RESUMO
The polycyclic aromatic hydrocarbon emissions in particulate and gas phases generated from smoldering mosquito coils containing various atomic H/C ratios were examined. Five types of mosquito coils were burned in a test chamber with a total airflow rate of 8.0 L/min at a constant relative humidity and temperature. The concentrations of individual PAHs were determined using the GC/MS technique. Among the used mosquito coils, the atomic H/C ratio ranged from 1.23 to 1.57, yielding total mass, gaseous, and particulate PAH emission factors of 28.17-78.72 mg/g, 26,139.80-35,932.98 and 5735.22-13,431.51 ng/g, respectively. The various partitions of PAHs in the gaseous and particulate phases were in the ranges, 70.26-83.70% and 16.30-29.74% for the utilized mosquito coils. The carcinogenic potency of PAH emissions in the particulate phase (203.82-797.76 ng/g) was approximately 6.92-25.08 times higher than that of the gaseous phase (26.27-36.07 ng/g). Based on the analyses of PAH emissions, mosquito coils containing the lowest H/C ratio, a low oxygen level, and additional additives (i.e., CaCO3) are recommended for minimizing the production of total PAH emission factors and carcinogenic potency.
Assuntos
Poluentes Atmosféricos/análise , Controle de Mosquitos/instrumentação , Hidrocarbonetos Policíclicos Aromáticos/análise , Poluição do Ar em Ambientes Fechados/análise , Carcinógenos/análise , Controle de Mosquitos/métodos , Material Particulado/análiseRESUMO
Polycyclic aromatic hydrocarbons in the particulate phase generated from burning various incense was investigated by a gas chromatography/mass spectrometry. Among the used incenses, the atomic H/C ratio ranged from 0.51 to 1.69, yielding the emission factor ranges for total particulate mass and PAHs of 4.19-82.16 mg/g and 1.20-9.50 µg/g, respectively. The atomic H/C ratio of the incense was the key factor affecting particulate mass and the PAHs emission factors. Both the maximum emission factor and the slowest burning rate appear at the H/C ratio of 1.57. The concentrations of the four-ring PAHs predominated and the major species among the 16 PAHs were fluoranthene, phenanthrene, pyrene, and chrysene for most incense types. The benzo[a]pyrene, benzo[a]anthracene, benzo[b]fluoranthene, and dibenzo[a,h]anthracene accounted for 87.08-93.47% of the total toxic equivalency emission factor.
Assuntos
Poluentes Atmosféricos/análise , Hidrocarbonetos Aromáticos/análise , Material Particulado/análise , Fumaça/análise , Poluentes Atmosféricos/química , Carbono/análise , Cromatografia Gasosa-Espectrometria de Massas , Hidrocarbonetos Aromáticos/química , Hidrogênio/análiseRESUMO
The electron ionization (EI) mass spectra of a series of 3,3-difluoro-1-halo-2-arylcyclo- propenes (1, 2) give the fragments [M-X](+) (X: Br, Cl) as the base peaks. A comparison of tandem mass spectrometry (MS/MS) profiles of the m/z 151 ions recorded from compounds 1 and 2 and 3-bromo-3,3-difluoro-1-phenylcyclopropyne (5), 1,1,2,2-tetrafluoro-3-phenyl- cyclopropane (6), 1,1,2,2-tetrafluoroindane (7), and 2,3,3-trifluoroindene (8) suggested that the structure of the derived [M-X](+) fragment ion is more likely that of a substituted cyclopropenium ion. The results from calculations using the density functional theory (DFT) method support this MS/MS analysis.
RESUMO
Density functional theory (DFT) quantum chemical calculations of the structure and NMR parameters for highly strained hydrocarbon [2.2]paracyclophane 1 and its three derivatives are presented. The calculated NMR parameters are compared with the experimental ones. By least-squares fitting of the (1)H spectra, almost all J(HH) coupling constants could be obtained with high accuracy. Theoretical vicinal J(HH) couplings in the aliphatic bridges, calculated using different basis sets (6-311G(d,p), and Huz-IV) reproduce the experimental values with essentially the same root-mean-square (rms) error of about 1.3 Hz, regardless of the basis set used. These discrepancies could be in part due to a considerable impact of rovibrational effects on the observed J(HH) couplings, since the latter show a measurable dependence on temperature. Because of the lasting literature controversies concerning the symmetry of parent compound 1, D(2h) versus D(2), a critical analysis of the relevant literature data is carried out. The symmetry issue is prone to confusion because, according to some literature claims, the two hypothetical enantiomeric D(2) structures of 1 could be separated by a very low energy barrier that would explain the occurrence of rovibrational effects on the observed vicinal J(HH) couplings. However, the D(2h) symmetry of 1 with a flat energy minimum could also account for these effects.
Assuntos
Compostos Policíclicos/química , Espectroscopia de Ressonância Magnética/normas , Estrutura Molecular , Teoria Quântica , Padrões de Referência , EstereoisomerismoRESUMO
The electron ionization (EI) fragmentation of nitro-beta,beta-dihalostyrenes depends strongly on the specific halogens present as well as on the position of the nitro group. Beta,beta-difluorostyrenes yielded mainly fluoroacetylene ions as the base peaks and o-nitro-beta,beta-dihalostyrene possibly furnished the ion with a structure similar to that of benzo[a]isoxazole (11). The structural identity of the ion was verified by comparing the collision-induced dissociation (CID) spectra of m/z 119 ions from p- and o-nitro-beta,beta-difluorostyrene, o-nitro-beta,beta-dibromostyrene and compound 11.
Assuntos
Cromatografia Gasosa-Espectrometria de Massas , Espectrometria de Massas por Ionização por Electrospray , Estirenos/química , Hidrocarbonetos Halogenados/química , NitrocompostosRESUMO
The disinfection of hospital wastewaters using the ozonization process was studied. The concentrations of ozone required to reach a sudden drop of coliform and Pseudomonas aeruginosa in the wastewater are 4.0-7.0 and 3.0-5.0 mg L(-1), respectively. For the hospital wastewater, the disinfection efficiencies were 0.518S(-1.1) for coliforms, 0.509S(-1.06) for Pseudomonas aeruginosa and 0.254S-(1.54) for total count, respectively. As to the effects of ozone input methods on the disinfection efficiency, the continuous ozonization process was ten times higher than the batch input process. The low COD removal rate was obtained at 25.0 mgL(-1) of ozone concentration for hospital wastewater. However, more biodegradable compounds resulted in the treated mixture.
Assuntos
Desinfecção/métodos , Eliminação de Resíduos de Serviços de Saúde/métodos , Oxidantes Fotoquímicos/química , Ozônio/química , Eliminação de Resíduos Líquidos/métodos , Purificação da Água/métodos , Biodegradação Ambiental , Enterobacteriaceae/isolamento & purificação , Hospitais , Pseudomonas aeruginosa/isolamento & purificaçãoRESUMO
Hexahydro[2.2]paracyclophane (6) and related compounds were prepared from the extrusion of sulfur dioxide from 2,11-dithia-4,5,6,7,8,9-hexahydro[3.3]paracyclophane 2,2,11,11-tetraoxide (9) by either the Ramberg-Backlund reaction or a flash pyrolysis. Compound 6 is the first cyclophane to contain both a benzene ring and a cyclohexane ring. Birch reduction of compound 6 gave a diene containing two double bonds in the same ring, which is different from the dienes obtained from the catalytic hydrogenation of [2.2]paracyclophane.