Oxidation Of Polycyclic Aromatic Hydrocarbons Research Articles

Oxidation characteristics of polycyclic aromatic hydrocarbons in flue gas over Pd/γ-Al 2O 3 catalyst

A series of Pd/γ-Al 2O 3 catalysts with various Pd loadings was prepared via incipient-wetness impregnation method under different synthesis conditions. The structural and textural properties of the synthesized catalysts were characterized by XRD, N 2 adsorption/desorption, TEM, H 2-TPR, and SEM-MAPS; their catalytic performance in the elimination of polycyclic aromatic hydrocarbons (PAHs) in coal-fired flue gas by oxidation was investigated. The results revealed that the PAHs removal efficiency over various Pd-loaded catalysts fluctuates between 67.3% and 93.5%; the conversion of PAHs increases with the Pd loading in the catalyst. Moreover, a better oxidation activity of these catalysts is observed for the PAHs with higher ring-cycles; nevertheless, the removal rates based on the toxicity equivalence quantity (TEQ) for all PAHs are higher than 90%. The Pd/γ-Al 2O 3 with a Pd loading of 0.2% and calcined at 600°C exhibits the best catalytic performance for PAHs oxidation, with a removal rate of 93.5% at 300°C.

Single Zone Simulation of Polycyclic Aromatic Hydrocarbon Formation in n-Heptane HCCI Combustion

A computational study was performed for the formation of polycyclic aromatic hydrocarbons (PAHs) in the n-heptane laminar premixed flame and the homogeneous charge compression ignition (HCCI) combustion. A detailed reaction mechanism describing fuel pyrolysis and oxidation, benzene formation, and PAHs mass growth and oxidation including 107 species and 542 elementary reactions was adopted. The species concentration distributions were analyzed numerically in the laminar premixed n-heptane flame. The computational results compared well with experimental data show that this reaction mechanism can be used to predict reaction products in premixed n-heptane combustion. A single zone model which can numerical simulate the combustion process and emissions of HCCI engine were built. The formation and evolvement mechanisms of PAHs in n-heptane HCCI combustion were simulated.

Catalytic removal of NO and PAHs over AC-supported catalysts from incineration flue gas: Bench-scale and pilot-plant tests

For dioxin removal from incineration flue gas, the common method is absorption using activated carbon (AC). In order to reduce the consumption of energy, it is worth to evaluate the destruction removal efficiency (DRE) of NO and polycyclic aromatic hydrocarbons (PAHs) over AC with a few metals loading while dioxin is physical absorbed by AC. As a result, in the present work, the use of AC as a catalyst support for simultaneous NO reduction and PAHs catalytic oxidation was investigated as an alternative technology to improve incinerator processes. This study examined the selective removal of NO and PAHs from incineration flue gas containing O 2, N 2, CO 2, H 2O, NO, organic compounds and fly ash over M/AC catalysts (M = Fe, Co, Ni, and Cu) using bench-scale and pilot-plant tests. Investigations on the effects of the incineration flue gas composition and the structure of the metal active site on NO and PAHs conversion revealed that the conversion activity increases as the atomic number of the transition metals increase, except for Ni. Carbon monoxide can act as a reductant to increase the NO removal efficiency. The M/AC catalysts showed high reactivity for simultaneous PAHs oxidation and NO reduction. The results provide useful information for the design and application of AC injection or selective catalyst reduction systems for waste incineration plants.

Oxidation of Polycyclic Aromatic Hydrocarbons with Hydrogen Peroxide in the Presence of Transition Metal Mono‐Substituted Keggin‐Type Polyoxometalates

AbstractThe oxidation of anthracene, naphthalene, 1‐ethylnaphthalene, and 2‐ethylnaphthalene with environmentally benign hydrogen peroxide has been studied in the presence of the tetrabutylammonium salts of iron and manganese mono‐substituted Keggin‐type polyoxometalates [XW11M(H2O)O39]n− (X=P, Si, or B, M=MnIII or FeIII). The reactions were performed under homogeneous conditions at 80 °C, using acetonitrile as the solvent. For all the catalysts studied, anthracene was selectively oxidized to 9,10‐anthraquinone at 100 % conversion in the presence of [BW11Mn(H2O)O39]6−. The oxidation of 1‐ethylnaphthalene and 2‐ethylnaphthalene occurs mainly at the alkyl substituent, along with the formation of phthalic anhydrides, which resulted from aromatic ring oxidation, with iron substituted anions. Naphthalene could not be oxidized with the conditions used. To understand the reaction pathways, the oxidation of several products was performed in the presence of [PW11Fe(H2O)O39]4−. Under the conditions used, the oxidation of vinylnaphthalene derivatives gave rise to mainly carbon–carbon double‐bond cleavage, affording the corresponding naphthaldehydes in high yields (>67 %). Possible reaction pathways are presented and the role of different catalysts is discussed.

The Chemistry of Ultrasonic Degradation of Organic Compounds

The destruction of toxic organic molecules using advanced oxidation processes (AOPs) is a potent tool for pollution control and environmental protection. Ultrasound is a convenient and effective method of generating hydroxyl radicals which is the key oxidant in AOPs. This review describes the use of ultrasound and associated chemical reactions, with and without additives, as a powerful means of remediating water contaminated with organic pollutants. After a brief introduction to ultrasound and sonochemistry, their application for the oxidation of polycyclic aromatic hydrocarbons, phenol and substituted phenols is considered. Next is the decomposition of chlorinated phenols, and other chlorinated organics, then removal of recalcitrant smaller organic molecules. A discussion follows of recent work that has investigated the effects of initial concentration of substrates; the use of different ultrasonic frequencies; the inclusion of oxidising species, inorganic particles, or salts and their contribution to enhanced degradation. Finally, brief comments are made on the status of ultrasound as an AOP treatment. Keywords: Sonication, degradation, oxidation, pollutants, hydroxyl radicals, advanced oxidation process, Ultrasonic Degradation, ultrasound, organic pollutants, sonochemistry, chlo-rinated phenols, multi-hyphenated processes, sono-electrochemistry, sonophotochemistry, sono-luminescene, hydrodynamic cavitational techniques, dimerisation, Polycyclic Aromatic Hydrocarbons (PAHs), sono-degradation, radical scavenging, sonolysis, sonoproducts, Henry's Law constants, Fenton-like conditions, ultrasound irradiation, phenol mineralisation, advanced Fenton process, organic carbon (TOC), Degradation of Substituted Phenols, ar-gon-saturated water, oxidative-pyrolytic degradation, acoustic pressure, oestogenic activity, sono-Fenton process, fungus Paecilomyces lilacinus, humic acids, sonicator, HPLC analyses, bisphenol-A (BPA), classi-cal Fenton reaction, DEGRADATION OF CHLORINATED ORGANICS, degrade aromatic pollutants, pyrolysis, copper catalysed Fenton reactions, Polychlorinated phenols, Pentachlorophenol (PCP), 2-chloro-5-methylphenol (2C5MP), 2,4-dichlorophenoxyacetic acid, chlorobenzene (CB), Nitro-aromatics, zeolites, sonochemi-cal oxidation, sonochemical reactor, hexagonal flow cell, cup-horn reactor, methyl t-butyl ether (MTBE), 2-methylisoborneol (MIB), geosmin (GSM), Ibuprofen (IBP)

A new semi-empirical model for the oxidation of polycyclic aromatic hydrocarbon (PAHs) molecules physisorbed on soot. II. Application to the reaction PAH + OH for a series of large PAH molecules

In the present paper, we apply our new semi-empirical method to characterize the oxidation by OH of a series of large polycyclic aromatic hydrocarbons (PAHs) adsorbed on a soot surface modeled by a large graphene-like cluster. This method is based on an electrostatic and induction contribution calculated at the SCF AM1 level to which a sum of two-body terms of the C (6)/ R 6 form has been added to represent the dispersion interactions. This so-called AM1-D method is used to compare the oxidation reaction kinetics at carbonaceous surfaces and in the gas phase. First, the satisfying comparison between the calculated adsorbed energies of a series of eight PAH molecules and the recent determinations of experimental values demonstrates the validity of this method. Moreover, our calculations evidence a small inhibition of the oxidation process by the carbonaceous surface, at least for a majority of the PAH molecules considered in our study. This result is in qualitative agreement with recent experimental conclusions.

Oxidation of polycyclic aromatic hydrocarbons by the bacterial laccase CueO from E. coli

Laccases produced by white rot fungi are capable of rapidly oxidizing benzo[a]pyrene. We hypothesize that the polycyclic aromatic hydrocarbon (PAH)-degrading bacteria producing laccase can enhance the degree of benzo[a]pyrene mineralization. However, fungal laccases are glycoproteins which cannot be glycosylated in bacteria, and there is no evidence to show that bacterial laccases can oxidize benzo[a]pyrene. In this study, the in vitro oxidation of PAHs by crude preparations of the bacterial laccase, CueO, from Escherichia coli was investigated. The results revealed that the crude CueO catalyzed the oxidation of anthracene and benzo[a]pyrene in the same way as the fungal laccase from Trametes versicolor, but showed specific characteristics such as thermostability and copper dependence. In the presence of 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid), high amounts of anthracene and benzo[a]pyrene, 80% and 97%, respectively, were transformed under optimal conditions of 60°C, pH 5, and 5 mmol l(-1) CuCl(2) after a 24-h incubation period. Other PAHs including fluorene, acenaphthylene, phenanthrene, and benzo[a]anthracene were also oxidized by the crude CueO. These findings indicated the potential application of prokaryotic laccases in enhancing the mineralization of benzo[a]pyrene by PAH-degrading bacteria.

Ozone Oxidation of Surface-Adsorbed Polycyclic Aromatic Hydrocarbons: Role of PAH−Surface Interaction

The heterogeneous chemistry of surface-adsorbed polycyclic aromatic hydrocarbons (PAHs) plays key roles in nanoscience, environmental science, and public health. Experimental evidence shows that the substrate can influence the heterogeneous oxidation of surface-bound PAHs, however, a mechanistic understanding of the role of the surface is still lacking. We examine the effects of the PAH-substrate interaction on the oxidation of surface-adsorbed anthracene, pyrene, and benzo[a]pyrene by ozone (O(3)) using density functional theory. We find that some O(3) oxidation mechanisms for these planar PAH molecules lead to nonplanar intermediates or products, the formation of which may necessitate partial desorption or "lift-off" from a solid substrate. The energy penalty for partial desorption of each PAH from the surface is estimated for four different substrate types on the basis of literature data and accounted for in the thermodynamic analysis of the reaction pathways. We find that the attractive PAH-substrate interaction may render oxidation pathways involving nonplanar intermediates or products thermodynamically unfavorable. The influence of the PAH-substrate interaction could contribute in part to the variations in PAH oxidation kinetics and product distributions that have been observed experimentally. Our choice of test molecules enabled us to identify trends in reactivity and product formation for four types of potentially reactive site (zigzag, armchair, bridge, and internal), allowing us to infer products and mechanisms of O(3) oxidation for PAHs of larger sizes. Implications for atmospheric chemistry and the stability of graphene in the presence of O(3) are discussed.

Catalytic activity of ferroalloy slags

869 Slags obtained in ferrous metallurgy may poten� tially be used as catalysts in the deep oxidation of poly� cyclic aromatic hydrocarbons from metallurgical pro� duction (1). Accordingly, it is of interest to study the catalytic properties of ferroalloy slags. In the present work, we investigate the catalytic properties of ferroalloy slags in the deep oxidation of polycyclic aromatic hydrocarbons. The output of ferroalloy slags in the Common� wealth of Independent States is more than 5 million t/yr. Slags obtained in the production of ferrochrome alloys differ in chemical and mineralogical composi� tion and in physicochemical properties. The following ferrochrome slags are formed: regular carbon slags, lowcarbon and carbonfree refining slags, and mod� eratecarbon converter slags (2, 3). Structurally, the slags consist of highrefractory spinels, forsterite, and glass saturated with spinel inclusions. The slags con� tain 2-4% chromospinelide (Mg, Fe)O ⋅ (Cr, Al)2O3; 10-15% spinel MgO ⋅ Al2O3; 15-20% forsterite 2MgO ⋅ Si 2 O 3 ; 50-55% glass; up to 1% metallic beads (Cr, Fe); and 0.7-1.0% sulfide phase FeS-CrS. The slags from silicochrome production contain a small quantity (0.3-0.5%) of chromium oxides; its basic components are oxides of silicon, aluminum, and cal� cium. Analysis of the chemical composition and physico� chemical properties of ferroalloy slags suggests that converter slags from the production of moderateand lowcarbon ferrochrome are the best for the catalysis of deep oxidation. Such slags contain the greatest quantity of catalytically active oxides: up to 70% chro� mium oxides and 2% iron oxides. In the present work, we investigate moderatecarbon ferrochrome slag from Aktyubinsk ferroalloy plant. In smelting manganese alloys, slag that is rich in manganese oxide (14.0-52.5%) is formed, as we see in the table (2, 4). Slag from the production of lowphos� phorus manganese corresponds to Technical Specifi� cations TU 14�11�85-73, and contains at least 65% manganese. Manganese slag is formed from the reduc� tion products of higher manganese oxides and fluxing additives (quartzite). The basic components of this slag are manganese oxide MnO (up to 60%), silica SiO 2 (up to 30%), alumina Al2O3 (up to 3%), calcium oxide CaO (up to 4%), and magnesium oxide MgO (up to 3%). Up to 3% K2O and Na2O are present. The melting point of the slag is around 1208°C. In smelting silicomanganese, slag containing 14-17% MnO is formed. The slag mainly consists of silicate of close� packed manganese-calciumsilicate glass of busta� mite type (CaO ⋅ MnO ⋅ 2SiO2); metal beads are present. The slag from the production of carbon and moderatecarbon ferromanganese consists mainly of oxides of manganese (40-50%), silicon (25-35%), alu� minum (0.9-3.0%), and calcium (7-23%). In mineral� ogical composition, the slags consist mainly of tephroite (2MnO ⋅ SiO 2 ) and forsterite (2MgO ⋅ SiO 2 ), with small quantities of bustamite (CaO ⋅ MnO ⋅ 2SiO 2 ). Analysis of the chemical and mineralogical com� position indicates that all the manganese slags consid� ered contain catalytically active oxides; their content is greatest in lowphosphorus manganese slag. All the slags are tested in deep catalytic oxidation.

Platinum catalysts supported on hydrothermally stable mesoporous aluminosilicate for the catalytic oxidation of polycyclic aromatic hydrocarbons (PAHs)

Abstract Catalytic oxidation of polycyclic aromatic hydrocarbons (PAHs) was studied over platinum catalysts supported on the hydrothermally stable mesoporous aluminosilicate (SM-41). Naphthalene was chosen as a model reactant of PAHs, due to the simplest and the least toxic PAHs. Zeolite seeds crystallization method was used for synthesis of SM-41. Pt/SM-41 catalyst showed higher activity than Pt/MCM-41 for catalytic oxidation of naphthalene in the presence of 10 vol.% water vapor. Hydrothermal stability and hydrophobicity of Pt/SM-41 must be beneficial for the catalytic oxidation of naphthalene in the presence of water vapor.

Electrochemical degradation of PAH compounds in process water: a kinetic study on model solutions and a proof of concept study on runoff water from harbour sediment purification

The present study has investigated the possibility to apply electrochemical oxidation in the treatment of polycyclic aromatic hydrocarbon (PAHs) pollutants in water. The reaction kinetics of naphthalene, fluoranthene, and pyrene oxidation have been studied in a batch recirculation experimental setup applying a commercial one-compartment cell of tubular design with Ti/Pt(90)-Ir(10) anode. The rate of oxidation has been evaluated upon variations in current density, electrolyte composition and concentration. All three PAHs were degraded by direct anodic oxidation in 0.10 M Na(2)SO(4) electrolyte, and the removal rates were significantly enhanced by a factor of two to six in 0.10 M NaCl due to contribution from the indirect hypochlorite oxidation. Second order reaction kinetics was observed for the degradation of naphthalene in all electrolytes whereas fluoranthene and pyrene followed first order kinetics. Decreased current densities from 200 to 15 mA cm(-2) in the NaCl electrolyte also decreased the removal rates, but significantly enhanced the current efficiencies of the PAH oxidation, based on a defined current efficiency constant, k(q). This observation is believed to be due to the suppression of the water oxidation side reaction at lower applied voltages. A proof of concept study in real polluted water demonstrated the applicability of the electrochemical oxidation technique for larger scale use, where especially the indirect chloride mediated oxidation approach was a promising technique. However, the risk and extent of by-product formation needs to be studied in greater detail.

Degradation of Polycyclic Aromatic Hydrocarbons by Crude Extracts from Spent Mushroom Substrate and its Possible Mechanisms

Biodegradation of polycyclic aromatic hydrocarbons (PAHs) by pure laccase has been reported, but the high cost limited its application in environmental bioremediation. Here, we reported a study about PAHs degradation by crude extracts (CEs) containing laccase, which were obtained by extracting four spent mushroom (Agaricus bisporus, Pleurotus eryngii, Pleurotus ostreatus, and Coprinus comatus) substrates. The results showed that anthracene, benzo[a]pyrene, and benzo[a]anthracene were top three degradable PAHs by CEs while naphthalene was most recalcitrant. The PAHs oxidation was enhanced in the presence of 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). Laccase included in CE might play a major role in PAHs degradation. The maximum degradation rate of anthracene and benzo[a]pyrene was observed by using crude extracts from P. eryngii while the highest laccase activities were found in crude extracts from A. bisporus, moreover, crude extracts from P. eryngii, which contained less laccase activities, degraded more anthracene and benzo[a]pyrene than pure laccase with higher laccase activities. The lack of correlation between laccase activity and PAHs degradation rate indicated that other factors might also influence the PAHs degradation. Boiled CEs were added to determine the effect on PAHs degradation by laccase. The results showed that all four boiled CEs had improved the PAHs oxidation. The maximum improvement was observed by adding CEs from P. eryngii. It suggested that some mediators indeed existed in CEs and CEs from P. eryngii contained most. As a result, CEs from P. eryngii has the most application potential in PAHs bioremediation.

Trace gas adsorption thermodynamics at the air−water interface: Implications in atmospheric chemistry

Abstract The thermodynamics of adsorption of gaseous organic compounds such as polycyclic aromatic hydrocarbons (PAHs) on water films is reviewed and discussed. The various experimental methods available to determine the thermodynamic equilibrium constant and the structure–activity relationships to correlate and estimate the same are reviewed. The atmospheric implications of the adsorption and oxidation of PAHs at the air–water interface of thin films of water such as existing in fog droplets, ice films, and aerosols are also enumerated.

Production and accumulation of surfactants during the chemical oxidation of PAH in soil

A soil contaminated with polycyclic aromatic hydrocarbons (PAH) was treated in laboratory slurry reactors with three chemical oxidants: (1) modified Fenton chemistry (MFC) with hydrogen peroxide (HP), (2) MFC with calcium peroxide (CP) (Cool-Ox ™), and (3) sodium persulfate activated with Fe chelated using ethylenediaminetetraacetic acid (EDTA). A bioreactor served as a control. Samples of slurry filtrate were tested to quantify emulsification of PAH and concentrations of bulk surfactants, using the critical micelle dilution method. All three oxidants produced surfactants reaching levels above the critical micelle concentration (CMC), though the surfactants were removed at the end of treatment. The surfactants emulsified the PAH, and resulted in greater overall removal of 5- and 6-ring PAH than biodegradation alone. Treatment with CP-MFC resulted in the highest concentration of surfactants (four times the CMC), the most emulsification of PAH, and the highest removal of 5- and 6-ring PAH. None of the chemical treatments significantly reduced counts of culturable heterotrophic microorganisms.

Actions of Mycobacterium sp. Strain AP1 on the Saturated- and Aromatic-Hydrocarbon Fractions of Fuel Oil in a Marine Medium

The pyrene-degrading Mycobacterium sp. strain AP1 grew in nutrient-supplemented artificial seawater with a heavy fuel oil as the sole carbon source, causing the complete removal of all linear (C(12) to C(40)) and branched alkanes from the aliphatic fraction, as well as an extensive degradation of the three- and four-ring polycyclic aromatic hydrocarbons (PAHs) phenanthrene (95%), anthracene (80%), fluoranthene (80%), pyrene (75%), and benzo(a)anthracene (30%). Alkylated PAHs, which are more abundant in crude oils than the nonsubstituted compounds, were selectively attacked at extents that varied from more than 90% for dimethylnaphthalenes, methylphenanthrenes, methylfluorenes, and methyldibenzothiophenes to about 30% for monomethylated fluoranthenes/pyrenes and trimethylated phenanthrenes and dibenzothiophenes. Identification of key metabolites indicated the utilization of phenanthrene, pyrene, and fluoranthene by known assimilatory metabolic routes, while other components were cooxidized. Detection of mono- and dimethylated phthalic acids demonstrated ring cleavage and further oxidation of alkyl PAHs. The extensive degradation of the alkanes, the two-, three-, and four-ring PAHs, and their 1-, 2-, and 3-methyl derivatives from a complex mixture of hydrocarbons by Mycobacterium sp. strain AP1 illustrates the great substrate versatility of alkane- and PAH-degrading mycobacteria.

Oxidation of PAHs in a simplified system using peroxy-acid and glass beads: Identification of oxidizing species

Polycyclic aromatic hydrocarbons (PAHs) are organic contaminants of concern due to their ubiquity, persistence in the natural environment and adverse health effects. Numerous studies have looked into the removal and treatment of these contaminants, with mixed results. High molecular weight PAHs have been particularly problematic due to their hydrophobicity and high affinity for organics, resulting in mass transfer limitations for even the fastest advanced oxidation processes (AOPs). The peroxy-acid process has been used to successfully treat PAH contaminated matrices. Experiments were conducted on benzo[a]pyrene contaminated glass beads in order to elucidate the reaction mechanisms responsible for the effectiveness of this process. For the first time peracetic acid (PAA) was identified as the important oxidant in this reaction. Different v/v/v ratios of hydrogen peroxide/acetic acid/DI water were studied which illustrated the importance of reaction ratio on oxidant concentration and rate of formation. Approximately 60% degradation of benzo[a]pyrene was achieved in 24 hours with 1.7% PAA. Observations of the reaction kinetics suggest that the slow desorption/dissolution of benzo[a]pyrene limits the efficiency of the peroxy-acid process. Modifications of the reaction setup supported this observation as treatment efficiencies increased with reactive surface area, and an increase in system agitation. These limitations were also overcome by increasing the concentration of PAA delivered to the contaminated matrix. Greater than 80% degradation of benzo[a]pyrene was achieved in 24 hours with approximately 9.2% PAA.

Photocatalytic oxidation of polycyclic aromatic hydrocarbons: Intermediates identification and toxicity testing

Polycyclic aromatic hydrocarbons (PAHs) are hydrophobic pollutants and their low water solubility limits their degradation in aqueous solution. The presence of water-miscible solvent such as acetone can increase the water solubility of PAHs, however acetone will also affect the degradation of PAH. In this study the effects of acetone on the photocatalytic degradation efficiency and pathways of 5 selected PAHs, namely naphthalene (2 rings), acenaphthylene (3 rings), phenanthrene (3 rings), anthracene (3 rings) and benzo[a]anthracene (4 rings) were investigated. The Microtox ® toxicity test was used to determine whether the PCO system can completely detoxify the parental PAHs and its intermediates. The addition of 16% acetone can greatly alter the degradation pathway of naphthalene and anthracene. Based on intermediates identified from degradation of the 5 PAHs, the location of parental PAHs attacked by reactive free radicals can be correlated with the localization energies of different positions of the compound. For toxicity analysis, irradiation by UV light was found to induce acute toxicity by generating intermediates/degradation products from PAHs and possibly acetone. Lastly, all PAHs (10 mg l −1) can be completely detoxified by titanium dioxide (100 mg l −1) within 24 h under UVA irradiation (3.9 mW cm −2).

Bioremediation of phenanthrene, chrysene and benzo[a]pyrene by fungi screened from nature

Laccase of Polyporus sp. S133 was able to oxidize most of the 3 different rings amount polycyclic aromatic hydrocarbons (PAHs) tested. Phenanthrene was removed by 89% followed by chrysene and benzo(a)pyrene which were oxidized by 66 and 55%, respectively. Addition of 1- hydroxybenzotriazole (HBT) to the reaction mixture increased oxidation of PAHs, especially phenanthrene was almost completely removed from the reaction mixture. Oxidation of chrysene and benzo(a)anthracene increased 12 and 10% with the mediator to 78 and 65% in the presence of HBT. PAH- quinones as oxidation products were formed from all PAH to different extents. A part of PAH was polymerized in the laccase/mediator system to products of weight-average molecular weight (MW). The correlation of the ionization potentials of PAH with the oxidation of these compounds is limited to the alternating PAH.

YEAR TIME MODULATION OF n-ALKANES, PAH, NITRO-PAH AND ORGANIC ACIDS AT MONTELIBRETTI ROME, ITALY

The organic fraction of airborne particulates was investigated at Montelibretti RM, Italy, over 12 months and n-alkanes, polycyclic aromatic hydrocarbons, nitrated polycyclic aromatics and aliphatic acids were evaluated. The year time modulations were acquired from all groups of compounds, both in quantitative (cumulative concentrations) and qualitative (percent compositions) terms. Some distribution indexes and diagnostic ratio rates drawn from congener abundances provided information about the twin nature (anthropogenic and biogenic) of sources of organic particulate. Briefly, unlike past decades the appearance of the Montelibretti location was that of a site affected overall by local pollution, as a consequence of both direct anthropogenic emissions and secondary oxidized compounds. The occurrence of polycyclic aromatic hydrocarbons (PAHs) seemed to depend overall upon vehicle emission (diesel powered in particular), although a second, unknown source with year time modulation was present, apparently not associated with biomass/wood burning. By contrast, nitro-PAHs were mainly associated to oxidation of parent PAHs. In summer, PAHs were found at concentrations similar to those measured in 1993–1995, whilst in winter they were three times more abundant than previously reported.

Oxidation of polycyclic aromatic hydrocarbons with hydrogen peroxide catalyzed by Iron(III)porphyrins

Abstract A variety of iron-metallated functional porphyrins have been synthesized and their catalytic activity to oxidize polycyclic aromatic hydrocarbons, (PAHs) using hydrogen peroxide as oxidant was investigated. It was found that iron-metallated porphyrins bearing strong electronegative groups at β-pyrrolic positions show an exceptionally high catalytic efficiency.