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1.
Water Sci Technol ; 82(5): 829-842, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33031063

RESUMO

A high-surface-area and inexpensive activated carbon has been produced from lemon peel using chemical activation with H3PO4 at 500 °C in a N2 atmosphere. Afterwards, the synthesized cobalt nanoparticles using coprecipitation method were adsorbed on the activated carbon surface, and as a result magnetic activated carbon was obtained. Sample characterization has been assessed via X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, nitrogen adsorption-desorption and magnetic properties. It was found that magnetic activated carbon-cobalt nanoparticles (MAC/Co) synthesized had a high saturation magnetization. The MAC/Co revealed super-paramagnetic behaviors at room temperature, and have been readily isolated from solution by using an exterior magnet. Next, adsorption behavior of malachite green and Pb(II) onto the generated MAC/Co has been examined. Sorption kinetics and equilibrium have been studied using batch procedure. The kinetic and isothermal adsorption results were matched completely with the Elovich and Langmuir models, respectively. Based on the Langmuir model, the highest adsorption capacities of malachite green dye and Pb(II) ion respectively were 263.2 and 312.5 mg g-1 at room temperature. Based on the results, the MAC/Co is a probable economic and effective adsorbent that can be employed as a new adsorbent to remove malachite green dye and Pb(II) from wastewater.


Assuntos
Nanopartículas , Poluentes Químicos da Água , Carvão Vegetal , Cobalto , Chumbo , Fenômenos Magnéticos , Corantes de Rosanilina , Águas Residuárias , Poluentes Químicos da Água/análise
2.
Chemosphere ; 254: 126898, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32957293

RESUMO

The utilization of Microcystis biomass is an urgent issue in the mitigation of cyanobacterial bloom. In this study, Microcystis-derived biochar (MB) and Fe3O4-modified biochar (Fe3O4/MB) were fabricated for the U(VI) elimination. The results showed that U(VI) sorption process by either MB or Fe3O4/MB was pH-dependent and ionic strength-independent. The maximum sorption capacity of MB was higher than that of Fe3O4/MB. According to the analysis of X-ray photoelectron spectroscopy, U(VI) sorption on both MB and Fe3O4/MB was mainly ascribed to the surface complexation between U(VI) and oxygen-containing functional groups on the surface of MB. Fe3O4 particles on the surface of MB didn't provide extra active sites for the sorption of U(VI), but it enabled the adsorbent to be magnetically separated. Five consecutive sorption/desorption cycles verified the good reusability of Fe3O4/MB in this study. Therefore, the investigation is not only meaningful for the utilization of nuisance biomass from cyanobacterial blooms, but also provides novel adsorbents for the U(VI) removal from aqueous solutions.


Assuntos
Carvão Vegetal/química , Eutrofização , Óxido Ferroso-Férrico/química , Microcystis/química , Urânio/análise , Poluentes Radioativos da Água/análise , Purificação da Água/métodos , Adsorção , Biomassa , Concentração de Íons de Hidrogênio , Fenômenos Magnéticos , Modelos Teóricos , Concentração Osmolar
3.
Bioresour Technol ; 317: 124035, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32871333

RESUMO

In the present work, laccase was successfully immobilized in peroxidase mimicking magnetic metal organic frameworks (MMOFs) within 30 min using a facile approach. The integration of magnetic nanoparticles during synthesis significantly eases the separation of prepared biocatalyst using an external magnet. The immobilization of laccase was confirmed using different characterization techniques. The laccase@MMOFs found spherical in nature with an average particle size below 100 nm. The synthesized laccase embedded framework exhibits supermagnetic property with the saturation magnetization (Ms) of 34.12 emu/gm. The prepared bio-metallic frameworks maintain high surface area and thermal stability. The laccase@MMOFs was successfully exploited for the degradation of industrial dyes in batch and continuous mode with an average degradation efficiency of 95%. The prepared laccase structure had an excellent recyclability retaining upto 89% residual activity upto 10th cycle and can be stored at room temperature upto 30 days without any significant loss of activity.


Assuntos
Lacase , Estruturas Metalorgânicas , Corantes , Enzimas Imobilizadas , Fenômenos Magnéticos , Peroxidase
4.
Nat Commun ; 11(1): 4714, 2020 09 18.
Artigo em Inglês | MEDLINE | ID: mdl-32948754

RESUMO

The application of forces and torques on the single molecule level has transformed our understanding of the dynamic properties of biomolecules, but rare intermediates have remained difficult to characterize due to limited throughput. Here, we describe a method that provides a 100-fold improvement in the throughput of force spectroscopy measurements with topological control, which enables routine imaging of 50,000 single molecules and a 100 million reaction cycles in parallel. This improvement enables detection of rare events in the life cycle of the cell. As a demonstration, we characterize the supercoiling dynamics and drug-induced DNA break intermediates of topoisomerases. To rapidly quantify distinct classes of dynamic behaviors and rare events, we developed a software platform with an automated feature classification pipeline. The method and software can be readily adapted for studies of a broad range of complex, multistep enzymatic pathways in which rare intermediates have escaped classification due to limited throughput.


Assuntos
DNA/química , Fenômenos Magnéticos , Magnetismo/métodos , Nanotecnologia , Análise Espectral/métodos , Ciprofloxacino/farmacologia , DNA/efeitos dos fármacos , Quebras de DNA/efeitos dos fármacos , Conformação de Ácido Nucleico , Pinças Ópticas , Fenômenos Físicos , Software
5.
Mar Pollut Bull ; 159: 111489, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32892922

RESUMO

A bacterial consortium immobilized in magnetic floating biochar gel beads is proposed to remove high-molecular-weight polycyclic aromatic hydrocarbons. The microbial consortium performed better than single strains and consisted of four strains of marine bacteria for degrading pyrene (PYR), two strains for benzo(a)pyrene (BAP), and three strains for indeno(1,2,3-cd)pyrene (INP), which were isolated from oil-contaminated seawater. The immobilized cells could biodegrade 89.8%, 66.9% and 78.2% of PYR, BAP and INP, respectively, and had better tolerance to pH, temperature and salinity than free cells. The Andrews model was used to explore the biodegradation kinetics, and when the initial concentrations of PYR, BAP, and INP were 7.80, 3.05, and 3.41 mg/L, the specific biodegradation rates reached maximum values of 0.2507, 0.1286, and 0.1930 d-1, respectively. The immobilized microbial consortium had a high HMW-PAH removal ability and good floatability and magnetic properties and could be collected by an external magnetic field.


Assuntos
Hidrocarbonetos Policíclicos Aromáticos , Poluentes do Solo , Biodegradação Ambiental , Carvão Vegetal , Campos Magnéticos , Fenômenos Magnéticos , Consórcios Microbianos
6.
Chemosphere ; 258: 127276, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32947657

RESUMO

It is crucial for water environment security to remove its p-arsanilic acid (p-ASA) efficiently. Namely, removing p-arsanilic acid from aqueous media through magnetic separation, has become a novel method of removing toxic pollutants from water. Batch adsorption experiments demonstrated a higher adsorption of lignin-based magnetic activated carbon (201.64 mg g-1) toward p-ASA. In addition, LMAC nanoparticles exhibited typical magnetism (35.63 emu g-1 of saturation magnetization) and could be easily separated from the aqueous solution. Meanwhile, the endothermic adsorption of p-ASA over LMAC could spontaneously proceed and be well described by the pseudo-first-order and pseudo-second-order model as well as the intra-particle diffusion model. Moreover, the mechanisms during p-ASA adsorption over LMAC included the electrostatic attraction, surface complexation, π-π stacking and hydrogen bonding interaction. Importantly, lignin-based magnetic activated carbon has high absorbability and preferable reusability in real water samples. Consequently, this paper provides insights into preparation of the lignin-based magnetic activated carbon may be potential adsorbents for the remediation of organoarsenic compounds.


Assuntos
Ácido Arsanílico/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Adsorção , Carvão Vegetal , Cinética , Lignina , Fenômenos Magnéticos , Magnetismo , Imãs , Água , Poluentes Químicos da Água/análise
7.
Anticancer Res ; 40(9): 5151-5158, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32878803

RESUMO

BACKGROUND/AIM: Magnetic stimulation is used in the treatment of a diversity of diseases, but a complete understanding of the underlying mechanisms of action requires further investigation. We examined the effect of static magnetic stimulation (SMS) in different cell lines. MATERIALS AND METHODS: A culture plate holder with attached NeFeB magnets was developed. Different magnetic field intensities and periods were tested in tumoral and non-tumoral cell lines. To verify the cellular responses to SMS, cell viability, cell death, cell cycle and BDNF expression were evaluated. RESULTS: Exposure of SH-SY5Y cells to SMS for 24 hours led to a decrease in cell viability. Analysis 24 h after stimulation revealed a decrease in apoptotic and double-positive cells, associated with an increase in the number of necrotic cells. CONCLUSION: The effects of SMS on cell viability are cell type-specific, inducing a decrease in cell viability in SH-SY5Y cells. This suggests that SMS may be a potential tool in the treatment of neuronal tumors.


Assuntos
Sobrevivência Celular/efeitos da radiação , Fenômenos Magnéticos , Apoptose/efeitos da radiação , Fator Neurotrófico Derivado do Encéfalo/genética , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Ciclo Celular/efeitos da radiação , Linhagem Celular Tumoral , Regulação Neoplásica da Expressão Gênica/efeitos da radiação , Humanos , Neuroblastoma/genética , Neuroblastoma/metabolismo , Especificidade de Órgãos/efeitos da radiação
8.
J Environ Manage ; 271: 110964, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32778273

RESUMO

In the last decades, the use of magnetic nanocomposites as a catalyst was considered for removal of organic pollutants due to its easy separation. Therefore, initially, TiO2@ZnFe2O4/Pd nanocomposite was prepared and then used in the photodegradation of diclofenac under direct solar irradiation in the batch and continuous systems. The structure, morphology and other specifications of produced nanocatalyst were determined via XRD, VSM, FESEM/EDX, FTIR, GTA, UV-Vis, Zeta potential, XPS and ICP-OES. The effective factors on diclofenac removal via nanophotocatalyst viz. pH, catalyst concentration, initial concentration of diclofenac, and flow rate and column length on diclofenac photodegradation were studied. Based on the results, the optimal rate for pH, catalyst concentration, and initial concentration of diclofenac was 4, 0.03 g/l and 10 mg/l respectively. Pd-coated TiO2@ZnFe2O4 magnetic photocatalyst had higher photocatalytic activity in diclofenac photodegradation in relation to ZnFe2O4 and TiO2@ZnFe2O4 under solar light irradiation. The findings showed that after five recycles, the photocatalytic efficiency did not show much reduction i.e. the removal efficiency from 86.1% in the first cycle reduced only to 71.38% in the last cycle. Likewise, in this study, with flow rate reduction and column length increase diclofenac degradation rate increased.


Assuntos
Poluentes Ambientais , Nanocompostos , Preparações Farmacêuticas , Catálise , Luz , Fenômenos Magnéticos , Titânio
9.
J Environ Manage ; 271: 110970, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32778274

RESUMO

The concentrative isolation of metal traces from aqueous solutions is of vital importance for environmental and industrial processes. Developing reliable systems of nanoscale that can be fine-tuned to effectively isolate these metals remains an intriguing aim which can potentially beget economic benefits and mitigate major environmental concerns. Here we demonstrate a conceptual metal extraction system where magnetic multi-wall carbon nanotubes (M-MWCNTs) are surface-equipped with a molecular network of polyethylenimine (PEI) to serve as a reusable nano-ionic exchanger, referred to as "M-MWCNTs-PEI". The designed nano-ionic exchanger forms readily stable suspensions with the metal-bearing aqueous solutions eliminating the need for vigorous agitation. Besides, it can be magnetically manipulated and separated in/from the solution. To exemplify its potential for the isolation of metal traces, the M-MWCNTs-PEI was tested with the uranium trace ions in aqueous media. The M-MWCNTs-PEI featured distinct sorption capacity of ~488 mg/g at pH 6, with moderate, but stable, binding affinity toward uranium ions. As such, excellent isolation performance is demonstrated while bound uranium ions are effectively concentrated and recovered from the interfacial PEI molecular network. This was efficiently achieved by exposing the loaded M-MWCNTs-PEI to solutions of small volumes and specific chemistry. Such combined qualities of large capacity and reusability have not been observed with the previously reported ion exchange systems. Altogether, our observations here demonstrate how functional systems of nanoscale can be adapted for industrial applications while this concept can be extended to address other important resources such as rare-earth and lanthanide elements.


Assuntos
Nanotubos de Carbono , Urânio , Adsorção , Concentração de Íons de Hidrogênio , Cinética , Fenômenos Magnéticos , Soluções , Suspensões
10.
Viruses ; 12(8)2020 08 07.
Artigo em Inglês | MEDLINE | ID: mdl-32784757

RESUMO

Rapid large-scale testing is essential for controlling the ongoing pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The standard diagnostic pipeline for testing SARS-CoV-2 presence in patients with an ongoing infection is predominantly based on pharyngeal swabs, from which the viral RNA is extracted using commercial kits, followed by reverse transcription and quantitative PCR detection. As a result of the large demand for testing, commercial RNA extraction kits may be limited and, alternatively, non-commercial protocols are needed. Here, we provide a magnetic bead RNA extraction protocol that is predominantly based on in-house made reagents and is performed in 96-well plates supporting large-scale testing. Magnetic bead RNA extraction was benchmarked against the commercial QIAcube extraction platform. Comparable viral RNA detection sensitivity and specificity were obtained by fluorescent and colorimetric reverse transcription loop-mediated isothermal amplification (RT-LAMP) using a primer set targeting the N gene, as well as RT-qPCR using a primer set targeting the E gene, showing that the RNA extraction protocol presented here can be combined with a variety of detection methods at high throughput. Importantly, the presented diagnostic workflow can be quickly set up in a laboratory without access to an automated pipetting robot.


Assuntos
Betacoronavirus/química , Betacoronavirus/genética , Técnicas de Laboratório Clínico/métodos , Infecções por Coronavirus/virologia , Pneumonia Viral/virologia , RNA Viral/isolamento & purificação , Betacoronavirus/isolamento & purificação , Infecções por Coronavirus/diagnóstico , Humanos , Fenômenos Magnéticos , Técnicas de Diagnóstico Molecular/métodos , Técnicas de Amplificação de Ácido Nucleico/métodos , Pandemias , Pneumonia Viral/diagnóstico , RNA Viral/genética , Reação em Cadeia da Polimerase em Tempo Real/métodos , Transcrição Reversa , Sensibilidade e Especificidade
11.
J Chromatogr A ; 1626: 461362, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797841

RESUMO

Exploring new material as adsorbent for the efficient enrichment of pollutants is always of great significance in analytical chemistry. In this work, a magnetic azobenzene framework (labeled as MAzo) was constructed as a magnetic solid phase extraction (MSPE) adsorbent by a simple and environmentally benign strategy. The MAzo exhibited the attractive features of strong magnetism, outstanding adsorption performance, as well as good reusability. Combining MAzo-based MSPE with high performance liquid-phase chromatography, a simple and effective method was developed for simultaneous determination of four phenylurea herbicides in pear juice and apple juice samples. Under optimized experimental conditions, the method offered low limits of detection of 0.05-0.15 ng mL-1, high recoveries of 86.7-109.2% with RSD less than 7%. Density functional theory calculation indicated that the good adsorption performance of MAzo for PUHs can be ascribed to the strong H-bonding forces and weak π-π interactions. The facile, green, low-cost synthesis method together with the excellent adsorption performance endows the MAzo great application prospect in sample preparation.


Assuntos
Compostos Azo/química , Poluentes Ambientais/análise , Herbicidas/análise , Compostos de Fenilureia/análise , Extração em Fase Sólida/métodos , Adsorção , Cromatografia Líquida de Alta Pressão , Poluentes Ambientais/isolamento & purificação , Sucos de Frutas e Vegetais/análise , Herbicidas/isolamento & purificação , Fenômenos Magnéticos , Malus , Estruturas Metalorgânicas , Compostos de Fenilureia/isolamento & purificação , Pyrus
12.
Environ Monit Assess ; 192(9): 583, 2020 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-32803620

RESUMO

In this study, a new analytical strategy was developed to determine trace cadmium in aqueous samples with high sensitivity and accuracy. A combination of magnetic nickel nanoparticles (Ni-MNPs) based dispersive solid-phase extraction (DSPE) and flame atomic absorption spectrometry fitted with a slotted quartz tube (SQT-FAAS) lowered the detection limit of cadmium. The magnetic Ni nanoparticles were synthesized, characterized, and thoroughly optimized in a stepwise approach. The quartz tube was custom cut in the laboratory to suit the specifics of the flame burner. Using the optimized conditions, a limit of detection value of 0.58 µg/L and limit of quantification value of 1.93 µg/L were obtained. To demonstrate accuracy and applicability of the developed method, well water samples were analyzed for their Cd content, and matrix effect on the extraction yield was investigated. The percent recovery results calculated ranged from 93.8 to 108.2%, with corresponding standard deviation values ranging from 1.7 to 7.7. These results established the developed method as sensitive, accurate, and precise for determination of cadmium at trace levels.


Assuntos
Microextração em Fase Líquida , Poluentes Químicos da Água/análise , Cádmio/análise , Monitoramento Ambiental , Fenômenos Magnéticos , Quartzo , Extração em Fase Sólida , Espectrofotometria Atômica
13.
Sci Total Environ ; 737: 140283, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32783860

RESUMO

The agricultural wastes disposal and polluted water purification are always the key issues of environmental restoration. In this work, a magnetic biogas residue-based biochar (mBR-C) by direct pyrolysis and sonochemical method was prepared from biogas residue (BR). Response design methodology based on Box-Behnken design was used for the preparation parameters optimization. The characterization results identified that mBR-C had well-developed pore structure and surface area, which was beneficial to diffuse and capture heavy metal ions. Traces of toxic heavy metal in mBR-C was leached (˂0.04 mg/L) through TCLP method, indicating the environmental safety of the magnetic biochar. Meanwhile, the mBR-C exhibited excellent solid-liquid separation efficiency because of its strong magnetism. The series of adsorption experiments indicated that mBR-C could capture Cu2+ and Pb2+ rapidly, and the maximum adsorption capacity for Cu2+ and Pb2+ was 75.76 and 181.82 mg/g, respectively, which was higher than some other biochars previously reported. mBR-C was further applied in the synthetic wastewater treatment, which could effectively purify at least 600 mL (150 BV) to meet emission standards. After several column adsorption-desorption cycles, the adsorption capacity could still reach 85%, implying that mBR-C has good reusability and stability. Overall, the mBR-C can be used as an eco-friendly, desirable, economic and recyclable biosorbent in heavy metal polluted water treatment, providing a new idea for a combination of biogas residue recycle and wastewater treatment.


Assuntos
Biocombustíveis , Metais Pesados , Adsorção , Carvão Vegetal , Fenômenos Magnéticos
14.
Water Sci Technol ; 81(11): 2322-2336, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32784277

RESUMO

Water-resistant magnetic graphene-anchored zeolite imidazolate (Fe3O4/ZIF-8-G) composite materials with the largest surface area are formed by directly growing a hydrophobic ZIF-8 skeleton onto a graphene support through self-assembly in methanol. Fe3O4/ZIF-8-G hybrid composite has water resistance and super strong adsorption capacity, and is used as an effective adsorbent for adsorption and removal of residual tetracycline in wastewater. The morphologies and structure, as well as water resistance of Fe3O4/ZIF-8-G, were characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetry analysis (TGA), N2 adsorption and pHPZC. The adsorption for tetracycline (TC), oxytetracycline (OTC) and chlortetracycline (CTC) followed pseudo-second-order kinetics and fitted the Freundlich adsorption model with the simultaneous adsorption capacity for TC (382.58 mg g-1), OTC (565.94 mg g-1) and CTC (608.06 mg g-1) at pH 5-6 for 10 h. These were much higher than previously reported results for the removal of tetracycline from aqueous solutions. The used Fe3O4/ZIF-8-G could be effectively reused and recycled at least five times without significant loss of adsorption capacity. The hydrophobic and π-π interaction between the aromatic rings of TCs and the aromatic imidazole rings of the ZIF-8-G framework were the main adsorption mechanism on the surface of Fe3O4/ZIF-8-G. Constructing a hydrophobic surface of ZIF-8/G framework resulted in a reduction of the hydrophilic sites of the surface. This can improve stability and selective adsorption of ZIF-8-G framework. In addition, the results show no significant difference in the adsorption kinetics and adsorption capacity of Fe3O4/ZIF-8-G for TC, OTC and CTC in pure water and wastewater.


Assuntos
Grafite , Poluentes Químicos da Água/análise , Purificação da Água , Zeolitas , Adsorção , Fenômenos Magnéticos , Espectroscopia de Infravermelho com Transformada de Fourier , Tetraciclinas , Águas Residuárias , Água
15.
Bioresour Technol ; 315: 123797, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32683288

RESUMO

Fenton modification, involving iron-promoted pyrolysis followed by H2O2 oxidation, was first employed to improve the adsorptive and magnetic capabilities of biochar. Modified biochars were prepared from rubber tree bark and coconut shell through iron-promoted pyrolysis and subsequent H2O2 oxidation, and their adsorption behaviors toward Cr (VI) and MB were evaluated in aqueous solution. The modified biochars pyrolyzed at 300 and 400 ˚C displayed much higher adsorption capabilities than corresponding pristine biochars for Cr (VI) and MB, respectively, ascribing to introduction of COOH, CO and C-O groups by Fenton oxidation. More importantly, saturation magnetization could be enhanced by transforming nonmagnetic iron oxides into γ-Fe2O3 through H2O2 oxidation. The removal of Cr (VI) and MB could be primarily contributed to the adsorption of biochar matrix by reduction/hydrogen bonding/cation exchange/electrostatic interaction and hydrogen bonding/cation exchange/electrostatic interaction, respectively. This would provide a novel and efficient strategy for making highly adsorptive magnetic biochar.


Assuntos
Peróxido de Hidrogênio , Poluentes Químicos da Água/análise , Adsorção , Carvão Vegetal , Cromo , Fenômenos Magnéticos
16.
Bioresour Technol ; 315: 123848, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32707505

RESUMO

Low temperatures can lead to an increase of N2O generation and emission from the nitrogen removal process in wastewater treatment plants. This study investigated the effect of the addition of magnetic powder on N2O generation and emission from a sequencing batch reactor treating domestic sewage at low temperatures. The results showed that the magnetic powder simultaneously inhibited N2O generation and emission and improved the removal of NH4+, total nitrogen (TN), and chemical oxygen demand at low temperatures. Furthermore, the conversion rate of N2O (N2O generation to TN removal) was reduced. The efficacy of the magnetic powder depended on its concentration, which could be ordered as 1 mg/L > 2 mg/L > 4 mg/L. With the addition of magnetic powder, especially at the 1 mg/L level, the activities of nitrification and denitrification enzymes in activated sludge were significantly improved and the growth of ammonium and nitrite oxidizing bacteria was also promoted.


Assuntos
Óxido Nitroso/análise , Águas Residuárias , Reatores Biológicos , Desnitrificação , Fenômenos Magnéticos , Nitrificação , Nitrogênio , Esgotos , Temperatura
17.
Bioresour Technol ; 315: 123834, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32712515

RESUMO

The objective of this work was to use corncob as raw material to prepare green reusable magnetic biochar for removal of dyes in wastewater. For this purpose, an environmentally friendly NiAl layered double oxides modified magnetic corncob biochar (MC1/NiAl-LDO) was obtained by pyrolysis of NiAl layered double hydroxides modified magnetic corncob biochar (MC1/NiAl-LDH) at 700 °C for 3 h. The surface area of MC1/NiAl-LDO is 552.62 m2·g-1, which was much higher than that of MC1 (26.83 m2·g-1). MC1/NiAl-LDO for acridine orange (AO) exhibited higher adsorption ability, the adsorption capacity of MC1/NiAl-LDO was increased by 90% compared with MC1. Adsorption experiments for AO on MC1/NiAl-LDO were carried with effect of pH, adsorption time, initial concentrations of AO and ionic strength. MC1/NiAl-LDO can be recycled nine times. The results exhibited that MC1/NiAl-LDO was a low cost adsorbent, providing good example for th agricultural waste recycling.


Assuntos
Alumínio , Óxidos , Laranja de Acridina , Adsorção , Carvão Vegetal , Fenômenos Magnéticos , Níquel , Zea mays
18.
J Environ Manage ; 270: 110839, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32721303

RESUMO

We aim at fabricating a ternary magnetic recyclable Bi2WO6/BiOI@Fe3O4 composite that could be applied for photodegradation of tetracycline (TC) from synthetic wastewater. To identify any changes with respect to the composite's morphology and crystal structure properties, ΧRD, FTIR, FESEM-EDS, PL and VSM analyses are carried out. The effects of Fe3O4 loading ratio on the Bi2WO6/BiOI for TC photodegradation are evaluated, while operational parameters such as pH, reaction time, TC concentration, and photocatalyst's dose are optimized. Removal mechanisms of the TC by the composite and its photodegradation pathways are elaborated. With respect to its performance, under the same optimized conditions (1 g/L of dose; 5 mg/L of TC; pH 7; 3 h of reaction time), the Bi2WO6/BiOI@5%Fe3O4 composite has the highest TC removal (97%), as compared to the Bi2WO6 (63%). After being saturated, the spent photocatalyst could be magnetically separated from solution for subsequent use. In spite of three consecutive cycles with 71% of efficiency, the spent composite still has reasonable photocatalytic activities for reuse. Overall, this suggests that the composite is a promising photocatalyst for TC removal from aqueous solutions.


Assuntos
Antibacterianos , Tetraciclina , Fenômenos Magnéticos , Magnetismo , Fotólise
19.
J Chromatogr A ; 1625: 461305, 2020 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-32709348

RESUMO

A novel kind of magnetic porous carbon nano-fibers (Fe3O4@P-CNFs) materials was successfully prepared and used as an adsorbent. Based on the above-mentioned adsorbent, a simple and effective magnetic disperse solid-phase extraction (MSPE) method was developed and first utilized to the enrichment and purification of five Sudan dyes (including Sudan I, Sudan II, Sudan III, Sudan IV, and Sudan Red 7B) in foodstuffs for the first time. High-performance liquid chromatography was used to determine the content of the Sudan dyes. The parameters affecting the extraction performance were studied and optimized, including the amount of the adsorbent and inorganic salt, type and the volume of the eluent, pH of the sample solution and extraction time. Under the optimized experimental conditions, the results show that the proposed method has a good linear relationship (r≥ 0.9993). The limits of detection range from 0.88 µg L-1 to 1.27 µg L-1. The recoveries range from 86.6% to 99.7% with the relative standard deviations ranging from 0.6% to 7.9% in the methodology validation. The above-mentioned results indicate that the proposed method is a sensitive and reliable procedure with good reproducibility for the detection of Sudan dyes residues in foodstuffs.


Assuntos
Compostos Azo/análise , Fibra de Carbono/química , Corantes/análise , Análise de Alimentos , Fenômenos Magnéticos , Nanofibras/química , Adsorção , Compostos Azo/química , Corantes/química , Concentração de Íons de Hidrogênio , Limite de Detecção , Nanofibras/ultraestrutura , Porosidade , Análise de Regressão , Reprodutibilidade dos Testes , Sais/química , Fatores de Tempo
20.
J Chromatogr A ; 1625: 461340, 2020 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-32709363

RESUMO

In this study, a magnetized polyethylene composite has been prepared using ball milling procedure and employed as an efficient sorbent in magnetic dispersive solid phase extraction combined with dispersive liquid-liquid microextraction. This method has been utilized for the extraction and preconcentration of some pesticides from fruit juices prior to their quantification by gas chromatography-flame ionization detection. The prepared sorbent consisted of the natural iron oxide (obtained from sand) coated with polyethylene. In the present work, first a few mg of the magnetic composite is added into an aqueous solution containing the analytes and vortexed. After that the analytes are eluted with iso-propanol from the surface of the composite particles separated in the presence of a strong external magnetic field. For further enrichment of the analytes, 1,2-dibromoethane (at µL-level) as an extraction solvent is mixed with the obtained eluent and hastily injected into deionized water. The composite was characterized using techniques including vibrating sample magnetometry, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, Brunauer-Emmett-Teller nitrogen sorption, and Fourier transform infrared spectrophotometry. Under optimal conditions, the method provided low limits of detection (0.94-1.9 µg L-1) and quantification (3.2-5.9 µg L-1), high enrichment factors (570-692), good linearity (r2 ≥ 0.994), and satisfactory repeatabilities (relative standard deviations ≤ 8% for intra- and inter-day precisions at a concentration of 15 µg L-1 of each analyte).


Assuntos
Fenômenos Magnéticos , Praguicidas/isolamento & purificação , Polietileno/química , Polietileno/síntese química , Adsorção , Centrifugação , Cromatografia Gasosa , Sucos de Frutas e Vegetais/análise , Concentração de Íons de Hidrogênio , Limite de Detecção , Microextração em Fase Líquida , Concentração Osmolar , Praguicidas/análise , Praguicidas/química , Reprodutibilidade dos Testes , Extração em Fase Sólida , Solventes/química , Espectroscopia de Infravermelho com Transformada de Fourier , Fatores de Tempo , Difração de Raios X
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