performance were explored. Removal of TOrCs in all processes investigated in this study was found to be sensitive to matrix effects. Heuristic guidelines for selection of sequenced treatment processes for TOrCs management were established. A field reconnaissance of natural process of TOrCs was conducted by analyzing the occurrence and fate of a suite of TOrCs, as well as estrogenic activity in water and sediments in the Santa Cruz River, an effluent-dependent stream in Tucson, Arizona. Some TOrCs, including contributors to estrogenic activity, were rapidly attenuated with distance of travel in the river. TOrCs that have low biodegradability and low octanolwater partitioning coefficients were less removed. Results of independent experiments indicated potential indirect photodegradation of estrogenic compound by reactive species generated from photolysis of effluent organic matter. Utilizing advanced oxidation processes (AOPs) as tertiary water and wastewater treatment is an option to prevent discharge of TOrCs into the environment. Compared to conventional AOPs, the ability of generating hydroxyl radicals (•OH) without additional doses of hydrogen peroxide (H2O2) or ozone makes ultraviolet (UV) photolysis of ferric hydroxo complexes a novel AOP, especially in acidic environments. A Fe(III)/UV254 kinetic model, which combines Fenton-like mechanism, and photolyses of Fe3+, FeOH2+ and H2O2 was proposed and experimentally validated to predict Fenton-like and H2O2 direct UV254 photolysis scenarios, individually. Nevertheless, the model underestimated the ferrous ion development during Fe(III)/UV254 photolysis, perhaps due to the overprediction of the oxidation of Fe2+ by •OH. The UV/H2O2 AOP was also studied in this work. A predictive kinetic model was developed to evaluate process efficiency of oxidation of p-cresol by UV/H2O2 photolysis based on a complete reaction mechanism, including reactions of intermediates with •OH. Results of this study highlight the significance of consideration of radical scavenging effects by the byproducts from oxidation of organic matter in model prediction performance.

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Every year, new trace chemicals are detected in natural waters as well as treated wastewater effluents all over the world. Public health and environmental concerns have driven the development of new technologies to treat water and eliminate chemicals that may pose risk to humans and wildlife. This work presents a detailed statistical analysis on the removal of some of the most widely occurring chemicals of emerging concern in wastewater based on information available in the literature. Results show that existing water treatment processes only partially eliminate most of these contaminants. Advanced oxidation processes (AOPs) are some of the technologies that have shown the most promising results for the removal of recalcitrant organics in water. Hydrogen peroxide photolysis (UV/H₂O₂) and Fenton’s reaction are some examples of AOPs that use hydroxyl radicals to oxidize organics. The kinetics of UV/H₂O₂ and Fenton’s reaction were studied from the experimental and mathematical points of view. Comprehensive models with no adjustable parameters successfully accounted for radical initiation via photolysis of H₂O₂ or radical initiation via Fenton’s mechanism; reaction of organic targets such as p-cresol and nonylphenol with hydroxyl radicals; and recombination mechanisms, as well as changes in solution pH due to evolution of carbon dioxide because of target mineralization. The presence of radical scavengers was successfully handled by the models, suggesting that they can be generalized to the treatment of complex matrices. The UV/H₂O₂ model was also extended to solar catalyzed applications. Using an atmospheric solar irradiation model (SMART) and data from the Giovanni-NASA online database, ground-level solar spectral irradiance were obtained and used as model inputs. The kinetic model provided an excellent fit to experimental results obtained with p-cresol and fluorescein targets using no fitted parameters. The UV/H₂O₂ process was also studied in commercial flow-through UV reactors with monochromatic and polychromatic light sources. Organic targets of interest such as pcresol can be degraded effectively in these reactors at relatively low peroxide concentrations. Results with wastewater effluents suggest that these commercial reactors can be used for AOP tertiary treatment as a way to reduce dissolved organic matter and eliminate potential harmful chemicals present in the water.