http://nova.newcastle.edu.au/vital/access/services/Feed ${session.getAttribute("locale")} 5 http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:12285 This contribution studies the decomposition of folpet fungicide under oxidative conditions and compares the product species with those of captan fungicide, which is structurally related to folpet. Toxic products arising from folpet comprised carbon disulfide (highest emission factor of 4.9mg g¹ folpet), thiophosgene (14.4), phosgene (34.1), hydrogencyanide(2.6), tetrachloroethylene (111), hexachloroethane (167), and benzonitrile (4.5). Owing to the irrelated molecular structures, folpet emitted similar products to captan but at different yields, under the same experimental conditions. It appears that the availability of easily abstractable H atoms, in the structure of captan but not in that of folpet, defines the product distribution. In conjunction with the quantum chemical calculations, these experimental measurements afford an enhanced explanation of the formation pathways of hazardous decomposition products of these two structurally related fungicides. 2013-01-30T04:12:32.618Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:9981 The reaction of CHF₃ with CH₄ in the presence of small amounts of CH₃OH (5% of CHF₃ concentration) was investigated in a tubular alumina reactor at temperatures between 900 K and 1150 K. The presence of CH₃OH has a significant influence on both the conversion and selectivity of the reaction. Increasing the CH₃OH concentration enhances the conversion of CHF₃ by a factor of 1−4 times at temperatures between 873 K and 1123 K, although the rate of formation of the major products (CH₂═CF₂) does not increase. A reaction scheme, based on NIST HFC and GRI-Mech mechanisms, is developed to model the reactions. Satisfactory agreement between experimental results and predictions is achieved for the conversion of reactants and formation of products. Based on experimental measurements and modeling results, a detailed reaction mechanism is proposed, and insight into how CH₃OH influences the reaction of CHF₃ with CH₄ is presented. 2012-02-09T02:00:03.861Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:1965 The nonoxidative gas-phase reaction of halon 1211 (CBrClF₂) with methane was studied using a tubular plug-flow alumina reactor at atmospheric pressure, over the temperature range of 673-1073 K, and at residence times between 0.1 and 1.3 s. With an equimolar feed of CBrClF₂ and CH₄, complete halon conversion was achieved at 1073 K for all residence times considered. The initial products of the reaction are CHClF₂ and CH₃Br, which are replaced by C₂H₂F₂ at elevated temperatures. We suggest C₂H₂F₂ is produced from the direct coupling of CH₃ and CF₂Cl radicals, which rapidly decompose to C₂H₂F₂ and HCl. Minor products formed during reaction include C₂H₃F, CHF₃, C₂F₄, CHBrF₂, and C₂HBrF₂. The formation of CHClF₂, C₂F₄, CHBrF₂, and C₂HClF₂ was observed to reach a maximium at specific residence times, and formation of soot was detected above 943 K. Possible mechanistic pathways for major and some minor species are discussed. 2010-04-27T06:57:37.610Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:622 Thermal pyrolysis of halon 1211 (CBrClF2), diluted in nitrogen, in a tubular alumina reactor, has been studied over the temperature range of 773-1073 K at residence times from 03 to 2 s. At temperatures below 973 K, the major products were CCl2F2, CBr2F2, C2Cl2F4, C2BrClF4, C2F4, and C2Br2F4. Further increasing temperature resulted in the formation of CBrF3, CClF3, and many other species whose formation necessitated the rupture of C-F bonds. Coke formation was also observed on the surface of the reactor at high temperatures. A kinetic reaction scheme involving 16 species and 25 reaction steps was developed and applied to model the thermal pyrolysis of halon 12 11 over the temperature range of 773-973 K. Sensitivity analysis suggests that the reaction CBrClF2 + CClF2 --> CCl2F2 + CBrF2 constitutes the major pathway for the decomposition of halon 1211 under the conditions investigated. 2010-04-27T05:41:13.650Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:4438 This study investigates the kinetic parameters of the formation of the chlorophenoxy radical from the 2-chlorophenol molecule, a key precursor to polychlorinated dibenzo-p-dioxins and dibenzofurans (PCCD/F), in unimolecular and bimolecular reactions in the gas phase. The study develops the reaction potential energy surface for the unimolecular decomposition of 2-chlorophenol. The migration of the phenolic hydrogen to the ortho-C hearing the hydrogen atom produces 2-chlorocyclohexa-2,4-dienone through an activation barrier of 73.6 kcal/mol (0 K). This route holds more importance than the direct fission of Cl or the phenolic H. Reaction rate constants for the bimolecular reactions, 2-chlorophenol + X → X-H + 2-chlorophenoxy (X = H, OH, Cl, O₂) are calculated and compared with the available experimental kinetics for the analogous reactions of X with phenol. OH reaction with 2-chlorophenol produces 2-chlorophenoxy by direct abstraction rather than through addition and subsequent water elimination. The results of the present study will find applications in the construction of detailed kinetic models describing the formation of PCDD/F in the gas phase. 2010-04-27T05:32:31.909Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:4449 The gas-phase pyrolysis of n-C₄F₁₀ has been studied experimentally in a plug flow, isothermal α-alumina reactor at atmospheric pressure and various residence times over the temperature range of 873 to 1148 K. The major products are C₂F₆, C₂F₄, C₃F₈, and C₃F₆ (CF₃-CF=CF₂). Minor products include cycio-C₄F₈ (c-C₄F₈) and CO₂. CF₄ is detected in trace amounts at high temperatures. A kinetic reaction scheme involving 20 species and 30 reactions is developed and used to model n-C₄F₁₀ pyrolysis. A generally satisfactory agreement between experimental and modeling results is obtained on the conversion levels of n-C₄F₁₀ and the rates of formation of C₂F₆ and C₃F₈. 2010-04-27T04:58:49.446Z ]]>