In this study, two regenerative thermal oxidizers (RTO) were used to test the thermal destruction, thermal recovery efficiency and the gas pressure drop over the beds characteristics when burning, respectively, airborne chlorine- and nitrogen-containing volatile organic compounds (VOCs). First, an electrically-heated RTO containing two 0.5 m ¡Ñ 0.5 m ¡Ñ 2.0 m (L ¡Ñ W ¡Ñ H) beds, both packed with gravel particles with an average diameter of around 0.0116 m and a height of up to 1.48 m with a void fraction of 0.41 in the packed section was used to study the destruction characteristics of chlorine-containing VOCs (trichloroethane, TCE and dichloromethane, DCM). With a valve switch time (ts) of 1.5 min, preset maximum destruction temperatures (TS) of 500-800 oC and superficial gas velocity (Ug) of 0.17-0.33 m/s (evaluated at an influent air temperature of around 27 ¢J), tests on the thermal recovery efficiency (TRE) and the pressure drop for the air stream without VOC in the influent air stream have been performed. With a ts of 1.5 min, Ts of 500-800 oC and Ug of 0.17-0.24 m/s (evaluated at an influent air temperature of around 27 ¢J), tests on the degree thermal destruction of VOCs with influent air streams containing one of the two VOCs: trichloroethylene (TCE) and dichloromethane (DCM) have been done. Second, an electrically-heated RTO containing two 0.152 m ¡Ñ 0.14 m ¡Ñ 1.0 m (L ¡Ñ W ¡Ñ H) beds, both packed with gravel particles with an average diameter of around 0.0111 m and a height of up to 1.0 m with a void fraction of 0.42 in the packed section was used to study the destruction and NOx formation characteristics of DMF (N, N-dimethylformamide). With a ts of 1.5 min, Ts of 750-850 ¢Jand Ug of 0.39-0.78 m/s (evaluated at an influent air temperature of around 30 ¢J), TRE and the pressure drop for the air stream without VOC in the influent air stream have been tested. With a ts of 1.5 min, a Ug of 0.39 m/s (evaluated at an influent air temperature of around 30 ¢J), and Ts of 750-950 ¢J and, thermal destruction efficiencies and nitrogen oxides (NOx) formation characteristics in burning air streams containing either DMF or DMF mixed with methyl ethyl ketone (MEK) were performed. Results demonstrate that: (1) a RTO is suitable for destruction of low concentrations (<1,000 ppm as methane) of airborne highly chlorinated VOCs such as TCE and DCM and the destructed products contain no chlorine and only trace of COCl2 (< 1% of the influent VOC); (2) for TS = 800 oC and Ug = 0.17-0.24 m/s, complete oxidation products of TCE and DCM are HCl, CO2, and H2O, and the main intermediates are CO and COCl2; (3) with ts of 1.5 min, a Ug of 0.39 m/s (evaluated at an influent air temperature of around 30 oC) and TS of 750-950 ¢J, no NOx was present in the effluent gas from the RTO when it was loaded with DMF-free air; (4) when only DMF was present in the influent air, the average destruction efficiencies exceeded 96%, and increased with the influent DMF concentration from 300 to 750 mg/Nm3. The ¡§NOx-N formation/DMF-N destruction¡¨ mass ratios were in the range 0.76-1.05, and decreased as the influent DMF concentration increased within the experimental range; (5) when both DMF and MEK were present in the influent gas, the NOx formation ratio was almost the same and the DMF destruction efficiency increased with the influent MEK/DMF ratio from 150/300 to 4500/300 (mg/mg) and in the preset temperature range. The NOx formation ratios were in the range 0.75-0.96; (6) the TRE decreased as Ug increased but was invariant with Ts; and (7) the Ergun equation was found to suffice in the estimation of the pressure drop when the gas flowed over the packing beds.

Recent studies have shown that general-base assisted catalysis is a viable mechanistic pathway for hydrolysis of smaller anhydrides. Therefore, it is the central purpose of the present work to compare and contrast the number of hydrogen atoms in-flight and stationary in the transition state structure of the base-catalyzed mechanisms of 2 hydrolytic reactions as well as determine if any solvent effects occur on the mechanisms. The present research focuses on the hydrolytic mechanisms of N,N-dimethylformamide (DMF) and acetic anhydride in alkali media of varying deuterium oxide mole fractions. Acetic anhydride has been included in this study to enable comparisons with DMF hydrolysis. Comparative studies may give synergistic insight into the detailed structural features of the activated complexes for both systems. Hydrolysis reactions in varying deuterium oxide mole fractions were conducted in concentrations of 2.0M, 2.5M, and 3.0M for DMF and 0.10M for acetic anhydride at 25°C. Studies in varying deuterium mole fractions allow for proton inventory analysis, which sheds light on the number and types of hydrogen atoms involved in the activated complex. For these systems, this type of study can distinguish between direct nucleophilic attack of the hydroxide ion on the carbonyl center and general-base catalysis by the hydroxide ion to facilitate a water molecule attacking the carbonyl center. The numerical data are used to discuss 3 possible mechanisms in the hydrolysis of DMF.

Photofragment velocity-map imaging (VMI) has generally been employed to investigate the photodissociation dynamics of relatively small molecular systems (< 5 atoms). The work reported in this thesis focuses on the application of this technique for the investigation of the unimolecular photodissociation of larger chemical systems, which are of interest to a broad cross section of the chemical community. Typically, VMI studies involve state-selective detection of one particular fragmentation product, and so are often limited to the investigation of a single dissociation channel. By employing vacuum ultra-violet (VUV) photoionization, we are able to detect most, if not all of the fragments resulting from the dissociation of a neutral species, with ‘universal’ ionization being achieved in the ideal case when the fragment ionization energies are all lower than the VUV photon energy. This capability becomes particularly important when investigating larger systems, since these often display complex dynamics with multiple competing fragmentation pathways. Our approach allows us to investigate the different photofragmentation processes occurring for a particular system, to evaluate the relative importance of the active dissociation channels, and to gain insight into the energy partitioning amongst the fragments. A study of the UV photodissociation of two neutral alkyl iodide molecules demonstrates the first use in our laboratory of ‘universal’ ionization in combination with VMI. Studies into the photofragmentation processes resulting from 193 nm photoexcitation of neutral N,N-dimethylformamide, a small-molecule model for a peptide bond, and a number of neutral cyclic alkenes, which undergo the retro-Diels-Alder reaction, are also presented. The remaining studies presented in this thesis have investigated the photofragmentation processes of ionic species, generated by means of VUV photoionization. In the case of ion dissociation each fragmentation channel necessarily produces one charged species, which may be detected using the VMI technique. Therefore, such studies provide an insight into all of the active channels. An in-depth VMI study of the UV photodissociation of two ethyl halide cations is presented, which demonstrates the successful investigation of the multiple photofragmentation pathways of these ionic species. The remainder of the cation photodissociation studies are of relevance to a number of common processes known to occur in mass spectrometry, including the McLafferty rearrangement, the retro-Diels-Alder reaction, and ‘peptide’ bond fragmentation. By velocity-map imaging the products of these reactions, further information is obtained concerning these dissociation processes, which are no doubt of interest to the wider chemical community. This work forms part of the velocity-map imaging mass spectrometry (VMImMS) project. VMImMS involves imaging each of the fragmentation products that result from dissociation of a parent molecule of interest, with the aim of increasing the amount of information that can be obtained from a mass-spectrometry-type experiment. The work presented in this thesis demonstrates that VMImMS allows us to unravel details of the dissociation dynamics of both neutral and ionic species, and is potentially a powerful technique for investigating the fragmentation processes of increasingly complex systems.

L’industrie produit de grandes quantités d’effluents aqueux qu’il convient de traiter. Des traitements alternatifs aux procédés biologiques doivent être développés pour certains effluents toxiques et/ou non biodégradables. L’oxydation en voie humide catalytique repose sur l’action de l’oxygène sur les polluants en phase aqueuse à haute température et haute pression. Préalablement à cette étude, des catalyseurs au Ru ou Pt supportés sur ZrO2 ou TiO2très actifs et très stables pour l’OVHC de polluants modèles et de quelques effluents réels ont été développés. Ce travail a examiné ces catalyseurs sur d’autres effluents réels : un effluent provenant d’une unité de production de membranes contenant du glycérol et du DMF, uneffluent de sauce de couchage provenant de l’industrie papetière et un concentrât de lixiviatde décharge. Les catalyseurs se sont révélés très actifs et stables pour la minéralisation du glycérol, mais une forte lixiviation a été observée lors de l’OVHC du DMF du fait de la présence d’amines. L’oxydation de l’effluent de sauce de couchage permet de minéraliser la charge organique, facilitant le recyclage de la charge minérale, avec une amélioration accrue de la biodégradabilité du surnageant en présence des catalyseurs. Enfin, l’ajout de catalyseurs lors de l’OVH du concentrât de lixiviat de décharge permet d’améliorer sa minéralisation et d’éliminer totalement les ions ammonium / Industries produce huge volumes of effluents which need to be treated before disposal.Alternative treatments to the more classical biological techniques are required in the case oftoxic and/or non biodegradable effluents. The wet air oxidation (WAO) and catalytic wet airoxidation (CWAO) are based on the reaction of an oxidant (oxygen) with the pollutants in aqueous phase at high temperature and pressure. Ru or Pt catalysts supported on zirconium and titanium oxides were previously shown to be highly active and stable in the CWAO of awide range of model compounds and real complex effluents. These catalysts were evaluated in the CWAO of problematic effluents: one containing glycerol and DMF, one paper coatingslip effluent and one concentrated landfill leachate. The catalysts showed high activity and stability in the CWAO of glycerol, while the metal leached upon DMF CWAO due to the presence of amines. WAO leads to the partial mineralization of the organic load in paper coating slip, allowing an easy separation recycling of mineral pigments, with an improved biodegradability of the supernatant with the use of a catalyst. The use of a catalyst upon landfill leachate WAO leads higher COT conversion and complete ammonia elimination