Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 15.454
Filtrar
1.
Tumour Biol ; 42(5): 1010428320918685, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32367771

RESUMO

We aimed to assess the antitumor activity of Orobanche crenata methanolic extract and evaluate its cytotoxic effect on different cancer cell lines to develop an effective natural anticancer drug. Components of O. crenata methanolic extract were analyzed using gas chromatography-mass spectrometry. The extract's antioxidant activity was assessed by 2,2-diphenyl-1-picrylhydrazyl and ferric reducing antioxidant power procedures and cytotoxicity of the extract was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and lactate dehydrogenase assays. Caspase-3 activity was also estimated. O. crenata methanolic extract shows powerful antioxidant activity. The extract inhibited the propagation of human hepatocellular carcinoma (HepG2), human prostate cancer (PC3), human breast adenocarcinoma (MCF-7), and human colon carcinoma (HCT-116) in a dose-dependent manner. O. crenata-treated cells displayed obvious morphological structures distinctive of apoptosis. MTT assay exposed that the extract presented prevention of cell persistence in a dose-dependent means and revealed extremely cytotoxic activity against HepG2, PC3, MCF-7, and HCT-116 with 50% inhibitory concentration values 30.3, 111, 89.6, and 28.6 µg/mL, respectively, after 24 h of incubation. In addition, treatment of HCT-116 with various concentrations of the extract caused the release of lactate dehydrogenase and induction of caspase-3 activity in a dose-dependent way. In conclusion, our findings suggested that the O. crenata extract possesses potent antioxidant, cytotoxic activity, and anticancer properties which are possibly due to the principal bioactive phytochemical composites existing in this plant. These results can be used to develop new drugs for cancer treatment.


Assuntos
Antineoplásicos Fitogênicos/farmacologia , Orobanche/química , Extratos Vegetais/farmacologia , Antineoplásicos Fitogênicos/química , Antioxidantes/química , Antioxidantes/farmacologia , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Metanol , Extratos Vegetais/química
3.
J Environ Manage ; 262: 110295, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-32250784

RESUMO

The paper describes transesterification of oil by methanol with use of cosolvents such as ethyl acetate, tetrahydrofuran, hexane, acetone and diethyl ether at catalyst homogeneous (potassium hydroxide) and heterogeneous (mixed oxides). The cosolvents dissolve oil and methanol to form a single (homogeneous) phase, which increases the reaction rate. Therefore, the biodiesel production will be environmentally friendly because less energy is consumed, which increases sustainability. The whole binodal curve of ternary plots of oil, methanol and cosolvent was determined to find the molar ratio, in which the reaction mixture forms a single phase. The ethyl acetate and tetrahydrofuran have relatively small heterogeneous region, because of the similarity of their electric dipole moment with methanol. After transesterification, the detailed analysis of ester and also glycerol phase was carried out. For homogeneous catalyst, the highest esters content in the ester phase was achieved with tetrahydrofuran. For heterogeneous catalyst, the ester content was lower with cosolvent than without cosolvent, probably due to dilution of reaction components by cosolvent or bonding of cosolvent to the active sites of the catalyst.


Assuntos
Biocombustíveis , Ésteres , Catálise , Esterificação , Metanol , Óleos Vegetais
4.
Food Chem ; 321: 126672, 2020 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-32244136

RESUMO

The phenols in Diaphragma juglandis fructus (DJF), walnut pellicle (WP), and flowers of Juglans regia (FJR) from walnut were extracted using three methods (methanolic condensation reflux extraction, ultrasonic wave extraction, and enzyme assisted-extraction), and phenolics and antioxidant capacities of different extractions were compared. Overall, 50 phenolics were identified by HPLC-MS/MS with 41 compounds in DJF, 32 in WP, and 29 in FJR. It was observed that tannins in WP was higher than those in DJF and FJR. As for PCA, more than 70% of the variance was explained with the obvious comparison between the phenolic constituents. The phenolics in walnut contributed to remarkable antioxidant effect, with the highest effect observed in WP. This study presents the analysis and comparison of the phenols can be further extended for the development of functional walnut instant foods.


Assuntos
Juglans/química , Fenóis/química , Antioxidantes/análise , Cromatografia Líquida de Alta Pressão , Flores/química , Frutas/química , Metanol/química , Extratos Vegetais/química , Espectrometria de Massas em Tandem , Ondas Ultrassônicas
5.
Mutat Res ; 852: 503168, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32265044

RESUMO

A large number of species belonging to the genus Teucrium are used in pharmacy and traditional medicine for the treatment of different diseases. This study aimed to evaluate the polyphenolic composition as well as genotoxic and cytotoxic effects of methanolic extracts from T. arduini and T. flavum, two native species found in Montenegro. We determined the total phenolic and flavonoid contents of these plants using spectrophotometric methods; the qualitative content of polyphenolic compounds was investigated by high-performance liquid chromatography (HPLC). Genotoxicity in cultured human lymphocytes was measured in the cytokinesis-block micronucleus assay (CBMN) and comet assay in the range between 125 and 1000 µg/mL. Cytotoxicity was assessed by the MTT viability assay in normal human MRC-5 fibroblasts and MDA-MB-231 breast carcinoma cells. The content of total phenolics and flavonoids in T. arduini extract was higher than in T. flavum (200.35 mg GA/g vs. 171.08 mg GA/g; 96.32 mg RU/g vs. 78.14 mg RU/g). The polyphenolic composition of both extracts was qualitatively similar and eight phenol compounds were identified. The most commonly present phenol was caffeic acid and among four flavonoids, the most common was quercetin. Both plant extracts were genotoxic in both the CBMN and comet assays at concentrations of 250, 500 and 1000 µg/mL. After 72 h of exposure, the extracts of T. arduini and T. flavum were found to induce cytotoxicity in MRC-5 fibroblasts but not in MDA-MB-231 breast cancer cells. The results suggest that the constituents of both plant species are genotoxic and cytotoxic, therefore these extracts warrant additional evaluation to be safely applied in humans.


Assuntos
Flavonoides/toxicidade , Mutagênicos/toxicidade , Polifenóis/toxicidade , Teucrium/química , Linhagem Celular , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Ensaio Cometa , Relação Dose-Resposta a Droga , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/patologia , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Flavonoides/isolamento & purificação , Humanos , Metanol/química , Testes para Micronúcleos , Montenegro , Mutagênicos/isolamento & purificação , Especificidade de Órgãos , Extratos Vegetais/química , Plantas Medicinais , Polifenóis/isolamento & purificação , Solventes/química
7.
Chemosphere ; 251: 126350, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32151806

RESUMO

Brown carbon (BrC), a significant wavelength-dependent atmospheric absorber of solar radiation, plays a key role in photochemistry and long-lasting haze episodes. Herein, two types of BrC extracted from one-year PM2.5 samples (June 2017-May 2018 in Nanjing), i.e. methanol-extracted organic carbon (MSOC) and ultrapure water-extracted organic carbon (WSOC), were obtained to investigate distinct optical properties of atmospheric BrC. The extraction efficiency of BrC was as high as 91% in methanol solution, and the corresponding light absorption coefficient (Abs) of MSOC at 365 nm (Abs365-MSOC, 7.75 ± 3.95 Mm-1) was approximately 1.6 times that of WSOC (Abs365-WSOC, 4.84 ± 2.97 Mm-1), indicating that the water-insoluble compounds mostly affected the light absorption of BrC. The seasonal variations of Abs365-WSOC and Abs365-MSOC were followed the sequence of winter > spring > autumn > summer, due to the dominated emissions from fossil fuel combustion and biomass burning in the cooling seasons. Additionally, four fluorescent chromophores in WSOC and MSOC, containing three humic-like chromophores and one protein-like chromophore, exhibited the highest fluorescent intensities in winter but weakest in summer. The lower humification index (HIX) in MSOC reflects that humic-like chromophores were preferentially water-soluble, in coordination with high degree of photo-oxidation and aromaticity. Fluorescence index (FI) of BrC was also higher in winter because of the effects of photo-bleaching, whereas biological index (BIX) remained stable throughout a year. Considering the correlation between primary organic carbon (POC) and secondary organic carbon (SOC), aside from the contribution of primary emissions, secondary formation has become another major source to atmospheric BrC in Nanjing.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental , Aerossóis/análise , Biomassa , Carbono/análise , China , Corantes , Combustíveis Fósseis , Metanol , Material Particulado/análise , Estações do Ano , Água/química
8.
Electron. j. biotechnol ; 44: 58-59, Mar. 2020. ilus
Artigo em Inglês | LILACS | ID: biblio-1087710

RESUMO

BACKGROUND: Methanol can be effectively removed from air by biofiltration (Shareefdeen et al., 1993; Babbitt et al., 2009 [1,2]). However, formaldehyde is one of the first metabolic intermediates in the consumption of methanol in methylotrophic microorganisms (Negruta et al., 2010 [3]), and it can be released out of the cell constituting a secondary emission. RESULTS: The total removal of methanol was achieved up to input loads of 263 g m−3 h−1 and the maximum elimination capacity of the system was obtained at an empty bed residence times of 90 s and reached 330 g m−3 h−1 at an input methanol load of 414 g m−3 h−1 and 80% of removal efficiency. Formaldehyde was detected inside the biofilter when the input methanol load was above 212 g m−3 h−1 . Biomass in the filter bed was able to degrade the formaldehyde generated, but with the increase of the methanol input load, the unconsumed formaldehyde was released outside the biofilter. The maximum concentration registered at the output of the system was 3.98 g m−3 when the methanol load was 672 g m−3 h−1 in an empty bed residence times of 60 s. CONCLUSIONS: Formaldehyde is produced inside a biofilter when methanol is treated in a biofiltration system inoculated with Pichia pastoris. Biomass present in the reactor is capable of degrading the formaldehyde generated as the concentration of methanol decreases. However, high methanol loads can lead to the generation and release of formaldehyde into the environment.


Assuntos
Pichia/química , Metanol/química , Formaldeído/análise , Volatilização , Filtros Biológicos , Biomassa , Reatores Biológicos , Meio Ambiente
9.
World J Microbiol Biotechnol ; 36(2): 31, 2020 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-32048066

RESUMO

Biogenic production of nanoparticles is eco-friendly, less expensive method with various medical and biological applications. Nanotechnology along with photodynamic therapy is gaining tremendous importance with enhanced efficacy. The present work was aimed to evaluate methanolic extracts and nanoparticles of two selected plants (Datura suavolens and Verbina tenuisecta) for cytotoxic photodynamic, antioxidant and antimicrobial study. Both extract and silver (5 mM) nanoparticles of Datura plant showed significant activities against bacterial strains. Maximum ZOI of 27.3 ± 1.6 mm was observed with nanoparticles of Datura branches with minimum inhibitory (MIC) value of 32 µg/ml. In case of antifungal and antioxidant assay samples were moderately active. Silver nanoparticles and extracts were effective against rhabdomyosarcoma cell line with lowest IC50 value of 42.5 ± 0.6 µg/ml and percent viability of 25.6 ± 1.3 of Verbena tenuisecta. However, nanoparticles of Datura leaves and branches were more potent with IC50 value of 2.4 ± 0.9 µg/ml and 7.8 ± 1.1 µg/ml respectively. The result of photodynamic study showed that efficacy of photosensitizer was enhanced and percent viability reduced when nanoparticles used as an adjunct. The color change and UV spectra (415‒425 nm) indicated the production of nanoparticles. Fourier transform infrared spectroscopy (FTIR) spectra showed presence of different functional groups e.g., hydroxyl, carbonyl and amino. Nanoparticles are sphenoid in morphology and size ranges between 20-150 nm. Current study showed these silver nanoparticles can be used as cytotoxic agent in photodynamic therapy and can play a critical role to establish medicinal potential of selected plants.


Assuntos
Datura/química , Metanol/farmacologia , Prata/farmacologia , Verbena/química , Anti-Infecciosos/química , Anti-Infecciosos/isolamento & purificação , Anti-Infecciosos/farmacologia , Antineoplásicos/química , Antineoplásicos/isolamento & purificação , Antineoplásicos/farmacologia , Antioxidantes/química , Antioxidantes/isolamento & purificação , Antioxidantes/farmacologia , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Humanos , Nanopartículas Metálicas , Metanol/química , Metanol/isolamento & purificação , Testes de Sensibilidade Microbiana , Fármacos Fotossensibilizantes/química , Fármacos Fotossensibilizantes/isolamento & purificação , Fármacos Fotossensibilizantes/farmacologia , Extratos Vegetais/química , Folhas de Planta/química , Prata/química , Prata/isolamento & purificação
10.
Nat Commun ; 11(1): 1083, 2020 02 27.
Artigo em Inglês | MEDLINE | ID: mdl-32107386

RESUMO

Methanol is a clean liquid energy carrier of sunshine and a key platform chemical for the synthesis of olefins and aromatics. Herein, we report the conversion of biomass-derived polyols and sugars into methanol and syngas (CO+H2) via UV light irradiation under room temperature, and the bio-syngas can be further used for the synthesis of methanol. The cellulose and even raw wood sawdust could be converted into methanol or syngas after hydrogenolysis or hydrolysis pretreatment. We find Cu dispersed on titanium oxide nanorod (TNR) rich in defects is effective for the selective C-C bond cleavage to methanol. Methanol is obtained from glycerol with a co-production of H2. A syngas with CO selectivity up to 90% in the gas phase is obtained via controlling the energy band structure of Cu/TNR.


Assuntos
Biocombustíveis , Biomassa , Nanotubos/química , Raios Ultravioleta , Monóxido de Carbono/efeitos da radiação , Catálise/efeitos da radiação , Celulose/química , Celulose/efeitos da radiação , Cobre/química , Hidrólise , Metanol/síntese química , Metanol/efeitos da radiação , Nitrogênio/efeitos da radiação , Polímeros/química , Polímeros/efeitos da radiação , Açúcares/química , Açúcares/efeitos da radiação , Titânio/química , Madeira/química , Madeira/efeitos da radiação
11.
Chemosphere ; 249: 126215, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32088460

RESUMO

Nonthermal plasma (NTP) degradation has been shown to be a promising method for volatile organic compounds (VOCs) removal from air. However, there have been few studies on the degradation of indoor VOCs using NTP, and even less on their reaction kinetics. In this study, NTP degradation of acetone, a representative of oxygenated VOCs, in a closed-loop reactor operating in recirculation mode was investigated. Acetone and organic by-products were characterized in real-time by proton transfer reaction time-of-flight mass spectrometry. The results showed that approximately 85.7% of the acetone degraded within 7.5 h with dielectric barrier discharge treatment at 4.3 W. Methanol, acetaldehyde, formic acid, and acetic acid were observed to be the main organic byproducts with concentrations time-dependent on the order of ppb/ppm. The concentrations of the inorganic by-products O3 and NO2 are also time-dependent and can decrease to nearly 0 after a sufficient degradation time. Based on the concentration measurement in real-time, several rate laws were used to fit the concentration variations of acetone and the organic by-products, and it was observed that they strictly followed the simple kinetic reaction rate laws: acetone followed the first-order rate law, and formic acid formation followed the one-half-order rate law, etc. This study provides a good example of characterizing NTP removal of VOCs in airtight spaces and has important theoretical and practical significance in designing a better NTP device, predicting NTP degradation reaction rate, and accelerating the practical application of NTP technology for indoor air treatment.


Assuntos
Acetona/química , Acetaldeído , Cinética , Estudos Longitudinais , Espectrometria de Massas/métodos , Metanol , Modelos Químicos , Compostos Orgânicos Voláteis/análise , Compostos Orgânicos Voláteis/química
12.
Water Res ; 174: 115595, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32097807

RESUMO

Nitrate removal efficiency of aerobic methane oxidation coupled with denitrification (AME-D) process was elevated by enhancing the methanol-linked synergy in a membrane biofilm reactor (MBfR) under a low O2:CH4 ratio. After 140 days' enrichment, the nitrate removal rate increased significantly from 3 to 4 mg-N L-1 d-1 to 22.09 ± 1.21 mg-N L-1 d-1 and the indicator, mol CH4 consumed/mol reduced NO3--N (C/N ratio), decreased to 1.79 which was very close to the theoretical minimum value (1.27-1.39). The increased nitrate removal efficiency was largely related to the enhanced relationship between aerobic methanotrophs and methanol-utilizing denitrifiers. Type I methanotrophs and some denitrifiers, especially those potential methanol-utilizing denitrifiers from Methylobacillus, Methylotenera, Methylophilus and Methyloversatilis, were abundant in the MBfR sludge. Aerobic methanotrophs and potential methanol-utilizing denitrifiers were closely associated in many globular aggregates (5-10 µm diameter) in the MBfR sludge, which may have promoted the denitrifiers to capture methanol released by methanotrophs efficiently. If we assume methanol is the only cross-feeding intermediate in the MBfR, about 38-60% of the CH4 supplied would be converted to methanol and secreted rather than continuing to be oxidized. At least 63% of this secreted methanol should be utilized for denitrification instead of being oxidized by oxygen in the MBfR. These findings suggest that the nitrate removal efficiency of the AME-D process could be significantly improved.


Assuntos
Reatores Biológicos , Metanol , Biofilmes , Desnitrificação , Metano , Nitratos , Oxirredução
13.
Food Chem ; 317: 126359, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32097820

RESUMO

High content of steviol glycosides in stevia leaves is a cause of their high popularity as. a natural sweetener of various sugar-free food products. Stevioside (13-[(2-O-ß-d-glucopyranosyl-ß-d-glucopyranosyl)oxy]-ent-kaur-16-en-19-oic acid ß-d-glucopyranosyl ester) is one of the main steviol glycosides in stevia leaves known for its hydrolytic instability responsible for the formation of simple steviol glucosides (steviolbioside, rubusoside, steviol monoside) and steviol. However, the formation of hydroxy and alkoxy adducts of stevioside and of its hydrolysis products has not yet been reported. The performed experiments prove that water and alkoxy adducts are formed not only during temperature processing of stevioside but also of stevia and stevia-containing food products. Their quantities depend on environment pH, water concentration and food composition. Although they are formed in small amounts their biological activity is unknown and should be recognized.


Assuntos
Diterpenos de Caurano/química , Glucosídeos/química , Stevia/química , Análise de Alimentos , Concentração de Íons de Hidrogênio , Hidrólise , Metanol/química , Folhas de Planta/química , Folhas de Planta/metabolismo , Stevia/metabolismo , Edulcorantes/química , Temperatura , Água/química
14.
Bioresour Technol ; 304: 123022, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32070839

RESUMO

Type I (Methylomicrobium album) and II (Methyloferula stellata) methanotrophs were encapsulated by alginate and polyvinyl alcohol (PVA) to improve methanol production from simulated biogas [methane (CH4) and carbon dioxide (CO2)] in the presence of CH4 vector. Polymeric matrix alginate (2%) and PVA (10%) were found to be optimum for the immobilization of both the methanotrophs, with a relative efficiency of methanol production up to 80.6 and 88.7%, respectively. The stability of methanol production by immobilized cells was improved up to 13.2-fold under repeated batch-culture over free cells. The addition of CH4 vectors showed 1.7-fold higher methanol production on using simulated biogas than in the control. The maximum methanol production of 7.46 and 7.14 mmol/L was noted for PVA-encapsulated M. album and M. stellata, respectively. This study successfully established the beneficial effects of CH4 vectors on methanol production by methanotrophs from greenhouse gases that can be applied for real biogas feedstock.


Assuntos
Metano , Methylococcaceae , Biocombustíveis , Metanol , Polímeros
15.
J Chromatogr A ; 1616: 460795, 2020 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-31918849

RESUMO

Based on our previous work with "pseudostationary-ion exchanger sweeping", we use this strategy to develop a sensitive, reliable and robust method for the analysis of the newly-FDA approved hepatitis C antiviral drugs namely; sofosbuvir (SOV), daclatasvir (DAC), ledipasvir (LED) and velpatasvir (VEP) in their pure forms and co-formulated pharmaceutical dosage forms using micellar electrokinetic chromatography (MEKC) as a separation method. For the first time, a successful separation of all the investigated compounds was achieved in less than 8 min using a basic background electrolyte (BGE) composed of 25 mmol L-1 SDS + 20% (v/v) ACN (acetonitrile) in 10 mmol L-1 disodium tetraborate buffer (final apparent pH is 9.90). A special focus was given to optimize the composition of the sample matrix to maintain the solubility of the analytes within the sample zone while gaining additional benefits regarding analyte zone focusing. It was found that replacing phosphoric acid (as a sample matrix) with a zwitterionic/isoelectric buffering compound (L-glutamic acid) has a substantial positive impact on the obtained enrichment efficiency. The interplay of other enrichment principles such as the retention factor gradient effect (RFGE) is also discussed. A full validation study is performed based on the pharmacopeial and ICH guidelines. The obtained limits of detection and quantitation are as low as 0.63 and 1.3 µg mL-1; respectively for SOV and DAC and 1.3 and 2.5 µg mL-1; respectively for LED and VEP using UV-DAD as a detection method. The selectivity of the developed method for determination of the studied compounds in their pharmaceutical dosage forms or in the presence of ribavirin (RIB) or elbasvir (ELB), which are other prescribed medications in the treatment regimen of patients with hepatitis C virus infection, is demonstrated. It is shown that with acidic sample matrix and basic BGE, an efficient and precise approach was designed in which analyte adsorption on the capillary wall was minimized while keeping repeatable peak height, peak area and migration time together with the highest possible enrichment efficiency.


Assuntos
Antivirais/análise , Cromatografia Capilar Eletrocinética Micelar/métodos , Hepacivirus/efeitos dos fármacos , Sofosbuvir/análise , Adsorção , Antivirais/química , Benzimidazóis , Benzofuranos , Carbamatos/análise , Carbamatos/química , Ciclodextrinas/química , Formas de Dosagem , Eletrólitos/química , Fluorenos , Compostos Heterocíclicos de 4 ou mais Anéis/análise , Compostos Heterocíclicos de 4 ou mais Anéis/química , Humanos , Imidazóis/análise , Imidazóis/química , Limite de Detecção , Modelos Lineares , Metanol/química , Reprodutibilidade dos Testes , Sofosbuvir/química , Solubilidade , Temperatura , Ureia/química
16.
Environ Sci Technol ; 54(3): 1938-1945, 2020 02 04.
Artigo em Inglês | MEDLINE | ID: mdl-31904227

RESUMO

Normal temperature catalytic ozonation (NTCO) is a promising yet challenging method for the removal of volatile organic compounds (VOCs) because of limited activity of the catalysts at ambient temperature. Here, we report a series of Pt/FeOx catalysts prepared by the co-precipitation method for NTCO of gaseous methanol. All samples were found to be active and among them, the Pt/FeOx-400 (calcined at 400 °C) catalyst with a Pt cluster loading of 0.2% exhibited the highest activity, able to completely convert methanol into CO2 and H2O at 30 °C. Extensive experimental research suggested that the superior catalytic activity could be attributed to the highly dispersed Pt clusters and an appropriate molar ratio of Pt0/Pt2+. Furthermore, electron paramagnetic resonance and density functional theory computational studies revealed the mechanism that the Pt/FeOx-400 catalyst could activate O3 and water effectively to produce hydroxyl radicals responsible for the catalytic oxidation of methanol. The findings of this work may foster the development of technologies for normal temperature abatement of VOCs with low energy consumption.


Assuntos
Metanol , Ozônio , Catálise , Platina , Temperatura
17.
Bioresour Technol ; 300: 122657, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31918300

RESUMO

Organosolv is a promising pretreatment for lignocellulose biorefinery on the integrated utilization of full components from lignocellulosic biomass. A highly efficient pretreatment process using methanol/dioxane binary solvent with microwave irradiation is proposed in this study. Poplar wood was fractionated to high quality cellulosic residue, lignin, and monosaccharide derivatives under mild conditions (120 °C, 10 min). The follow-up enzymatic hydrolysis of resulting cellulosic residues achieved almost theoretical glucan conversion over 99%. The 2D-NMR and GPC results showed that the recovered lignin precipitates contain low amount of condensed structures and have relatively narrow molecular weight distributions. The composition analysis of monosaccharide derivatives indicated that the methanol/dioxane solvent tends to convert monosaccharides into glycosides rather than further degradation by-products. The mass balance result estimated that totally 74.2% of raw poplar can be utilized by the pretreatment proposed in this study.


Assuntos
Metanol , Madeira , Biomassa , Dioxanos , Hidrólise , Lignina , Micro-Ondas , Solventes
18.
J Environ Manage ; 258: 110008, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31929052

RESUMO

Microbial chain elongation (MCE) is a bioprocess that could utilise a mixed-culture fermentation to valorise organic waste. MCE converting ethanol and short chain fatty acids (SCFA; derived from organic waste) to caproate has been studied extensively and implemented. Recent studies demonstrated the conversion of SCFAs and methanol or ethanol into isomerised fatty acids as novel products, which may expand the MCE application and market. Integrating caproate and isomerised fatty acid production in one reactor system is theoretically feasible given the employment of a mixed culture and may increase the economic competence of MCE; however, the feasibility of such has never been demonstrated. This study investigated the feasibility of using two electron donors, i.e. methanol and ethanol, for upgrading SCFAs into isobutyrate and caproate concurrently in MCE Results show that supplying methanol and ethanol in MCE simultaneously converted acetate and/or butyrate into caproate and isobutyrate, by a mixed-culture microbiome. The butyrate supplement stimulated the caproate production rate from 1.5 to 2.6 g/L.day and induced isobutyrate production (1.5 g/L.day). Further increasing ethanol feeding rate from 140 to 280 mmol carbon per litre per day enhanced the direct use of butyrate for caproate production, which improved the caproate production rate to 5.9 g/L.day. Overall, the integration of two electron donors, i.e. ethanol and methanol, in one chain-elongation reactor system for upgrading SCFAs was demonstrated. As such, MCE could be applied to valorise organic waste (water) streams into a wider variety of value-added biochemical.


Assuntos
Caproatos , Etanol , Ácidos Graxos , Ácidos Graxos Voláteis , Fermentação , Isobutiratos , Metanol
19.
Water Res ; 172: 115512, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31986401

RESUMO

This study proposes a novel method to directly treat reject water with a high ammonium content, without relying on dilution. The originality of this method resides in leveraging the coordinated action of a methane- and methanol-dependent bacterial consortium and the biogas generated from wastewater treatment facilities. Specifically, ammonium is removed through autotrophic assimilation in the glutamate cycle of methanotrophs and Methylophilus while, simultaneously, methanol generated by methanotrophs is treated through formaldehyde assimilation as Methylophilus undergo the same ribulose monophosphate cycle as methanotrophs. Using this method, the backflow of high-concentration ammonium into the wastewater treatment process was reduced to 59% in a single operation using a sequencing batch reactor at a mean influent concentration of 877.3 mg L-1. However, the removal rate temporarily declined to an average of 37.6% at a concentration of 800 mg L-1 or above, which was imputed to the influence of toxic intermediates.


Assuntos
Metano , Águas Residuárias , Reatores Biológicos , Metanol , Nitrogênio , Eliminação de Resíduos Líquidos , Água
20.
Chemosphere ; 242: 125247, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31896173

RESUMO

Wood vinegar (WV) was applied alone or combined with biochar (BC) to observe their efficiency on suppressing the ammonia (NH3) volatilization from rice paddy soil. Five treatments, i.e., control (240 kg N ha-1 applied in urea), WV-5 and WV-10 (240 kg N ha-1 plus 5 and 10 t WV ha-1, respectively), and their counterparts WV-5-BC and WV-10-BC (WV-5 and WV-10 plus 7 t BC ha-1), were evaluated by a soil columns experiment. The N fertilizer was split applied as basal and two supplementary fertilizations (named BF, SF1 and SF2, respectively). The results showed that WV-5 treatment increased rice grain yield up to 11.2% compared to the control. Compared with the control, four WV-amended treatments, exhibited lower pH values of the floodwater (7.94-8.18 vs 8.47 and 7.85-7.91 vs 7.98) and the topsoil (6.52-6.76 vs 6.82 and 6.82-6.92 vs 6.99) during the BF and SF1 periods. Both WV-5 and WV-10 increased the NH4+-N contents of topsoil by 10.9-17.8% and 16.1-36.2% after BF and SF1, respectively, than control treatment. Additionally, the floodwater of the WV-amended treatments had higher NH4+-N concentration than control during the first three days after N fertilization, which can be attributed to the stimulating effect of WV on soil urease enzyme activity. WV did not effectively reduce NH3 volatilization as hypothesized. Interestingly, four WV-amended had relatively reduced the yield-scale NH3 volatilization by 13.6% than the control. It is suggested that WV needs to be applied with BC at a moderate rate to achieve optimum rice yield and mitigate NH3 volatilization.


Assuntos
Ácido Acético , Amônia/análise , Carvão Vegetal/química , Metanol , Amônia/química , Grão Comestível/química , Fertilizantes/análise , Nitrogênio/análise , Oryza/química , Solo/química , Ureia/química , Volatilização
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA