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Precise wording is important in every field of study, including operational procedures. Confusion in the wording "organic" and "inorganic" may have contributed to substitution of an organic kitty litter for an inorganic adsorbent used to prepare nuclear waste for disposal at an underground salt repository. Adsorbents prevent liquids like nitric acid from causing corrosion within the waste drums. However, combination of organic material with nitric acid can cause heat- and gas-generating reactions resulting in thermal runaway, rapid pressurization, and drum rupture. In 2014, waste Drum 68660 containing nitric acid-soaked organic kitty litter exploded and released transuranic waste into the repository. The cause of the accident was never identified. Here we show that the root cause of Drum 68660 igniting was restriction of the drum vent resulting in accelerated nitric acid chemistry, thermal runaway, and radiation dispersal. [Display omitted] [ABSTRACT FROM AUTHOR]

The gas-phase pyrolysis of proline, glucose, 1-[(2′-carboxy)pyrrolidinyl]-1-deoxy-d-fructose (the proline Amadori compound), and a 1:1 mixture by weight of proline and glucose was investigated at high temperatures (600–840 °C) and short residence time (i.e. 1.0 s) in an inert atmosphere to determine if glucose or Maillard reaction products enhance the formation of nitrogen containing polycyclic aromatic compounds (N-PACs) and polycyclic aromatic hydrocarbons (PAHs) in the pyrolysis of proline. To study the gas-phase formation of N-PACs and PAHs, the substrates were sublimed into the pyrolysis furnace at 460 °C. Thermogravimetric analysis showed that glucose, the proline/glucose mixture, and the proline Amadori compound undergo solid-state decomposition reactions before subliming. Thus, the substrates were pyrolyzed in two stages: at 460 °C during the sublimation and at 600–840 °C. At 800 °C with a residence time of 1.0 s, proline produced low yields of N-PACs, such as quinoline, isoquinoline, indole, acridine, and carbazole, and PAHs, such as phenanthrene, pyrene, benz[a]anthracene, benzofluoranthene isomers, and benzo[a]pyrene. Increasing the temperature and residence time increased the yield of these products. Under similar pyrolysis conditions, the proline Amadori compound produced 2–8 fold more N-PACs and PAHs than proline. A 1:1 mixture of proline and glucose produced a similar slate of pyrolysis products as the proline Amadori compound, but it is unclear whether the proline Amadori compound was an intermediate in the reaction. In general, the proline Amadori compound produced a higher yield of N-PACs and PAHs than the proline/glucose mixture, but glucose clearly enhances the low temperature gas-phase formation of N-PACs and PAHs from the pyrolysis of proline. For example, a 1:1 mixture of proline and glucose was found to produce low yields of quinoline, isoquinoline, and indole at 600 °C while proline alone does not produce these compounds until 800 °C. Thus, glucose provides a low temperature pathway for the decomposition of proline, which leads to formation of N-PACs and PAHs. [Copyright &y& Elsevier]

Abstract: Hydrogen abstraction reactions play a key role in many thermal and catalytic processes involved in the production of fuels and chemicals. In this paper, the hydrogen abstraction reactions on toluene and tetralin by the benzyl radical are investigated by ab initio methods. These reactions are representatives of similar reactions occurring in the thermolysis of lignin model compounds containing the phenethyl phenyl ether (PPE) structural moiety. The title reactions serve to calibrate the theoretical methods to be used in the study of PPE pyrolysis through comparison of the reaction barriers with reliable experimental values. We used two different hybrid density functionals (BHandHLYP, B3LYP) and second-order perturbation theory to obtain equilibrium and transition state geometries. We recomputed selected energy barriers at the B3LYP geometries with the coupled cluster singles and doubles (CCSD) method. Multiple transition states were found for both reactions. BHandHLYP underestimates and second-order perturbation theory overestimates the reaction barriers; B3LYP energy barriers agree well with experiment and the corresponding CCSD energy barriers. The flat potential energy surface around the saddle points causes numerical inaccuracies. We observe the break down of the harmonic approximation in the calculation of low frequencies. [Copyright &y& Elsevier]

Abstract: The oxidation of carbon nanofibers (CNFs) with various oxidizing agents; 6M HNO3, KMnO4, RuO4, and a mixture of concentrated H2SO4/HNO3 is studied to determine the reaction conditions that optimizes yield and chemical functionalization. The oxidized nanofibers were examined by scanning electron microscopy, and Raman spectroscopy to characterize the defects caused by oxidation. The amount of acidic sites generated during oxidative treatment was quantified by reacting them with amine terminated octadecane and the subsequent quantification of the products of this grafting process by Fourier transform infrared spectroscopy. The concentrated H2SO4/HNO3 mixture created the maximum number of carboxylic acid groups and the highest amount of defect sites, but had very low yield (∼12%). Six molar of HNO3 generated fewer defect sites and a lower number of –COOH groups, but did exhibit a 70% yield. RuO4 and KMnO4 resulted in similar amounts of overall defect sites, however the yield and amount of –COOH groups for KMnO4 treated CNF were significantly lower than the RuO4 treatment. Overall, oxidation of these CNF with RuO4 provides the best balance of yield and carboxylation. [Copyright &y& Elsevier]