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1.
Bioresour Technol ; 304: 123035, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32111454

RESUMO

The aim of this study was to investigate the characteristic of a newly isolated strain Comamonas sp. ZF-3 involved in typical organics degradation in coking wastewater (CWW). The results showed that the isolated strain had efficient biodegradability of phenolic compounds and heterocyclic compounds in CWW, meanwhile, phenol and indole could be respectively used as sole carbon source for its growth, which demonstrated the bioaugmentation potential of the isolated strain in CWW treatment. During phenol and indole degradation processes, part of metabolites (e.g., 2,3-hexanedione, 2-ethyl-1-hexanol, nonanal, 2-propyl-1-heptanol, butanoic acid, butyl ester and butanoic acid, anhydride) remained in effluents, with NH4+-N concentration having no obvious reduction, which implied the biological treatment of CWW should be accomplished by complex microbial communities in many steps.


Assuntos
Coque , Comamonas , Fenol , Esgotos , Águas Residuárias
2.
Bratisl Lek Listy ; 121(2): 122-128, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32115964

RESUMO

BACKGROUND: Cancer is a major public health problem in many areas of the world. Many anticancer drugs in current clinical use have been isolated from plant species or are based on such substances. Thymol (5-methyl-2-isopropylphenol) is an oxygenated aromatic compound from monoterpene group. It is the main constituent of thyme essential oil and shows antioxidant, antiseptic and antiproliferative properties. The aim of this study is to determine the antiproliferative activity and apoptotic effect of thymol on prostate cancer (PC-3, DU145), breast cancer (MDA-MB-231), and lung cancer (KLN205) cell lines. METHODS: The cancer cells were treated with different concentrations of thymol (100, 200, 400, 600, 800 µM) at 24 h, 48 h and 72 h. The cell viability was investigated by MTT assay and analysis of apoptosis was determined with annexin V assay. RESULTS: The study showed the dose and time-dependent cytotoxic effect of thymol in PC-3, DU145, MDA-MB-231, and KLN205 cancer cell lines. Thymol significantly induced apoptosis in all groups in a dose-dependent manner. Statistical analysis showed a significant difference between thymol­treated cell lines compared to the control (p < 0.001). CONCLUSION: The data in the present study demonstrated that thymol has apoptotic and antiproliferative properties in lung, breast and prostate cancer cell lines. Thymol could serve as a potential therapeutic agent in the future (Fig. 5, Ref. 26).


Assuntos
Apoptose , Fenol , Timol , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral/efeitos dos fármacos , Humanos , Masculino , Monoterpenos , Timol/farmacologia
3.
J Agric Food Chem ; 68(8): 2506-2515, 2020 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-32013414

RESUMO

Thiol groups of cysteine (Cys) residues in proteins react with quinones, oxidation products of polyphenols, to form protein-polyphenol adducts. The aim of the present work was to quantify the amount of adduct formed between Cys residues and 4-methylcatechol (4MC) in minced beef. A Cys-4MC adduct standard was electrochemically synthesized and characterized by liquid chromatography-mass spectrometry (LC-MS) as well as NMR spectroscopy. Cys-4MC adducts were quantified after acidic hydrolysis of myofibrillar protein isolates (MPIs) and LC-MS/MS analysis of meat containing either 500 or 1500 ppm 4MC and stored at 4 °C for 7 days under a nitrogen or oxygen atmosphere. The concentrations of Cys-4MC were found to be 2.2 ± 0.3 nmol/mg MPI and 8.1 ± 0.9 nmol/mg MPI in meat containing 500 and 1500 ppm 4MC, respectively, and stored for 7 days under oxygen. The formation of the Cys-4MC adduct resulted in protein thiol loss, and ca. 62% of the thiol loss was estimated to account for the formation of the Cys-4MC adduct for meat containing 1500 ppm 4MC. Furthermore, protein polymerization increased in samples containing 4MC as evaluated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and the polymerization was found to originate from protein-polyphenol interactions as evaluated by a blotting assay with staining by nitroblue tetrazolium.


Assuntos
Cisteína/química , Guaiacol/química , Carne/análise , Fenol/química , Animais , Bovinos , Proteínas Musculares/química , Oxirredução , Quinonas/química , Espectrometria de Massas em Tandem
4.
J Phys Chem Lett ; 11(5): 1940-1946, 2020 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-32073271

RESUMO

We present vibrational and electronic photodissociation spectra of a model chromophore of the green fluorescent protein in complexes with up to two water molecules, prepared in a cryogenic ion trap at 160-180 K. We find the band origin of the singly hydrated chromophore at 20 985 cm-1 (476.5 nm) and observe partially resolved vibrational signatures. While a single water molecule induces only a small shift of the S1 electronic band of the chromophore, without significant change of the Franck-Condon envelope, the spectrum of the dihydrate shows significant broadening and a greater blue shift of the band edge. Comparison of the vibrational spectra with predicted infrared spectra from density functional theory indicates that water molecules can interact with the oxygen atom on the phenolate group or on the imidazole moiety, respectively.


Assuntos
Proteínas de Fluorescência Verde/metabolismo , Teoria da Densidade Funcional , Proteínas de Fluorescência Verde/química , Imidazóis/química , Oxigênio/química , Fenol/química , Água/química , Água/metabolismo
5.
Science ; 367(6484): 1385-1390, 2020 03 20.
Artigo em Inglês | MEDLINE | ID: mdl-32054697

RESUMO

The profitability and sustainability of future biorefineries are dependent on efficient feedstock use. Therefore, it is essential to valorize lignin when using wood. We have developed an integrated biorefinery that converts 78 weight % (wt %) of birch into xylochemicals. Reductive catalytic fractionation of the wood produces a carbohydrate pulp amenable to bioethanol production and a lignin oil. After extraction of the lignin oil, the crude, unseparated mixture of phenolic monomers is catalytically funneled into 20 wt % of phenol and 9 wt % of propylene (on the basis of lignin weight) by gas-phase hydroprocessing and dealkylation; the residual phenolic oligomers (30 wt %) are used in printing ink as replacements for controversial para-nonylphenol. A techno-economic analysis predicts an economically competitive production process, and a life-cycle assessment estimates a lower carbon dioxide footprint relative to that of fossil-based production.


Assuntos
Alcenos , Pegada de Carbono , Fenóis , Madeira , Biomassa , Carboidratos , Catálise , Fracionamento Químico , Lignina , Fenol
6.
Environ Sci Technol ; 54(5): 2975-2984, 2020 03 03.
Artigo em Inglês | MEDLINE | ID: mdl-32023045

RESUMO

It has been documented that contaminants could be degraded by hydroxyl radicals (•OH) produced upon oxygenation of Fe(II)-bearing sediments. However, the dependence of contaminant degradation on sediment characteristics, particularly Fe(II) species, remains elusive. Here we assessed the impact of the abundance of Fe(II) species in sediments on contaminant degradation by •OH during oxygenation. Three natural sediments with different Fe(II) contents and species were oxygenated. During 10 h oxygenation of 200 g/L sediment suspension, 2 mg/L phenol was negligibly degraded for sandbeach sediment (Fe(II): 9.11 mg/g), but was degraded by 41% and 52% for lakeshore (Fe(II): 9.81 mg/g) and farmland (Fe(II): 19.05 mg/g) sediments, respectively. •OH produced from Fe(II) oxygenation was the key reactive oxidant. Sequential extractions, X-ray diffraction, Mössbauer, and X-ray absorption spectroscopy suggest that surface-adsorbed Fe(II) and mineral structural Fe(II) contributed predominantly to •OH production and phenol degradation. Control experiments with specific Fe(II) species and coordination structure analysis collectively suggest the likely rule that Fe(II) oxidation rate and its competition for •OH increase with the increase in electron-donating ability of the atoms (i.e., O) complexed to Fe(II), while the •OH yield decreases accordingly. The Fe(II) species with a moderate oxidation rate and •OH yield is most favorable for contaminant degradation.


Assuntos
Radical Hidroxila , Minerais , Compostos Ferrosos , Oxirredução , Fenol
7.
Water Res ; 172: 115494, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31954934

RESUMO

Microbial degradation is an elimination method for removal of organic contaminants from soil and water. However, the main factor limiting its practical application is high bacterial sensitivity to environmental factors such as pH, toxicity, and mass transfer. In this study, biochar was produced pyrolytically from peanut shells at 350 °C, 550 °C, and 750 °C (referred to as BC350, BC550, and BC750, respectively) and their promotion on phenol biodegradation in wastewater by the bacterium Pseudomonas citronellolis was investigated. Higher initial phenol concentration (>400 mg L-1) showed obvious inhibition on biodegradation with the removal efficiencies being less than 46%, and even the bacterium failed to survive at the phenol concentrations of higher than 1000 mg L-1. With biochar incorporated, the removal efficiencies of phenol increased from below 46% to up to 99% at the initial concentrations of 400-1200 mg L-1. Immobilization of strains in biochar by calcium alginate further increased the microbial tolerance to high concentrations of phenol (i.e., 63% removal at 1200 mg L-1). Scanning electron microscopy demonstrated that biochar acted as shelter to support the bacterium to struggle with extreme conditions. The initial adsorption of phenol by biochar alleviated the initial toxicity of phenol to bacterium and the subsequent gradual desorption controlled the bioavailability of phenol. In this regard, BC350 showed a comparable sorption capacity with BC550 and BC750, while a higher desorption potential than them, thus balanced better the toxicity and bioavailability of phenol to microbes. Alkalinity of BC550 and BC750 played important roles in rescuing the microbes from being damaged by pH shock via neutralizing the fast generation of acidic intermediates. The extractable organic substances in BC350 could be consumed by bacterium as substrates, which was confirmed by incubating the strains in water-extractable solution. Results of this study indicate that incorporation of microbes with biochar could promote the biodegradation of high concentration organic wastewater.


Assuntos
Fenol , Águas Residuárias , Adsorção , Biodegradação Ambiental , Carvão Vegetal , Concentração de Íons de Hidrogênio , Fenóis , Pseudomonas
8.
Water Res ; 171: 115456, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31927091

RESUMO

This study investigated the regeneration of phenol saturated activated carbon fiber (ACF) with a novel electro-peroxydisulfate (E-PDS) process. Compared with traditional electrochemical regeneration, E-PDS process could simultaneously regenerate the exhausted ACF and mineralize desorbed contaminants by activating PDS in water with a much lower energy consumption (1/6). According to the estimation of relative contributions involved in E-PDS process, reactive oxygen species (ROS), especially sulfate radical (SO4•-), played a dominant role in the degradation of phenol and its byproducts. It was worth noting that the accumulation of byproducts in solution increased significantly after SO4•- concentration decreased in aqueous solution. Further study proved that the regeneration efficiency of ACF could be improved by the application of multiple doses of PDS for the effective reduction of byproduct accumulation. However, application of multiple doses of PDS could not prevent ACF from being oxidized by ROS generated in the system, subsequently leading to loss of ACF adsorption capacity. This limitation is a significant concern in treatment technologies based on carbon materials activated by peroxides and such technologies should be studied further to obtain additional insights on their potential and applicability in industrial practice. Nevertheless, the adsorption capacity of ACF remained above 40% after three regeneration cycles in the E-PDS process. Therefore, E-PDS process showed promise for further evaluation as a potentially viable approach for the regeneration of carbons saturated with organic pollutants.


Assuntos
Carvão Vegetal , Poluentes Químicos da Água , Fibra de Carbono , Eletrodos , Oxirredução , Fenol
9.
Environ Sci Technol ; 54(5): 2902-2912, 2020 03 03.
Artigo em Inglês | MEDLINE | ID: mdl-31967796

RESUMO

Phenols are ubiquitous environmental pollutants, whose biotransformation involving phenol coupling catalyzed by cytochromes P450 may produce more lipophilic and toxic metabolites. Density functional theory (DFT) computations were performed to explore the debated phenol-coupling mechanisms, taking triclosan as a model substrate. We find that a diradical pathway facilitated by compound I and protonated compound II of P450 is favored vs alternative radical addition or electron-transfer mechanisms. The identified diradical coupling resembles a "two-state reactivity" from compound I characterized by significantly high rebound barriers of the phenoxy radicals, which can be formulated into three equations for calculating the ratio [coupling]/[hydroxylation]. A higher barrier for rebound than for H-abstraction in high-spin triclosan can facilitate the phenoxy radical dissociation and thus enable phenol coupling, while H-abstraction/radical rebound causing phenol hydroxylation via minor rebound barriers mostly occurs via the low-spin state. Therefore, oxidation of triclosan by P450 fits the first equation with a ratio [coupling]/[hydroxylation] of 1:4, consistent with experimental data indicating different extents of triclosan coupling (6-40%). The high rebound barrier of phenoxy radicals, as a key for the mechanistic identification of phenol coupling vs hydroxylation, originates from their weak electron donor ability due to spin aromatic delocalization. We envision that the revealed mechanism can be extended to the cross-coupling reactions between different phenolic pollutants, and the coupling reactions of several other aromatic pollutants, to infer unknown metabolites.


Assuntos
Poluentes Ambientais , Fenol , Biotransformação , Hidroxilação , Fenóis
10.
Chem Biodivers ; 17(1): e1900394, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31618522

RESUMO

We aimed in the present study to investigate the chemical composition, the antioxidant capacities as well as the in vitro fermentation properties of Salvia officinalis leaves aqueous extract (SOLAE) grown in four regions of northwestern Tunisia. Our data firstly indicated a spatial variation (P<0.05) in condensed tannins, total lipids, polyphenols and flavonoids contents. The HPLC-PDA-ESI-MS/MS-LC/HR-ESI-MS technique allowed to the identification of 13 phenolic compounds and showed that protocatechuic acid is the major constituent of the plant leaves grown in Tabarka, Ain Draham and Testour. The SOLAE of the plant grown in Tabarka presents the most potent scavenging activity against DPPH radical and had the highest percentage of inhibition. More importantly, we found in the present study that the digestibility of dry matter and in vitro fermentation showed a significant variation between the regions and the animal species. Also, we showed a very positive correlation between antioxidant properties and phenolic compounds contents. In conclusion, we suggest that SOLAE had potential beneficial effects owing in part to its antioxidant and ROS scavenging activities. Therefore, S. officinalis can be proposed as an additive food for animals' nutrition and health.


Assuntos
Antioxidantes/farmacologia , Compostos de Bifenilo/antagonistas & inibidores , Fermentação , Compostos Fitoquímicos/farmacologia , Picratos/antagonistas & inibidores , Salvia officinalis/metabolismo , Animais , Antioxidantes/análise , Antioxidantes/metabolismo , Compostos de Bifenilo/metabolismo , Cromatografia Líquida de Alta Pressão , Avaliação Pré-Clínica de Medicamentos , Cabras , Hidroxibenzoatos/análise , Hidroxibenzoatos/metabolismo , Hidroxibenzoatos/farmacologia , Espectrometria de Massas , Fenol/análise , Fenol/metabolismo , Fenol/farmacologia , Compostos Fitoquímicos/análise , Compostos Fitoquímicos/metabolismo , Picratos/metabolismo , Folhas de Planta/química , Folhas de Planta/metabolismo , Salvia officinalis/química , Salvia officinalis/crescimento & desenvolvimento , Ovinos , Tunísia
11.
J Sci Food Agric ; 100(3): 926-935, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31523827

RESUMO

BACKGROUND: The effects were studied of different inoculation strategies for selected starters -yeasts and lactic acid bacteria (LAB) - used for the fermentation process of two Greek olive cultivars, Conservolea and Kalamàta. The LAB strains applied were Leuconostoc mesenteroides K T5-1 and L. plantarum A 135-5; the selected yeast strains were S. cerevisiae KI 30-16 and Debaryomyces hansenii A 15-44 for Kalamàta and Conservolea olives, respectively. RESULTS: Table olive fermentation processes were monitored by performing microbiological analyses, and by monitoring changes in pH, titratable acidity and salinity, sugar consumption, and the evolution of volatile compounds. Structural modifications occurring in phenolic compounds of brine were investigated during the fermentation using liquid chromatography / diode array detection / electrospray ion trap tandem mass spectrometry (LC/DAD/ESI-MSn ) and quantified by high-performance liquid chromatography (HPLC) using a diode array detector. Phenolic compounds in processed Kalamàta olive brines consisted of phenolic acids, verbascoside, caffeoyl-6-secologanoside, comselogoside, and the dialdehydic form of decarboxymethylelenolic acid linked to hydroxytyrosol, whereas oleoside and oleoside 11-methyl ester were identified only in Conservolea olive brines. CONCLUSION: Volatile profile and sensory evaluation revealed that the 'MIX' (co-inoculum of yeast and LAB strain) inoculation strategy led to the most aromatic and acceptable Kalamàta olives. For the Conservolea table olives, the 'YL' treatment gave the most aromatic and the overall most acceptable product. © 2019 Society of Chemical Industry.


Assuntos
Debaromyces/metabolismo , Microbiologia de Alimentos/métodos , Lactobacillales/metabolismo , Olea/química , Olea/microbiologia , Fenol/metabolismo , Saccharomyces cerevisiae/metabolismo , Fermentação , Frutas/química , Frutas/microbiologia , Humanos , Fenol/análise , Sais/análise , Sais/metabolismo , Paladar
12.
Chemosphere ; 241: 125066, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31622888

RESUMO

A porous carbon aerogel (CA) was prepared to activate persulfate (PS) for the removal of phenol. The adsorption of phenol on CA and its removal in CA/PS system was fitted to a second-order model and first-order kinetic model, respectively. Influencing factors of CA/PS such as pH, CA dose, PS concentration, phenol concentration and temperature were investigated. CA/PS presented good performance on phenol removal over a pH range of 3-11 with the highest removal obtained at pH 7. Four kinds of organic pollutants including tetracycline, Rhodamine B, Safranine T and malachite green were investigated in the CA/PS system, proving that the adsorption of the contaminants benefitted their subsequent oxidation removal. The removal of aromatic compounds (phenol, p-diphenol, p-chlorophenol, and p-nitrophenol) in CA/PS system followed a decreasing order of hydroxyl > chlorine > nitro. The radical scavenging experiments suggested the removal of phenol was mainly through a non-radical pathway. The study presented the preparation and application of a green catalyst to activate PS, which is very promising for the development of the technology and the treatment of phenolic wastewater.


Assuntos
Carbono/química , Fenol/química , Poluentes Químicos da Água/química , Adsorção , Catálise , Clorofenóis , Radical Hidroxila/química , Cinética , Nitrofenóis , Oxirredução , Porosidade , Sulfatos/química , Tetraciclina , Águas Residuárias/química , Poluentes Químicos da Água/análise
13.
Environ Technol ; 41(3): 366-377, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30010506

RESUMO

2,4-Dichlorophenol (2,4-DCP) is a priority pollutant according to US Environmental Protection Agency. Its use in various chemical industries and its presence in the effluent necessitate effective removal studies. The present study focuses on degradation of 2,4-DCP by phenol adapted bacteria Bacillus licheniformis strain SL10 (MTCC 25059) at a relatively faster rate. The organism exhibited tolerance to 150 ppm of 2,4-DCP and showed a linear relationship between the growth and substrate concentration (µmax 0.022/h) and the inhibitory concentration was 55.74 mg/L. The degradation efficiency of the organism was 74% under optimum conditions but increased to 97% when the growth medium containing nil sodium chloride. The degradation of 2,4-DCP was effected by the action of extracellular cocktail enzyme containing Catechol 2, 3 dioxygenase (C23DO), phenol hydroxylase and Catechol, 1,2 dioxygenase (C12DO). In vitro enzymatic degradation studies exhibit 98% degradation of 50 ppm of 2,4-DCP within 2 h. Analyses of degradation products infer that the chosen organism followed a meta-cleavage pathway while degrading 2,4-DCP. In conclusion, the bacteria Bacillus licheniformis strain SL10 finds potential application in the remediation of 2,4-DCP.


Assuntos
Bacillus licheniformis , Clorofenóis , Bactérias , Biodegradação Ambiental , Fenol
14.
J Chem Ecol ; 46(2): 150-162, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31872313

RESUMO

The botanical source of Brazilian green propolis (BGP) is Baccharis dracunculifolia DC, which interacts not only with Apis mellifera, but also with galling insects. In the last decade, because of green propolis´ important biologic activities, the international demand for BGP overcame the production capacity, consequently, new approaches are required to increase this production. Hence, the understanding of the chemical ecology interactions of B. dracunculifolia with galls and bees in field conditions may provide insights to increase BGP's production. A "bee pasture" experiment aiming to better understand this plant-insect interaction was therefore performed. For that, 48 B. dracunculifolia individuals, being 24 females and 24 males, were cultivated and investigated for the following parameters: (1) phenolic and volatile compounds in both B. dracunculifolia leaves and green propolis, (2) environmental variables, (3) visiting rate by bees, (4) time of resin collection, and (5) number of galls. Regression analyses by independent linear mixed-effect models were run to correlate phenolic and volatile compounds concentration with the environmental and field variables. Significant differences in chemical profile and field variables were observed between male and female plants. Male plants showed higher infestation by galling insects while female plants showed higher number of visiting bees, time of resin collection and terpenes concentration, contributing to the differences observed in the field. The obtained results suggest that increasing the percentage of female B. dracunculifolia plants in the field may attract more bees and therefore enhance propolis production.


Assuntos
Baccharis/química , Abelhas/fisiologia , Própole/química , Animais , Baccharis/metabolismo , Comportamento Animal/efeitos dos fármacos , Cromatografia Líquida de Alta Pressão , Feminino , Masculino , Espectrometria de Massas , Fenol/análise , Fenol/química , Fenol/farmacologia , Folhas de Planta/química , Folhas de Planta/metabolismo , Tumores de Planta/parasitologia , Própole/análise , Própole/farmacologia , Compostos Orgânicos Voláteis/análise , Compostos Orgânicos Voláteis/química , Compostos Orgânicos Voláteis/farmacologia
15.
Bioresour Technol ; 295: 122243, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31622918

RESUMO

Rice husk is a widespread agriculture waste in rice-farming country. High silica content in rice husk prevent its efficient utilization. So in this work, concept of poly-generation was introduced to improve its utilization value. This study provided CO-rich syngas, phenol-abundant bio-oil, high-adsorption porous carbon and amorphous SiO2 as four end products for first time via combination of acid washing and activated carbon catalyst. Specifically, acid washing effectively decreasedsoluble ash, which altered pyrolysis paths, increased volatiles release and reduced impurities in bio-char. After catalytic pyrolysis, phenol content of 65.56% and CO of 56.09 vol% were detected in bio-oil and syngas from AWRH. For solid products, acid washing benefited both bio-char and silica. A low-cost porous carbon with developed pores and rich surface functional groups was prepared for water absorption. And high purity amorphous SiO2 was recycled from alkali etching solution. Finally, a green process with no waste emission was proposed.


Assuntos
Oryza , Fenol , Adsorção , Biomassa , Fenóis , Óleos Vegetais , Polifenóis , Porosidade , Pirólise , Dióxido de Silício
16.
Food Chem ; 309: 125673, 2020 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-31784073

RESUMO

New types of precooked pasta products have been developed based on refined and wholegrain wheat and spelt flours. The resulting dry pasta was then assessed for chemical composition, including amino acids composition, phenolics content, as well as antioxidant activity. The precooked pasta quality was also evaluated for starch gelatinization degree, physical properties, hardness, color profile of dry and hydrated pasta, and sensory characteristics. We found that the application of the extrusion-cooking technique for wheat and spelt pasta processing allows to achieve instant products with good nutritional characteristics and high degree of gelatinization, as well as attractive quality and sensory profiles. Microstructure showed compact and dense internal structure with visible bran particles if wholegrain flours were used. Wholegrain wheat and wholegrain spelt precooked pasta were characterized by better nutritional composition and greater antioxidant potential, but lower firmness and increased adhesiveness when compared with refined flours.


Assuntos
Culinária/métodos , Farinha/análise , Triticum/química , Aminoácidos/análise , Antioxidantes/química , Dureza , Fenol/química
17.
Chemosphere ; 239: 124686, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31494321

RESUMO

Oxidative degradation of aniline in aqueous solution was performed by the sono-activated peroxydisulfate coupled with PbO process, wherein a dramatic synergistic effect was found. Experiments were carried out in the batch-wise mode to investigate the influence of various operation parameters on the sonocatalytic behavior, such as ultrasonic power intensity, peroxydisulfate anion concentrations and PbO dosages. According to the scavenging effect of ethanol, methanol and tert-butyl alcohol, the principal oxidizing agents were presumed to be sulfate radicals descended from peroxydisulfate anions, activated via ultrasound or sonocatalysis of PbO. Based on the results attained from gas chromatograph-mass spectrometer, it was hypothesized that aniline was initially oxidized into iminobenzene radicals, followed with formation of nitrosobenzene, p-benzoquinonimine and nitrobenzene respectively. Condensation of nitrosobenzene with aniline generated azobenzene. Phenol was detected as one of degradation intermediates, which was sequentially converted into hydroquinone and p-benzoquinone.


Assuntos
Compostos de Anilina/química , Chumbo/química , Óxidos/química , Fenol/química , Sulfatos/química , Compostos Azo/síntese química , Benzoquinonas/síntese química , Etanol/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Hidroquinonas/síntese química , Metanol/metabolismo , Nitrobenzenos/síntese química , Compostos Nitrosos/síntese química , Oxidantes , Oxirredução , Semicondutores , Ondas Ultrassônicas , terc-Butil Álcool/metabolismo
18.
Chemosphere ; 240: 124921, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31726593

RESUMO

The interplay of phenolic molecules with 3d transition metals, such as Fe and Cu, and their oxide surfaces, provide important fingerprints for environmental burdens associated with thermal recycling of e-waste and subsequent generation of notorious dioxins compounds and phenoxy-type Environmental Persistent Free Radicals (EPFRs). DRIFTS and EPR measurements established a strong interaction of the phenol molecule with transition metal oxides via synthesis of phenolic- and catecholic-type EPFRs intermediates. In this contribution, we comparatively examined the dissociative adsorption of a phenol molecule, as the simplest model for phenolic-type compounds, on Cu and Fe surfaces and their partially oxidized configurations through accurate density functional theory (DFT) studies. The underlying aim is to elucidate the specific underpinning mechanism forming phenoxy- or phenolate-type EFPRs. Simulated results show that, the phenol molecule undergoes fission of its hydroxyl's O-H bond via accessible activation energies. These values are lower by 46.5-74.1% when compared with the analogous gas phase value. Physisorbed molecules of phenol incur very low binding energies in the range of -2.1 to -5.5 over clean Cu/Fe and their oxides surfaces. Molecular attributes based on charge transfer and geometrical features are in accord with the very weak interaction in physisorbed states. Thermo-kinetic parameters established over the temperature region of 300 and 1000 K, exhibit a lower activation energy for scission of phenolic's O-H bonds over the oxide surfaces in reference to their pure surfaces (24.7 and 43.0 kcal mol-1vs 38.4 and 47.0 kcal mol-1).


Assuntos
Radicais Livres/química , Fenol/química , Fenóis/química , Adsorção , Catecóis , Dioxinas , Radical Hidroxila , Oxirredução , Óxidos/química , Temperatura Ambiente , Elementos de Transição
19.
Chemosphere ; 238: 124621, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31454740

RESUMO

Present study prepared a new magnetic and thermo dual-responsive core-shell nanomaterial (Fe@SiO2@poly(N-isopropylacrymide-co-methacrylic acid, Fe@SiO2@PNIPAM-co-MAA), which was characterized by transmission electron microscopy and X-ray diffraction techniques. The new nanomaterials integrated with the magnetism of nanoscale zero valent iron material and thermo-response of the copolymers, and were utilized to investigate the adsorption capacity for typical phenols such as bisphenol A, phenol and hydroquinone from water samples, and the results showed that the magnetic and thermo dual-responsive core-shell nanomaterial exhibited good adsorption ability to typical phenols. Based on these, a sensitive method was developed for the determination of bisphenol A, phenol and hydroquinone using as-prepared magnetic nanoparticles as the magnetic solid phase extraction sorbent prior to high performance liquid chromatography coupled with variable wavelength detection. Under the optimal conditions, linear linearity was obtained over the range of 0.1-500 µg L-1 with the correlation coefficients (r2) above 0.996. The detection limits of three analytes were in the range of 0.019-0.031 µg L-1, and the precisions were all less than 4.8% (n = 6). The developed method was evaluated with real water samples and excellent spiked recoveries in the range of 94.0-105.4% were achieved. These results indicated that the proposed method was a robust analytical tool and a useful alternative for routine analysis of such pollutants.


Assuntos
Compostos Benzidrílicos/isolamento & purificação , Hidroquinonas/isolamento & purificação , Magnetismo , Nanoestruturas/química , Fenol/isolamento & purificação , Fenóis/isolamento & purificação , Extração em Fase Sólida/métodos , Poluentes Químicos da Água/isolamento & purificação , Compostos Benzidrílicos/análise , Hidroquinonas/análise , Fenol/análise , Fenóis/análise , Temperatura Ambiente , Poluentes Químicos da Água/análise
20.
Chemosphere ; 239: 124714, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31499309

RESUMO

Enhanced mineralization of phenol in brines with high chloride content was investigated by employing an electrochemical advanced oxidation treatment that couples anodic oxidation, electrochlorination and electro-Fenton in a single process. Experimental work was carried out in a pilot scale unit with an undivided plate-and-frame cell equipped with a boron-doped diamond anode and a carbon-PTFE gas diffusion electrode as cathode, in batch recirculation mode. The effects of operating conditions on phenol degradation, including current density, air flow rate, water feed flow rate, Fe2+ dosage and pH as well as of the water matrix, were evaluated. Applied current exhibited the greatest effect on phenol degradation/mineralization efficiency. Complete degradation of phenol (of initial concentration 50 mg L-1) was achieved under the near-optimum operating conditions (40 mA cm-2, pH 7, 0.4 m3 h-1 water circulation rate) within 30 min. Both air flow rate and Fe2+ dosage did not show a measurable impact on phenol removal. However, increasing the chloride content of water significantly improved the efficiency of treatment due to the enhanced indirect oxidation by the electrogenerated chlorine. Several trihalomethane intermediates (chloroform, bromodichloromethane) and chlorinated/brominated phenol byproducts forming during treatment, were eliminated after 60 min of processing time.


Assuntos
Técnicas Eletroquímicas/métodos , Fenol/isolamento & purificação , Salinidade , Poluentes Químicos da Água , Cloro/farmacologia , Eletrodos , Peróxido de Hidrogênio/química , Oxirredução , Projetos Piloto , Águas Salinas , Poluentes Químicos da Água/isolamento & purificação
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