Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 674
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Chemosphere ; 249: 126178, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32087454

RESUMO

Norfloxacin is employed as in veterinary and human medicine against gram-positive and gram-negative bacteria. Due to the ineffective treatment at the wastewater treatment plants it becomes an emergent pollutant. Electro-oxidation appears as an alternative to its effective mineralization. This work compares Norfloxacin electro-oxidation on different anodic materials: two ceramic electrodes (both based on SnO2 + Sb2O3 with and without CuO, named as CuO and BCE, respectively) and a boron doped diamond (BDD). First, the anodes were characterized by cyclic voltammetry, revealing that NOR direct oxidation occurred at 1.30 V vs. Ag/AgCl. The higher the scan rate the higher both the current density and the anodic potential of the peak. This behavior was analyzed using the Randles-Sevcik equation to calculate the Norfloxacin diffusion coefficient in aqueous media, giving a value of D = 7.80 × 10-6 cm2 s-1 at 25 °C), which is close to the predicted value obtained using the Wilke-Chang correlation. The electrolysis experiments showed that both NOR and TOC decay increased with the applied current density, presenting a pseudo-first order kinetic. All the anodes tested achieved more than 90% NOR degradation at each current density. The CuO is not a good alternative to BCE because although it acts as a catalyst during the first use, it is lost from the anode surface in the subsequent uses. According to their oxidizing power, the anodes employed are ordered as follows: BDD > BCE > CuO.


Assuntos
Cobre/química , Norfloxacino/química , Poluentes Químicos da Água/química , Antibacterianos , Antimônio/química , Boro , Cerâmica , Cloretos , Cloro , Diamante , Eletrodos , Eletrólise , Bactérias Gram-Negativas , Bactérias Gram-Positivas , Norfloxacino/análise , Oxirredução , Compostos de Estanho/química , Águas Residuárias , Poluentes Químicos da Água/análise
2.
Environ Pollut ; 257: 113566, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31813702

RESUMO

Soil organic matter (SOM) affects arsenic (As) and antimony (Sb) mobility in soils under waterlogged conditions by acting as an electron donor, by catalyzing redox-cycling through electron shuttling and by acting as a competing ligand. This study was set up to disentangle these different effects of SOM towards As and Sb sorption in anaerobic soils. Nine samples were taken at different depths in an agricultural soil profile to collect samples with a natural SOM gradient (<1-40 g soil organic carbon kg-1). The samples were incubated either or not under waterlogged conditions in an anaerobic chamber for 63-70 days, and glucose (5 g C kg-1) was either or not added to the anaerobic incubated samples as an electron donor that neither acts as an electron shuttle nor as a competing ligand. The solid-liquid distribution coefficients (KD) of As and Sb were measured at trace levels. The KD values of As decreased ∼2 orders of magnitude upon waterlogging the SOM rich topsoil, while no additional changes were observed when glucose was added. In contrast, smaller changes in the As KD values were found in the low SOM containing subsoil samples, unless glucose was added that mobilised As. The Sb KD values increased upon reducing conditions up to factor 20, but again only in the high SOM topsoil samples. Surprisingly, the Sb immobilisation during waterlogging only occurred in Sb amended soils whereas the geogenic Sb was mobilised upon reducing conditions, although total dissolved Sb concentrations remained low (<10 nM). The change in As and Sb sorption upon waterlogging was similar in the SOM rich topsoil as in the low SOM subsoil amended with glucose. This suggests that the SOM dependent changes in As and Sb mobility in response to soil waterlogging are primarily determined by the role of SOM as electron donor.


Assuntos
Antimônio/química , Arsênico/química , Poluentes do Solo/química , Agricultura , Anaerobiose , Antimônio/análise , Arsênico/análise , Carbono , Modelos Químicos , Solo , Poluentes do Solo/análise
3.
Chemosphere ; 241: 125042, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31606577

RESUMO

The fate of antimony (Sb) leached from electronic and electrical equipment plastic when disposed of in a municipal solid waste (MSW) landfill was assessed using simulated anaerobic landfill lysimeters and three different batch leaching tests: toxicity characteristic leaching procedure (TCLP), EPA method 1313, and MSW leachate extractions. Plastic from cathode ray tube televisions sets was noted to have the highest Sb concentrations, and was thus the focus of the study. Sb leachability from EPA 1313 stat and TCLP were similar at approximately 0.1% by weight at the same pH (4.93), while MSW landfill leachates extracted less Sb at approximately 0.02% by weight. Solution pH was not the controlling factor, and other conditions resulting from the landfill leachate resulted in lower concentrations of leached Sb. In simulated landfill experiments, Sb leached at approximately 0.01% by weight after a liquid-to-solid ratio of 3. Sb behaves differently in the landfill environment than arsenic leaching from a similar study, most likely from the reducing conditions brought on by the decomposing waste.


Assuntos
Antimônio/química , Resíduo Eletrônico , Plásticos/química , Resíduos Sólidos , Instalações de Eliminação de Resíduos , Antimônio/isolamento & purificação , Arsênico , Concentração de Íons de Hidrogênio , Eliminação de Resíduos/métodos , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/isolamento & purificação
4.
Environ Pollut ; 259: 113815, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31884210

RESUMO

Increasing soil contamination of arsenic (As) and antimony (Sb) is posing a serious concern to human health. Due to insufficient studies on Sb, the biogeochemical behaviour and plant uptake of Sb are assumed to be similar to that of As. As part of extensive research unravelling As and Sb biogeochemistry and plant uptake, the diffusive gradients in thin films (DGT) technique and sequential extraction procedure (SEP) were applied to evaluate As and Sb uptake by the white icicle radish (Raphanus sativus) cultivated in diluted cattle dip soils contaminated with As only and diluted mining soils contaminated with both As and Sb under agricultural conditions. Labile As and Sb in these soils measured by DGT (CDGT), soil solution (Csol), and SEP (CSEP-labile), were compared with As and Sb bioaccumulation in R. sativus tissues. Regardless of contamination sources and measurement techniques, the results showed that As was consistently more labile than Sb although total As concentrations in two soil types were lower than total Sb. Labile As in cattle dip soils was higher than that in mining soils, although there were no significant differences in soil As concentrations. The analysis of R. sativus tissues revealed that the overall As bioaccumulation was 4.5-fold higher than for Sb, and that As translocation to shoots was limited. In contrast, considerable Sb translocation to shoots was observed. The As and Sb bioaccumulation were strongly correlated with their CSEP-labile, CDGT, and Csol (R2 = 0.87-0.99), demonstrating the effectiveness of these techniques in predicting As and Sb in the white icicle radish. Compared with the cherry bell radish previously studied, the white icicle radish exhibited higher bioaccumulation factors (BAF) for Sb, but lower BAF for As, and lower translocation of As and Sb to shoots, providing understanding of how As and Sb are accumulated by radish cultivars.


Assuntos
Antimônio/metabolismo , Arsênico/metabolismo , Monitoramento Ambiental , Raphanus/metabolismo , Poluentes do Solo/metabolismo , Antimônio/química , Arsênico/química , Humanos , Solo , Poluentes do Solo/química
5.
Chemosphere ; 245: 125604, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31855755

RESUMO

Environmental pollution caused by antimony (Sb) has attracted worldwide attention recently. Here, we employed a flow-through electro-Fenton system for the rapid and efficient detoxification of highly toxic Sb(III). A FeOCl modified carbon nanotube (CNT) filter served as functional cathode, where FeOCl as nanocatalyst promoted the generation of HO by facilitating effective Fe3+/Fe2+ cycling. Upon application of a proper potential, an ultra-rapid conversion of Sb(III) to less toxic Sb(V) can be achieved in situ just by a single-pass filtration (>99% within 2 s). Compared with the conventional batch reactor, the proposed system demonstrated ultra-rapid Sb(III) detoxification kinetics due to the convection-enhanced mass transport. The proposed flow-through E-Fenton system works effectively across a wide pH range (e.g., 3-9). EPR technique and radical quenching experiments indicate that HO and HO2 were the dominant radical species responsible for Sb(III) detoxification. At -0.4 V vs. Ag/AgCl, a >96.4% Sb(III) conversion efficiency still can be achieved when challenged with 500 µg L-1 Sb(III)-spiked tap water. The as-produced Sb(V) can be removed effectively by another Sb(V)-specific CNT filter functionalized with nanoscale iron oxides. The outcome of this research provides a promising strategy by integrating state-of-the-art electro-Fenton, membrane separation, carboncatalysis and nanotechnology for detoxification of Sb(III) and other similar heavy metal ions in polluted water.


Assuntos
Antimônio/química , Técnicas Eletroquímicas/métodos , Filtração/métodos , Peróxido de Hidrogênio/química , Ferro/química , Poluentes Químicos da Água/química , Antimônio/isolamento & purificação , Eletrodos , Compostos Férricos/química , Filtração/instrumentação , Radical Hidroxila/química , Compostos de Ferro/química , Cinética , Nanotubos de Carbono/química , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos
6.
Chemosphere ; 245: 125601, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31862553

RESUMO

Low levels of antimony (Sb) can be effectively removed from water by adsorption onto various materials, and searching for low-cost and high-efficiency new adsorbents has been a hot topic in recent years. In the present study, the performance of cetyltrimethylammonium bromide (CTAB) modified MnFe2O4/MnO2 composites (CTAB/MnFe2O4/MnO2) as an adsorbent for Sb(III) removal from aqueous solution was investigated. Kinetic study revealed that adsorption of Sb(III) by CTAB/MnFe2O4/MnO2 was fast in the first 430 min and the equilibrium was achieved within 1440 min. The adsorption kinetic data were well fitted with pseudo-second-order model. The maximum adsorption capacity of the synthesized adsorbent for Sb(III) at pH 7 calculated from Langmuir adsorption isotherms in batch experiments was 321.03 mg g-1. During the adsorption process, Sb(III) can be simultaneously oxidized to Sb(V) and the average oxidation percentage reached 95.43% within 1440 min. The adsorption capacity did not significantly vary with pH. Common metal cations (Ca2+ and Mg2+) slightly enhanced Sb(III) adsorption at pH 7. In comparison, the effect of anions (Cl-, NO3-, and PO43-) on Sb(III) adsorption was not obvious. The results suggest that CTAB/MnFe2O4/MnO2 is a potential cost-effective adsorbent for Sb(III) removal in water treatment.


Assuntos
Antimônio/isolamento & purificação , Cetrimônio/química , Estanho/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Adsorção , Antimônio/química , Compostos Férricos/química , Concentração de Íons de Hidrogênio , Cinética , Compostos de Manganês/química , Oxirredução , Óxidos/química , Poluentes Químicos da Água/química
7.
Chemosphere ; 239: 124715, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31499311

RESUMO

Electrodeposition is an economical and efficient way to prepare Ti/SnO2-Sb electrode for electrochemical oxidizing pollutants in wastewater. The solvent used for electrodeposition has a great effect on electrode performance. The conventional Ti/SnO2-Sb electrode electrodeposited using aqueous solvent has poor electrochemical activity and short service life. In this study, a Ti/SnO2-Sb electrode was prepared via electrodeposition using a deep eutectic solvent (DES). This new Ti/SnO2-Sb-DES electrode performed a rate constant of 0.571 h-1 for methylene blue decolorization and long accelerated service life of 12.9 h (100 mA cm-2; 0.5 M H2SO4), which were 1.7 times and 3.2 times as high as that of the electrode prepared in aqueous solvent, respectively. The enhanced properties were related to the 1.3 times increased electrochemically active surface area of Ti/SnO2-Sb-DES electrode which had a rough, multilayer and uniform surface structure packed with nano-sized coating particles. In conclusion, this study developed a facile, green and efficient pathway to prepare Ti/SnO2-Sb electrode with high performance.


Assuntos
Antimônio/química , Técnicas Eletroquímicas/métodos , Galvanoplastia/métodos , Solventes/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Eletrodos/normas , Azul de Metileno/química , Oxirredução , Compostos de Estanho/química , Titânio/química , Águas Residuárias/química
8.
Chemosphere ; 245: 125684, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31875573

RESUMO

The improper disposal of E-waste flame retardant plastics laden with antimony (Sb) and bromine (Br) has brought enormous environmental hazards, however, rare information on the effective removal of Sb and Br is available. In this study, through building an alkaline sulfide system under hydrothermal conditions, Sb and Br were simultaneously extracted from flame retardant plastic with high efficiency of 85.60% and 90.13%, respectively. Sulfur ion through mass transfer reacted with encapsulated Sb2O3 to form safe and non-toxic SbS33-. Alkaline solution trapped the Br through substitution or neutralization reaction to inhibit the formation of brominated organic compounds. The results showed that the optimum temperature, residence time, Na2S and NaOH concentration for hydrothermal removal of Sb and Br were 220 °C, 2 h, 50 g/L and 20 g/L. The results also revealed that both Na2S and NaOH played an interrelated role in the process of Sb removal. However, NaOH was the only factor controlling the process of debromination. Moreover, the FTIR structure of plastic after alkaline sulfide hydrothermal treatment remained unchanged, which implies that the treated plastic can be reused, and is an added advantage of this technology. The TG-DTG analysis proved the effectiveness of alkaline sulfide hydrothermal treatment in removing Sb and Br.


Assuntos
Antimônio/isolamento & purificação , Bromo/isolamento & purificação , Resíduo Eletrônico/análise , Recuperação e Remediação Ambiental/métodos , Plásticos/química , Antimônio/química , Bromo/química , Poluição Ambiental , Retardadores de Chama/análise , Hidróxido de Sódio , Sulfetos , Temperatura
9.
J Toxicol Sci ; 44(12): 845-848, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31813903

RESUMO

As the field of utilization of organic-inorganic hybrid molecules expands, the toxicology of these compounds is becoming more important. We have shown previously that there is a strong correlation between cytotoxicity and intracellular accumulation detected as metal content, which is modulated by the substituents, of organic-inorganic hybrid molecules. In this study, we investigated the cytotoxicity of pentavalent organoantimony compounds with three phenyl groups on cultured vascular endothelial cells. The results indicated that the cytotoxicity of pentavalent organoantimony compounds was not correlated with the hydrophobicity and intracellular accumulation of these compounds. Therefore, we suggest that hydrophobicity and intracellular accumulation are not necessarily predictive of cytotoxicity in organic-inorganic hybrid molecules.


Assuntos
Antimônio/toxicidade , Células Endoteliais/efeitos dos fármacos , Espaço Intracelular/metabolismo , Compostos Organometálicos/toxicidade , Animais , Antimônio/química , Antimônio/metabolismo , Bovinos , Técnicas de Cultura de Células , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Células Endoteliais/metabolismo , Espaço Intracelular/efeitos dos fármacos , Estrutura Molecular , Compostos Organometálicos/química , Compostos Organometálicos/metabolismo , Relação Estrutura-Atividade
10.
ACS Appl Mater Interfaces ; 11(51): 48290-48299, 2019 Dec 26.
Artigo em Inglês | MEDLINE | ID: mdl-31802657

RESUMO

A novel drug-delivery nanosystem based on near-infrared (NIR) light-degradable antimony nanoparticles (AMNP) have been developed for synergistic chemo-phototherapy in vitro. The monodispersed AMNP were synthesized by using a simple and cost-effective method. Positively charged doxorubicin hydrochloride (DOX) was loaded onto the negatively charged surface of AMNP via electrostatic interaction and finally modified by polyacrylic acid (PAA) to enhance biocompatibility. Under NIR (808 nm) laser irradiation of the AMNP-DOX-PAA nanosystem, not only was high photothermal conversion efficiency of AMNP achieved but also pH-dependent DOX release was enhanced due to laser-induced hyperthermia. As a consequence, almost all of the HeLa cells (around 97%) were killed because of the combined effects of chemotherapy and photothermal therapy. More interestingly, AMNP showed very fast (about 10 min) laser-induced degradation that may help to minimize long-term toxicity after therapy by using same-wavelength NIR laser irradiation (808 nm). Computational total energy calculations and molecular dynamics simulations based on density functional theory (DFT) suggest that the NIR laser irradiation induces a photothermally activated reaction on the surface of AMNP in water, which can lead to surface degradation via the formation of Sb-H bonds first and then Sb-OH bonds upon further increase of temperature. This work demonstrates a simple platform that has potential applications for synergistic and highly effective chemo-photothermal therapy based on photodegradable nanoparticles.


Assuntos
Antimônio/química , Doxorrubicina/química , Sistemas de Liberação de Medicamentos/métodos , Nanopartículas/química , Células HeLa , Humanos , Microscopia Eletrônica de Transmissão , Fototerapia/métodos
11.
J Environ Sci (China) ; 86: 213-224, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31787186

RESUMO

We investigated the adsorption performance of five Fe-based MOFs (Fe-BTC, MIL-100(Fe), MIL-101(Fe), MIL-53(Fe) and MIL-88C(Fe)) for removal of antimonite (Sb(III)) and antimonate (Sb(V)) from water. Among these MOFs, MIL-101(Fe) exhibited the best adsorption capacities for both Sb(III) and Sb(V) (151.8 and 472.8mg/g, respectively) which were higher than those of most adsorbents previously reported. The effect of steric hindrance was evident during Sb removal using the Fe-based MOFs, and the proper diameter of the smallest cage windows/channels should be considered an important parameter during the evaluation and selection of MOFs. Additionally, the adsorption capacities of MIL-101(Fe) for Sb(V) decreased with increasing initial pH values (from 3.0 to 8.0), while the opposite trend was observed for Sb(III). Chloride, nitrate and sulfate ions had a negligible influence on Sb(V) adsorption, while NO3- and SO42- improved Sb(III) adsorption. This result implies that inner sphere complexes might form during both Sb(III) and Sb(V) adsorption.


Assuntos
Antimônio/química , Ferro/química , Estruturas Metalorgânicas/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Adsorção
12.
J Vis Exp ; (154)2019 12 05.
Artigo em Inglês | MEDLINE | ID: mdl-31868178

RESUMO

We have designed a facile method to synthesize a dual-functional electrochemical filter consisting of two 1-D materials: titanate nanowires and carbon nanotubes. The hybrid titanate-CNT filter was prepared by a sonication coupled with a post-filtration route. Due to the synergistic effects of the increased number of exposed sorption sites, electrochemical reactivity, small pore size of the titanate-CNT network coupled with a flow-through design, simultaneous Sb(III) oxidation and sequestration can be readily achieved. Atomic fluorescence spectrometer technology demonstrated that the applied electrical field accelerates the Sb(III) conversion rate and the as-obtained Sb(V) were adsorbed effectively by the titanate nanowires due to their Sb specificity. This protocol provides a practical solution for the removal of highly toxic Sb(III) and other similar heavy metal ions.


Assuntos
Antimônio/química , Filtração/métodos , Oxirredução
13.
Sci Total Environ ; 694: 133693, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31756810

RESUMO

Designer biochars can be used to remediate organic and inorganic contaminant polluted soils. Here, a waste timber biochar (BC), a coconut shell activated biochar (aBC) and a wood shrub iron enriched designer biochar (Fe-BC) were investigated. Per- and polyfluorinated alkyl substances (PFAS) contaminated soils with different total organic carbon (TOC) contents (1.6 and 34.2%) were amended with six doses of BC and aBC. Two shooting range soils (TOC 5.2 and 10.2%) contaminated with heavy metals (mainly Pb and Sb) were amended with four doses of BC and Fe-BC. An amendment of 20% BC reduced the PFOS leachate concentration by 86% for the low TOC soil but was not effective for the high TOC soil. An amendment of 1% aBC reduced PFOS leachate concentrations by over >96% for both soils. For the low TOC shooting range soil, a 20% amendment of BC reduced Pb and Sb leaching by 61% and 12%, respectively. An amendment of 20% Fe-BC to soil with low TOC reduced Pb and Sb leaching by 99% and 40%, respectively. The need for "designer" biochars using processes such as iron enrichment or activation should be considered depending on the TOC of the soil, the type of contaminants and remediation goals.


Assuntos
Recuperação e Remediação Ambiental/métodos , Fluorcarbonetos/química , Metais Pesados/química , Poluentes do Solo/química , Antimônio/análise , Antimônio/química , Carvão Vegetal/química , Fluorcarbonetos/análise , Chumbo/análise , Chumbo/química , Metais Pesados/análise , Solo
14.
Environ Pollut ; 254(Pt B): 113112, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31479811

RESUMO

Antimony, as the Sb(V) species, often occurs in oxic soils and sediments as coprecipitates with poorly-crystalline Fe(III)-bearing minerals. It is common for these Sb(V)-Fe(III) coprecipitates to also contain varying quantities of co-occurring humic acid (HA). When exposed to reducing conditions, the production of Fe(II) may cause the initial metastable HA-Sb(V)-Fe(III) phases to undergo rapid transformations to more stable phases, thereby potentially influencing the geochemical behavior of coprecipitated Sb(V). However, little is known about the impacts of this transformation on the mobility and speciation of Sb. In this study, we reacted synthetic HA-Sb(V)-Fe(III) coprecipitates (Fe:Sb ratio = 4, and C:Fe molar ratios = 0, 0.3, 0.8 and 1.3) with 0, 1 or 10 mM Fe(II) under O2-free conditions at pH 7.0 for 15 days. Fe K-edge EXAFS spectroscopy revealed that solid-phase Fe(III) in the initial coprecipitates contained a mixture of ∼4/5 ferrihydrite (Fe10O14(OH)2) and ∼1/5 tripuhyite (FeSbO4), regardless of the corresponding amount of coprecipitated HA. Tripuhyite persisted throughout the full experiment duration, while ferrihydrite was partially replaced by goethite (FeOOH) when either 1 or 10 mM Fe(II)aq was added to the coprecipitates. The greatest level of goethite formation (∼55% of solid-phase Fe) was observed in the HA-free/10 mM Fe(II)aq treatment, with ferrihydrite transformation being partially attenuated at higher levels of HA. Mobilisation of aqueous Sb was the greatest for 1 mM Fe(II) treatments at high HA:Fe ratios. Sb K-edge XANES spectroscopy showed that the largest reduction of Sb(V) to Sb(III) (∼37%) and the greatest repartitioning of Sb to the mineral surface (∼7.9-9.8%) occurred in the coprecipitates with the highest HA contents in the presence of 10 mM Fe(II). The results indicate that the amount of HA in HA-Sb(V)-Fe(III) coprecipitates can greatly influence mobility and speciation of Sb in Fe(II)-rich conditions. The results of this study provide new insights into alterations in Sb mobility and retention in response to Fe cycling under organic matter-rich reducing conditions.


Assuntos
Antimônio/química , Compostos Férricos/química , Compostos Ferrosos/química , Substâncias Húmicas , Poluentes do Solo/química , Compostos de Ferro/química , Minerais/química , Oxirredução , Espectroscopia por Absorção de Raios X
15.
Environ Int ; 133(Pt A): 105157, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31520959

RESUMO

Electrochemical degradation of trace antiretroviral drug stavudine was investigated by using a reactive electrochemical membrane (REM) with Ti/SnO2-Sb anode. From the results it was evident that the stavudine degradation followed pseudo-first-order kinetics, with the values of the degradation rate constant and half-life being 0.24 min-1 and 2.9 min, respectively, at a current density of 8 mA cm-2. The degradation rate was obviously decreased under alkaline condition (pH = 11.0) and the degradation was also inhibited in the presence of NO3- and Cl-. Five intermediates were identified in the electrochemical degradation of stavudine, and the degradation pathways were proposed. Density functional theory calculation revealed that the double bond carbon atom nearby hydroxymethyl group was the site attacked by OH and the cleavage of CN bond was the rate-determining step in the electrochemical degradation of stavudine. The nitrogen in stavudine was mainly converted to nitrate and ammonium. Quantitative structure-activity relationship model indicated that the toxicity of some intermediates was higher than the parent compound stavudine. The electric energy consumption for 90% stavudine degradation ranged from 0.87 to 2.29 Wh L-1 at the experimental conditions, indicating that stavudine can be degraded efficiently by the REM with Ti/SnO2-Sb anode.


Assuntos
Antimônio/química , Antivirais/isolamento & purificação , Estavudina/isolamento & purificação , Titânio/química , Águas Residuárias/química , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Eletrodos , Oxirredução , Porosidade , Compostos de Estanho/química
16.
Chemosphere ; 237: 124489, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31549638

RESUMO

The present study provides the starch-mediated carbothermal preparation of magnetic-responsible ferrihydrite (MFHP) based on Fe-rich precipitates which is recovered by mine drainage for immobilization of arsenate and antimonate in water. Fe K-edge X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) represented partial transformation from ferrihydrite to magnetite in MFHP due to the carbothermal reduction process, resulting in an effective saturation magnetism (= 19.2 emu/g). As and Sb K-edge EXAFS revealed that arsenate ion combines onto the surface of MFHP as inner-sphere binuclear bidentate surface complex, and antimonate forms inner-sphere mononuclear bidentate complex. In addition, the leachability by toxicity characteristic leaching procedure (TCLP) implies the environmental friendly preparation method for preparing magnetic-responsible adsorbents using mining waste.


Assuntos
Antimônio/química , Arseniatos/química , Adsorção , Compostos Férricos/química , Óxido Ferroso-Férrico , Imobilização , Mineração , Análise Espectral/métodos , Espectroscopia por Absorção de Raios X , Raios X
17.
IET Nanobiotechnol ; 13(6): 593-596, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31432791

RESUMO

In this study, the synthesis of ultra-fine grade antimony trioxide (Sb2O3) using plant extract for the first time is reported. Antimony chloride was used as a starting material and Dioscorea alata tuber extract was used as a reducing and capping agent. The synthesised nanoparticles were characterised by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), dynamic light scattering (DLS), and Fourier transform infrared spectroscopy. XRD analysis indicates the formation of pure Sb2O3 nanoparticles. The result from FE-SEM and DLS showed that the particles have a cube-like morphology and have an average size of 346.4 nm which falls within the range of ultra-fine grade Sb2O3.


Assuntos
Antimônio/química , Dioscorea/química , Química Verde/métodos , Nanopartículas Metálicas/química , Extratos Vegetais/química , Teste de Materiais , Testes de Sensibilidade Microbiana , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Tamanho da Partícula , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X
18.
Parasitol Res ; 118(10): 3077-3084, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31401656

RESUMO

Clinically available drugs for mucocutaneous and cutaneous leishmaniases (CL) include mainly pentavalent antimony (Sb(V)) complexes, liposomal amphotericin B, and miltefosine (HePC). However, they present at least one of the following limitations: long-term parenteral administration through repeated doses, severe side effects, drug resistance, and high cost. HePC is the only oral drug available, but the appearance of resistance has resulted in changes of its use from monotherapy to combination therapy. Amphiphilic Sb(V) complexes, such as SbL8 obtained from reaction of Sb(V) with N-octanoyl-N-methylglucamide, were recently found to be orally active against experimental CL. The property of SbL8 to self-assemble in aqueous solution, forming nanostructures, led us to investigate the incorporation of HePC into SbL8 nanoassemblies and the therapeutic efficacy of SbL8/HePC nanoformulation by oral route in a murine model of CL. HePC incorporation into the SbL8 nanosystem was evidenced by using a fluorescent analog of HePC. The antileishmanial activity of SbL8/HePC nanoassemblies was evaluated after daily oral administration for 30 days in Leishmania amazonensis-infected BALB/c mice, in comparison with monotherapies (SbL8 or HePC) and saline control. All the treatments resulted in significant reduction in the lesion size growth, when compared with control. Strikingly, only SbL8/HePC nanoassemblies promoted a significant decrease of the parasite burden in the lesion. This work establishes the therapeutic benefit of SbL8/HePC association by oral route in a CL model and constitutes an important step towards the development of new orally active drug combination.


Assuntos
Antimônio/química , Antiprotozoários/administração & dosagem , Leishmania mexicana/efeitos dos fármacos , Leishmaniose Cutânea/tratamento farmacológico , Fosforilcolina/análogos & derivados , Administração Oral , Animais , Antimônio/administração & dosagem , Antiprotozoários/química , Modelos Animais de Doenças , Feminino , Leishmaniose Cutânea/parasitologia , Camundongos Endogâmicos BALB C , Nanopartículas/administração & dosagem , Nanopartículas/química , Fosforilcolina/administração & dosagem , Fosforilcolina/química
19.
Environ Sci Pollut Res Int ; 26(26): 27372-27384, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31321725

RESUMO

In order to enhance the removal of Sb(III) in wastewater, hyperbranched polyamide-functionalized sodium alginate (HA@SA) microsphere was prepared by grafting of hyperbranched polyamide (HA) on the surface of sodium alginate (SA) microsphere. Adsorption properties of Sb(III) were investigated via static and dynamic adsorption tests. The cycling reusability of HA@SA microspheres was explored through adsorption-desorption tests. The changes of HA@SA microspheres before and after adsorption were characterized by FT-IR, SEM-EDS, and XPS. Results showed that the maximum Sb(III) adsorption capacity of HA@SA microspheres reached up to 195.7 mg/g, improved by 1.16 times in comparison with SA microspheres. The Sb(III) adsorption processes of HA@SA microspheres were depicted by pseudo-second-order kinetics and the Langmuir isotherm models with accuracy. It covered a homogeneous single-layer adsorption controlled by chemisorption along with exotherm spontaneously. After recycling for 8 times, the adsorption capacity of HA@SA microspheres still retained higher than 90% of the original value.


Assuntos
Alginatos/química , Antimônio/isolamento & purificação , Nylons/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Antimônio/química , Concentração de Íons de Hidrogênio , Cinética , Microscopia Eletrônica de Varredura , Microesferas , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Fatores de Tempo , Águas Residuárias/química , Poluentes Químicos da Água/química
20.
ACS Appl Mater Interfaces ; 11(30): 26664-26673, 2019 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-31287947

RESUMO

The ever-growing global crisis of multidrug-resistant bacteria has triggered a tumult of activity in the design and development of antibacterial formulations. Here, atomically thin antimony selenide nanosheets (Sb2Se3 NSs), a minimal-toxic and low-cost semiconductor material, were explored as a high-performance two-dimensional (2D) antibacterial nanoagent via a liquid exfoliation strategy integrating cryo-pretreatment and polyvinyl pyrrolidone (PVP)-assisted exfoliation. When cultured with bacteria, the obtained PVP-capped Sb2Se3 NSs exhibited intrinsic long-term antibacterial capability, probably due to the reactive oxygen species generation and sharp edge-induced membrane cutting during physical contact between bacteria and nanosheets. Upon near-infrared laser irradiation, Sb2Se3 NSs achieved short-time hyperthermia sterilization because of strong optical absorption and high photothermal conversion efficiency. By virtue of the synergistic effects of these two broad-spectrum antibacterial mechanisms, Sb2Se3 NSs exhibited high-efficiency inhibition of conventional Gram-negative Escherichia coli, Gram-positive methicillin-resistant Staphylococcus aureus, and wild bacteria from a natural water pool. Particularly, these three categories of bacteria were completely eradicated after being treated with Sb2Se3 NSs (300 µM) plus laser irradiation for only 5 min. In vivo wound healing experiment further demonstrated the high-performance antibacterial effect. In addition, Sb2Se3 NSs depicted excellent biocompatibility due to the biocompatible element constitute and bioinert PVP modification. This work enlightened that atomically thin Sb2Se3 NSs hold great promise as a broad-spectrum 2D antibacterial nanoagent for various pathogenic bacterial infections.


Assuntos
Antimônio/farmacologia , Escherichia coli/efeitos dos fármacos , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Antibacterianos/química , Antibacterianos/farmacologia , Antimônio/química , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Humanos , Hipertermia Induzida/métodos , Raios Infravermelhos , Staphylococcus aureus Resistente à Meticilina/patogenicidade , Nanoestruturas/administração & dosagem , Nanoestruturas/química , Fototerapia , Povidona/química
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA