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1.
Chemosphere ; 247: 125910, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32069715

RESUMO

The photocatalytic degradation of the antibiotic ciprofloxacin in water was carried out with nanosheets of graphitic carbon nitride (g-C3N4) as catalyst and visible light irradiation using low-power (4 × 10 W) white light LEDs. The aim of this study was to identify the intermediate by-products formed during the degradation and to propose a pathway for CIP degradation. To achieve this goal, photocatalytically degraded CIP solutions were analysed by liquid chromatography coupled to high-resolution mass spectrometry using a QTOF instrument. The accurate mass and the MS/MS data of the detected ions allowed us to determine the elementary composition of eight by-products and to propose the chemical structures for seven of them. Three of these by-products have been reported for the first time and the elementary composition of a fourth one that had been wrongly reported in the literature was accurately established. CIP degradation followed a pseudo-first order kinetics with a pseudo-first order kinetic constant of 0.035 min-1. In addition, a study of the influence of several scavengers showed that only the presence of triethanolamine dramatically reduced the pseudo-first order kinetic constant (0.00072 min-1), pointing out that the reactive species were the holes produced in the catalyst. Finally, the main pathway of CIP degradation seems to be the attack to the piperazine group by ·OH radicals, following heterocycle breakup and the subsequent loss of two of its carbon atoms as CO2 molecules, and then defluorination, oxidation and cleavage of the cycles of this intermediate.


Assuntos
Ciprofloxacino/química , Grafite/química , Compostos de Nitrogênio/química , Poluentes Químicos da Água/química , Antibacterianos/química , Carbono/química , Catálise , Cromatografia Líquida , Cinética , Luz , Oxirredução , Espectrometria de Massas em Tandem , Poluentes Químicos da Água/análise
2.
Chemosphere ; 247: 125784, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31978669

RESUMO

Graphitic carbon nitride (g-C3N4) has enormous potentials for photocatalysis, yet it only possesses moderate activity because of excitonic effects and sluggish charge transfer. Here, we develop a novel two-dimensional g-C3N4/WO3/MoS2 (CWM) ternary nanocomposite through a facile co-calcination and a hydrothermal process to reach a highly-efficient photocatalyst for organic pollutant elimination under visible light. The WO3 and MoS2 nanoparticles were dispersed on the ultra-thin g-C3N4 nanosheets, in which the electronegative g-C3N4 facilitates formation of oxygen vacancies in WO3. Compared to pure g-C3N4, WO3, and binary composites, CWM exhibited higher photocatalytic activities for various organic pollutants removal under visible light irradiation. For instance, the CWM showed a removal ratio of ∼99% for RhB after only 10 min irradiation of visible light (λ > 420 nm) and nearly 100% for ciprofloxacin after 2 h of operation. The results showed that OH radicals are the main active species for organic degradation, which suggests a direct Z-scheme heterojunction in CWM that improved spatial separation of charge carries. Furthermore, the collection of electrons is significantly enhanced by MoS2 for oxygen reduction reaction, and the increased oxygen vacancies of WO3 further enhanced the separation of electron-hole pairs; therefore, it led to an effective suppression of charge carriers recombination. The above synergistic effects of ternary photocatalyst result in higher photocatalytic oxidation performance for wastewater treatment compared with pure WO3, g-C3N4 and their binary composites.


Assuntos
Grafite/química , Nanocompostos/química , Compostos de Nitrogênio/química , Águas Residuárias/química , Purificação da Água/métodos , Compostos Benzidrílicos/isolamento & purificação , Catálise , Dissulfetos , Luz , Molibdênio , Óxidos , Fenóis/isolamento & purificação , Tungstênio , Poluentes Químicos da Água/isolamento & purificação
3.
Chemosphere ; 248: 125973, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32000037

RESUMO

Understanding transport behavior of graphitic carbon nitride (g-C3N4) in porous media plays an important role in preventing its possible causing the underground environmental problems. The transport behavior of g-C3N4 in porous media were investigated by packed column experiments at different flow rates, ionic strengths (ISs), pHs and multivalent cations. The experimental results showed that the transport ability of g-C3N4 decreased with the IS increasing, and most of the g-C3N4 was retained in the sand column for the IS greater than 0.0001 M. The flow rate had little effect on the transport behavior of g-C3N4, and the recovery of g-C3N4 increased slightly with increasing flow rate. In addition, the migration ability of g-C3N4 under acidic conditions was drastically reduced compared with neutral alkaline conditions. Moreover, it was found that 1.51%, 30.33%, 34.91%, and 60.54% of g-C3N4 was retained in the column when g-C3N4 was leached through the quartz sand column at Al3+, Ca2+, Mg2+, and K+, which was consistent with the Schulze-Hardy rule. Finally, FTIR spectrum showed that the infrared absorption peak of the g-C3N4 mixed quartz sand were shifted to certain degrees under different conditions, which confirmed that hydrogen bond was formed in the transport of carbon nitride with the quartz sand surface. This study provides a new perspective on the role of hydrogen bond in the transport and fate of nanomaterials.


Assuntos
Grafite/química , Modelos Químicos , Compostos de Nitrogênio/química , Grafite/análise , Hidrodinâmica , Nitrilos , Compostos de Nitrogênio/análise , Concentração Osmolar , Porosidade , Quartzo , Soluções
4.
J Photochem Photobiol B ; 204: 111783, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31954265

RESUMO

Cadmium sulfide-graphitic carbon nitride nanocomposite was synthesized by pulsed laser ablation in liquid, and it was found from the results of optical and morphological characterizations that the proper anchoring of nanostructured cadmium sulfide on the nano-sheets of graphitic carbon nitride took place, which brought about the positive attributes such as enhanced visible light absorption and reduced photo-generated charge recombination, the key features required for an efficient photo-catalyst by solar light harvesting. The pulsed laser ablation in liquid method adopted for the synthesis of cadmium sulfide-graphitic carbon nitride has the following advantages: the shape and size of the synthesized particles can be controlled by altering the experimental parameters such as laser wavelength, pulse laser duration, the pH of the solution, the surfactants and the temperature of the solution, pulsed laser ablation in liquid method neither requires cumbersome equipment nor does it require intermediate chemicals and catalysts nor does it necessitate the post synthesis purification. The enhancement of photo-catalytic activity of cadmium sulfide-graphitic carbon nitride nanocomposite was tested for the photo-catalytic deactivation of Escherichia coli bacteria in water under visible light radiation. As anticipated, a significant improvement of photo-catalytic deactivation was observed, which is attributed to the enhanced and extended light absorption in the visible spectral region, and the formation of herterojunction between the semiconductors, which is instrumental in inhibiting the undesired recombination of photo-generated charge carriers. Quantitatively, the presence of cadmium sulfide on the graphitic carbon nitride surface contributed to a remarkable 129% increase of photo-catalytic degradation constant compared to pure graphitic carbon nitride, which resulted in the decrease of total depletion time of Escherichia coli from 156 min to 67 min with the cadmium sulfide-graphitic carbon nitride nanocomposite synthesized by pulsed laser ablation in liquid method. Our results on the efficient photo-catalytic deactivation of Escherichia coli under visible light assures that cadmium sulfide-graphitic carbon nitride nanocomposite can very well be used for photo-catalytic water purification by harvesting the abundant solar light.


Assuntos
Compostos de Cádmio/química , Grafite/química , Luz , Nanocompostos/química , Compostos de Nitrogênio/química , Sulfetos/química , Purificação da Água/métodos , Catálise , Escherichia coli/efeitos dos fármacos , Nanocompostos/toxicidade , Estudos Prospectivos
5.
Chemosphere ; 241: 124927, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31590029

RESUMO

Plasma treated g-C3N4 (PT-g-C3N4) was obtained by a simple and rapid DBD plasma modification process on the pristine g-C3N4. Compared with the pristine g-C3N4, the grain size of the PT-g-C3N4 decreased from 99.2 nm to 57.2 nm, the specific surface area and the pore volume increased by 15% and 33.8%, respectively. Oxygen-containing groups such as -NO2 and -COOH were observed to form on the surface of PT-g-C3N4 so the hydrophilic property of PT-g-C3N4 was much higher than that of pristine g-C3N4. More importantly, the photocatalytic H2O2 production activity of PT-g-C3N4 was significantly improved on account of the treatment in plasma atmosphere for only 5 min, the H2O2 yield of which was about 13 times that of the pristine g-C3N4. Our finding is not only of great significance for effectively promoting the production of H2O2 under mild conditions, but also proposes an innovative DBD plasma method to modify the g-C3N4 photocatalyst, which effectively promotes the improvement of photocatalytic activity and provides valuable insights for catalyst modification studies.


Assuntos
Grafite/química , Peróxido de Hidrogênio/química , Compostos de Nitrogênio/química , Catálise , Interações Hidrofóbicas e Hidrofílicas , Tamanho da Partícula , Fotoquímica/métodos , Porosidade , Propriedades de Superfície
6.
J Environ Sci (China) ; 87: 149-162, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31791488

RESUMO

A graphite carbon nitride (g-C3N4) modified Bi4O5I2 composite was successfully prepared in-situ via the thermal treatment of a g-C3N4/BiOI precursor at 400°C for 3 hr. The as-prepared g-C3N4/Bi4O5I2 showed high photocatalytic performance in Methyl Orange (MO) degradation under visible light. The best sample presented a degradation rate of 0.164 min-1, which is 3.2 and 82 times as high as that of Bi4O5I2 and g-C3N4, respectively. The g-C3N4/Bi4O5I2 was characterized by X-ray powder diffractometer (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman, X-ray photoelectron spectroscopy (XPS), ultraviolet-visible diffuse reflectance spectra (DRS), electrochemical impedance spectroscopy (EIS) and transient photocurrent response in order to explain the enhanced photoactivity. Results indicated that the decoration with a small amount of g-C3N4 influenced the specific surface area only slightly. Nevertheless, the capability for absorbing visible light was improved measurably, which was beneficial to the MO degradation. On top of that, a strong interaction between g-C3N4 and Bi4O5I2 was detected. This interplay promoted the formation of a favorable heterojunction structure and thereby enhanced the charge separation. Thus, the g-C3N4/Bi4O5I2 composite presented greater charge separation efficiency and much better photocatalytic performance than Bi4O5I2. Additionally, g-C3N4/Bi4O5I2 also presented high stability. •O2- and holes were verified to be the main reactive species.


Assuntos
Compostos Azo/química , Processos Fotoquímicos , Grafite/química , Luz , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Compostos de Nitrogênio/química , Espectroscopia Fotoeletrônica
7.
Chemosphere ; 239: 124713, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31494320

RESUMO

Ultra-thin layered structures and modified bandgaps are two efficient strategies to increase the photocatalytic performance of various materials for the semiconductor industry. In the present study, we combined both strategies in one material to form carbon-doped graphitic carbon nitride (g-C3N4) nano-layered structures by the method of melamine thermal condensation, in the presence of different mass ratios of biochar. The characterization showed that the composite with the best ratio retained the g-C3N4 polymeric framework and the bond with g-C3N4. The biochar was established via π-π stacking interactions and ether bond bridges. The π-conjugated electron systems provided from biochar can elevate charge separation efficiency. The ultra-thin structure also curtailed the distance of photogenerated electrons migrating to the surface and enlarge specific surface area of materials. The presence of carbon narrowed the bandgap and increased light absorption at a wider range of wavelengths of g-C3N4. The biochar/melamine ratio of 1:15 presented the best performance, 2.8 and 5 times faster than g-C3N4 degradating Rhodamine and Methyl Orange, respectively. Moreover, the catalyst presented a good stability for 4 cycles. In addition to that, biochar from waste biomass can be considered a sustainable, cost-effective, and efficient option to modify g-C3N4-based photocatalysts.


Assuntos
Carvão Vegetal/farmacologia , Grafite/química , Luz , Nitrilos/química , Compostos de Nitrogênio/química , Fotólise/efeitos dos fármacos , Compostos Azo/química , Catálise , Carvão Vegetal/química , Rodaminas/química
8.
Chemosphere ; 239: 124612, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31499301

RESUMO

The degradation of carboxylic acid has been identified as one of the rate-determining steps in the mineralization of organic pollutants by ozonation. In this study, Ce(III)-doped graphitic carbon nitride (Ce-CN) composites with different Ce(III) contents were synthesized and used as catalysts for the ozonation of oxalate. The morphology and structure of the Ce-CN were comprehensively characterized using various techniques such as SEM, XRD, FTIR, and XPS. The results show that the structure of g-C3N4 provided an ideal site for the accommodation of Ce(III) and thus facilitated the formation of surface hydroxyl groups. With 2.5%Ce-CN as a catalyst, the degradation efficiency of oxalate was increased by 47.1% after reaction for 30 min. The decomposition of ozone was accelerated in the presence of Ce-CN. Hydroxyl radicals were recorded by electron spin resonance and identified as the major actives species. Under the catalysis of 2.5%Ce-CN, the production of hydroxyl radicals was increased by 40%. The Ce(III) and surface hydroxyl groups that distributed uniformly on the surface of Ce-CN were speculated as the dual catalytic sites for the complexation of oxalate and activation of ozone, respectively. Ce-CN had a high stability and reutilization capability. It is proposed that a complex was formed between surface Ce(III) and oxalate, and this complex could be more easily attacked by the surrounding ozone and hydroxyl radicals than free oxalate. As oxalate is a typical recalcitrant carboxylic acid, the findings from this study are expected to promote the application of ozonation in the removal of organic pollutants.


Assuntos
Cério/química , Grafite/química , Compostos de Nitrogênio/química , Oxalatos/química , Ozônio/química , Poluentes Químicos da Água/química , Catálise , Radical Hidroxila/química , Compostos Orgânicos
9.
Chem Commun (Camb) ; 55(87): 13082-13084, 2019 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-31608901

RESUMO

Herein, a photoelectrochemical biosensor was successfully constructed on the basis of a sensitization strategy of doxorubicin sensitized graphitic carbon nitride for the ultrasensitive detection of microRNA-141 with the assistance of a target-activated enzyme-free DNA walker.


Assuntos
Antibióticos Antineoplásicos/farmacologia , Técnicas Biossensoriais , DNA/efeitos dos fármacos , Doxorrubicina/farmacologia , Técnicas Eletroquímicas , Grafite/química , MicroRNAs/análise , Compostos de Nitrogênio/química , Antibióticos Antineoplásicos/química , Doxorrubicina/química , Processos Fotoquímicos
10.
Nanoscale ; 11(39): 18416-18425, 2019 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-31576862

RESUMO

As a widely studied photoactive antibacterial nanomaterial, the intrinsic antibacterial traits of graphitic carbon nitride (g-C3N4) as a two-dimensional nanomaterial have not been reported so far. Herein, nitrogen-plasma-treated g-C3N4 (N-g-C3N4) nanosheets and their influence on bactericidal characteristics are investigated. Bactericidal rates of more than 99% have been successfully achieved for 8 kinds of foodborne pathogenic bacteria by N-g-C3N4 with 8 h incubation in the dark. The achieved rates are percentage wise 10 times higher than those for pristine g-C3N4. Cell rupture caused by direct mechanical contact between g-C3N4 nanosheets and cell membranes is observed. X-ray photoelectron spectroscopy revealed a substantial loss of surface defects and nitrogen vacancies in N-g-C3N4. Molecular dynamics simulations further indicated that the largely sealed defects of N-g-C3N4 enhanced the electrostatic attraction between inherent pores and lipid heads; thus, further insertion of N-g-C3N4 was promoted, resulting in enhanced antibacterial activity. This study establishes novel fabrication and application strategies for carbon based antibacterial nanomaterials.


Assuntos
Antibacterianos/química , Grafite/química , Nanoestruturas/química , Compostos de Nitrogênio/química , Gases em Plasma/química , Espectroscopia Fotoeletrônica
11.
Anal Chim Acta ; 1089: 48-55, 2019 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-31627818

RESUMO

Combining of amperometric and square wave voltammetric methods (SWV), the dual-signal sandwich electrochemical immunosensor was developed for quantitative determination of amyloid ß-protein (Aß). Cu was doped into Al2O3 lattice (Cu-Al2O3) and reacts with graphite carbon nitride (g-C3N4) to generate Cu-Al2O3-g-C3N4 with internal dual-reaction center structure, which has good catalytic properties of hydrogen peroxide (H2O2). Subsequently, palladium nanoparticles (Pd NPs) was introduced into Cu-Al2O3-g-C3N4 (Cu-Al2O3-g-C3N4-Pd) that not only synergistically catalyzed H2O2 but also immobilized anti-Aß (Ab1) via Pd-NH2. The Cu-Al2O3-g-C3N4-Pd was used as matrix material to modify the electrode, which can produce obviously electrochemical signals through Amperometry i-t curve. Meanwhile, the Zr6O4(OH)4(CO2)12 (UiO-66) modified with polyaniline (PANI) has the large specific surface, good conductivity and adsorption capacity, which can support methylene blue (MB) as signal label of anti-Aß (Ab2). Therefore, the UiO-66@PANI-MB can provide an obviously electrochemical signal about MB through SWV. Under optimal conditions, the dual-signal sandwich electrochemical immunosensor has salient analytical performance and both signal platforms provide more accurate results. The linear range of detection obtained by the immunosensor was 10 fg/mL-100 ng/mL, and the detection limit was 3.3 fg/mL. This method not only provided a reliable guarantee for the experimental detection but also provided an effective strategy for the detection of other biological.


Assuntos
Peptídeos beta-Amiloides/sangue , Técnicas Eletroquímicas/métodos , Imunoensaio/métodos , Estruturas Metalorgânicas/química , Nanocompostos/química , Óxido de Alumínio/química , Peptídeos beta-Amiloides/imunologia , Compostos de Anilina/química , Anticorpos Imobilizados/imunologia , Cobre/química , Grafite/química , Limite de Detecção , Nanopartículas Metálicas/química , Azul de Metileno/química , Compostos de Nitrogênio/química , Paládio/química , Reprodutibilidade dos Testes
12.
Artigo em Inglês | MEDLINE | ID: mdl-31484371

RESUMO

A novel graphite-phase carbon nitride (g-C3N4)/bismuth ferrite (BiFeO3)/carbon nanotubes (CNTs) ternary magnetic composite (CNBT) was prepared by a hydrothermal synthesis. Using this material, Cr(VI) and methylene blue (MB) were removed from wastewater through synergistic adsorption and photocatalysis. The effects of pH, time, and pollutant concentration on the photocatalytic performance of CNBT, as well as possible interactions between Cr(VI) and MB species were analyzed. The obtained results showed that CNTs could effectively reduce the recombination rate of electron-hole pairs during the photocatalytic reaction of the g-C3N4/BiFeO3 composite, thereby improving its photocatalytic performance, while the presence of MB increased the reduction rate of Cr(VI). After 5 h of the simultaneous adsorption and photocatalysis by CNBT, the removal rates of Cr(VI) and MB were 93% and 98%, respectively. This study provides a new theoretical basis and technical guidance for the combined application of photocatalysis and adsorption in the treatment of wastewaters containing mixed pollutants.


Assuntos
Bismuto/química , Cromo/química , Compostos Férricos/química , Grafite/química , Azul de Metileno/química , Nanocompostos/química , Nanotubos de Carbono/química , Compostos de Nitrogênio/química , Raios Ultravioleta , Poluentes Químicos da Água/química , Adsorção , Catálise , Compostos Férricos/efeitos da radiação , Grafite/efeitos da radiação , Nanocompostos/efeitos da radiação , Nanotubos de Carbono/efeitos da radiação , Compostos de Nitrogênio/efeitos da radiação , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias , Poluentes Químicos da Água/efeitos da radiação
13.
Mater Sci Eng C Mater Biol Appl ; 104: 109846, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31500002

RESUMO

Bacterial pathogens of water origin have potential public threats thus suggesting the need of developing efficient and sustainable water disinfection strategies from waterborne pathogens. We set out to synthesize different controlled morphologies of graphitic carbon nitride (g-C3N4) polymer, evaluate their comparative effects on the generation of reactive oxygen species (ROS), and investigate potential applications in water purification systems. Characterization of the synthesized microstructures of g-C3N4, such as melamine-cyanuric acid (MCA)-based rosette-type, rod-type, 2D hexagonal, and 3D cubic mesoporous silica was accomplished using Fourier transform infrared (FT-IR), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), X-ray diffractometry (XRD), and transmission electron microscopy (TEM). The microbial inhibitory potential of 2D g-C3N4 photocatalyst against waterborne Escherichia coli, Staphylococcus aureus, and Salmonella typhimurium was evaluated based on the effective activity of 2D g-C3N4 upon visible light excitations. The microbicidal efficiency of 2D g-C3N4 was evident within 30 min of visible light exposure via direct interaction, while other microstructures of g-C3N4 demonstrated only slight antimicrobial effects after 120 min, with insufficient ROS generation. The antimicrobial and ROS-generating effects of 2D g-C3N4 depended on the type and surface area of the synthesized 2D g-C3N4 material. Considering its availability and excellent disinfection activity, 2D g-C3N4 obtained from simple and convenient facile synthesis is a promising solar-driven photocatalyst for clearing microbial contamination from water.


Assuntos
Grafite/química , Luz , Compostos de Nitrogênio/química , Polímeros/química , Esterilização/métodos , Microbiologia da Água , Bactérias/efeitos dos fármacos , Bactérias/efeitos da radiação , Catálise , Espécies Reativas de Oxigênio/metabolismo , Difração de Raios X
14.
Nanoscale ; 11(32): 14993-15003, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-31380525

RESUMO

Quantum dots (QDs) have extensive application prospects in the fields of optics, magnetism, catalysis, and biomedicine. New carbon-doped QDs are currently being used in these research fields. Graphitic carbon nitride QDs (g-CNs) composed of only carbon and nitrogen have attracted attention because of their unique optical and catalytic properties. g-CNs have numerous electronic properties and can be used as photocatalytic modifiers in a wide range of applications in electrochemistry. Additionally, g-CNs also have biological potential and due to their chemical composition have extremely low toxicity; their blue light emission can be applied to biological imaging, and their appropriate energy level (2.7 eV) allows electrons to be deposited on their surface, which allows g-CNs to be used as photosensitizers in optical therapy. Finally, g-CNs can be combined with other nanomaterials to form composite materials, which can result in new advantages not seen in either of the materials alone. In this manuscript, we thoroughly report the most recent findings regarding the synthesis of g-CNs and their respective properties. We report the advantages of g-CNs conferred by their unique properties and their advantages for application in current biology and medicines.


Assuntos
Grafite/química , Nanocompostos/química , Compostos de Nitrogênio/química , Animais , Técnicas Biossensoriais/métodos , Humanos , Nanocompostos/uso terapêutico , Neoplasias/tratamento farmacológico , Fármacos Fotossensibilizantes/química , Fármacos Fotossensibilizantes/farmacologia , Fármacos Fotossensibilizantes/uso terapêutico , Pontos Quânticos/química , Cicatrização/efeitos dos fármacos
15.
Biosens Bioelectron ; 142: 111546, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31387026

RESUMO

This work presents a novel hexagonal boron nitride (h-BN) based self-powered photoelectrochemical (PEC) aptasensor for ultrasensitive detection of diazinon (DZN) with excellent photoelectric conversion efficiency. It was the first time that h-BN based materials were applied to PEC aptasensor, in which the construction of Z-scheme heterojunction of h-BN and graphitic carbon nitride (CN) via doping sulfur into h-BN was innovatively proposed. Meanwhile, Au nanoparticles (AuNPs) were utilized for the surface plasmon resonance (SPR) effect and the formation of new recombination centers. The charge transfer mechanism was expounded and verified by the electron spin resonance (ESR) spin-trap technique. The proposed PEC aptasensor for determination of DZN exhibited a wide linear range from 0.01 to 10000 nM and a low detection limit of 6.8 pM with superb selectivity and remarkable stability. Moreover, the constructed PEC aptasensor performed well with excellent recoveries in three different real samples. This work illustrated that PEC aptasensor is a promising alternative to conventional analytical technologies for the detection of DZN and other organophosphorus (OP) pesticides. The designing ideas of the proposed h-BN based material can provide a foothold for the innovative construction of photoactive materials for PEC bioanalysis.


Assuntos
Aptâmeros de Nucleotídeos/química , Técnicas Biossensoriais/métodos , Compostos de Boro/química , Diazinon/análise , Praguicidas/análise , Técnicas Eletroquímicas/métodos , Poluentes Ambientais/análise , Ouro/química , Grafite/química , Limite de Detecção , Nanopartículas Metálicas/química , Modelos Moleculares , Compostos de Nitrogênio/química
16.
Environ Sci Pollut Res Int ; 26(30): 30941-30953, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31452123

RESUMO

The entrance of some hard-degradable pharmaceutical contaminants can cause irreparable damage to humans and other organisms; therefore, removing these pollutants from water is one of the most important activities in water purification field. In this work, the mineralization of morphine was performed using photocatalytic degradation method. Graphitic carbon nitride (g-C3N4) nanosheets, due to their promising tunable characteristics, were chosen as visible-light-driven nanostructured heterogeneous photocatalyst. To enhance the photocatalytic activity, g-C3N4 was doped with Ag noble metal due to its surface plasmon resonance effect and acting as an electron sink. The photodegradation of morphine was evaluated under different pH values, the dosage of the photocatalyst, initial concentration of morphine, and Ag% loading under sunlight as green energy. The maximum efficiency was obtained in the very low concentration of Ag@g-C3N4 photocatalyst with the superior low value of 0.17 g L-1. Near complete mineralization of morphine was achieved by Ag@g-C3N4 with metal content percentage equal to 5 in 180 min and pH = 2. Also, using various active species scavengers, superoxide anion radical was identified as the main responsible species in the photocatalysis reaction of morphine degradation.


Assuntos
Grafite/química , Morfina/química , Nanoestruturas/química , Compostos de Nitrogênio/química , Prata/química , Catálise , Poluentes Ambientais/química , Luz , Processos Fotoquímicos , Fotólise , Luz Solar , Ressonância de Plasmônio de Superfície
17.
Anal Chim Acta ; 1077: 281-287, 2019 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-31307720

RESUMO

Herein, a novel signal-off photoelectrochemical (PEC) aptasensor was proposed for sensitive detection of thrombin on the basis of C60@C3N4 nanocomposites as quencher and Au nanoparticles (depAu) decorated perylene tetracarboxylic acid (PTCA) as sensing platform. Owing to the excellent membrane-forming of PTCA and superior conductivity of depAu, the PTCA between two depAu layers can simply and effectively produce an extremely high initial photocurrent to afford a precondition for sensitive biodetection. Thereafter, the assembly of C60@C3N4 nanocomposites on electrode via typical sandwich reaction enabled the generation of a significantly decreased photocurrent. Here, the C3N4 with high surface area not only provided massive binding sites for C60 immobilization, but also partly competed with PTCA in light absorption for producing a significantly smaller photocurrent in the presence of electron donor ascorbic acid (AA). Additionally, both the C3N4 and C60 have the poor conductivity, which could inhibit the electron transfer to achieve a further decreased photocurrent, effectively improving the sensitivity of proposed biosensor. As a result, the PEC biosensor in a "signal-off" mode showed an extremely low detection limit down to 1.5 fM, providing a sensitive and universal strategy for protein detection.


Assuntos
Fulerenos/química , Grafite/química , Nanopartículas Metálicas/química , Nanocompostos/química , Compostos de Nitrogênio/química , Perileno/análogos & derivados , Trombina/análise , Aptâmeros de Nucleotídeos/química , Técnicas Biossensoriais/métodos , Técnicas Eletroquímicas/métodos , Fulerenos/efeitos da radiação , Ouro/química , Grafite/efeitos da radiação , Limite de Detecção , Nanocompostos/efeitos da radiação , Compostos de Nitrogênio/efeitos da radiação , Perileno/química , Reprodutibilidade dos Testes , Raios Ultravioleta
18.
Molecules ; 24(13)2019 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-31284536

RESUMO

In the present study, an adsorbent material for removal of organic contaminants in wastewater is synthetized by a green and facile mechanochemical method. It is composed of Ti3C2Tx MXene layers (obtained by mechanochemical etching of MAX phase with concentrated HF) pillared with terephthalate by rapid direct reaction. Such material shows high specific surface area (135.7 m2 g-1) and excellent adsorption capability of methylene blue (209 mg g-1) because of the larger interlayer space among MXene sheets and free carboxylate groups of terephthalate. The spent adsorbent is reutilized (with addition of sole aluminum) to synthetize the MAX phase by mechanochemical procedure, where the terephthalate and the pollutant are carbonized into the carbide. In this way, new MXene-based adsorbent can be re-synthetized for further use.


Assuntos
Carbono/química , Recuperação e Remediação Ambiental/métodos , Compostos de Nitrogênio/química , Elementos de Transição/química , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Cinética
19.
J Environ Sci (China) ; 84: 1-12, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31284901

RESUMO

A series of functional organic-metal AgCl-decorated graphitic carbon nitride (AgCl-CNx) composites were synthesized and applied for the degradation of oxalic acid (OA) under visible light. The highest photocatalytic activity was achieved with AgCl decoration ratio of 1.0 (denoted as AgCl-CN1.0). The pseudo-first-order constant for OA degradation was 0.0722 min-1 with the mineralization efficiency of 90.80% after 60 min reaction in the photocatalytic process with AgCl-CN1.0. A variety of characterization techniques including Brunauer-Emmett-Teller, X-ray diffraction, scanning electron microscope, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectra, ultraviolet-visible diffuse reflectance spectra, photoluminescence, and Mott-Schottky were utilized to elucidate the physicochemical, microstructure, and optical properties contributing to the improvement of the photocatalytic performance. The results showed that AgCl-CN1.0 had an oblate flaky erythrocyte-like structure with a moderate band gap energy of ~3.00 eV. In addition, the effects of the key parameters (i.e., AgCl-CN1.0 dosage, initial OA concentration, solution pH, and presence of natural organic matter) on OA degradation were systematically investigated. Radical scavenger experiments indicated that photogenerated holes, electrons, superoxide anion radicals, and hydroxyl radicals were the dominant reactive species. Moreover, AgCl-CN1.0 exhibited excellent stability and reusability for OA degradation without detectable Ag+ release in the solution over multiple reaction cycles. The efficient OA mineralization could be mainly ascribed to the moderate specific surface area, increased numbers of active sites, and effective interfacial charge transfer of AgCl-CN1.0. Overall, the AgCl-CN1.0 composite was demonstrated to be a highly efficient, stable, and recoverable photocatalyst.


Assuntos
Grafite/química , Compostos de Nitrogênio/química , Ácido Oxálico/química , Fotólise , Compostos de Prata/química , Poluentes Químicos da Água/química
20.
J Chromatogr A ; 1606: 460382, 2019 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-31353072

RESUMO

In this work, magnetic metal-organic frameworks-101 functionalized with graphite-like carbon nitride material (Fe3O4/g-C3N4/MIL-101) has been simply prepared for the efficient enrichment of glucocorticoids in cosmetics. Due to the introduction of g-C3N4, the water stability of MIL-101 has been greatly improved. This composite material also showed better selectivity for glucocorticoids than those for polycyclic aromatic hydrocarbons and benzene compounds due to the hydrogen bonding effect with g-C3N4 and the size-matching effect with MIL-101. When the prepared material was used as the sorbents in magnetic solid-phase extraction (MSPE) and coupled with ultra-performance liquid chromatography-mass spectrometry (UPLC-MS/MS), a sensitive MSPE-UPLC-MS/MS method was developed. Under the optimal conditions, the calibration curves were linear over the concentration ranging from 0.01 to 2 µg/L with correlation coefficients (R2) between 0.9915 and 0.9995. The limit of detection (LOD) was as low as 2 ng/L with the RSDs lower than 5.5%. The recoveries ranged from 77.3% to 113%. The LOD of glucocorticoids in real samples analysis was improved by nearly three orders of magnitude compared to current literature records. The results indicated that Fe3O4/g-C3N4/MIL-101 could be used as MSPE extractant to determine glucocorticoids in complex cosmetics matrix.


Assuntos
Cosméticos/análise , Glucocorticoides/análise , Grafite/química , Fenômenos Magnéticos , Estruturas Metalorgânicas/química , Compostos de Nitrogênio/química , Adsorção , Limite de Detecção , Estruturas Metalorgânicas/ultraestrutura , Espectroscopia Fotoeletrônica , Extração em Fase Sólida/métodos , Água/química
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