Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 8.512
Filtrar
1.
Water Sci Technol ; 81(9): 1894-1913, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32666944

RESUMO

A silver phosphate/hydroxyapatite (Ag3PO4/HA) composite was produced from phosphate waste rocks, firstly by the valorization of these wastes to HA and then by the treatment of this prepared HA with a silver nitrate solution. A type of response surface methodology, Box-Behnken experimental design, was used to find optimum synthesis parameters (silver to HA weight ratios, calcination temperature and calcination time). The visible light photodegradation of Rhodamine B in aqueous solution was used as the experimental response. The analysis of variance for the results showed that silver weight ratio is the most influential parameter on photoactivity of the synthesized photocatalyst. The optimum conditions were predicted to give an RhB degradation yield of 98.609%/4 hours under visible light conditions. In this context, a Ag/HA weight ratio of 14%, a calcination temperature of 300 °C, and a calcination time of 30 min were found to be the optimum conditions. Samples synthesized under the optimum condition were characterized by the use of X-ray diffraction, X-ray fluorescence spectrometer, Fourier transform infrared spectrum analysis, scanning electron microscopy, transmission electron microscopy and ultraviolet-visible diffuse reflection spectroscopy. By comparison with pure HA, the characterization results clearly showed the successful synthesis of the Ag3PO4/HA composite.


Assuntos
Durapatita , Luz , Catálise , Rodaminas
2.
Water Sci Technol ; 81(5): 906-914, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32541109

RESUMO

Activated carbon (AC) was modified by MgO and MnO2 through an impregnation-precipitation-calcination procedure. The batch experiments of adsorption of Rhodamine B (RB) by a modified adsorption material, an MgO-MnO2-AC composite, were carried out and the characteristics of the composite adsorbent were evaluated. The results showed that manganese/magnesium loading changed the surface area, pore volume and increased the number of active adsorption sites of AC. The highest Brunauer-Emmett-Teller (BET) surface area (1,036.18 m2·g-1) was obtained for MgO-MnO2-AC compared with AC. The content of AC loaded with magnesium and manganese was 34.24 and 5.51 mg·g-1 respectively. The adsorption of RB on MgO-MnO2-AC was significantly improved. The maximum adsorption capacity of RB on MgO-MnO2-AC was 16.19 mg·g-1 at 25 °C under the RB concentration of 50 mg·L-1. The adsorption of RB by AC and MgO-MnO2-AC increased with the initial concentration of RB. The adsorption of RB increased first and then decreased when pH was between 3 and 11. The results indicated that the pseudo-second-order kinetic equation and Langmuir equation can be used to describe the adsorption of RB on MgO-MnO2-AC.


Assuntos
Carvão Vegetal , Poluentes Químicos da Água , Adsorção , Cinética , Óxido de Magnésio , Compostos de Manganês , Óxidos , Rodaminas
3.
Water Sci Technol ; 81(5): 1080-1089, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32541124

RESUMO

Bismuth oxyhalides (BiOXs, X = Cl, Br and I) are emerging photocatalytic materials with unique layered structure, flexible band structure and superior photocatalytic activity. The purpose of this study was to develop a facile alcoholysis route to prepare BiOClxI1-x nanosheet solid solutions at room temperature. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), photoluminescence emission spectroscopy (PL) and Brunauer-Emmett-Teller (BET) surface area analyzer were used to characterize the as-prepared photocatalysts. These results revealed that two-dimension BiOClxI1-x nanosheet solid solutions could be obtained with high percentage of {001} crystal facets exposed. Moreover, the formation of solid solution could regularly change the optical absorption thresholds and band gaps of BiOClxI1-x photocatalysts. The photocatalytic experiments indicated that BiOCl0.75I0.25 exhibited the highest photocatalytic performance for the degradation of Rhodamine B (RhB) under simulated sunlight irradiation and the photocatalytic process followed a pseudo-first-order kinetic equation. A possible mechanism of RhB photodegradation over BiOClxI1-x solid solutions was proposed based on the structural properties of BiOClxI1-x solid solutions and RhB photosensitization.


Assuntos
Luz , Água , Catálise , Rodaminas
4.
Chemosphere ; 256: 127082, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32450350

RESUMO

Significant degradation of organic contaminants in biochar sorption systems has recently been reported, demonstrating a promising potential application of biochar in pollution control. We hypothesized that the degradation of organic chemicals by biochar may be further enhanced under irradiation by UV light due to the photocatalytic activities of carbonaceous materials. Our results confirmed that UV conditions increased the degradation of rhodamine B (RhB) by up to three times compared to dark conditions. Washing biochar with ultrapure water further increased RhB photodegradation by up to ten times. This photodegradation increase was the highest for biochar produced at 1000 °C. HF treatment and the addition of biochar supernatant did not increase RhB photodegradation. Therefore, the biochar properties mediating RhB photodegradation may be related to solid particles, mostly the combination of graphite structures and organic functional groups. Based on XPS and FTIR analysis, we propose that the quinoid CO in biochar may play an essential role in RhB photodegradation. Further research on identifying the photoactive components of biochar will be fundamental for improved biochar manufacture and application.


Assuntos
Carvão Vegetal/química , Recuperação e Remediação Ambiental , Rodaminas/química , Adsorção , Poluição Ambiental , Compostos Orgânicos , Fotólise , Raios Ultravioleta
5.
Water Sci Technol ; 81(4): 720-731, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32460275

RESUMO

In the study the electrochemical oxidation process for decolorization of Rhodamine-B dye was studied using an anode coated with mixed metal oxides: TiO2, RuO2, and IrO2. Batch experimental studies were conducted to assess the effect of four important performance variables, current density, electrolyte concentration, initial pH and electrolysis time, on the decolorization and energy consumption. The process was modeled using an artificial neural network. Response surface methodology using central composite design (CCD) was utilized for optimization of the decolorization process. Based on the experimental design given by CCD, the results obtained by the statistical analysis show that the electrolysis time was the most influential parameter for decolorization whereas the current density had the greatest influence on the energy consumption. According to the optimized results given by the CCD model, maximum color removal of 97% and minimum energy consumption of 1.01 kWh/m3 were predicted in 4.9 minute of electrolysis time, using 0.031 M NaCl concentration at current density 10 mA/cm2 and an initial pH of 3.7. A close conformity was observed between the optimized predicted results and experimental results. The process was found to be efficient and consisted of indirect chemical oxidation producing strong oxidizing agents such as Cl2, HClO and OCl-.


Assuntos
Eletrólise , Poluentes Químicos da Água , Eletrodos , Metais , Oxirredução , Óxidos , Rodaminas
6.
Phys Rev Lett ; 124(15): 158102, 2020 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-32357050

RESUMO

We analyze the nonequilibrium shape fluctuations of giant unilamellar vesicles encapsulating motile bacteria. Owing to bacteria-membrane collisions, we experimentally observe a significant increase in the magnitude of membrane fluctuations at low wave numbers, compared to the well-known thermal fluctuation spectrum. We interrogate these results by numerically simulating membrane height fluctuations via a modified Langevin equation, which includes bacteria-membrane contact forces. Taking advantage of the lengthscale and timescale separation of these contact forces and thermal noise, we further corroborate our results with an approximate theoretical solution to the dynamical membrane equations. Our theory and simulations demonstrate excellent agreement with nonequilibrium fluctuations observed in experiments. Moreover, our theory reveals that the fluctuation-dissipation theorem is not broken by the bacteria; rather, membrane fluctuations can be decomposed into thermal and active components.


Assuntos
Vesículas Citoplasmáticas/química , Lipídeos de Membrana/química , Modelos Biológicos , Modelos Químicos , Bacillus subtilis/química , Bacillus subtilis/citologia , Bacillus subtilis/metabolismo , Vesículas Citoplasmáticas/metabolismo , Locomoção , Lipídeos de Membrana/metabolismo , Fosfatidiletanolaminas/química , Rodaminas/química , Termodinâmica , Lipossomas Unilamelares/química , Lipossomas Unilamelares/metabolismo
7.
Water Sci Technol ; 81(3): 436-444, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32385197

RESUMO

Biochar was prepared from rabbit faeces (RFB550) at 550 °C through pyrolysis and was characterised using elemental analysis, scanning electron microscopy, Brunauer-Emmett-Teller analysis and Fourier transform infrared spectroscopy (FTIR). The related factors, kinetics, isothermal curves and thermodynamics of the adsorption behaviours were investigated by conducting batch experiments. The results revealed the adsorption equilibrium of rhodamine B (RhB) and Congo red (CR) onto RFB550 with initial concentrations of 30 mg · L-1 at 25 °C and 210 min, and the best adsorption was observed when the pH of the RhB and CR solutions was 3 and 5, respectively. Pseudo-second-order kinetics was the most suitable model for describing the adsorption of RhB and CR onto RFB550, indicating that the rate-limiting step was mainly chemical adsorption. The isotherm data were best described by the Freundlich model, and the adsorption process was multi-molecular layer adsorption. Thermodynamic parameters revealed the spontaneous adsorption of RhB and CR onto RFB550. According to the results of the FTIR analysis, the oxygen-containing functional groups and aromatic structures on the surface of RFB550 provided abundant adsorption sites for RhB and CR, and the adsorption mechanism was potentially related to the hydrogen bonds and π-π bonds.


Assuntos
Vermelho Congo , Poluentes Químicos da Água , Adsorção , Animais , Carvão Vegetal , Concentração de Íons de Hidrogênio , Cinética , Esterco , Coelhos , Rodaminas , Espectroscopia de Infravermelho com Transformada de Fourier , Termodinâmica
8.
Chemistry ; 26(35): 7912-7917, 2020 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-32274865

RESUMO

A series of phosphine oxide-bridged rhodamines (P-rhodamines) bearing various acyclic and cyclic amine moieties, including dimethyl- and diethylamine, azetidine, pyrrolidine and 7-azabicyclo[2,2,1]heptane (7ABH), have been synthesized. The photophysical properties as well as chemical and photostability of these dyes have been studied in detail. Among these dyes, the 7ABH-substituted dye shows stronger fluorescence in the near-infrared (NIR) region, relative to the other P-rhodamines. This dye could be applied to live-cell imaging, wherein lysosomes were selectively stained in a pH-independent manner. It was also found that the ring fusion of the amine moieties gives rise to remarkably redshifted spectra, with absorption and emission maxima at 770 and 820 nm, respectively, spectrally close to that of indocyanine green (ICG). Importantly, the ring-fused P-rhodamines showed much higher photostability than ICG, indicative of their promising utility as the NIR-emissive dyes.


Assuntos
Aminas/química , Lisossomos/química , Rodaminas/química , Fluorescência , Verde de Indocianina
9.
Chemosphere ; 254: 126813, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32334261

RESUMO

TiO2/cement composites were prepared by a spraying method to degrade organic pollutants. After coated with waterproof liquid, pure cement pastes/mortars were sprayed with TiO2 suspensions with different TiO2 contents and spraying times. Photocatalytic properties, mechanical strength and durability were studied. Maximum photocatalytic activity and uniform TiO2 distribution were achieved at the optimal conditions of 10 wt% TiO2 content in suspension and 3 spraying times. The TiO2/cement pastes had better degradation performance over Rhodamine B (RhB) and methylene blue (MB) than that over methyl orange (MO). After 20 times of cycling degradation, the photocatalytic efficiencies had no significant reduction. The TiO2/cement mortars had good mechanical strengths, meeting the mechanical demands of wastewater treatment tanks. In durability, the TiO2/cement mortars had better water penetration resistance, chloride penetration resistance and anti-carbonation than pure cement mortars.


Assuntos
Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/química , Compostos Azo , Catálise , Poluentes Ambientais , Azul de Metileno , Rodaminas , Titânio/química , Raios Ultravioleta , Águas Residuárias
10.
Chemosphere ; 254: 126823, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32334264

RESUMO

Environmentally toxic organic pollutants, namely methylene blue (MB), neutral red (NR), Rhodamine B (RhB), and methyl orange (MO) dyes contain highly toxic, carcinogenic, non-biodegradable, and colored pigments which cause harm for humans and aquatic organisms even at low concentrations. To detoxify these toxic organic pollutants from the wastewater, the bimetallic solid solution-typed In-Mo(O,S)2 catalyst with various indium (In) contents were synthesized at low temperature through a simple precipitation method. The morphological, structural, chemical compositions, electrochemical and optical properties of the catalysts were thoroughly characterized. The photodegradation performance of the In-Mo(O,S)2 catalysts over the cationic, anionic and neutral dyes were studied under visible light irradiation. It has been observed that the photocatalytic activity was enhanced as In was added to the Mo(O,S)2 catalyst, and In-Mo(O,S)2-20 was found to be the best composition to completely degrade four organic dyes. The dye degradation had rate constant values of 9.5 × 10-2 min-1, 6.3 × 10-2 min-1, 4.4 × 10-2 min-1, and 15.7 × 10-1 min-1 for MB (20 ppm), NR (20 ppm), RhB (10 ppm), and MO (10 ppm) dyes, respectively. The active species for degradation of MB is different from those for RhB and MO. Single phase In-Mo(O,S)2-20 capable to degrade four kinds of dyes at a fast rate is a good photocatalyst.


Assuntos
Corantes/análise , Poluentes Químicos da Água/análise , Compostos Azo , Catálise , Corantes/química , Índio , Luz , Azul de Metileno/química , Modelos Químicos , Fotólise , Rodaminas , Sulfetos , Águas Residuárias , Poluentes Químicos da Água/química
11.
Chemosphere ; 253: 126655, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32302899

RESUMO

The degradation kinetics and mechanisms of Rhodamine B (RhB) dye by •OH and SO4•- based advanced oxidation processes were investigated. The •OH and SO4•- radicals were generated by UV photolysis of hydrogen peroxide and persulfate (i.e., UV/H2O2 and UV/PS), respectively. The effects of initial solution pH, RhB concentration, oxidant dosage, Fe2+ concentration, and water matrices were examined. The results showed that the degradation of RhB followed pseudo-first-order kinetics in both processes, with the UV/H2O2 process exhibiting better performance than that of the UV/PS process. Acidic conditions were favorable to the degradation of RhB in both systems. Increasing the oxidant dosage or decreasing the contaminant concentration could enhance the degradation of RhB. Photo-Fenton-like processes accelerated the performance when Fe2+ was added into both systems. The removal efficiency of RhB was inhibited upon the addition of humic substances. The addition of Cl- displayed no significant effect and promoted RhB degradation in UV/H2O2 and UV/PS systems, respectively. The presence of NO3- promoted RhB degradation, while H2PO4- and C2O42- showed an inhibitory effect on both UV/H2O2 and UV/PS processes. Radical scavenging tests revealed the dominant role of SO4•- radicals in the UV/PS system. Furthermore, the evolution of low molecular weight organic acids and NH4+ during the degradation of RhB in these two processes were compared. Both UV/H2O2 and UV/PS systems led to similar formation trends of NH4+ and some ring-opening products (e.g., formic acid, acetic acid, and oxalic acid), suggesting some analogies in the decay pathways of RhB by •OH and SO4•--induced oxidation processes.


Assuntos
Rodaminas/química , Poluentes Químicos da Água/química , Substâncias Húmicas , Peróxido de Hidrogênio/química , Radical Hidroxila/química , Cinética , Compostos Orgânicos , Oxirredução , Processos Fotoquímicos , Fotólise , Sulfatos/química , Raios Ultravioleta , Poluentes Químicos da Água/análise
12.
Chemosphere ; 253: 126751, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32302913

RESUMO

A novel n-n type inorganic/organic heterojunction of flaky-like BiOCl/PDI photocatalyst was constructed by water bath heating method. Meanwhile, a simple method - secondary self-assembly was used to prepare the BiOCl/PDI with a special band structure. The photocatalytic activities were evaluated by degrading aqueous organic pollutants under visible light (λ > 420 nm). The removal rates of 5 mg L-1 phenol (non-ionic type), methyl orange (MO, anionic type), rhodamine B (RhB, cationic type) and 10 mg L-1 RhB by secondary self-assembly BiOCl/PDI (BiOCl/PDI-2) were 8.0%, 3.4%, 27.8% and 78.9% higher than self-assembly BiOCl/PDI (BiOCl/PDI-1) under visible light (λ > 420 nm). The better photocatalytic activity for BiOCl/PDI-2 was attributed to the optimization of energy-band structures, which arose from different exposed surfaces, narrower interplanar spacing and stronger visible light absorption performance. Under acidic condition, BiOCl/PDI-2 showed a good photocatalytic activity, which was not affected by neutral ionic intensity and had good recycling properties. Moreover, the photocatalytic mechanism was explored by free radical capture test and electron paramagnetic resonance (EPR), and contribution of active species was calculated. The main active species of BiOCl/PDI-2 were ·O2-, 1O2 and h+. Our work may provide a route to design efficient inorganic/organic heterojunctions for organic pollutants degradation.


Assuntos
Bismuto/química , Imidas/química , Luz , Nanoestruturas/química , Perileno/análogos & derivados , Poluentes Químicos da Água/análise , Compostos Azo/análise , Compostos Azo/efeitos da radiação , Catálise , Perileno/química , Fenóis/análise , Fenóis/efeitos da radiação , Rodaminas/análise , Rodaminas/efeitos da radiação , Propriedades de Superfície , Poluentes Químicos da Água/efeitos da radiação
13.
Food Chem ; 320: 126666, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32229400

RESUMO

A novel dendritic silicon dioxide nanocomposite coated with a highly dispersed graphene-like boron nitride nanosheet (g-BN(x)@SiO2) was in-situ synthesized and employed as a solid-phase extraction material for the Rhodamine B (RhB) and Rhodamine 6G (R6G) enrichment in food samples prior to their quantitation by HPLC. The structures and morphologies of g-BN(x)@SiO2 were characterized by XRD, FTIR, BET and TEM. The adsorption performance and mechanism were investigated and showed an enhanced maximum adsorption capacity of 625 mg/g for RhB on the nanocomposite loaded with 1% of g-BN via a fast, spontaneous process. Under optimal extraction conditions, this method showed low detection and quantification limits (2.8 µg/L for RhB, 2.1 µg/L for R6G and 9.2 µg/L for RhB, 6.9 µg/L for R6G, respectively), good repeatability (RSD% <3.7%), and satisfactory spiked recoveries of 94.8%-103.1% for RhB and R6G in real chili powder and beverage. Therefore, the g-BN(1%)@SiO2-based materials possess significant potential.


Assuntos
Análise de Alimentos/métodos , Nanocompostos/química , Rodaminas/isolamento & purificação , Extração em Fase Sólida/métodos , Adsorção , Bebidas/análise , Cromatografia Líquida de Alta Pressão/métodos , Contaminação de Alimentos/análise , Grafite/química , Concentração de Íons de Hidrogênio , Limite de Detecção , Microscopia Eletrônica de Transmissão , Concentração Osmolar , Reprodutibilidade dos Testes , Dióxido de Silício/química , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X
14.
Int J Nanomedicine ; 15: 1745-1758, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32214808

RESUMO

Purpose: Solid lipid nanoparticles are largely used in biomedical research and are characterized by high stability and biocompatibility and are also able to improve the stability of various loaded molecules. In vitro studies demonstrated that these nanoparticles are low cytotoxic, while in vivo studies proved their efficiency as nanocarriers for molecules characterized by a low bioavailability. However, to our knowledge, no data on the systemic biodistribution and organ accumulation of solid lipid nanoparticles in itself are presently available. Methods: In this view, we investigated the solid lipid nanoparticles biodistribution by a multimodal imaging approach correlating in vivo and ex vivo analyses. We loaded solid lipid nanoparticles with two different fluorophores (cardiogreen and rhodamine) to observe them with an optical imager in the whole organism and in the excised organs, and with fluorescence microscopy in tissue sections. Light and transmission electron microscopy analyses were also performed to evaluate possible structural modification or damage due to nanoparticle administration. Results: Solid lipid nanoparticles loaded with the two fluorochromes showed good optic characteristics and stable polydispersity. After in vivo administration, they were clearly detectable in the organism. Four  hours after the injection, the fluorescent signal occurred in anatomical districts corresponding to the liver and this was confirmed by the ex vivo acquisitions of excised organs. Brightfield, fluorescence and transmission electron microscopy confirmed solid lipid nanoparticles accumulation in hepatocytes without structural damage. Conclusion: Our results support the systemic biocompatibility of solid lipid nanoparticles and demonstrate their detailed biodistribution from the whole organism to organs until the cells.


Assuntos
Nanopartículas/análise , Nanopartículas/química , Animais , Disponibilidade Biológica , Corantes Fluorescentes/química , Verde de Indocianina/química , Lipídeos/química , Fígado/efeitos dos fármacos , Fígado/ultraestrutura , Masculino , Camundongos Nus , Microscopia Eletrônica de Transmissão , Microscopia de Fluorescência , Imagem Multimodal/métodos , Rodaminas/química , Distribuição Tecidual
15.
Toxicon ; 178: 61-68, 2020 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-32112787

RESUMO

Snakebites cause upwards of 1.8 million envenomings, 138,000 deaths and 500,000 cases of long term morbidity each year. Viper snake venoms (family Viperidae) generally contain a high proportion of proteases which can cause devastating effects such as hemorrhage, coagulopathy, edema, necrosis, and severe pain, in envenomed victims. In this study, analytical techniques were combined with enzymatic assays to develop a novel method for the detection of snake venom protease activity by using rhodamine-110-peptide substrate. In the so called at-line nanofractionation set up, crude venoms were first separated with reversed phase liquid chromatography, after which fractions were collected onto 384-well plates. Protease activity assays were then performed in the 384-well plates and bioassay chromatograms were constructed revealing protease activity. Parallel obtained UV absorbance, MS and proteomics data from a previous study facilitated toxin identification. The application of the rhodamine-110-peptide substrate assay showed significantly greater sensitivity compared to prior assays using casein-FITC as the substrate. Moreover, cross referencing UV and MS data and resulted in the detection of a number of tentative proteases suspected to exhibit protease activity, including snake venom serine proteases from Calloselasma rhodostoma and Daboia russelli venom and a snake venom metalloproteinase from the venom of Echis ocellatus. Our data demonstrate that his methodology can be a useful tool for selectively identifying snake venom proteases, and can be applied to provide a better understanding of protease-induced pathologies and the development of novel therapeutics for treating snakebite.


Assuntos
Venenos de Víboras/química , Animais , Fracionamento Químico , Cromatografia de Fase Reversa , Ensaios de Triagem em Larga Escala , Metaloproteases , Peptídeos , Rodaminas , Serina Proteases/química , Mordeduras de Serpentes , Viperidae
16.
Chemosphere ; 252: 126581, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32222517

RESUMO

The development of visible light-responsive photocatalytic membranes (vis-PMs) has opened a promising direction in water purification field. Herein, supramolecular aggregates from cyanuric acid (C), melamine (M), and urea (U) in dimethyl sulfoxide (DMSO) were used to prepare the porous carbon nitride nanosheet (MCU-C3N4) with excellent photocatalytic performance. A sort of 3D heterostructure PMs consisting of MCU-C3N4 and carbon nanotube (CNTs) interposed into graphene oxide (GO) on the PVDF membrane was firstly fabricated by the layer-by-layer (LbL) assembly method, in which CNTs/MCU-C3N4/GO material was immobilized on the polyelectrolytes (PE) modified PVDF based on their electrostatic attractions. Such PMs with abundant nano-channels had excellent mechanical strength, satisfactory water permeability (14.35 L m-2 h-1 bar-1) and synergetic removal efficiency of rhodamine B (RhB, 98.31%) in long -term operation, relative to the pristine GO membrane and MCU-C3N4/GO membrane fabricated by the same method. In addition, such PMs also exhibited the satisfactory tetracycline hydrochloride (TC) removal rate (84.81%) under visible light irradiation. Construction and performance of such carbon-based PMs might provide guidance for development of vis-PMs in terms of bonding strength, multidimensional morphology and water purification application.


Assuntos
Luz , Purificação da Água/métodos , Catálise , Grafite , Nitrilos , Porosidade , Rodaminas , Tetraciclina , Triazinas
17.
Phys Chem Chem Phys ; 22(14): 7516-7523, 2020 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-32219241

RESUMO

The chiroptical properties of multi-chromophoric systems are governed by the intermolecular arrangement of the monomeric units. We report on a computational and experimental study of the linear optical properties and supramolecular structure of a rhodamine heterodimer assembled on a DNA scaffold. The experimental absorption and circular dichroism (CD) profiles confirm the dimer formation. Computationally, starting from low-cost DFT/TDDFT simulations of the bare dimer we attribute the measured -/+ CD sign sequence of the S1/S2 bands to a specific chiral conformation of the heterodimer. In the monomers, as typical for rhodamine dyes, the electric transition dipole of the lowest π-π* transition is parallel to the long axis of the xanthene planes. We show that in the heterodimer the sign sequence of the two CD bands is related to the orientation of these long axes. To account explicitly for environment effects, we use molecular dynamics (MD) simulations for characterizing the supramolecular structure of the two optical isomers tethered on DNA. Average absorption and CD-profiles were modeled using ab initio TDDFT calculations at the geometries sampled along a few nanosecond MD run. The absorption profiles computed for both optical isomers are in good agreement with the experimental absorption spectrum and do not allow one to discriminate between them. The computed averaged CD profiles provide the orientation of monomers in the enantiomer that is dominant under the experimental conditions.


Assuntos
DNA/química , Modelos Moleculares , Rodaminas/química , Dicroísmo Circular , Química Computacional , Simulação de Dinâmica Molecular , Estrutura Molecular
18.
Chem Commun (Camb) ; 56(21): 3183-3186, 2020 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-32067022

RESUMO

A novel nanoarchitecture (MSN-Tb-UbR) was prepared by modifying rhodamine B-labelled Ubs (Ub-Rs) on the surface of mesoporous silica nanoparticles (MSNs) loaded with Tb3+-complexes. The MSN-Tb-UbR exhibits ratiometric sensing ability for DUB (UCH-L1) with good sensitivity and selectivity.


Assuntos
Nanopartículas/química , Dióxido de Silício/química , Ubiquitina Tiolesterase/análise , Transferência Ressonante de Energia de Fluorescência/métodos , Corantes Fluorescentes/química , Porosidade , Rodaminas/química , Propriedades de Superfície , Térbio/química
19.
J Chromatogr A ; 1620: 460968, 2020 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-32087880

RESUMO

A high sampling rate, good stability, high throughput masking fluorescence detection system with easy positioning of each channel for capillary array electrophoresis was prepared and studied. A special mask combined with convex lenses was designed to modulate signals, without using any extra device to position each channel. The signal of each channel was detected by a photomultiplier tube, classified and saved by software. The design was used to evidently reduce the rotational vibration of optical components and to stabilize the system, so a high sampling rate was obtained by increasing the DC motor speed. To improve the optical system, optical fibers instead of conventional bulky optical components were used to transmit optical signal and to collect fluorescences in multiple directions, which greatly raised the sensitivity. Other important parameters including sampling rate, rotating speed and driven voltage laser diode (LDs) have also been investigated. Under optimal conditions, the performance of the detection system was evaluated. This novel system had a well-designed structure, and allowed independent multiple capillary operations and easy microanalysis. Its limit of detection for rhodamine 6G was 2.0 × 10-2 µg/mL.


Assuntos
Eletroforese Capilar/métodos , Análise de Alimentos/métodos , Fluorescência , Corantes Fluorescentes/análise , Fibras Ópticas , Preparações Farmacêuticas/análise , Rodaminas/análise
20.
Chemosphere ; 250: 126291, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32109695

RESUMO

In the present study, industrial wood flour waste was selected for the first time as the precursor to produce biochar (WFB). The WFB was then used to prepare WFB/BiOBr visible-light photocatalysts, in which WFB acted as the carbon support to enhance the photocatalytic performance of BiOBr. Specifically, the impact of WFB pyrolysis temperature on the visible-light photo-removal performance of WFB/BiOBr was studied through degrading rhodamine B and reducing Cr(VI). The results indicated that when the pyrolysis temperature was 600 °C, the prepared WFB (600-WFB) had the highest graphitization degree, which afterwards significantly enhanced the visible-light photocatalysis performance of the BiOBr. Having higher graphitization degree, 600-WFB/BiOBr exhibited the highest photocatalytic capability. With a dosage of 0.5 g/L, the 600-WFB/BiOBr could completely remove to 20 mg/L of RhB and 5 mg/L of Cr(VI) within 90 min. Since wood flour is an abundantly existed industrial bioresource waste and easily pyrolyzed to prepare biochar, WFB is a promising alternative to replace traditional carbonaceous materials for the design of green and high-efficient visible-light photocatalysts for environmental remediation.


Assuntos
Bismuto/química , Recuperação e Remediação Ambiental , Catálise , Carvão Vegetal/química , Farinha , Luz , Pirólise , Rodaminas , Madeira/química
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA