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1.
Artigo em Inglês | MEDLINE | ID: mdl-33322520

RESUMO

Activated carbon that has been widely used for several environmental applications is typically produced from carbon-based raw materials including agricultural by-products. To that end, extensive date palm-tree farming across the globe with millions of palm trees, also results in various types of agricultural waste including date palm-tree branches (DPB) during the regular trimming phase of palm-trees. Furthermore, air pollution also remains a serious concern in many global regions, requiring the application of appropriate treatment technologies to mitigate the respective negative effects on human health and environment. The present study thus assessed the efficiency of activated carbon (AC) derived from date palm-tree branches to treat gaseous toluene (C6H5CH3) streams under varying dynamic flow conditions. The produced activated carbon showed BET specific surface area (SSABET) of 800.87 m2/g with micro and mesoporous structure. The AC FTIR results indicated several surface groups including oxygen based functional groups. Furthermore, the dynamic gas treatment results showed that the respective activated carbon can successfully treat gaseous toluene under varying gas flow rates, gas concentrations and activated carbon bed depths. An increase in the carbon bed depth and decrease in toluene gas concentration and/or flow rate, yielded higher breakthrough time (BT) and exhaustion time (ET) values. Adsorption modeling employing the response surface methodology (RSM) approach successfully modeled the respective gaseous toluene removal experimental findings, with breakthrough time (BT) and exhaustion time (ET) as the response factors. The respective model-fitting parameters showed good outcomes using natural logarithmic transform model.


Assuntos
Carvão Vegetal , Phoeniceae , Tolueno/isolamento & purificação , Adsorção , Árvores
2.
J Chromatogr A ; 1633: 461627, 2020 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-33128970

RESUMO

A Poly (3,4-ethylenedioxothiophene) (PEDOT)/UiO-66 composite was electrodeposited on an etched stainless-steel wire as head-space solid-phase microextraction (HS-SPME) coating. A robust, well controlled thickness, and uniform coating of metal organic framework composites can be realized by the electrodeposited strategy. The incorporated UiO-66 not only enhanced the uniformity and stability of the composite coating, but also effectively decreased the stacking phenomenon of PEDOT and improved its extraction efficiency, which was over 100 times higher than that of the PEDOT coating without UiO-66. The composite coating was used to enrich seven types of volatile organic compounds (VOCs) in ion-exchange resins, including methyl cyclohexane, benzene, toluene, ortho-xylene, styrene, para-xylene and divinyl-benzene. The results of adsorption isotherm analysis showed that π stacking effect played dominant role between the composite coating and VOCs in the extraction process. The composite coating was characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared and thermogravimetric analysis, respectively. A determination method for seven kinds of VOCs was established by HS-SPME coupled with gas chromatography-flame ionization detection (GC-FID). Under the optimal experimental conditions, the detection linear range (LRs) was 0.09-100 ng mL-1, and the detection limit (LODs) was 0.03-0.06 ng mL-1 (S/N = 3). The method was applied for the migration detection of VOCs in four types of ion-exchange resin, which showed satisfactory recovery (84.5-117.2%).


Assuntos
Técnicas de Química Analítica/métodos , Estruturas Metalorgânicas/química , Compostos Organometálicos/química , Ácidos Ftálicos/química , Polímeros/química , Tiofenos/química , Compostos Orgânicos Voláteis/isolamento & purificação , Adsorção , Benzeno/análise , Benzeno/isolamento & purificação , Cromatografia Gasosa , Ionização de Chama , Resinas de Troca Iônica/química , Limite de Detecção , Microextração em Fase Sólida , Aço Inoxidável/química , Tolueno/análise , Tolueno/isolamento & purificação , Compostos Orgânicos Voláteis/análise , Xilenos/análise , Xilenos/isolamento & purificação
3.
Mikrochim Acta ; 187(7): 387, 2020 06 14.
Artigo em Inglês | MEDLINE | ID: mdl-32535659

RESUMO

A deep eutectic solvent functionalized graphene oxide composite adsorbent (DFG) was synthesized through reversible-addition fragmentation chain-transfer polymerization. The synthesized DFG had multiple adsorption interactions after covalent modification with a deep eutectic solvent (allyltriethylammonium bromide/ethylene glycol). Adsorption isotherms and kinetics studies of DFG indicate that the adsorption of hippuric acid (HA) and methylhippuric acid (MHA) was monolayer chemical adsorption. The comparison of DFG with commercial adsorbents demonstrates that the adsorption ability of DFG was superior. This was due to the multiple adsorption interactions of DFG for the three analytes (mainly π-interaction, hydrogen bonding, electrostatic adsorption, and hydrophobic interaction). The DFG adsorbent was applied to miniaturized pipette-tip solid-phase extraction (MPT-SPE), followed by high-performance liquid chromatography (HPLC) to determine biomarkers in urine for toluene and xylene exposure. The DFG-MPT-SPE-HPLC method required only 2.00 mg of DFG as adsorbent, 0.50 mL of washing solvent, and 0.40 mL of elution solvent to achieve a wide linear range (0.200-200 µg mL-1), high recoveries (90.9-99.1%), and high precision (RSD ≤ 6.3%). The proposed method was applied to determine HA and MHA in urine samples from occupational workers. Graphical abstract Deep eutectic solvent functionalized graphene oxide composite adsorbent for miniaturized pipette-tip solid-phase extraction of toluene and xylene exposure biomarkers in urine prior to their determination with HPLC-UV.


Assuntos
Grafite/química , Líquidos Iônicos/química , Tolueno/urina , Xilenos/urina , Adsorção , Biomarcadores/química , Biomarcadores/urina , Cromatografia Líquida de Alta Pressão , Grafite/síntese química , Humanos , Líquidos Iônicos/síntese química , Compostos de Amônio Quaternário/síntese química , Compostos de Amônio Quaternário/química , Extração em Fase Sólida/instrumentação , Extração em Fase Sólida/métodos , Solventes/síntese química , Solventes/química , Tolueno/química , Tolueno/isolamento & purificação , Xilenos/química , Xilenos/isolamento & purificação
4.
Chemosphere ; 258: 127334, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32540536

RESUMO

Herein, MgO cathode and graphene Mn-Ce bimetallic oxide were utilized to jointly enhance the removal of toluene in pulsed discharge plasma (PDP). Compared to the common cathode, the MgO cathode enhanced the density of high energy electrons, and then induced to higher removal of toluene. However, the removal of toluene by PDP/MgO system was still insufficient, and there was a large amount of underutilized O3 in the products. Based on this, Mn-Ce/graphene catalysts were introduced into PDP/MgO system. The Mn-Ce (8:1)/graphene catalyst had the highest catalytic activity. Under the discharge power of 2.1 W, toluene degradation rate and CO2 selectivity increased by 27.5% and 22.0%, respectively. This was ascribed to the synergistic effect of the solid solution formed between MnOx and CeOx, increasing the proportion of Oads on the surface of the catalyst. The higher Oads/Olatt ratio lead to the better catalytic activity, which was conducive to the complete transformation of the intermediate products to CO2 and H2O. According to the detected products, the degradation pathway and the mechanism of toluene degradation were proposed finally. The PDP itself, field emission effect of MgO cathode and catalytic effect of Mn-Ce/graphene for jointly improve the toluene removal and CO2 selectivity.


Assuntos
Técnicas Eletroquímicas/métodos , Grafite/química , Óxido de Magnésio/química , Tolueno/isolamento & purificação , Dióxido de Carbono , Catálise , Cério/química , Eletrodos , Compostos de Manganês/química , Óxidos/química , Água
5.
PLoS Negl Trop Dis ; 14(5): e0008339, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32437349

RESUMO

Trypanothione reductase (TR) is a key enzyme that catalyzes the reduction of trypanothione, an antioxidant dithiol that protects Trypanosomatid parasites from oxidative stress induced by mammalian host defense systems. TR is considered an attractive target for the development of novel anti-parasitic agents as it is essential for parasite survival but has no close homologue in humans. We report here the identification of spiro-containing derivatives as inhibitors of TR from Trypanosoma brucei (TbTR), the parasite responsible for Human African Trypanosomiasis. The hit series, identified by high throughput screening, was shown to bind TbTR reversibly and to compete with the trypanothione (TS2) substrate. The prototype compound 1 from this series was also found to impede the growth of Trypanosoma brucei parasites in vitro. The X-ray crystal structure of TbTR in complex with compound 1 solved at 1.98 Å allowed the identification of the hydrophobic pocket where the inhibitor binds, placed close to the catalytic histidine (His 461') and lined by Trp21, Val53, Ile106, Tyr110 and Met113. This new inhibitor is specific for TbTR and no activity was detected against the structurally similar human glutathione reductase (hGR). The central spiro scaffold is known to be suitable for brain active compounds in humans thus representing an attractive starting point for the future treatment of the central nervous system stage of T. brucei infections.


Assuntos
Antiprotozoários/farmacologia , Inibidores Enzimáticos/farmacologia , NADH NADPH Oxirredutases/antagonistas & inibidores , Tolueno/análogos & derivados , Trypanosoma brucei brucei/efeitos dos fármacos , Antiprotozoários/isolamento & purificação , Sítios de Ligação , Cristalografia por Raios X , Avaliação Pré-Clínica de Medicamentos , Inibidores Enzimáticos/isolamento & purificação , Ensaios de Triagem em Larga Escala , NADH NADPH Oxirredutases/química , Ligação Proteica , Conformação Proteica , Tolueno/isolamento & purificação , Tolueno/farmacologia , Trypanosoma brucei brucei/enzimologia
6.
Sci Rep ; 10(1): 6027, 2020 04 07.
Artigo em Inglês | MEDLINE | ID: mdl-32265479

RESUMO

Spray paint exhaust gas contains recalcitrant volatile organic compounds (VOCs), such as benzene, toluene and xylene (BTX). Treating BTX with a biofilter often achieves unsatisfactory results because the biofilter lacks efficient microbial community. In this work, three strains for BTX degradation were isolated and identified as Pseudomonas putida, Bacillus cereus and Bacillus subtilis by using 16S rRNA sequencing technology. A consortium of highly efficient microbial community was then constructed on a stable biofilm to treat BTX in a biofilter. A relatively suitable ratio of P. putida, B. cereus and B. subtilis was obtained. An efficiency of over 90% was achieved in the biofilter with VOC concentration of 1000 mg/m3 through inoculation with the microbial community after only 10 days of operation. Thus, fast start-up of the biofilter was realised. Analysis of intermediate products by gas chromatography-mass spectrometry indicated that BTX was degraded into short-chain aldehydes or acids via ring opening reactions.


Assuntos
Bactérias/metabolismo , Benzeno/metabolismo , Poluentes Ambientais/metabolismo , Tolueno/metabolismo , Compostos Orgânicos Voláteis/metabolismo , Xilenos/metabolismo , Bacillus cereus/metabolismo , Bacillus subtilis/metabolismo , Benzeno/isolamento & purificação , Biodegradação Ambiental , Poluentes Ambientais/isolamento & purificação , Recuperação e Remediação Ambiental/métodos , Pintura/análise , Pseudomonas putida/metabolismo , Tolueno/isolamento & purificação , Compostos Orgânicos Voláteis/isolamento & purificação , Xilenos/isolamento & purificação
7.
Artigo em Inglês | MEDLINE | ID: mdl-31662034

RESUMO

Toluene is highly toxic and mutagenic, and it is generally used as an industrial solvent. Thus, toluene removal from air is necessary. To solve the problem of reducing high toluene concentrations with a short gas retention time (GRT), a quorum-sensing molecule [N-(3-oxododecanoyl)-L-homoserine lactone] (OHL) was added to a biotrickling filter (BTF). In this study, a BTF was used to treat synthetic and natural waste gases containing toluene. An extensive analysis was performed to understand the removal efficiency, removal characteristics, and bacterial community of the BTF. The addition of 20 µM OHL to the BTF significantly improved toluene removal, and more than 99.2% toluene removal was achieved at a GRT of 0.5 min when natural waste gas containing toluene (590-1020 ppm or 2.21-3.83 g m-3) was introduced. The maximum inlet load for toluene was 337.9 g m-3 h-1. Moreover, the BTF exhibited satisfactory adaptability to shock loading and shutdown operations. Pseudomonadaceae (33.0%) and Comamonadaceae (26.3%) were predominant bacteria in the system after a 98-day operation. These bacteria were responsible for toluene degradation. The optimal moisture content and low pressure drop for system operations demonstrated that the BTF was energy and cost efficient. Therefore, processing through a BTF with OHL is a favorable technique for toluene treatment.


Assuntos
Poluentes Atmosféricos/isolamento & purificação , Filtração/métodos , Microbiota , Percepção de Quorum , Tolueno/isolamento & purificação , 4-Butirolactona/análogos & derivados , 4-Butirolactona/metabolismo , Poluentes Atmosféricos/metabolismo , Bactérias/classificação , Bactérias/genética , Bactérias/isolamento & purificação , Bactérias/metabolismo , Biodegradação Ambiental , Reatores Biológicos/microbiologia , Filtração/instrumentação , Gases/isolamento & purificação , Gases/metabolismo , Homosserina/análogos & derivados , Homosserina/metabolismo , Microbiota/genética , Tolueno/metabolismo
8.
Ecotoxicol Environ Saf ; 184: 109618, 2019 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-31487569

RESUMO

Photocatalytic membrane coupled to biodegradation offers potential for degrading volatile organic compounds (VOCs) in photocatalytic membrane biofilm reactor. An intimately coupled photocatalysis and biodegradation reactor was operated in continuous operation for 500 days to treat simulated waste gas containing toluene. Toluene removal efficiency obtained 99%, with the elimination capacity of 550 g m-3·h-1. Membrane photocatalysis coupled to biodegradation was created to improve toluene removal from 11 to 20%. The dominant genera were Lysinibacillus, Hydrogenophaga, Pseudomonas at 30 d, Rudaea, Dongia, Litorilinea at 230 d xyl, Tod, Tcb, Bed, Tmo, Tbu, Tou, Dmp, Cat were functional genes of toluene metabolism, as shown by16S rDNA and metagenomic sequencing. Photocatalysis destroyed part of the toluene into biodegradable intermediates that were immediately mineralized by microorganisms in biofilm, some toluene was directly degraded by toluene degrading bacterial community into carbon dioxide and water. The novel hybrid photocatalytic membrane biofilm reactor is a cost-effective and robust alternative to VOCs treatment.


Assuntos
Reatores Biológicos/microbiologia , Consórcios Microbianos/fisiologia , Tolueno/metabolismo , Bactérias/classificação , Bactérias/genética , Bactérias/metabolismo , Biodegradação Ambiental , Biofilmes , Membranas , Oxirredução , Processos Fotoquímicos , Tolueno/isolamento & purificação , Compostos Orgânicos Voláteis/isolamento & purificação , Compostos Orgânicos Voláteis/metabolismo
9.
J Hazard Mater ; 380: 120860, 2019 12 15.
Artigo em Inglês | MEDLINE | ID: mdl-31302359

RESUMO

The negative effects of volatile organic compounds (VOCs) on humans' health and the environment have boosted the enforcement of regulations, resulting in the need of effective and environmentally friendly off-gas treatment technologies. In this work, the synergism between microalgae and bacteria was investigated as a sustainable platform to enhance the biological degradation of toluene, herein selected as a model VOC. An innovative algal-bacterial tubular photobioreactor (TPBR) was systematically compared with a conventional biotrickling filter (BTF). The BTF supported average removal efficiencies close to those obtained in the TPBR (86 ±â€¯9% and 88 ±â€¯4%, respectively) at the highest inlet load (∼23 g m3  h-1) and lowest gas residence time (0.75 min). However, the BTF was more sensitive towards the accumulation of secondary metabolites. In this regard, photosynthetic O2 supplementation (resulting in dissolved oxygen concentrations of ∼7.3 mg O2 L-1) and CO2 consumption by microalgae (which reduced the impact of acidification) enhanced toluene abatement performance and process stability.


Assuntos
Filtração/instrumentação , Fotobiorreatores , Tolueno/metabolismo , Bactérias/genética , Bactérias/metabolismo , Biodegradação Ambiental , Dióxido de Carbono/química , Microalgas/genética , Microalgas/metabolismo , RNA Ribossômico 16S/genética , Tolueno/isolamento & purificação , Compostos Orgânicos Voláteis/química
10.
Chemosphere ; 234: 388-394, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31228841

RESUMO

The main aim of this work is to study gas-phase toluene removal in one- and two-liquid phase biotrickling filters (O/TLP-BTF) and model the BTF performance using artificial neural networks (ANNs). The TLP-BTF was operated for 60 d in the presence of silicone oil at empty bed residence times (EBRTs) of 120, 60, and 45 s, respectively, and toluene concentrations in the range of 0.9-3.1 g m-3. A t-test analysis indicated that increasing the silicone oil volume ratio from 5 to 10% v/v, did not significantly improve the TLP-BTF performance (p-value = 0.65 > 0.05). The results from ANN modeling showed that toluene removal was more negatively affected by the inlet concentration (casual index, CI = -5.63) due to the kinetic limitation. The CI values for inlet concentration (+4.01) and liquid trickling rate (-2.45) indicated that the diffusion-limited regime controlled the removal process in the OLP-BTF.


Assuntos
Filtração/métodos , Redes Neurais de Computação , Óleos de Silicone , Tolueno/isolamento & purificação , Poluentes Atmosféricos/isolamento & purificação , Gases , Cinética , Óleos de Silicone/química , Óleos de Silicone/farmacologia
11.
J Chromatogr A ; 1601: 35-44, 2019 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-31103201

RESUMO

In this research, a miniaturized version of matrix solid phase dispersion (MSPD) method was developed for successful extraction of five nitrotoluenes from soil samples. The terpene based deep eutectic solvent (DES) composed of borneol and DL-menthol was used simultaneously as extraction solvent and dispersing liquid. Graphitic-carbon nitride (g-C3N4) as sorbent was prepared by pyrolysis of melamine at a muffle furnace. The MSPD mixture was obtained by grinding soil, DES, and g-C3N4. Minimum amount of acetonitrile was used in the elution step. Some experimental variables including type and volume of DES, type of dispersant, mass ratio of dispersant to sample, volume of elution solvent, grinding time, and ultrasonication time were evaluated. Analysis of extracted samples was performed by high performance liquid chromatography-ultra violet detection. Under the optimized conditions; the limits of detection were achieved in the range of 0.12-0.33 µg g-1, and the relative standard deviations were equal to or lower than 9.3%. The extraction recoveries were ranged from 78 to 96%. This straightforward and fast method is effective for environmentally friendly extraction of nitrotoluenes from soil samples.


Assuntos
Cromatografia Líquida de Alta Pressão , Monitoramento Ambiental/métodos , Solo/química , Tolueno , Estudos de Viabilidade , Limite de Detecção , Nitrilas/química , Poluentes do Solo/análise , Poluentes do Solo/isolamento & purificação , Solventes/química , Tolueno/análise , Tolueno/isolamento & purificação
12.
Environ Sci Pollut Res Int ; 26(20): 20908-20919, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31115812

RESUMO

Large amount of volatile organic compounds (VOCs) are emitted from industrial, mobile, and domestic sources, causing adverse effects on human health and environment. Among VOCs, toluene and isopropanol (IPA) are commonly used as solvent, soldering flux, and spray paint and their emissions need to be reduced. Several VOCs abatement technologies are available to reduce VOC emission and photocatalytic oxidation of VOC is regarded as a viable technique due to its advantage of utilizing solar energy. TiO2 has been investigated for its oxidation capability toward VOCs because of its good photocatalytic activity. However the utilization is limited to UV due to its wider bandgap; furthermore, its fast recombination rate of electron-hole pair reduces the oxidation rate of VOCs. Black-TiO2 and perovskite-type photocatalyst such as LaFeO3 can be applied to enhance photocatalytic activity due to narrower bandgap and longer electron-hole pair lifetime. In this study, black-TiO2 and LaFeO3 are prepared and investigated for their photocatalytic oxidation rates toward toluene and IPA. Results show that toluene removals achieved with black-TiO2 and LaFeO3 are 89% and 98% while IPA removals are 90% and 94%, respectively. Both photocatalysts show better photocatalytic activity than TiO2 and good absorption capability toward visible light. Graphical abstract.


Assuntos
2-Propanol/química , Poluentes Atmosféricos/química , Compostos de Cálcio/química , Óxidos/química , Titânio/química , Tolueno/química , 2-Propanol/isolamento & purificação , Poluentes Atmosféricos/isolamento & purificação , Catálise , Recuperação e Remediação Ambiental , Luz , Oxirredução , Processos Fotoquímicos , Tolueno/isolamento & purificação
13.
J Chromatogr A ; 1603: 396-400, 2019 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-30975526

RESUMO

One of the most critical aspects of chromatographic analysis is effective data acquisition and processing. Typical approaches include software platforms designed for specific instruments or commercial data acquisition hardware boards, both of which require expensive licenses to use and operate. To increase the access and affordability of chromatographic data acquisition, especially for systems in which software control has become obsolete or must be written in-house, an open-source digital stripchart recorder has been developed. This system is built upon a Raspberry Pi single-board computer and a plug-in printed circuit board with the necessary integrated circuits for data acquisition. Using an open-source software called Processing, a complete user interface to control the system was developed that enables the acquisition, filtering, and processing of chromatographic data. The system performs comparably to more expensive platforms, with calculated values for peak area, retention time, and plate count all within 3% of the values calculated by a widely used commercial chromatography data software package.


Assuntos
Cromatografia/economia , Cromatografia/instrumentação , Custos e Análise de Custo , Software , Compostos de Bifenilo/isolamento & purificação , Naftalenos/isolamento & purificação , Tolueno/isolamento & purificação , Uracila/isolamento & purificação
14.
Chemosphere ; 226: 766-773, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30965247

RESUMO

A new reactor of array double dielectric barrier discharge (DDBD) combined with catalysis was prepared, and the effect of different factors on removal efficiency of toluene at pilot scale were investigated. The possible degradation mechanism was explored. The results indicate that the removal efficiency of toluene in the exhaust gas decreases with the increasing of the toluene initial concentration and the gas flow rate, but increases with the increasing of the specific energy density. When the air relative humidity is 55%, the removal efficiency of toluene is higher than that of the relative humidity by 85%. The results of XPS, FT-IR and GC-MS analysis show that the main intermediate products of removing toluene by DDBD combined with TiO2/Al2O3 catalyst are phenol, benzaldehyde, benzyl alcohol, benzoic acid, N-benzyl formamide, dimethyl terephthalate, dimethyl isophthalate and other substances. There are five possible pathways to degrade toluene by DDBD combined with TiO2/Al2O3.


Assuntos
Óxido de Alumínio/química , Eletroquímica/métodos , Titânio/química , Tolueno/isolamento & purificação , Catálise , Gases/análise , Gases em Plasma/análise , Dados Preliminares , Análise Espectral
15.
Environ Res ; 172: 649-657, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30878736

RESUMO

The catalytic oxidation of toluene with ozone at room temperature was carried out over hierarchically ordered mesoporous catalysts (CeO2 (meso), Mn2O3 (meso), ZrO2 (meso), and γ-Al2O3 (meso)) and Al2O3 with various textural properties and phases (γ-Al2O3 (meso), γ-Al2O3 (13 nm), and α-Al2O3) to examine the effects of the nature of the catalyst on the catalytic activity. The catalysts were characterized by N2-physisorption measurements, powder X-ray diffraction, temperature programmed reduction, X-ray photoelectron spectroscopy and scanning transmission electron microscopy with energy dispersive spectroscopy. Among the ordered mesoporous catalysts, γ-Al2O3 (meso) had the highest toluene removal efficiency because of its highest surface area and pore volume, which in turn was selected for further investigation. Manganese (Mn) was introduced to various Al2O3 to improve the toluene removal efficiency. Comparing the Mn-loaded catalysts supported on various Al2O3 with different crystalline phases or pore structures, Mn/γ-Al2O3 (meso), had the highest catalytic activity as well as the highest CO2/CO ratio. The higher activity was attributed to the larger surface area, weaker interaction between Mn and Al2O3, and larger portion of Mn2O3 phase. The increase in ozone concentration led to an improvement in the carbon balance but this enhancement was insufficient due to the deposition of by-products on the catalyst. After long term tests at room temperature, the reaction intermediates and carbonaceous deposits of the used catalysts were identified.


Assuntos
Técnicas de Química Analítica , Ozônio , Tolueno , Óxido de Alumínio/química , Catálise , Técnicas de Química Analítica/métodos , Manganês/química , Ozônio/química , Temperatura , Tolueno/isolamento & purificação
16.
Environ Sci Pollut Res Int ; 26(4): 3991-3999, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30552613

RESUMO

With raising awareness of gaseous air pollutants and their harmful impact, adsorption is considered one of the most prominent techniques for gaseous emissions control. The usage of polyaniline as a gas adsorbent is an innovative idea. This work aims to compare the efficacy of synthesized polyaniline nanotubes (PANT) as a novel adsorbent towards inorganic gases (ammonia NH3) and volatile organic compounds (toluene vapor). PANT was prepared via a sol-gel preparation technique. The molecular structure of prepared PANT was characterized by Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The morphological structure was confirmed using transmission electron microscopy (TEM) and scanning electron microscope (SEM). The PANT adsorbent surface area was determined using Brunner Emmett Teller (BET). Dynamic behavior of simulated feed gas mixture of NH3 and toluene in air were examined using a fixed bed adsorption arrangement. The same adsorption conditions (inlet concentration, gas mixture feed flow rate, and a fixed amount of adsorbent) were applied for both NH3 and toluene adsorption test. The NH3 and toluene removal efficiencies were 100% and 96% respectively. Consequently, PANT is an auspicious adsorbent that can be utilized to control the indoor and outdoor gaseous air emissions. Graphical Abstracts ᅟ.


Assuntos
Poluentes Atmosféricos/química , Amônia/química , Compostos de Anilina/química , Tolueno/química , Adsorção , Poluentes Atmosféricos/isolamento & purificação , Amônia/isolamento & purificação , Gases/química , Ácido Clorídrico/química , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Estrutura Molecular , Nanotubos/química , Espectroscopia de Infravermelho com Transformada de Fourier , Tolueno/isolamento & purificação , Difração de Raios X
17.
Sci Total Environ ; 655: 633-640, 2019 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-30476844

RESUMO

One of the challenges in the petroleum hydrocarbon contaminated groundwater remediation by oxygen releasing compounds (ORCs) is to identify the remediation mechanism and determine the impact of ORCs on the environment and the intrinsic groundwater microorganisms. In this research, the application of encapsulated magnesium peroxide (MgO2) nanoparticles in the permeable reactive barrier (PRB) for bioremediation of the groundwater contaminated by toluene and naphthalene was studied in the continuous flow sand-packed plexiglass columns within 50 d experiments. For the biodiversity studies, next generation sequencing (NGS) of the 16S rRNA gene was applied. The results showed that naphthalene was metabolized (within 20 days) faster than toluene (after 30 days) by microorganisms of the aqueous phase. By comparing the contaminant removal in the biotic (which resulted in the complete contaminant removal) and abiotic (around 32% removal for naphthalene and 36% for toluene after 50 d) conditions, the significant role of microorganisms on the decontamination process was proved. Furthermore, the attached microbial communities on the porous media were visualized by scanning electron microscopy (SEM). Microbial community structure analysis by NGS technique revealed that the microbial species which were able to degrade toluene and naphthalene such as P. putida and P. mendocina respectively were stimulated by addition of MgO2 nanoparticles. The presented study resulted in a momentous insight into the application of MgO2 nanoparticles in the hydrocarbon compounds removal from groundwater.


Assuntos
Recuperação e Remediação Ambiental/métodos , Compostos de Magnésio/química , Nanopartículas/química , Naftalenos/metabolismo , Peróxidos/química , Tolueno/metabolismo , Poluentes Químicos da Água/metabolismo , Purificação da Água/métodos , Biodegradação Ambiental/efeitos dos fármacos , Água Subterrânea/química , Água Subterrânea/microbiologia , Compostos de Magnésio/farmacologia , Microbiota/efeitos dos fármacos , Naftalenos/isolamento & purificação , Peróxidos/farmacologia , RNA Ribossômico 16S/genética , Tolueno/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação
18.
J Chromatogr A ; 1578: 99-105, 2018 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-30337168

RESUMO

A novel ionic liquid (1-allyl-methylimidazolium chloride, AlMeIm+Cl-) polymer monolith poly(ionic liquid-co-ethylene dimethacrylate) incorporated with zeolitic imidazolate framework-8 (ZIF-8-poly(IL-co-EDMA)) was firstly synthesized as stationary phases of monolithic column for capillary electrochromatography by one-step copolymerization. Incorporation of ZIF-8 into ionic liquid polymer monolith evidently enhanced the separation selectivity for four alkylbenzenes in reversed phase capillary electrochromatography (CEC), due to the synergistic effect derived from the same imidazole ring structure of ionic liquid and organic ligands of ZIF-8. Meanwhile, electroosmotic flow (EOF) was generated by ionic liquid in a wide range of pH values from 2.0 to 12.0. The resultant monolithic columns were characterized by scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR). The results indicated that the prepared monolithic columns had good permeability and mechanism stability. The resultant monolithic columns were applied for the separation of neutral compounds, anilines and phenols. The highest column efficiency was 2.07 × 105 plates m-1 (theoretical plates, N) for toluene. Under optimal conditions, reproducibility was obtained with relative standard deviations (RSDs) of the retention time for run-to-run, day-to-day, column-to-column and batch-to-batch were in the range of 1.58 - 3.19%, 1.92 - 3.87%, 3.84 - 4.96% and 2.63 - 4.33%, respectively. Incorporation ZIF-8 into ionic liquid polymer monolith was a promising way for the application of new materials in the fabrication of novel monolithic columns.


Assuntos
Eletrocromatografia Capilar , Técnicas de Química Analítica/métodos , Imidazóis/química , Líquidos Iônicos/química , Técnicas de Química Analítica/normas , Eletro-Osmose , Íons , Metacrilatos/química , Fenóis/isolamento & purificação , Polimerização , Polímeros/química , Reprodutibilidade dos Testes , Espectroscopia de Infravermelho com Transformada de Fourier , Tolueno/isolamento & purificação , Zeolitas/química
19.
J Dermatol Sci ; 92(2): 188-196, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30219520

RESUMO

BACKGROUND: Atopic dermatitis (AD) is an inflammatory skin disease with an associated barrier dysfunction and Staphylococcus aureus infection. The mainstay steroid and calcineurin inhibitor therapy shows some adverse effects. 2,4-Dimethoxy-6-methylbenzene-1,3-diol (DMD) is a benzenoid isolated from Antrodia camphorata. OBJECTIVE: We investigated the inhibitory effect of DMD on methicillin-resistant S. aureus (MRSA), the chemokine production in stimulated keratinocytes, and the AD-like lesion found in ovalbumin (OVA)-sensitized mice. METHODS: The antimicrobial effect and cutaneous barrier function were evaluated using an in vitro culture model and an in vivo mouse model of AD-like skin. RESULTS: DMD exhibited a comparative minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against MRSA with nalidixic acid, a conventional antibiotic. The MIC and MBC for DMD was 78.1 and 156.3 µg/ml, respectively. DMD also showed the ability to eliminate the clinical bacteria isolates with resistance to methicillin and vancomycin. The DNA polymerase and gyrase inhibition evoked by DMD for bacterial lethality was proposed. In the activated keratinocytes, DMD stopped the upregulation of chemokines (CCL5 and CCL17) and increased the expression of differentiation proteins (filaggrin, involucrin, and integrin ß-1). Topical application of DMD facilely penetrated into the skin, with AD-like skin displaying 2.5-fold greater permeation than healthy skin. The in vivo assessment using the mouse model with OVA sensitization and MRSA inoculation revealed a reduction of transepidermal water loss (TEWL) and bacterial burden by DMD by about 2- and 100-fold, respectively. Differentiation proteins were also restored after topical DMD delivery. CONCLUSION: Our data demonstrated an advanced concept of AD treatment by combined barrier repair and bacterial eradication with a sole agent for ameliorating the overall complications.


Assuntos
Antibacterianos/farmacologia , Antrodia/química , Dermatite Atópica/tratamento farmacológico , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Infecções Cutâneas Estafilocócicas/tratamento farmacológico , Tolueno/análogos & derivados , Tolueno/farmacologia , Administração Cutânea , Animais , Antibacterianos/isolamento & purificação , Antibacterianos/uso terapêutico , Linhagem Celular , Quimiocinas/imunologia , Quimiocinas/metabolismo , Dermatite Atópica/imunologia , Dermatite Atópica/microbiologia , Modelos Animais de Doenças , Avaliação Pré-Clínica de Medicamentos , Proteínas Filagrinas , Humanos , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Staphylococcus aureus Resistente à Meticilina/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Testes de Sensibilidade Microbiana , Ácido Nalidíxico/farmacologia , Ácido Nalidíxico/uso terapêutico , Ovalbumina/imunologia , Pele/efeitos dos fármacos , Pele/imunologia , Pele/metabolismo , Pele/microbiologia , Infecções Cutâneas Estafilocócicas/imunologia , Infecções Cutâneas Estafilocócicas/microbiologia , Suínos , Tolueno/isolamento & purificação , Tolueno/uso terapêutico , Resultado do Tratamento , Perda Insensível de Água/efeitos dos fármacos
20.
Chemosphere ; 208: 922-930, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30068036

RESUMO

The degradation of toluene in dielectric barrier discharge (DBD) reactor packed with zeolites or MnOx/zeolites was investigated. The supported catalysts were prepared by loading 3 wt% of manganese on different zeolites (MCM-41, ZSM-5 and 13X) and were characterized in detail using N2 adsorption, XRD, TEM, H2-TPR and XPS analysis technology. Compared to the non-thermal plasma (NTP) alone system, the toluene degradation was improved significantly in NTP-MnOx/zeolites system. The highest toluene conversion of 99.4%, the CO2 selectivity of 73%, the carbon balance of 99.5% can be achieved in DBD reactor packed with MnOx/MCM-41. Both XRD and TEM results confirm that the manganese oxides were dispersed more uniformly on MnOx/MCM-41 than on MnOx/ZSM-5 or MnOx/13X. H2-TPR and XPS results suggest that manganese oxides on MnOx/MCM-41 are MnO2 and Mn2O3, while those on MnOx/ZSM-5 or MnOx/13X are MnO2 and MnO. These results indicate that the structures of zeolites play a significant role in the dispersion and oxidation state of manganese oxides, then affecting the activity of catalyst for toluene removal in plasma-catalysis system.


Assuntos
Reatores Biológicos , Compostos de Manganês/química , Óxidos/química , Gases em Plasma/química , Tolueno/isolamento & purificação , Zeolitas/química , Catálise , Oxirredução , Tolueno/química
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