On the applicability of a hybrid bioreactor operated with polymeric tubing for the biological treatment of saline wastewater.

PubMed

Tomei, M Concetta; Mosca Angelucci, Domenica; Stazi, Valentina; Daugulis, Andrew J

2017-12-01

Effective biological treatment of high salt content wastewater requires consideration of both salt and organic toxicity. This study treated a synthetic saline wastewater containing NaCl (100gL -1 ) and 2,4-dimethylphenol (1.2gL -1 ) with a hybrid system consisting of a biological reactor containing spiral-coiled polymeric tubing through which the mixed feed was pumped. The tubing wall was permeable to the organic contaminant, but not to the salt, which allowed transfer of the organic into the cell-containing bioreactor contents for degradation, while not exposing the cells to high salt concentrations. Different grades of DuPont Hytrel polymer were examined on the basis of organic affinity predictions and experimental partition and mass transfer tests. Hytrel G3548 tubing showed the highest permeability for 2,4-dimethylphenol while exerting an effective salt barrier, and was used to verify the feasibility of the proposed system. Very high organic removal (99% after just 5h of treatment) and effective biodegradation of the organic fraction of the wastewater (>90% at the end of the test) were observed. Complete salt separation from the microbial culture was also achieved. Copyright © 2017 Elsevier B.V. All rights reserved.

A Fuzzy ARTMAP Approach To The Incorporation Of Chromatographic Retention Time Information To An MS Based E-Nose

NASA Astrophysics Data System (ADS)

Burian, Cosmin; Brezmes, Jesus; Vinaixa, Maria; Llobet, Eduard; Vilanova, Xavier; Cañellas, Nicolau; Correig, Xavier

2009-05-01

This paper presents the work done with Fuzzy ARTMAP neural networks in order to improve the performance of mass spectrometry-based electronic noses using the time retention of a chromatographic column as additional information. Solutions of nine isomers of dimethylphenols and ethylphenols were used in this experiment. The gas chromatograph mass spectrometer response was analyzed with an in-house developed Fuzzy ARTMAP neural network, showing that the combined information (GC plus MS) gives better results than MS information alone.

Transport and biodegradation of creosote compounds in clayey till, a field experiment

NASA Astrophysics Data System (ADS)

Broholm, Kim; Nilsson, Bertel; Sidle, Roy C.; Arvin, Erik

2000-02-01

The transport and biodegradation of 12 organic compounds (toluene, phenol, o-cresol, 2,6-, 3,5-dimethylphenol, naphthalene, 1-methylnaphthalene, benzothiophene, dibenzofuran, indole, acridine, and quinoline) were studied at a field site located on the island of Funen, Denmark, where a clayey till 10-15 m deep overlies a sandy aquifer. The upper 4.8 m of till is highly fractured and the upper 2.5 m contains numerous root and worm holes. A 1.5-2 m thick sand lens is encountered within the till at a depth of 4.8 m. Sampling points were installed at depths of 2.5 m, 4 m, and in the sand lens (5.5 m) to monitor the downward migration of a chloride tracer and the organic compounds. Water containing organic compounds and chloride was infiltrated into a 4 m×4.8 m basin at a rate of 8.8 m 3 day -1 for 7 days. The mass of naphthalene relative to chloride was 0.39-0.98 for the sampling points located at a depth of 2.5 m, 0.11-0.61 for the sampling points located at a depth of 4 m, and 0-0.02 for the sampling points located in the sand lens. A similar pattern was observed for eight organic compounds for which reliable results were obtained (toluene, phenol, o-cresol, 2,6-, 3,5-dimethylphenol, 1-methylnaphthalene, benzothiophene, and quinoline). This shows that the organic compounds were attenuated during the downward migration through the till despite the high infiltration rate. The attenuation process may be attributed to biodegradation.

Polydimethylsiloxane/covalent triazine frameworks coated stir bar sorptive extraction coupled with high performance liquid chromatography-ultraviolet detection for the determination of phenols in environmental water samples.

PubMed

Zhong, Cheng; He, Man; Liao, Huaping; Chen, Beibei; Wang, Cheng; Hu, Bin

2016-04-08

In this work, covalent triazine frameworks (CTFs) were introduced in stir bar sorptive extraction (SBSE) and a novel polydimethylsiloxane(PDMS)/CTFs stir bar coating was prepared by sol-gel technique for the sorptive extraction of eight phenols (including phenol, 2-chlorophenol, 2-nitrophenol, 4-nitrophenol, 2,4-dimethylphenol, p-chloro-m-cresol and 2,4-dichlorophenol, 2,4,6-trichlorophenol) from environmental water samples followed by high performance liquid chromatography-ultraviolet (HPLC-UV) detection. The prepared PDMS/CTFs coated stir bar showed good preparation reproducibility with the relative standard deviations (RSDs) ranging from 3.5 to 5.7% (n=7) in one batch, and from 3.7 to 9.3% (n=7) among different batches. Several parameters affecting SBSE of eight target phenols including extraction time, stirring rate, sample pH, ionic strength, desorption solvent and desorption time were investigated. Under the optimal experimental conditions, the limits of detection (LODs, S/N=3) were found to be in the range of 0.08-0.30 μg/L. The linear range was 0.25-500 μg/L for 2-nitrophenol, 0.5-500 μg/L for phenol, 2-chlorophenol, 4-nitrophenol as well as 2,4-dimethylphenol, and 1-500 μg/L for p-chloro-m-cresol, 2,4-dichlorophenol as well as 2,4,6-trichlorophenol, respectively. The intra-day relative standard deviations (RSDs) were in the range of 4.3-9.4% (n=7, c=2 μg/L) and the enrichment factors ranged from 64.9 to 145.6 fold (theoretical enrichment factor was 200-fold). Compared with commercial PDMS coated stir bar (Gerstel) and PEG coated stir bar (Gerstel), the prepared PDMS/CTFs stir bar showed better extraction efficiency for target phenol compounds. The proposed method was successfully applied to the analysis of phenols in environmental water samples and good relative recoveries were obtained with the spiking level at 2, 10, 50 μg/L, respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

Prompt HO2 formation following the reaction of OH with aromatic compounds under atmospheric conditions.

PubMed

Nehr, Sascha; Bohn, Birger; Wahner, Andreas

2012-06-21

The secondary formation of HO(2) radicals following OH + aromatic hydrocarbon reactions in synthetic air under normal pressure and temperature was investigated in the absence of NO after pulsed production of OH radicals. OH and HO(x) (=OH + HO(2)) decay curves were recorded using laser-induced fluorescence after gas-expansion. The prompt HO(2) yields (HO(2) formed without preceding NO reactions) were determined by comparison to results obtained with CO as a reference compound. This approach was recently introduced and applied to the OH + benzene reaction and was extended here for a number of monocyclic aromatic hydrocarbons. The measured HO(2) formation yields are as follows: toluene, 0.42 ± 0.11; ethylbenzene, 0.53 ± 0.10; o-xylene, 0.41 ± 0.08; m-xylene, 0.27 ± 0.06; p-xylene, 0.40 ± 0.09; 1,2,3-trimethylbenzene, 0.31 ± 0.06; 1,2,4-trimethylbenzene, 0.37 ± 0.09; 1,3,5-trimethylbenzene, 0.29 ± 0.08; hexamethylbenzene, 0.32 ± 0.08; phenol, 0.89 ± 0.29; o-cresol, 0.87 ± 0.29; 2,5-dimethylphenol, 0.72 ± 0.12; 2,4,6-trimethylphenol, 0.45 ± 0.13. For the alkylbenzenes HO(2) is the proposed coproduct of phenols, epoxides, and possibly oxepins formed in secondary reactions with O(2). In most product studies the only quantified coproducts were phenols whereas only a few studies reported yields of epoxides. Oxepins have not been observed so far. Together with the yields of phenols from other studies, the HO(2) yields determined in this work set an upper limit to the combined yields of epoxides and oxepins that was found to be significant (≤0.3) for all investigated alkylbenzenes except m-xylene. For the hydroxybenzenes the currently proposed HO(2) coproducts are dihydroxybenzenes. For phenol and o-cresol the determined HO(2) yields are matching the previously reported dihydroxybenzene yields, indicating that these are the only HO(2) forming reaction channels. For 2,5-dimethylphenol and 2,4,6-trimethylphenol no complementary product studies are available.

MICROBIAL METABOLISM OF AROMATIC COMPOUNDS I.

PubMed Central

Tabak, Henry H.; Chambers, Cecil W.; Kabler, Paul W.

1964-01-01

Tabak, Henry H. (Robert A. Taft Sanitary Engineering Center, Cincinnati, Ohio), Cecil W. Chambers, and Paul W. Kabler. Microbial metabolism of aromatic carbon compounds. I. Decomposition of phenolic compounds and aromatic hydrocarbons by phenol-adapted bacteria. J. Bacteriol. 87:910–919. 1964.—Bacteria from soil and related environments were selected or adapted to metabolize phenol, hydroxy phenols, nitrophenols, chlorophenols, methylphenols, alkylphenols, and arylphenols when cultured in mineral salts media with the specific substrate as the sole source of carbon. A phenol-adapted culture (substrate-induced enzyme synthesis proven) was challenged in respirometric tests with 104 related compounds; probable significant oxidative activity occurred with 65. Dihydric phenols were generally oxidized; trihydric phenols were not. Cresols and dimethylphenols were oxidized; adding a chloro group increased resistance. Benzoic and hydroxybenzoic acids were oxidized; sulfonated, methoxylated, nitro, and chlorobenzoic acids were not; m-toluic acid was utilized but not the o- and p-isomers. Benzaldehyde and p-hydroxybenzaldehyde were oxidized. In general, nitro- and chloro-substituted compounds and the benzenes were difficult to oxidize. PMID:14137630

On-site GC/MS analysis of Chapman gasification separator liquor. Final report Jul 80-Mar 81

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thielen, C.J.; Magee, R.A.; Collins, R.V.

1981-08-01

The report gives results of a characterization of a wastewater stream from a coal gasification plant, using on-site extraction and GC/MS analysis. Extractable material in the wastewater was primarily phenols and alkylphenols, accounting for about 99% of the total mass identified. Several polynuclear aromatic compounds were also identified. The composition of the sample deteriorated even though the water was held in amber bottles at 4C: this was most evident in the concentration of dimethylphenols which dropped about 75% during 2 weeks of refrigerated storage. Ambient sample storage produced a greater decrease in the concentration of phenol, but did not appearmore » to affect the alkylphenols or the base/neutral compounds as much. The observed changes in composition should hamper any off-site wastewater treatbility studies with waters of this type. Diisopropyl ether (DIPE) extraction confirmed the 99-plus % removal efficiency of phenol which had been demonstrated in previous studies. Wet oxidation removed organics almost as efficiently as DIPE extraction, but may have limited use because of its high operating cost.« less

Anaerobic biodegradability of alkylphenols and fuel oxygenates in the presence of alternative electron acceptors.

PubMed

Puig-Grajales, L; Tan, N G; van der Zee, F; Razo-Flores, E; Field, J A

2000-11-01

Alkylphenols and fuel oxygenates are important environmental pollutants produced by the petrochemical industry. A batch biodegradability test was conducted with selected ortho-substituted alkylphenols (2-cresol, 2,6-dimethylphenol and 2-ethylphenol), fuel oxygenates (methyl tert-butyl ether, ethyl tert-butyl ether and tert-amylmethyl ether) and tert-butyl alcohol (TBA) as model compounds. The ortho-substituted alkylphenols were not biodegraded after 100 days of incubation under methanogenic, sulfate-, or nitrate-reducing conditions. However, biodegradation of 2-cresol and 2-ethylphenol (150 mg l(-1)) was observed in the presence of Mn (IV) as electron acceptor. The biodegradation of these two compounds took place in less than 15 days and more than 90% removal was observed for both compounds. Mineralization was indicated since no UV-absorbing metabolites accumulated after 23 days of incubation. These alkylphenols were also slowly chemically oxidized by Mn (IV). No biodegradation of fuel oxygenates or TBA (1 g l(-1)) was observed after 80 or more days of incubation under methanogenic, Fe (III)-, or Mn (IV)-reducing conditions, suggesting that these compounds are recalcitrant under anaerobic conditions. The fuel oxygenates caused no toxicity towards acetoclastic methanogens activity in anaerobic granular sludge.

Detection of phenolic compounds in flow systems based on tyrosinase-modified reticulated vitreous carbon electrodes.

PubMed

Peña, N; Reviejo, A J; Pingarrón, J M

2001-08-03

The fabrication and performance of a reticulated vitreous carbon (RVC)-based tyrosinase flow-through electrode, in which the enzyme was covalently immobilized, is reported. The bioelectrode was tested as an amperometric detector for phenolic compounds. Variables affecting the construction of the enzyme flow-through electrode such as the RVC chemical pretreatment procedure, the enzyme immobilization method in the RVC matrix, the enzyme loading and the pH value of the buffer solution used, were optimized by flow-injection with amperometric detection. A good immobilization of the enzyme in the RVC matrix, in spite of the hydrodynamic conditions, was found. The same tyrosinase-RVC electrode could be used with no significant loss of the amperometric response for around 20 days, and reproducible responses could be achieved with different electrodes constructed in the same manner. Moreover, the operational stability of the bioelectrode was tested under continuous monitorization conditions. Calibration plots by flow injection with amperometric detection at -0.20 V were obtained for phenol, 2,4-dimethylphenol; 3-chlorophenol; 4-chlorophenol; 4-chloro-3-methylphenol and 2-aminophenol, with detection limits ranging from 2 mug l(-1) (4-chloro-3-methylphenol) to 2 mg l(-1).

Mutagenicity testing in the Salmonella typhimurium assay of phenolic compounds and phenolic fractions obtained from smokehouse smoke condensates.

PubMed

Pool, B L; Lin, P Z

1982-08-01

Smokehouse smoke, which is used for flavouring meat products, was investigated for its mutagenic activity in the Salmonella typhimurium assay. We were chiefly concerned with the fractions free of polycyclic aromatic hydrocarbons but containing phenol compounds, which are responsible for the preservative and aromatizing properties of the smoke. The most abundantly occurring phenol compounds (phenol, cresols, 2,4-dimethylphenol, brenzcatechine, syringol, eugenol, vanilline and guaiacol) gave negative results when they were tested for mutagenicity at five concentrations up to 5000 micrograms/plate, with and without S-9 mix, using five strains of S. typhimurium. Even when phenol was further investigated in a variety of test conditions, no induction of his+ revertants was observed. When smokehouse smoke was condensed and fractionated the majority of the various phenolic fractions also gave negative results when tested at five concentrations using five strains of S. typhimurium. However there was a slight increase in the number of revertants in a few cases. The presence in the phenolic fractions of very small amounts of mutagenic impurities, the nature of which needs further investigation, cannot be excluded. These results support the further development of non-hazardous smoke-aroma preparations, based on the phenolic components of smokehouse smoke.

Liquid–Liquid Equilibrium Measurements for Model Systems Related to Catalytic Fast Pyrolysis of Biomass

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jasperson, Louis V.; McDougal, Rubin J.; Diky, Vladimir

Here in this paper we report liquid-liquid mutual solubilities for binary aqueous mixtures involving 2-, 3-, and 4-ethylphenol, 2-, 3-, and 4-methoxyphenol, benzofuran, and 1H-indene for the temperature range (300 < T/K < 360). Measurements in the water-rich phase for (2-ethylphenol + water) were extended to T = 440 K to facilitate comparison with literature values. Liquid-liquid equilibrium tie-line determinations were made for four ternary systems involving (water + toluene) mixed with a third component; phenol, 3-ethylphenol, 4-methoxyphenol, or 2,4-dimethylphenol. Literature values at higher temperatures are available for the three (ethylphenol + water) systems, and, in general, good agreement ismore » seen. The ternary system (water + toluene + phenol) has been studied previously with inconsistent results reported in the literature, and one report is shown to be anomalous. All systems are modeled with the predictive methods NIST-Modified-UNIFAC and NIST-COSMO-SAC, with generally good success in the temperature range of interest (300 < T/K < 360). This work is part of a larger project on the testing and development of predictive phase equilibrium models for compound types occurring in catalytic fast pyrolysis of biomass, and background information for the larger project is provided.« less

Liquid–Liquid Equilibrium Measurements for Model Systems Related to Catalytic Fast Pyrolysis of Biomass

DOE PAGES

Jasperson, Louis V.; McDougal, Rubin J.; Diky, Vladimir; ...

2016-11-02

Here in this paper we report liquid-liquid mutual solubilities for binary aqueous mixtures involving 2-, 3-, and 4-ethylphenol, 2-, 3-, and 4-methoxyphenol, benzofuran, and 1H-indene for the temperature range (300 < T/K < 360). Measurements in the water-rich phase for (2-ethylphenol + water) were extended to T = 440 K to facilitate comparison with literature values. Liquid-liquid equilibrium tie-line determinations were made for four ternary systems involving (water + toluene) mixed with a third component; phenol, 3-ethylphenol, 4-methoxyphenol, or 2,4-dimethylphenol. Literature values at higher temperatures are available for the three (ethylphenol + water) systems, and, in general, good agreement ismore » seen. The ternary system (water + toluene + phenol) has been studied previously with inconsistent results reported in the literature, and one report is shown to be anomalous. All systems are modeled with the predictive methods NIST-Modified-UNIFAC and NIST-COSMO-SAC, with generally good success in the temperature range of interest (300 < T/K < 360). This work is part of a larger project on the testing and development of predictive phase equilibrium models for compound types occurring in catalytic fast pyrolysis of biomass, and background information for the larger project is provided.« less

Transformations of Aromatic Compounds by Nitrosomonas europaea

PubMed Central

Keener, William K.; Arp, Daniel J.

1994-01-01

Benzene and a variety of substituted benzenes inhibited ammonia oxidation by intact cells of Nitrosomonas europaea. In most cases, the inhibition was accompanied by transformation of the aromatic compound to a more oxidized product or products. All products detected were aromatic, and substituents were often oxidized but were not separated from the benzene ring. Most transformations were enhanced by (NH4)2SO4 (12.5 mM) and were prevented by C2H2, a mechanism-based inactivator of ammonia monooxygenase (AMO). AMO catalyzed alkyl substituent hydroxylations, styrene epoxidation, ethylbenzene desaturation to styrene, and aniline oxidation to nitrobenzene (and unidentified products). Alkyl substituents were preferred oxidation sites, but the ring was also oxidized to produce phenolic compounds from benzene, ethylbenzene, halobenzenes, phenol, and nitrobenzene. No carboxylic acids were identified. Ethylbenzene was oxidized via styrene to two products common also to oxidation of styrene; production of styrene is suggestive of an electron transfer mechanism for AMO. Iodobenzene and 1,2-dichlorobenzene were oxidized slowly to halophenols; 1,4-dichlorobenzene was not transformed. No 2-halophenols were detected as products. Several hydroxymethyl (-CH2OH)-substituted aromatics and p-cresol were oxidized by C2H2-treated cells to the corresponding aldehydes, benzaldehyde was reduced to benzyl alcohol, and o-cresol and 2,5-dimethylphenol were not depleted. PMID:16349282

Filter-based treatment of leachate from an industrial landfill containing shredder residues of end-of-life vehicles and white goods.

PubMed

Kängsepp, P; Mathiasson, L; Mårtensson, L

2010-02-01

A pilot plant was set up to treat leachate from an industrial landfill containing shredder residues of end-of-life vehicles and white goods. The treatment plant consisted of aeration and sedimentation steps for pre-treatment, and a filter. The plant was designed to simultaneously remove various types of pollutants. The efficiencies of pre-treatment and of the main treatment step were investigated over a period of 3 years at the landfill site. By continuous aeration of the leachate the concentrations of Fe and Mn were reduced by 55% and 49%, respectively. By prolonged sedimentation suspended solid content was noticeably reduced (72%). In the filter, consisting of a mixture of peat and carbon-containing ash as a treatment medium, very high reduction of polar organic compounds, e.g. phenol (74%), o-and p-cresol (91%), and 2,4-dimethylphenol (73%), high average reduction of metals, e.g. Pb (78%), Fe (74%), Cu (73%), Mn (56%), Sn (55%), and Zn (47%), and good average reduction of DOC (26%), Tot-N (23%) and NH4-N (46%) were achieved. Sixty non-polar compounds in the leachate, identified by GC-MS screening, occurred at trace level. Most of them were considerably reduced in the filter.

Mitochondrial biotransformation of ω-(phenoxy)alkanoic acids, 3-(phenoxy)acrylic acids, and ω-(1-methyl-1H-imidazol-2-ylthio)alkanoic acids: A prodrug strategy for targeting cytoprotective antioxidants to mitochondria

PubMed Central

Roser, Kurt S.; Brookes, Paul S.; Wojtovich, Andrew P.; Olson, Leif P.; Shojaie, Jalil; Parton, Richard L.; Anders, M. W.

2010-01-01

Mitochondrial reactive oxygen species (ROS) generation and the attendant mitochondrial dysfunction are implicated in a range of disease states. The objective of the present studies was to test the hypothesis that the mitochondrial β-oxidation pathway could be exploited to deliver and biotransform the prodrugs ω-(phenoxy)alkanoic acids, 3-(phenoxy)acrylic acids, and ω-(1-methyl-1H-imidazol-2-ylthio)alkanoic acids to the corresponding phenolic antioxidants or methimazole. 3 -and 5-(Phenoxy)alkanoic acids and methyl-substituted analogs were biotransformed to phenols; rates of biotransformation decreased markedly with methyl-group substitution on the phenoxy moiety. 2,6-Dimethylphenol formation from the analogs 3-([2,6-dimethylphenoxy]methylthio)propanoic acid and 3-(2,6-dimethylphenoxy)acrylic acid was greater than that observed with ω-(2,6-dimethylphenoxy)alkanoic acids. 3- and 5-(1-Methyl-1H-imidazol-2-ylthio)alkanoic acids were rapidly biotransformed to the antioxidant methimazole and conferred significant cytoprotection against hypoxia-reoxygenation injury in isolated cardiomyocytes. Both 3-(2,6-dimethylphenoxy)propanoic acid and 3-(2,6-dimethylphenoxy)acrylic acid also afforded cytoprotection against hypoxia-reoxygenation injury in isolated cardiomyocytes. These results demonstrate that mitochondrial β-oxidation is a potentially useful delivery system for targeting antioxidants to mitochondria. PMID:20129794

Solid-phase microextraction Ni-Ti fibers coated with functionalised silica particles immobilized in a sol-gel matrix.

PubMed

Azenha, Manuel; Ornelas, Mariana; Fernando Silva, A

2009-03-20

One of the possible approaches for the development of novel solid-phase microextraction (SPME) fibers is the physical deposition of porous materials onto a support using high-temperature epoxy glue. However, a major drawback arises from decomposition of epoxy glue at temperatures below 300 degrees C and instability in some organic solvents. This limitation motivated us to explore the possibility of replacing the epoxy glue with a sol-gel film, thermally more stable and resistant to organic solvents. We found that functionalised silica particles could be successfully attached to a robust Ni-Ti wire by using a UV-curable sol-gel film. The particles were found to be more important than the sol-gel layer during the microextraction process, as shown by competitive extraction trials and by the different extraction profiles observed with differently functionalised particles. If a quality control microscopic-check aiming at the rejection of fibers exhibiting unacceptably low particle load was conducted, acceptable (6-14%) reproducibility of preparation of C(18)-silica fibers was observed, and a strong indication of the durability of the fibers was also obtained. A cyclohexyldiol-silica fiber was used, as a simple example of applicability, for the successful determination of benzaldehyde, acetophenone and dimethylphenol at trace level in spiked tap water. Recoveries: 95-109%; limits of detection: 2-7 microg/L; no competition effects within the studied range (

Chemical Composition and Antimicrobial Activity of Essential Oils from the Aerial Parts of Asteriscus graveolens (Forssk.) Less. and Pulicaria incisa (Lam.) DC.: Two Asteraceae Herbs Growing Wild in the Hoggar.

PubMed

Chaib, Faiza; Allali, Hocine; Bennaceur, Malika; Flamini, Guido

2017-08-01

In recent years, antimicrobial activities of essential oils have been intensively explored, mainly in researching and developing new antimicrobial agents to overcome microbial resistance. The present study investigates the chemical composition and antimicrobial activities of essential oils obtained from two Asteraceae: Asteriscus graveolens (Forssk.) Less. and Pulicaria incisa (Lam.) DC. Chemical analysis was performed using a combination of capillary GC-FID and GC/MS analytical techniques. The major component of Asteriscus graveolens were cis-chrysanthenyl acetate (31.1%), myrtenyl acetate (15.1%), and kessane (11.5%), while for Pulicaria incisa the main components were chrysanthenone (45.3%) and 2,6-dimethylphenol (12.6%). The oils obtained from the aerial parts were tested against sixteen microbial strains by agar well diffusion technique and dilution methods and showed minimum inhibitory concentrations (MIC) in the range of 19 - 1250 μg/ml. A good antibacterial activity against a common nosocomial pathogen, Acinetobacter baumanniiATCC 19606 was observed, especially from Pulicaria incisa essential oil, with a MIC value up to 19 μg/ml. These results give significant information about the pharmacological activity of these essential oils, which suggest their benefits to human health, having the potential to be used for medical purposes. © 2017 Wiley-VHCA AG, Zurich, Switzerland.

Modelling the photochemical attenuation pathways of the fibrate drug gemfibrozil in surface waters.

PubMed

Fabbri, Debora; Maurino, Valter; Minella, Marco; Minero, Claudio; Vione, Davide

2017-03-01

Gemfibrozil (GFZ) is a relatively persistent pollutant in surface-water environments and it is rather recalcitrant to biological degradation. The GFZ photochemical lifetimes are relatively short in shallow waters with low levels of dissolved organic carbon (DOC), but they can reach the month-year range in deep and high-DOC waters. The main reason is that GFZ undergoes negligible reaction with singlet oxygen or degradation sensitised by the triplet states of chromophoric dissolved organic matter, which are the usually prevalent photochemical pathways in deep and high-DOC sunlit waters. Nitrate and nitrite scarcely affect the overall GFZ lifetimes, but they can shift photodegradation from direct photolysis to the OH process. These two pathways are the main GFZ phototransformation routes, with the direct photolysis prevailing in shallow environments during summer. Under these conditions the GFZ photochemical lifetimes are also shorter and the environmental significance of photodegradation correspondingly higher. The direct photolysis of GFZ under UVB irradiation yielded several transformation intermediates deriving from oxidation or cleavage of the aliphatic lateral chain. A quinone derivative (2,5-dimethyl-1,4-benzoquinone), a likely oxidation product of the transformation intermediate 2,5-dimethylphenol, is expected to be the most acutely and chronically toxic compound arising from GFZ direct photolysis. Interestingly, literature evidence suggests that the same toxic intermediate would be formed upon OH reaction. Copyright © 2016 Elsevier Ltd. All rights reserved.

Sorption of phenol and alkylphenols from aqueous solution onto organically modified montmorillonite and applications of dual-mode sorption model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huh, J.K.; Song, D.I.; Jeon, Y.W.

2000-01-01

Single- and multisolute competitive sorptions were carried out in a batch reactor to investigate the uptake of phenol, 4-methylphenol (MeP), 2,4-dimethylphenol (DMeP), and 4-ethylphenol (EtP) dissolved in water at 25 C onto organically modified montmorillonite. Hexadecyltrimethylammonium (HDTMA) cation was exchanged for metal cations on the montmorillonite to the extent of the cation-exchange capacity (CEC) of the montmorillonite to prepare HDTMA-montmorillonite, changing its surface property from hydrophilic to organophilic. It was observed from the experimental results that the adsorption affinity on HDTMA-montmorillonite was in the order 4-EtP {approx} 2,4-DMeP > 4-MeP > phenol. The Langmuir, dual-mode sorption (DS), and Redlich-Peterson (RP)more » models were used to analyze the single-solute sorption equilibria. The competitive Langmuir model (CLM), competitive dual-mode sorption model (CDSM), and ideal adsorbed solution theory (IAST), coupled with the single-solute models (i.e., Langmuir, DS, and RP models), were used to predict the multisolute competitive sorption equilibria. All the models considered in this work yielded favorable representations of both single- and multisolute sorption behaviors. DSM, CDSM, and IAST coupled with the DSM were found to be other satisfactory models to describe the single- and multisolute sorption of the phenolic compounds onto HDTMA-montmorillonite.« less

Determination of Phenols Isomers in Water by Novel Nanosilica/Polydimethylsiloxane-Coated Stirring Bar Combined with High Performance Liquid Chromatography-Fourier Transform Infrared Spectroscopy.

PubMed

Zheng, Bei; Li, Wentao; Liu, Lin; Wang, Xin; Chen, Chen; Yu, Zhiyong; Li, Hongyan

2017-08-18

A novel nanosilica/polydimethylsiloxane (SiO 2 /PDMS) coated stirring bar was adopted in the sorption extraction (SBSE) of phenols in water, and the high performance liquid chromatography-fourier transform infrared spectroscopy (HPLC-FTIR) was subsequently used to determination of phenol concentration. The SiO 2 /PDMS coating was prepared by sol-gel method and characterized with respect to morphology and specific surface area. The results of field-emission scanning electron microscope (FE-SEM) and N 2 adsorption-desorption as well as phenol adsorption experiments denoted that SiO 2 /PDMS has larger surface area and better adsorption capacity than commercial PDMS. The extraction efficiency of phenol with SiO 2 /PDMS coated stirring bar was optimized in terms of ion strength, flow rate of phenol-involved influent, type of desorption solvent and desorption time. More than 75% of phenol desorption efficiency could be kept even after 50 cycles of extraction, indicating the high stability of the SiO 2 /PDMS coated stirring bar. Approximately 0.16 mg/L 2, 5-dimethylphenol (2, 5-DMP), which was 34-fold more toxic than phenol, was detected in water through HPLC-FTIR. However, 2, 5-DMP could be oxidized to 5-methy-2-hydroxy benzaldehyde after disinfection in drinking water treatment process. Therefore, the proposed method of SiO 2 /PDMS-SBSE-HPLC-FTIR is successfully applied in the analysis of phenols isomers in aqueous environment.

Multi-substrate biodegradation interaction of 1, 4-dioxane and BTEX mixtures by Acinetobacter baumannii DD1.

PubMed

Zhou, YuYang; Huang, Huanlin; Shen, Dongsheng

2016-02-01

This study evaluated substrate interactions during the aerobic biodegradation of 1, 4-dioxane and BTEX mixtures by a pure culture, Acinetobacter baumannii DD1, which is capable of utilizing 1, 4-dioxane for growth. A. baumannii DD1 could utilize BTEX as a sole carbon source, but could not utilize m-xylene and p-xylene. In binary mixtures, there was a lag of about 14 h before the degradation of BTE, and 1, 4-dioxane only started to be utilized when BTE was completely degraded by 1, 4-dioxane-grown DD1. Furthermore, the biodegradation rate of 1, 4-dioxane decreased from 73.33 to 40.74 mg/(h g dry weight) after the biodegradation of benzene. 1, 4-dioxane could not be degraded after the biodegradation of o-xylene in 80 h. DD1 could also not degrade m-xylene and p-xylene coexisting with 1, 4-dioxane. The ability of DD1 to degrade BTEX occurred in the following order: benzene > ethylbenzene > toluene > o-xylene > m-xylene = p-xylene. The biodegradation of 1, 4-dioxane was not activated in the mixture with o-xylene, primarily because of the accumulation of the specific toxic intermediate, 2, 3-dimethylphenol. The lag in BTE degradation was presumably because of the induction of enzymes necessary for BTE degradation. Additionally, SDS-PAGE analysis demonstrated that there were different proteins during the degradation of benzene and 1, 4-dioxane.

Purification and characterization of two novel peroxidases from the dye-decolorizing fungus Bjerkandera adusta strain CX-9.

PubMed

Bouacem, Khelifa; Rekik, Hatem; Jaouadi, Nadia Zaraî; Zenati, Bilal; Kourdali, Sidali; El Hattab, Mohamed; Badis, Abdelmalek; Annane, Rachid; Bejar, Samir; Hacene, Hocine; Bouanane-Darenfed, Amel; Jaouadi, Bassem

2018-01-01

Two extracellular peroxidases from Bjerkandera adusta strain CX-9, namely a lignin peroxidase (called LiP BA45) and manganese peroxidase (called MnP BA30), were purified simultaneously by applying successively, ammonium sulfate precipitation-dialysis, Mono-S Sepharose anion-exchange and Sephacryl S-200 gel filtration and biochemically characterized. The sequence of their NH 2 -terminal amino acid residues showed high homology with those of fungi peroxidases. Matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF/MS) analysis revealed that the purified enzymes MnP BA30 and LiP BA45 were a monomers with a molecular masses 30125.16 and 45221.10Da, respectively. While MnP BA30 was optimally active at pH 3 and 70°C, LiP BA45 showed optimum activity at pH 4 and 50°C. The two enzymes were inhibited by sodium azide and potassium cyanide, suggesting the presence of heme-components in their tertiary structures. The K m and V max for LiP BA45 toward 2,4-Dichlorolphenol (2,4-DCP) were 0.099mM and 9.12U/mg, respectively and for MnP BA30 toward 2,6-Dimethylphenol (2,6-DMP), they were 0.151mM and 18.60U/mg, respectively. Interestingly, MnP BA30 and LiP BA45 demonstrated higher catalytic efficiency than that of other tested peroxidases (MnP, LiP, HaP4, and LiP-SN) and marked organic solvent-stability and dye-decolorization efficiency. Data suggest that these peroxidases may be considered as potential candidates for future applications in distaining synthetic-dyes. Copyright © 2017 Elsevier B.V. All rights reserved.

Identification of a Novel Dioxygenase Involved in Metabolism of o-Xylene, Toluene, and Ethylbenzene by Rhodococcus sp. Strain DK17

PubMed Central

Kim, Dockyu; Chae, Jong-Chan; Zylstra, Gerben J.; Kim, Young-Soo; Kim, Seong-Ki; Nam, Myung Hee; Kim, Young Min; Kim, Eungbin

2004-01-01

Rhodococcus sp. strain DK17 is able to grow on o-xylene, benzene, toluene, and ethylbenzene. DK17 harbors at least two megaplasmids, and the genes encoding the initial steps in alkylbenzene metabolism are present on the 330-kb pDK2. The genes encoding alkylbenzene degradation were cloned in a cosmid clone and sequenced completely to reveal 35 open reading frames (ORFs). Among the ORFs, we identified two nearly exact copies (one base difference) of genes encoding large and small subunits of an iron sulfur protein terminal oxygenase that are 6 kb apart from each other. Immediately downstream of one copy of the dioxygenase genes (akbA1a and akbA2a) is a gene encoding a dioxygenase ferredoxin component (akbA3), and downstream of the other copy (akbA1b and akbA2b) are genes putatively encoding a meta-cleavage pathway. RT-PCR experiments show that the two copies of the dioxygenase genes are operonic with the downstream putative catabolic genes and that both operons are induced by o-xylene. When expressed in Escherichia coli, AkbA1a-AkbA2a-AkbA3 transformed o-xylene into 2,3- and 3,4-dimethylphenol. These were apparently derived from an unstable o-xylene cis-3,4-dihydrodiol, which readily dehydrates. This indicates a single point of attack of the dioxygenase on the aromatic ring. In contrast, attack of AkbA1a-AkbA2a-AkbA3 on ethylbenzene resulted in the formation of two different cis-dihydrodiols resulting from an oxidation at the 2,3 and the 3,4 positions on the aromatic ring, respectively. PMID:15574904

Effect of oxygen compounds addition on the hydrocracking of coal derived liquid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sato, Yoshiki; Kodera, Yoichi; Kamo, Tohru

1998-12-31

Coal derived liquid from liquefaction, coking and low temperature pyrolysis contains considerable amounts of alkylphenols with alkylbenzenes and alkylnaphthalenes. To produce and purify useful chemicals from coal-derived liquid, hydrocracking and hydrotreating of alkylphenol mixture is a very important process. In this study the effects of oxygen compounds such as dimethylcarbonate (DMC) addition on the hydrocracking of alkylphenols and coal-derived liquid were investigated to decrease hydrogen consumption due to the production of water from the removal of OH group. From the hydrocracking of 3,5-dimethylphenol (3,5-DMP) without DMC at 700 C, residence time of 3--10 sec under hydrogen-to-reactant molar ratio of moremore » than 10 using atmospheric flow apparatus with quartz reactor, m-xylene and m-cresol were produced with the production ratio of 1:1.8. However the dehydroxylation to produce m-xylene was decreased by the addition of 10% DMC with the 50% increased production ratio of 1:2.7. These are considered due to the strong interaction between OH group and DMC. Similar reaction behavior was observed in the hydrocracking of 2,5-DMP and the production ratio of (o-cresol + m-cresol)/p-xylene slightly increased from 3.0 to 3.5 by the addition of DMC. On the other hand, the products distribution did not change with and without DMC in the case of 2,6-DMP. This indicates the interaction is hindered by steric effect by the neighboring CH{sub 3} group. The effect of other oxygen compounds on the hydrocracking and the products distribution from the hydrocracking of coal-derived liquids is also discussed.« less

Amino modified multi-walled carbon nanotubes/polydimethylsiloxane coated stir bar sorptive extraction coupled to high performance liquid chromatography-ultraviolet detection for the determination of phenols in environmental samples.

PubMed

Hu, Cong; Chen, Beibei; He, Man; Hu, Bin

2013-07-26

In this work, amino modified multi-walled carbon nanotubes/polydimethylsiloxane (multi-walled carbon nanotubes-4,4'-diaminodiphenylmethane/polydimethylsiloxane, MWCNTs-DDM/PDMS) was synthesized, and utilized as a novel coating for stir bar sorptive extraction (SBSE) of seven phenols (phenol, 2-chlorophenol, 2-nitrophenol, 4-nitrophenol, 2,4-dimethylphenol, p-choro-m-cresol and 2,4,6-trichlorphenol) in environmental water and soil samples, followed by high performance liquid chromatography-ultraviolet detection (HPLC-UV). The prepared MWCNTs-DDM/PDMS coated stir bar was characterized and good preparation reproducibility was obtained with the relative standard deviations (RSDs) ranging from 4.7% to 11.3% (n=9) in one batch, and from 4.8% to 13.9% (n=8) among different batches. Several parameters affecting the extraction of seven target phenols by MWCNTs-DDM/PDMS-SBSE including extraction time, stirring rate, pH, ionic strength, desorption solvent and desorption time were investigated. Under the optimal experimental conditions, the limits of detection (LODs, S/N=3) were found to be in the range of 0.14μg/L (2-nitrophenol) to 1.76μg/L (phenol) and the limits of quantification (LOQs, S/N=10) were found to be in the range of 0.46μg/L (2-nitrophenol) to 5.8μg/L (phenol). The linear range was 5-1000μg/L for phenol and 4-nitrophenol, 1-1000μg/L for 2-nitrophenol and 2-1000μg/L for other phenols, respectively. The RSDs of the developed method were in the range of 6.2-11.6% (n=8, c=10μg/L) and the enrichment factors were from 6.5 to 62.8-fold (theoretical enrichment factor was 100-fold). The proposed method was successfully applied to the analysis of phenols in environmental water and soil samples, and good recoveries were obtained for the spiked samples. The proposed method is simple, highly sensitive and suitable for the analysis of trace phenols in environmental samples with complex matrix. Copyright © 2013 Elsevier B.V. All rights reserved.

Effect of urban stormwater runoff on ground water beneath recharge basins on Long Island, New York

USGS Publications Warehouse

Ku, H.F.; Simmons, D.L.

1986-01-01

Urban stormwater runoff was monitored during 1980-82 to investigate the source, type, quantity, and fate of contaminants routed to the more than 3,000 recharge basins on Long Island and to determine whether this runoff might be a significant source of contamination to the groundwater reservoir. Forty-six storms were monitored at five recharge basins in representative land use areas (strip commercial, shopping-mall parking lot, major highway, low-density residential, and medium-density residential). Runoff:precipitation ratios indicate that all storm runoff is derived from precipitation on impervious surfaces in the drainage area, except during storms of high intensity or long duration, when additional runoff can be derived from precipitation on permeable surfaces. Lead was present in highway runoff in concentrations up to 3300 micrograms/L, and chloride was found in parking lot runoff concentrations up to 1,100 mg/L during winter, when salt is used for deicing. In the five composite stormwater samples and nine groundwater grab samples that were analyzed for 113 EPA-designated ' priority pollutants, ' four constituents were detected in concentrations exceeding New York State guidelines of 50 micrograms/L for an individual organic compound in drinking water: p-chloro-m-cresol (79 micrograms/L); 2 ,4-dimethylphenol (96 micrograms/L); 4-nitrophenol (58 micrograms/L); and methylene chloride (230 micrograms/L in either groundwater or stormwater at the highway basin). One stormwater sample and two groundwater samples exceeded New York State guidelines for total organic compounds in drinking water (100 micrograms/L). The presence of these constituents is attributed to contamination from point sources rather than to the quality of runoff from urban areas. The median number of indicator bacteria in stormwater ranged from 0.1 to 10 billion MPN/100 ml. Fecal coliforms and fecal streptococci increased by 1 to 2 orders of magnitude during the warm season. The use of recharge basins to dispose of storm runoff does not appear to have significant adverse effects on groundwater quality in terms of the chemical and microbiological stormwater constituents studied. (Author 's abstract)

Thermochemical data and additivity group values for ten species of o-xylene low-temperature oxidation mechanism.

PubMed

Canneaux, Sébastien; Vandeputte, Romain; Hammaecher, Catherine; Louis, Florent; Ribaucour, Marc

2012-01-12

o-Xylene could be a good candidate to represent the family of aromatic hydrocarbons in a surrogate fuel. This study uses computational chemistry to calculate standard enthalpies of formation at 298 K, Δ(f)H°(298 K), standard entropies at 298 K, S°(298 K), and standard heat capacities C(p)°(T) over the temperature range 300 K to 1500 K for ten target species present in the low-temperature oxidation mechanism of o-xylene: o-xylene (1), 2-methylbenzyl radical (2), 2-methylbenzylperoxy radical (3), 2-methylbenzyl hydroperoxide (4), 2-(hydroperoxymethyl)benzyl radical (5), 2-(hydroperoxymethyl)benzaldehyde (6), 1-ethyl-2-methylbenzene (7), 2,3-dimethylphenol (8), 2-hydroxybenzaldehyde (9), and 3-hydroxybenzaldehyde (10). Δ(f)H°(298 K) values are weighted averages across the values calculated using five isodesmic reactions and five composite calculation methods: CBS-QB3, G3B3, G3MP2, G3, and G4. The uncertainty in Δ(f)H°(298 K) is also evaluated. S°(298 K) and C(p)°(T) values are calculated at B3LYP/6-311G(d,p) level of theory from molecular properties and statistical thermodynamics through evaluation of translational, rotational, vibrational, and electronic partition functions. S°(298 K) and C(p)°(300 K) values are evaluated using the rigid-rotor-harmonic-oscillator model. C(p)°(T) values at T ≥ 400 K are calculated by treating separately internal rotation contributions and translational, external rotational, vibrational, and electronic contributions. The thermochemical properties of six target species are used to develop six new additivity groups taking into account the interaction between two substituents in ortho (ORT/CH2OOH/ME, ORT/ET/ME, ORT/CHO/OH, ORT/CHO/CH2OOH) or meta (MET/CHO/OH) positions, and the interaction between three substituents (ME/ME/OH123) located one beside the other (positions numbered 1, 2, 3) for two- or three-substituted benzenic species. Two other additivity groups are also developed using the thermochemical properties of benzenic species taken from the literature: the C/CB/H2/OO and the CB/CO groups. These groups extend the capacities of the group additivity method to deal with substituted benzenic species.