- Mixed Contamination of Polyaromatic Hydrocarbons and Metals at Manufactured Gas Plant Sites: Toxicity and Implications to Bioremediation

2012 ◽  
pp. 368-391 ◽  
Keyword(s):  
Polyaromatic Hydrocarbons ◽  
Mixed Contamination ◽  
Manufactured Gas Plant

In the Quest for a Stable Triplet State in Small Polyaromatic Hydrocarbons : An In-Silico Tool for Rational Design and Prediction

2019 ◽  
Author(s):  
Madhumita Rano ◽  
Sumanta K Ghosh ◽  
Debashree Ghosh
Keyword(s):  
Triplet State ◽  
Small Molecules ◽  
In Silico ◽  
Qualitative Agreement ◽  
Rational Design ◽  
Polyaromatic Hydrocarbons ◽  
Spin Hamiltonian ◽  
Spin Frustration ◽  
Computationally Efficient ◽  
High Level

<div>Combining the roles of spin frustration and geometry of odd and even numbered rings in polyaromatic hydrocarbons (PAHs), we design small molecules that show exceedingly small singlet-triplet gaps and stable triplet ground states. Furthermore, a computationally efficient protocol with a model spin Hamiltonian is shown to be capable of qualitative agreement with respect to high level multireference calculations and therefore, can be used for fast molecular discovery and screening.</div>

The use of catalytic additives for hydrogenation of polyaromatic hydrocarbons

2020 ◽  
Vol 31 ◽  
pp. 611-614
Author(s):  
Darzhan Aitbekova ◽  
Araigul Bakytkyzy ◽  
Gulzhan Baikenova ◽  
Murzabek Baikenov
Keyword(s):  
Polyaromatic Hydrocarbons ◽  
Catalytic Additives

Selanyl and tellanyl electrophiles as a driving force in the construction of sophisticated polyaromatic hydrocarbons

2021 ◽  
Vol 45 (16) ◽  
pp. 7247-7255
Author(s):  
Pavel Arsenyan ◽  
Alla Petrenko ◽  
Sergey Belyakov
Keyword(s):  
Driving Force ◽  
Polyaromatic Hydrocarbons ◽  
Aromatic Rings ◽  
Carbazole Derivatives

Herein, we report the first examples of N-polyaromatic compounds bearing up to 13 fused aromatic rings, including 23H-benzo[12,1]tetrapheno[8,9-b]benzo[12,1]tetrapheno[9,8-h]carbazole derivatives.

The sediment of the Hostivar Reservoir (Prague, Czech Republic) as a memory of 45 years of pollution

2017 ◽  
Vol 28 (2) ◽  
pp. 204-213
Author(s):  
Lucie Soucková ◽  
Dana Kominkova
Keyword(s):  
Czech Republic ◽  
Design Methodology ◽  
Polyaromatic Hydrocarbons ◽  
Reservoir Sediment ◽  
Terrestrial Environment ◽  
Content Type ◽  
Sediment Extraction ◽  
History Of ◽  
Us Epa ◽  
Practical Implications

Purpose The purpose of this paper is to evaluate the historical pollution of the Hostivar Reservoir (largest reservoir in Prague) sediment by metals, polyaromatic hydrocarbons (PAH) and polychlorinated biphenyls (PCB) and identify the trends in pollution of aquatic environment. Design/methodology/approach Core samples, 140 cm long, recording the 45-year history of the reservoir, were separated to 5 cm width subsamples (approximately 1.5 years of sedimentation) and analyzed for metals (Cd, Pb, Cu, Zn, Cr, Ni, Al), PAH and PCB. Following methods were used: US EPA 3051 for metals, US EPA 505 and US EPA 8082 A for PCB, and ISO 18287:2006 for PAH. Findings Most of the contaminants had the highest concentration at the beginning of the existence of the reservoir, suggesting that the contamination results from construction activities. Significant decrease of Pb occurred in the second half of the 1990s. It was caused by termination of the addition of lead as a detonation suppressant to the gasoline. Most concentrations of PAHs, PCBs and metals, except copper do not present eco-toxicological risk. Practical implications The results show the volume of priority pollutants removed from the reservoir by sediment extraction, and point risk to the terrestrial environment due to application of the sediment in the construction of a noise protecting wall. Originality/value The paper presents unique data about historical contamination of the largest reservoir in Prague, the capital of Czech Republic. It shows how the watershed and the construction phase of the dam cause a pollution of the reservoir sediment and possible environmental risk for aquatic biota.

Density functional theory investigation of the effect of axial coordination and annelation on the absorption spectroscopy of nickel(II) and vanadyl porphyrins relevant to bitumen and crude oils

2013 ◽  
Vol 91 (9) ◽  
pp. 872-878 ◽  
Author(s):  
Stanislav R. Stoyanov ◽  
Cindy-Xing Yin ◽  
Murray R. Gray ◽  
Jeffrey M. Stryker ◽  
Sergey Gusarov ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Polyaromatic Hydrocarbons ◽  
Geometry Optimization ◽  
Soret Band ◽  
Heavy Oils ◽  
Visible Absorption ◽  
Functional Theory ◽  
Axial Coordination ◽  
Td Dft

The vanadium and nickel components in heavy oils and bitumen are important impurities in catalytic processing and form aggregates with other asphaltene components. Metalloporphyrins are commonly analyzed using the characteristic Soret band in the UV–vis absorption spectrum. However, the Soret band of metalloporphyrins in petroleum is broadened and weaker than expected based on the concentration of Ni and V in heavy oils and the extinction coefficients of isolated porphyrins. We hypothesize that the low intensity and broadening of the Soret band could be due to axial coordination of the metal center or fusion (annelation) of aromatic rings on the porphyrin π-system. This hypothesis is examined using the density functional theory for geometry optimization and time-dependent density functional theory (TD-DFT) for calculation of excited states of nickel(II) and vanadyl porphyrins with axially coordinated ligands and annelated polyaromatic hydrocarbons. Predictions of the excited electronic states performed using the tandem of TD-DFT and conductor-like polarizable continuum model of solvation support this hypothesis and provide insight into the extent of Soret band broadening and intensity decrease due to coordination and annelation. These computational results, validated with respect to visible absorption spectra, are important for understanding asphaltene aggregation and spectroscopic characterization and suggest methods for removal of transition metals from heavy oil.

PCBs and PAHs Restrain the Use of Sludge as a Renewable Resource

2014 ◽  
Vol 1001 ◽  
pp. 162-170
Author(s):  
Radmila Kučerová ◽  
Tomáš Sezima ◽  
Eugen Sikora ◽  
Ivana Truxová ◽  
Lucie Kučerová ◽  
...  
Keyword(s):  
Sewage Sludge ◽  
Polychlorinated Biphenyls ◽  
Laboratory Experiment ◽  
Pseudomonas Putida ◽  
Polyaromatic Hydrocarbons ◽  
Renewable Resource ◽  
Bacterial Cultures ◽  
Pure Bacterial Cultures

The aim of this research is to reduce the quantities of polyaromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in the samples of non-hygienized sewage sludge via laboratory biodegradation. Pure bacterial cultures of Pseudomonas putida, Rhodococcus sp. and their mixture in 1:1 proportion have been used. The laboratory experiment lasted for 28 days and the acquired values were compared with Decree 294/2005 Coll. The obtained results imply that biodegradation of such contaminated samples is practicable. Using the bacterial mixture, over 85 % Σ of PCBs were degraded, and applying Rhodococcus sp. as much as 95.86 % of the original concentration of PAHs were removed.

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