Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 3.712
Filtrar
1.
Ecotoxicol Environ Saf ; 191: 110175, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31954924

RESUMO

Prosulfocarb (PSC) is a thiocarbamate herbicide mainly used in winter cereals and a relevant aerosol precursor under OH radicals (OH) photooxidation conditions. We investigated the environmental risks, mechanisms, kinetics and products for the PSC withOH by employing theoretical chemical calculations. Two reaction types of H-abstraction andOH-addition reactions were taken into account. Whether in the atmosphere or aqueous particles, the most favorable pathway was the H-abstraction in the N-alkyl groups close to nitrogen atom. Subsequent reactions of primary intermediates were considered at different conditions. The total rate constants were determined as 2.62 × 10-10 cm3 molecule-1 s-1 and 4.96 × 10-11 cm3 molecule-1 s-1 at 298 K in atmosphere and aqueous particles, respectively. In natural water with theOH concentration of 10-15-10-18 mol l-1, the half-lives (t1/2) of PSC in theOH-initiated reactions were calculated as t1/2 = 2.40 × 104-2.40 × 107 s. With regard to the influence on human health and the ecosystem, oxidized products of PSC were estimated to be mutagenicity negative and had no obvious bioaccumulation potential. The aquatic toxicity of PSC and its degradation products was evaluated and the assessment results showed that the degradation of PSC was a toxicity-reduced process but they were still at toxic and harmful levels.


Assuntos
Aerossóis/química , Carbamatos/química , Poluentes Ambientais/química , Herbicidas/química , Radical Hidroxila/química , Aerossóis/toxicidade , Carbamatos/toxicidade , Poluentes Ambientais/toxicidade , Meia-Vida , Herbicidas/toxicidade , Cinética , Oxirredução , Medição de Risco
2.
Chemosphere ; 242: 125144, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31669994

RESUMO

Currently, many kinds of organic pollutants in air and water have a negative impact on humans and the environment. Notably, as a type of new functional materials, metal-organic frameworks (MOFs) with well-ordered porous structures and numerous active sites have been proven to be ideal photocatalysts for the degradation of organic pollutants. In the past few years, many encouraging achievements have been made in the research field of MOFs for photocatalysis. And a large number of functionalized MOFs have been constructed to improve photocatalytic activity. In this review, recent progress in the photocatalytic degradation of organic pollutants in both air and water using functionalized MOFs are summarized in detail. The focus is on photocatalytic mechanisms and some strategies employed to achieve higher degradation efficiency. Furthermore, the challenges and outlooks in this promising filed are also discussed. We hope this review would be useful for designing more functionalized MOFs with greater photocatalytic performance for the degradation of organic pollutants in the environment.


Assuntos
Poluentes Ambientais/química , Estruturas Metalorgânicas , Modelos Químicos , Compostos Orgânicos , Humanos , Porosidade , Água
3.
Environ Pollut ; 256: 113417, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31662269

RESUMO

A facile method was developed to fabricate porous tube-like ZnS by sulfurizing rod-like ZIF-L with thioacetamide (TAA) at different durations and the formation mechanism of the porous tube-like ZnS was discussed in detail. The series of sulfide products (ZS-X) were characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), solid-state nuclear magnetic resonance spectroscopy (SSNMR), transmission electron microscopy (TEM), UV-visible diffuse-reflectance spectroscopy (UV-vis DRS). The photocatalytic performances of ZS-X toward Cr(VI) reduction and organic pollutant degradation were explored. It was discovered that ZS-3 (porous tube-like ZnS) exhibited excellent activities under UV light and displayed good reusability and stability after several experimental cycles. In addition, Cr(VI) reduction and organic pollutant degradation were investigated under different pH values and existence of different foreign ions. The photocatalytic activities of ZS-3 were tested toward the matrix of Cr(VI) and reactive red X-3B. The mechanism was proposed and verified by both electrochemical analysis and electron spin resonance (ESR) measurement.


Assuntos
Cromo/química , Poluentes Ambientais/química , Catálise , Poluentes Ambientais/análise , Porosidade , Espectroscopia de Infravermelho com Transformada de Fourier , Sulfetos , Difração de Raios X , Compostos de Zinco
4.
Environ Sci Pollut Res Int ; 27(6): 6459-6475, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31873885

RESUMO

Nanostructures have great potential in catalysis and their compositions may cause some interferences in the reactivity. Therefore, the present study focuses on comparison between three metallic nanoparticle-based Ag, Au, and Pd as nano-catalyst in reduction of aromatic pollutants. To neglect any interpenetration in their catalytic reactivity, the metallic nanoparticles were prepared via a consistent and reproducible one-step method with alkali-activated dextran. Interestingly, small sized/spherical AgNPs, AuNPs, and PdNPs were successively prepared with particle size of 3.4, 8.3, and 17.1 nm, respectively. The catalytic performance of the synthesized NPs was estimated for the reduction of p-nitroaniline and methyl red dye as different aromatic pollutants. Regardless of the particle size, there was a strong relation between catalytic action and the type of metal which followed the order of PdNP > AuNPs > AgNPs. Graphical Abstract.


Assuntos
Poluentes Ambientais/química , Nanopartículas Metálicas/química , Catálise , Ouro , Tamanho da Partícula
5.
Chemosphere ; 239: 124815, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31526994

RESUMO

In this study, Pd-BiVO4 bearing highly dispersed Pd nanoparticles was prepared from pure BiVO4 using an impregnation method. The pure BiVO4 and Pd-BiVO4 catalysts were characterized by X-ray diffraction, scanning electron microscopy, UV-visible diffuse reflection, transmission electron microscopy, and X-ray photoelectron spectroscopy. The results showed that the prepared catalysts had a monoclinic scheelite structure and exhibited a flake-like morphology. Pd-BiVO4 showed a distinct response in the visible light region, with an extended absorption edge at 550 nm. According to the Scherrer formula, the nanocrystal particle sizes of the BiVO4 and Pd-BiVO4 catalysts were 35 and 28 nm, respectively. Highly dispersed Pd nanoparticles with sizes of 2.5 ±â€¯0.5 nm were observed on the BiVO4 surface. Two Pd valence states, Pd(II) and Pd(0), were identified in a 2:1 ratio. Pd-BiVO4 exhibited excellent activity for paracetamol (PCT) degradation, with 100% removal achieved in 1 h under visible light irradiation. During degradation, the mineralization ratio reached up to 40% total organic carbon removal. Two highly active species, namely, hydroxyl and superoxide radicals, were determined by electron spin resonance (ESR). Furthermore, the potential degradation of PCT in this system was proposed based on intermediate information obtained using HPLC-MS and Gauss analysis. The high dispersion and small size of Pd nanoparticles might favor the removal of emerging contaminants using the Pd-BiVO4 photocatalytic system.


Assuntos
Acetaminofen/efeitos da radiação , Poluentes Ambientais/química , Luz , Nanopartículas Metálicas/química , Paládio/química , Fotólise/efeitos da radiação , Vanadatos/química , Acetaminofen/química , Bismuto/química , Catálise , Poluentes Ambientais/efeitos da radiação , Radicais Livres/química , Microscopia Eletrônica , Fotólise/efeitos dos fármacos , Análise Espectral
6.
Chemosphere ; 240: 124958, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31726587

RESUMO

Degradation of insensitive munitions (IMs) by ultraviolet (UV) light has become a topic of concern following observations that some UV-degradation products have increased toxicity relative to parent compounds in aquatic organisms. The present investigation focused on the Army's IM formulation, IMX-101, which is composed of three IM constituents: 2,4-dinitroanisole (DNAN), 3-nitro-1,2,4-triazol-5-one (NTO), and nitroguanidine (NQ). The IM constituents and IMX-101 were irradiated in a UV photo-reactor and then administered to Daphnia pulex in acute (48 h) exposures comparing toxicities relative to the parent materials. UV-degradation of DNAN had little effect on mortality whereas mortality for UV-degraded NTO and NQ (and associated degradation products) increased by factors of 40.3 and 1240, respectively, making UV-degraded NQ the principle driver of toxicity when IMX-101 is UV-degraded. Toxicity investigations for specific products formed during UV-degradation of NQ, confirmed greater toxicity than the parent NQ for degradation products including guanidine, nitrite, ammonia, nitrosoguanidine, and cyanide. Summation of the individual toxic units for the complete set of individually measured UV-degradation products identified for NQ only accounted for 25% of the overall toxicity measured in the exposures to the UV-degraded NQ product mixture. From these toxic unit calculations, nitrite followed by CN- were the principal degradation products contributing to toxicity. Given the underestimation of toxicity using the sum toxic units for the individually measured UV-degradation products of NQ, we conclude that: (1) other unidentified NQ degradation products contributed principally to toxicity and/or (2) synergistic toxicological interactions occurred among the NQ degradation product mixture that exacerbated toxicity.


Assuntos
Anisóis/química , Guanidinas/efeitos da radiação , Triazóis/química , Raios Ultravioleta , Animais , Anisóis/toxicidade , Daphnia/efeitos dos fármacos , Poluentes Ambientais/química , Poluentes Ambientais/toxicidade , Guanidinas/toxicidade , Mutação , Nitrocompostos/química , Nitrocompostos/toxicidade , Testes de Toxicidade , Triazóis/toxicidade
7.
Chemosphere ; 240: 124979, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31726597

RESUMO

Activation of peroxymonosulfate (PMS) and persulfate (PS) by Fe2+ is widely used for oxidizing organic pollutants. However, their application is limited by the slow conversion rate of Fe3+ to Fe2+ and the accumulation of Fe3+. Here, we introduce commercial molybdenum disulfide (MoS2) to promote the activation of PMS and PS by Fe2+, and explore the mechanism of this promotion using experimental and theoretical methods. The Fe2+/PMS/MoS2 and Fe2+/PS/MoS2 systems achieved faster rate of PMS and PS conversion and also higher degradation efficiency toward pollutants. About 94.7% and 87.6% of rhodamine B (RhB) could be degraded in Fe2+/PMS/MoS2 (54 µM Fe2+, 1 mM PMS) and Fe2+/PS/MoS2 (54 µM Fe2+, 0.25 mM PS) system, respectively. MoS2 addition simultaneously promoted the Fe3+/Fe2+ cycle, the PMS and PS conversion, and the RhB mineralization. As a co-catalyst, MoS2 exhibited excellent stability for eight successive cycles of use. The predominant oxidant was identified as SO4- in Fe2+/PMS/MoS2 and Fe2+/PS/MoS2 systems. Theoretical calculations and a kinetic model were employed to evaluate the catalytic performance of the systems. These novel findings indicate that the combination of a commercially available MoS2 catalyst with a low dosage of Fe2+ is a promising and effective approach for efficient activation of PMS and PS to produce SO4- and OH.


Assuntos
Dissulfetos/química , Poluentes Ambientais/química , Ferro/química , Molibdênio/química , Peróxidos/química , Sulfatos/química , Catálise , Sinergismo Farmacológico , Cinética , Rodaminas/química
8.
Ecotoxicol Environ Saf ; 188: 109856, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31722800

RESUMO

In this study, we reported the design and the fabrication of Ag and TiO2 modified polycaprolactone (PCL) electrospun nanofiber (NF) mats. The as-prepared NF mats were fabricated by one-step electrospinning and it was exploited for three different purposes (i) reusable SERS substrate for quantitative analysis to trace organic pollutants, (ii) photocatalyst for degradation of organic pollutants and (iii) antibacterial agent for killing of bacteria. Three different nanofiber mats, PCL, PCL-TiO2, PCL/TiO2-Ag NFs. were fabricated and further investigated. The morphologies and structures of the as-prepared nanofiber mats were carried out using X-ray diffraction spectroscopy (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX) and fourier transform infrared spectroscopy (FT-IR) techniques. PCL/TiO2-Ag NFs served as a highly effective SERS platform with a detection limit of 10 nM for the detection of methylene blue dye (MB). A remarkable feature of the presented platform is the ability to reuse the PCL/TiO2-Ag NFs for SERS analysis of MB; availing from its capability for self-cleaning under UV light. By employing PCL/TiO2-Ag NFs nanocatalyst, complete photocatalytic degradation of the probe analytes MB and ibuprofen (Ibu) under UV irradiation was accomplished not more than 180 min. Moreover, PCL/TiO2-Ag NF mats showed a highly promising bactericidal feature against gram-negative Escherichia coli and gram-positive Staphylococcus aureus bacteria, which immensely emerged due to the presence of Ag NPs. This new trending nanofiber is assumed to lead a bunch of changes in the field of photocatalytic, SERS and antibacterial studies.


Assuntos
Nanofibras/química , Poliésteres/química , Prata/química , Titânio/química , Antibacterianos/química , Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Poluentes Ambientais/química , Azul de Metileno/química , Nanofibras/toxicidade , Fotólise , Análise Espectral Raman/instrumentação
9.
Carbohydr Polym ; 228: 115392, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31635740

RESUMO

The main source of nitroaromatic compounds in nature is anthropogenic activities. In the present report, a facile and green method was employed to fabricate highly efficient catalyst to turn toxic nitrophenols to more safe aminophenols. The Fe3O4/Ag@Ca-Al LDH hybrid (FAL hybrid) was synthesized by the Fe3O4 and Ag nanoparticles supported on layer double hydroxide (LDH) and the bionanocomposite (BNC) of this hybrid and starch was prepared via an in situ growth method. The FAL hybrid and BNC were characterized by different techniques. The reduction reaction of 4-nitrophenol in the presence of these catalysts indicated that both of them have high catalytic activity due to their large numbers of hydroxyl groups as capping agent. The comparison rate kinetics study between 4-nitrophenol and 2-nitrophenol showed that the FALS-BNC has higher potential in the case of the para derivative. Also, catalysts were recovered without difficulty and reused after completion of the reduction reaction.


Assuntos
Catálise , Química Verde/métodos , Nanopartículas de Magnetita/química , Nanocompostos/química , Nitrofenóis/química , Aminofenóis/química , Poluentes Ambientais/química , Substâncias Perigosas/química , Cinética , Nitrofenóis/toxicidade , Oxirredução , Prata/química , Amido/química
10.
Chemosphere ; 239: 124745, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31521939

RESUMO

A novel three dimensional MnO2 modified biochar-based porous hydrogel (MBCG) was fabricated to overcome the low sorption capacity and difficulty in solid-liquid separation of biochar (BC) for Cd(II) and Pb(II) removal. BC was initially modified by a rapid redox reaction between KMnO4 and Mn(II) acetate, and then incorporated into a polyacrylamide gel network via a rapid and facile free-radical polymerization. A foaming method was deliberately introduced during the fabrication to establish interpenetrated porous structure inside the network. Various characterizations were employed to examine the morphology, porous structures, chemical compositions, and mechanical properties of the samples. Adsorption performance of MBCG on Cd(II) and Pb(II) (isotherms and kinetics) as well as its desorption and reusability were also investigated. The results indicated that MnO2 modified biochars (MBC) were successfully introduced and homogeneously distributed in the porous bulk hydrogel, endowing MBCG with more uniform pore structure, excellent thermostability, remarkable mechanic strength, and superior adsorption performance. The maximum Langmuir adsorption capacity on Cd(II) and Pb(II) is 84.76 and 70.90 mg g-1, respectively, which is comparable or even larger than that of MBC. More importantly, MBCG can be rapidly separated and easily regenerated with an excellent reusability, which could retain 92.1% and 80.5% of the initial adsorption capacities of Cd(II) and Pb(II) after five cycles. These new insights make MBCG an ideal candidate in practical applications in water treatment and soil remediation contaminated with various heavy metals.


Assuntos
Cádmio/isolamento & purificação , Carvão Vegetal/química , Hidrogéis/química , Chumbo/isolamento & purificação , Compostos de Manganês/química , Óxidos/química , Resinas Acrílicas/química , Adsorção , Cádmio/química , Poluentes Ambientais/química , Poluentes Ambientais/isolamento & purificação , Chumbo/química , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Polimerização , Porosidade , Impressão Tridimensional , Espectroscopia de Infravermelho com Transformada de Fourier , Termogravimetria
11.
Chemosphere ; 239: 124766, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31527001

RESUMO

Iron (Fe)-doped ZrO2 tetragonal nanoparticles were synthesized by a facile and inexpensive hydrothermal technique, that were doped with Fe3+ ions (0.1, 0.3, and 0.5 mol%) into the host lattice without altering the morphology and crystal structure of the nanoparticles. SEM and TEM investigations indicated that the morphology of ZrO2 nanoparticles did not change even after incorporation of Fe, while the band gap of semiconducting ZrO2 nanoparticles was reduced from 4.97 to 1.77 eV. Such a in band gap was responsible to harvest more photons to stimulate the generation of more electrons in the valence band, thereby enhancing the photoelectrochemical (PEC) water splitting as well as photocatalytic and photoelectrocatalytic activities in the photodegradation of Rhodamine B. The 0.3 mol%-doped ZrO2 electrode showed enhanced photocurrent density (0.07 × 10-3 A/cm2), that was 45-times greater than the pure sample. The electrochemical impedance spectroscopy (EIS) confirmed that 0.3 mol%-doped ZrO2 exhibited the best charge transfer characteristics, which increased with PEC water splitting activity. The maximum photocurrent density and long-term photo-stability were achieved in the light on-off states.


Assuntos
Corantes/isolamento & purificação , Ferro/química , Nanopartículas Metálicas/química , Rodaminas/isolamento & purificação , Zircônio/química , Catálise , Corantes/química , Eletrodos , Poluentes Ambientais/química , Poluentes Ambientais/isolamento & purificação , Fotoquímica/instrumentação , Fotoquímica/métodos , Fotólise , Pontos Quânticos/química , Rodaminas/química , Água/química
12.
Environ Sci Process Impacts ; 21(12): 2118-2127, 2019 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-31667476

RESUMO

Although redox reactions of organic contaminants with manganese oxides have been extensively studied, the role of dissolved O2 in these processes has largely been overlooked. In this study, the oxidative degradation of phenol by δ-MnO2 was investigated under both oxic and anoxic conditions. Dissolved O2 inhibited phenol degradation due to its promoting role in the reoxidation and precipitation of reduced Mn(ii) to Mn(iii) on the δ-MnO2 surface, resulting in partial transformation of δ-MnO2 to "c-disordered" H+-birnessite at pH 5.5 and feitknechtite, manganite, and hausmannite at pH 7.0 and 8.5. The reformed Mn(iii) phases could reduce phenol oxidation by blocking reactive sites of δ-MnO2. In addition, dissolved O2 caused a higher degree of particle agglomeration and a more severe specific surface area decrease, and hence lower reactivity of δ-MnO2. These findings revealed that after reductive dissolution by phenol and reoxidation by dissolved O2 throughout continuous redox cycling, δ-MnO2 became less reactive rather than being regenerated. These results can provide new insights into the understanding of the oxidation of organic contaminants by manganese oxides in the natural environment.


Assuntos
Poluentes Ambientais/química , Compostos de Manganês/química , Modelos Teóricos , Óxidos/química , Oxigênio/química , Fenol/química , Poluentes Ambientais/análise , Cinética , Oxirredução , Fenol/análise , Solubilidade
13.
Ecotoxicol Environ Saf ; 186: 109822, 2019 Dec 30.
Artigo em Inglês | MEDLINE | ID: mdl-31634658

RESUMO

Nitroaromatic compounds (NACs) are an important type of environmental organic pollutants. However, it is lack of sufficient information relating to their potential adverse effects on human health and the environment due to the limited resources. Thus, using in silico technologies to assess their potential hazardous effects is urgent and promising. In this study, quantitative structure activity relationship (QSAR) and classification models were constructed using a set of NACs based on their mutagenicity against Salmonella typhimurium TA100 strain. For QSAR studies, DRAGON descriptors together with quantum chemistry descriptors were calculated for characterizing the detailed molecular information. Based on genetic algorithm (GA) and multiple linear regression (MLR) analyses, we screened descriptors and developed QSAR models. For classification studies, seven machine learning methods along with six molecular fingerprints were applied to develop qualitative classification models. The goodness of fitting, reliability, robustness and predictive performance of all developed models were measured by rigorous statistical validation criteria, then the best QSAR and classification models were chosen. Moreover, the QSAR models with quantum chemistry descriptors were compared to that without quantum chemistry descriptors and previously reported models. Notably, we also obtained some specific molecular properties or privileged substructures responsible for the high mutagenicity of NACs. Overall, the developed QSAR and classification models can be utilized as potential tools for rapidly predicting the mutagenicity of new or untested NACs for environmental hazard assessment and regulatory purposes, and may provide insights into the in vivo toxicity mechanisms of NACs and related compounds.


Assuntos
Poluentes Ambientais , Hidrocarbonetos Aromáticos , Mutagênicos , Nitrocompostos , Algoritmos , Simulação por Computador , Poluentes Ambientais/química , Poluentes Ambientais/toxicidade , Hidrocarbonetos Aromáticos/química , Hidrocarbonetos Aromáticos/toxicidade , Aprendizado de Máquina , Mutagênicos/química , Mutagênicos/toxicidade , Nitrocompostos/química , Nitrocompostos/toxicidade , Relação Quantitativa Estrutura-Atividade , Reprodutibilidade dos Testes , Salmonella typhimurium/efeitos dos fármacos , Salmonella typhimurium/genética
14.
Environ Sci Process Impacts ; 21(12): 2109-2117, 2019 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-31656961

RESUMO

A large quantity of emerging contaminants are ionizable, and the ionized compounds display different adsorption behaviors than their neutral counterparts. In particular, a strong intermolecular force, negative charge assisted hydrogen bonding ((-)CAHB), was recently identified, which explains the unusually strong adsorption of negatively charged compounds on carbon nanotubes with oxygen-containing functional groups. However, most previous studies only probed molecules with one benzene ring. The adsorption of ionizable compounds with more than one benzene ring and additional functional groups has not been examined. This study investigated the effect of surface functionalization, molecular size and structure of six aromatic carboxylic acids on their adsorption on multi-walled carbon nanotubes (MWNTs) in batch reactors. In addition, the short-range interactions of the neutral acids with MWNTs were calculated to evaluate the effect of aromaticity and bulkiness. Hydrophobicity and electrostatic interactions dominate the intermolecular forces between ionized contaminants and MWNT surfaces. pH dependent octanol/water partitioning coefficient (Dow) is a more precise indicator of the adsorption of ionizable compounds on MWNTs. (-)CAHB is a significant force only for compounds with one benzene ring. Hydroxyl and carboxyl functional groups displayed similar capacity to form (-)CAHB, as indicated by the release of hydroxide ions.


Assuntos
Ácidos Carboxílicos/química , Poluentes Ambientais/química , Hidrocarbonetos Aromáticos/química , Modelos Teóricos , Nanotubos de Carbono/química , Adsorção , Ácidos Carboxílicos/análise , Poluentes Ambientais/análise , Hidrocarbonetos Aromáticos/análise , Ligações de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Hidróxidos/análise , Hidróxidos/química , Estrutura Molecular , Propriedades de Superfície
15.
J Agric Food Chem ; 67(46): 12927-12935, 2019 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-31657558

RESUMO

Emerging and fugitive contaminants (EFCs) released to our biosphere have caused a legacy and continuing threat to human and ecological health, contaminating air, water, and soil. Polluted media are closely linked to food security through plants, especially agricultural crops. However, measuring EFCs in plant tissues remains difficult, and high-throughput screening is a greater challenge. A novel rapid freeze-thaw/centrifugation extraction followed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) analysis was developed for high-throughput quantification of 11 EFCs with diverse chemical properties, including estriol, codeine, oxazepam, 2,4-dinitrotoluene, 1,3,5-trinitroperhydro-1,3,5-triazine, bisphenol A, triclosan, caffeine, carbamazepine, lincomycin, and DEET, in three representative crops, corn, tomato, and wheat. The internal aqueous solution, i.e., sap, is liberated via a freeze/thaw cycle, and separated from macromolecules utilizing molecular weight cutoff membrane centrifugal filtration. Detection limits ranged from 0.01 µg L-1 to 2.0 µg L-1. Recoveries of spiked analytes in three species ranged from 83.7% to 109%. Developed methods can rapidly screen EFCs in agriculture crops and can assess pollutant distribution at contaminated sites and gain insight on EFCs transport in plants to assess transmembrane migration in vascular organisms. The findings contribute significantly to environmental research, food security, and human health, as it assesses the first step of potential entry into the food chain, that being transmembrane migration and plant uptake, the primary barrier between polluted waters or soils and our food.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Poluentes Ambientais/química , Lycopersicon esculentum/química , Extratos Vegetais/química , Espectrometria de Massas em Tandem/métodos , Triticum/química , Zea mays/química , Centrifugação , Poluentes Ambientais/isolamento & purificação , Filtração , Contaminação de Alimentos/análise , Química Verde/métodos , Ensaios de Triagem em Larga Escala/métodos , Extratos Vegetais/isolamento & purificação
16.
Environ Sci Pollut Res Int ; 26(31): 32368-32373, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31605360

RESUMO

Lead (Pb) persists among the most hazardous contaminant metals. Pb-induced genotoxic effects remain a matter of debate as they are a major cause of plant growth impairment, but assessing Pb genotoxicity requires the selection of Pb-sensitive genotoxic biomarkers. Seedlings of the ecotoxicological model species Pisum sativum L. were exposed to Pb2+ (≤ 2000 mg L-1). Flow cytometry (FCM) revealed that 28 days after, Pb2+ arrested root cell cycle at G2 but no eu/aneuploidies were found. Comet assay and FCM-clastogenicity assays showed that Pb2+ increased DNA breaks in roots at concentrations as low as 20 mg L-1. Leaves showed no variation in DNA-ploidy or cell cycle progression but had increased DNA breaks at the highest Pb2+ dose. We conclude that both Comet assay and the full-peak coefficient of variation (FPCV) were the most relevant endpoints of Pb-phytogenotoxicity. Also, the Pb-induced DNA breaks may be related with the arrest at the G2-checkpoint. Data will be relevant to better define Pb2+ ecogenotoxicological effects and their measuring tools and may contribute to a regulatory debate of this pollutant limits.


Assuntos
Poluentes Ambientais/química , Chumbo/metabolismo , Mutagênicos/toxicidade , Ervilhas/efeitos dos fármacos , Folhas de Planta/metabolismo , Plântula/efeitos dos fármacos , Divisão Celular , Ensaio Cometa , Dano ao DNA , Poluentes Ambientais/metabolismo , Chumbo/química , Ervilhas/química , Desenvolvimento Vegetal , Folhas de Planta/química
17.
Bull Environ Contam Toxicol ; 103(6): 763-765, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31628499

RESUMO

Quantifying the coupled kinetic reactions of metals/metalloids on iron and manganese oxides is essential for predicting the fate of contaminants in the environment. In this perspective, a few key issues related to developing the quantitative models for the coupled kinetic reactions of metal and metalloids are discussed, including adsorption/desorption processes, redox reactions, and mineral dissolution/transformation. Future research areas are also briefly discussed.


Assuntos
Poluentes Ambientais/química , Ferro/química , Compostos de Manganês/química , Metaloides/química , Metais/química , Óxidos/química , Adsorção , Cinética , Minerais/química , Modelos Químicos , Oxirredução
18.
Environ Sci Process Impacts ; 21(10): 1618-1641, 2019 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-31528928

RESUMO

Designs and applications of passive samplers for various environmental compartments have been broadened significantly since their introduction. Understanding the theory behind passive sampling is essential for proper development of sampling methods and for accurate interpretation of the results. Theoretical underpinnings of passive sampling have been explored using different approaches. The aim of this review is to describe passive sampling theory and modelling approaches presented in the literature in a manner that allows researchers to obtain comprehensive understanding of them and to recognize the assumptions behind each approach together with their applicability to a given passive sampling technique. A common approach originates from Whitman's two-film theory and produces an exponential model that describes the entire passive sampling process. This approach, however, is based on several assumptions including linear exchange kinetics between the sampled medium and the passive sampler. Two-phase air passive samplers with a well-defined barrier are commonly modeled based on the zero-sink assumption, which assumes efficient trapping of analytes in the receiving phase. This assumption may become invalid under various scenarios; consequently, other approaches to modelling have been introduced including simulation of the sampling process by approximate temporal-steady states in hypothetical segments in the adsorption phase. Another approach uses dynamic models to determine accumulation of analytes in passive samplers. Dynamic models are capable of describing mass accumulation in the passive sampler, its transient response, and its response to fluctuations in environmental concentrations. Finally, empirically calibrated models, attempting to simplify the process of passive sampling rate determination, are also presented. In general, dynamic models are used to establish a profound understanding of the sampling process and analyse the applicability of the simpler models and their assumptions, while the simplified models are desirable and practical for most users. Nonetheless, due to the advancement in the computational tools, application of the dynamic models could be made simple and user-friendly.


Assuntos
Monitoramento Ambiental/métodos , Calibragem , Poluentes Ambientais/análise , Poluentes Ambientais/química , Modelos Teóricos
19.
ACS Appl Mater Interfaces ; 11(41): 38321-38335, 2019 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-31549800

RESUMO

Material combinations of semiconductor with conducting polymer are gaining growing interest due to their enhanced activities in photocatalysis as well as electrochemical sensing. In this present work, we report a facile in situ synthesis of polypyrrole (PPy) polymer-incorporated silver molybdate (Ag2MoO4) nanocomposite that is utilized as a photocatalyst and electrocatalyst for the degradation of pollutant heavy metals, namely, methylene blue (MB) and heavy metal (Cr(VI)), and ciprofloxacin (CIP) and for detection of the drug, azomycin. The synthesized nanocomposite was characterized by various theoretical, spectral, and microscopic studies. Matching of the powder X-ray diffraction pattern with JCPDS no. 76-1747 confirmed the formation of α-Ag2MoO4/PPy. The surface topography and spherical morphology of the nanocomposite were studied using field emission-scanning electron microscopy and transmission electron microscopy. Fourier transform infrared spectral detail expounds the smooth incorporation of PPy to Ag2MoO4. The as-synthesized nanocomposite performs as an efficient photocatalyst in the degradation of MB (99.9%), Cr(VI) (99%), and CIP drug (99.8%) within 10 min. In addition to this, the Ag2MoO4/PPy-modified glassy carbon electrode (GCE) demonstrated excellent electrocatalytic activity in terms of a higher cathodic peak current and lower peak potential when compared with other modified and unmodified GCEs for the detection of azomycin. The Ag2MoO4/PPy/GCE displayed a broader linear response range and lower detection limit of 0.5-499 µM and 65 nM, respectively. Moreover, other potentially co-interfering compounds, such as a similar functional group-containing biological substances and inorganic species, have no interference effect toward azomycin sensing.


Assuntos
Poluentes Ambientais/química , Molibdênio/química , Nanocompostos/química , Polímeros/química , Pirróis/química , Prata/química , Catálise , Ciprofloxacino/química , Azul de Metileno/química , Nitroimidazóis/química
20.
Environ Sci Pollut Res Int ; 26(32): 33329-33340, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31520393

RESUMO

Peroxymonosulfate (PMS) activated by nanomaterials presents one of the most promising strategies to generate reactive species for remediation of organic pollutant-contaminated water. In this study, CoAl-layered double hydroxide (CoAl-LDH) and calcined CoAl-LDH (CoAl-CLDH) were employed as catalysts for PMS activation towards aqueous organic pollutants degradation. Our experiments showed that the leaching of metal ions from catalyst can be significantly mediated by calcination treatment, which can avoid the secondary contamination. The stable CoAl-CLDH exhibited a high catalytic activity, which is comparable to that of the unstable CoAl-LDH. Importantly, reactive species quenching and electron paramagnetic resonance (EPR) results revealed that singlet oxygen (1O2) is the dominant reactive species and plays a crucial role in the catalytic oxidation process in CoAl-CLDH/PMS system. A possible mechanism was proposed for the activation of PMS on the CoAl-CLDH. We demonstrate that CoAl-CLDH is a highly active and stable heterogeneous catalyst for efficient catalytic oxidation of organic pollutants (such as acetaminophen and rhodamine B (RhB)) via activation of PMS.


Assuntos
Acetaminofen/química , Poluentes Ambientais/química , Rodaminas/química , Acetaminofen/análise , Catálise , Poluentes Ambientais/análise , Hidróxidos/química , Metais , Modelos Químicos , Oxirredução , Peróxidos , Rodaminas/análise , Oxigênio Singlete , Água
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA