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1.
J Am Chem Soc ; 141(30): 11954-11962, 2019 Jul 31.
Artículo en Inglés | MEDLINE | ID: mdl-31241321

RESUMEN

Molecular engineering of efficient HER catalysts is an attractive approach for controlling the spatial environment of specific building units selected for their intrinsic functionality required within the multistep HER process. As the {Mo3S4} core derived as various coordination complexes has been identified as one as the most promising MoSx-based HER electrocatalysts, we demonstrate that the covalent association between the {Mo3S4} core and the redox-active macrocyclic {P8W48} polyoxometalate (POM) produces a striking synergistic effect featured by high HER performance. Various experiments carried out in homogeneous conditions showed that this synergistic effect arises from the direct connection between the {Mo3S4} cluster and the toroidal {P8W48} units featured by a stoichiometry that can be tuned from two to four {Mo3S4} cores per {P8W48} unit. In addition, we report that this effect is preserved within heterogeneous photoelectrochemical devices where the {Mo3S4}-{P8W48} (thio-POM) assembly was used as cocatalyst (cocat) onto a microstructured p-type silicon. Using a drop-casting procedure to immobilize cocat onto the silicon interface led to high initial HER performance under simulated sunlight, achieving a photocurrent density of 10 mA cm-2 at +0.13 V vs RHE. Furthermore, electrostatic incorporation of the thio-POM anion cocat into a poly(3,4-ethylenedioxythiophene) (PEDOT) film is demonstrated to be efficient and straightforward to durably retain the cocat at the interface of a micropyramidal silicon (SimPy) photocathode. The thio-POM/PEDOT-modified photocathode is able to produce H2 under 1 Sun illumination at a rate of ca. 100 µmol cm-2 h-1 at 0 V vs RHE, highlighting the excellent performance of this photoelectrochemical system.

2.
Chemistry ; 24(53): 14233-14241, 2018 Sep 20.
Artículo en Inglés | MEDLINE | ID: mdl-29978925

RESUMEN

Because mice and rats do not naturally develop Alzheimer's disease, genetically modified animals are required to study this pathology. This striking difference in terms of disease onset could be due to three alterations in the murine sequence (R5G, Y10F and H13R) of the amyloid-ß peptide with respect to the human counterpart. Whether the metal-ion binding properties of the murine peptide are at the origin of such different amyloidogenicity of the two peptides is still an open question. Herein, the main zinc binding site to the murine amyloid-ß at physiological pH has been determined through the combination of several spectroscopic and analytical methods applied to a series of six peptides with one or two of the key mutations. These results have been compared with the zinc binding site encountered in the human peptide. A coordination mechanism that demonstrates the importance of the H13R and R5G mutations in the different zinc environments present in the murine and human peptides is proposed. The nature of the minor zinc species present at physiological pH is also suggested for both peptides. Finally, the biological relevance and fallouts of the differences determined in zinc binding to human versus murine amyloid-ß are also discussed.


Asunto(s)
Péptidos beta-Amiloides/metabolismo , Arginina/genética , Glicina/genética , Histidina/genética , Zinc/metabolismo , Enfermedad de Alzheimer/metabolismo , Enfermedad de Alzheimer/patología , Péptidos beta-Amiloides/química , Péptidos beta-Amiloides/genética , Animales , Arginina/metabolismo , Sitios de Unión , Complejos de Coordinación/química , Complejos de Coordinación/metabolismo , Cobre/química , Cobre/metabolismo , Glicina/metabolismo , Histidina/metabolismo , Humanos , Concentración de Iones de Hidrógeno , Ratones , Mutagénesis Sitio-Dirigida , Resonancia Magnética Nuclear Biomolecular , Espectroscopía de Absorción de Rayos X , Zinc/química
3.
Anal Chem ; 89(3): 2155-2162, 2017 02 07.
Artículo en Inglés | MEDLINE | ID: mdl-28208266

RESUMEN

Being able to easily determine the Cu(II) affinity for biomolecules of moderate affinity is important. Such biomolecules include amyloidogenic peptides, such as the well-known amyloid-ß peptide involved in Alzheimer's disease. Here, we report the synthesis of a new water-soluble ratiometric Cu(II) dye with a moderate affinity (109 M-1 at pH 7.1) and the characterizations of the Cu(II) corresponding complex by X-ray crystallography, EPR, and XAS spectroscopic methods. UV-vis competition was performed on the Aß peptide as well as on a wide series of modified peptides, leading to an affinity value of 1.6 × 109 M-1 at pH 7.1 for the Aß peptide and to a coordination model for the Cu(II) site within the Aß peptide that agrees with the one mostly accepted currently.


Asunto(s)
Péptidos beta-Amiloides/metabolismo , Colorantes/química , Cobre/metabolismo , Espectrofotometría Ultravioleta/métodos , Secuencia de Aminoácidos , Péptidos beta-Amiloides/química , Animales , Sitios de Unión , Cristalografía por Rayos X , Espectroscopía de Resonancia por Spin del Electrón , Humanos , Concentración de Iones de Hidrógeno , Ratones , Solubilidad , Agua
4.
Chemistry ; 23(67): 17078-17088, 2017 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-28846165

RESUMEN

The pseudopeptide L, derived from a nitrilotriacetic acid scaffold and functionalized with three histidine moieties, is reminiscent of the amino acid side chains encountered in the Alzheimer's peptide (Aß). Its synthesis and coordination properties for CuΙ and CuΙΙ are described. L efficiently complex CuΙΙ in a square-planar geometry involving three imidazole nitrogen atoms and an amidate-Cu bond. By contrast, CuΙ is coordinated in a tetrahedral environment. The redox behavior is irreversible and follows an ECEC mechanism in accordance with the very different environments of the two redox states of the Cu center. This is in line with the observed resistance of the CuΙ complex to oxidation by oxygen and the CuΙΙ complex reduction by ascorbate. The affinities of L for CuΙΙ and CuΙ at physiological pH are larger than that reported for the Aß peptide. Therefore, due to its peculiar Cu coordination properties, the ligand L is able to target both redox states of Cu, redox silence them and prevent reactive oxygen species production by the CuAß complex. Because reactive oxygen species contribute to the oxidative stress, a key issue in Alzheimer's disease, this ligand thus represents a new strategy in the long route of finding molecular concepts for fighting Alzheimer's disease.


Asunto(s)
Péptidos beta-Amiloides/química , Cobre/química , Histidina/química , Oligopéptidos/química , Especies Reactivas de Oxígeno/química , Secuencia de Aminoácidos , Ácido Ascórbico/química , Sitios de Unión , Humanos , Cinética , Ligandos , Oxidación-Reducción , Estrés Oxidativo , Oxígeno/química , Unión Proteica , Conformación Proteica , Multimerización de Proteína , Termodinámica
5.
Inorg Chem ; 55(20): 10499-10509, 2016 Oct 17.
Artículo en Inglés | MEDLINE | ID: mdl-27665863

RESUMEN

The Zn(II) ion has been linked to Alzheimer's disease (AD) due to its ability to modulate the aggregating properties of the amyloid-ß (Aß) peptide, where Aß aggregation is a central event in the etiology of the disease. Delineating Zn(II) binding properties to Aß is thus a prerequisite to better grasp its potential role in AD. Because of (i) the flexibility of the Aß peptide, (ii) the multiplicity of anchoring sites, and (iii) the silent nature of the Zn(II) ion in most classical spectroscopies, this is a difficult task. To overcome these difficulties, we have investigated the impact of peptide alterations (mutations, N-terminal acetylation) on the Zn(Aß) X-ray absorption spectroscopy fingerprint and on the Zn(II)-induced modifications of the Aß peptides' NMR signatures. We propose a tetrahedrally bound Zn(II) ion, in which the coordination sphere is made by two His residues and two carboxylate side chains. Equilibria between equivalent ligands for one Zn(II) binding position have also been observed, the predominant site being made by the side chains of His6, His13 or His14, Glu11, and Asp1 or Glu3 or Asp7, with a slight preference for Asp1.


Asunto(s)
Péptidos beta-Amiloides/química , Zinc/química , Sitios de Unión , Histidina/química , Concentración de Iones de Hidrógeno , Espectroscopía de Protones por Resonancia Magnética , Espectroscopía de Absorción de Rayos X
6.
Ecotoxicol Environ Saf ; 124: 386-392, 2016 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-26599281

RESUMEN

Pharmaceuticals are emerging contaminants and their presence in different compartments of the environment has been detected in many countries. In this study, laboratory batch experiments were conducted to characterize the adsorption of diclofenac, a widely used non-steroidal anti-inflammatory drug, on six calcareous soils. The adsorption of diclofenac was relatively low, which may lead to a risk of groundwater contamination and plant uptake. A correlation between the soil-water distribution coefficient Kd and soil characteristics has been highlighted. Indeed, diclofenac adsorption as a function of soil organic matter content (% OM) and Rt=% CaCO3/% OM was successfully described through a simple empirical model, indicating the importance of considering the inhibiting effect of CaCO3 on OM retention properties for a better assessment of diclofenac fate in the specific case of calcareous soils. The simultaneous co-adsorption of diclofenac and copper - a ubiquitous pollutant in the environment - at the water/soil interface, was also investigated. It appeared quite unexpectedly that copper did not have a significant influence on diclofenac retention.


Asunto(s)
Cobre/química , Diclofenaco/química , Contaminantes del Suelo/química , Adsorción , Antiinflamatorios no Esteroideos/química , Carbonato de Calcio/química , Suelo
7.
Ecotoxicol Environ Saf ; 122: 470-6, 2015 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-26408826

RESUMEN

As a result of their consumption, excretion, disposal and persistence, antibiotics enter the soil environment and may be transported to surface and ground waters. During their transfer through soils, retention processes play a key role in their mobility. Antibiotics often coexist with heavy metals in soils due to agricultural practices and other sources of inputs. In this context, this study deals with the co-adsorption of Zn(II) and enrofloxacin (ENR), a widely-used veterinary antibiotic, on a calcareous soil using batch retention experiments and X-ray Absorption Near Edge Structure (XANES) spectroscopy. To improve our understanding of the interaction of this emerging organic contaminant with metal cations at the water-soil interface, the ternary system containing ENR, Zn(II) and a selected calcareous soil was investigated over a pH range between 7 and 10, at different solid-solution contact times and ENR concentrations. The presence of Zn(II) slightly influenced the retention of the antibiotic, leading to an increase of the adsorbed ENR amounts. The distribution coefficient Kd value increased from 0.66 Lg(-1) for single ENR adsorption to 1.04 Lg(-1) in presence of Zn(II) at a 1/2 ENR/Zn(II) ratio. The combination of adsorption isotherm data, solution speciation diagrams and XANES spectra evidenced a small proportion of Zn(II)-ENR complexes at soil pH leading to the slight increase of ENR adsorption in presence of zinc. These results suggest that it is necessary to consider the interaction between ENR and metal cations when assessing the mobility of ENR in soils.


Asunto(s)
Antibacterianos/análisis , Fluoroquinolonas/análisis , Contaminantes del Suelo/análisis , Suelo/química , Zinc/análisis , Adsorción , Agricultura , Enrofloxacina , Cinética , Modelos Teóricos , Espectroscopía de Absorción de Rayos X
8.
Environ Sci Technol ; 48(13): 7237-44, 2014 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-24899255

RESUMEN

Metal solid phase speciation plays an important role in the control of the long-term stability of metals in biosolid-amended soils. The present work used pH-adsorption edge experiments and synchrotron-based spectroscopy techniques to understand the solid phase speciation of copper, nickel and zinc in a biosolid-amended soil. Comparison of metal adsorption edges on the biosolid-amended soil and the soil sample showed that Cu, Ni, and Zn can be retained by both soil and biosolid components such as amorphous iron phases, organic matter and clay minerals. These data are combined with microscopic results to obtain structural information about the surface complexes formed. Linear combination fitting of K-edge XANES spectra of metal hot-spots indicated consistent differences in metal speciation between metals. While organic matter plays a dominant role in Ni binding in the biosolid-amended soil, it was of lesser importance for Cu and Zn. This study suggests that even if the metals can be associated with soil components (clay minerals and organic matter), biosolid application will increase metals retention in the biosolid-amended soil by providing reactive organic matter and iron oxide fractions. Among the studied metals, the long-term mobility of Ni could be affected by organic matter degradation while Cu and Zn are strongly associated with iron oxides.


Asunto(s)
Cobre/análisis , Níquel/análisis , Aguas del Alcantarillado/química , Suelo/química , Espectrometría por Rayos X , Espectroscopía de Absorción de Rayos X , Zinc/análisis , Adsorción , Concentración de Iones de Hidrógeno , Minerales/análisis , Contaminantes del Suelo/análisis
9.
J Hazard Mater ; 466: 133635, 2024 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-38306838

RESUMEN

The antidiabetic drug metformin and antiepileptic drug lamotrigine are contaminants of emerging concern that have been detected in biowaste-derived amendments and in the environment, and their fate must be carefully studied. This work aimed to evaluate their sorption behaviour on soil upon digestate application. Experiments were conducted on soil and digestate-amended soil as a function of time to study kinetic processes, and at equilibrium also regarding the influence of trace metals (Pb, Ni, Cr, Co, Cu, Zn) at ratio pharmaceutical/metal 1/1, 1/10, and 1/100. Pharmaceutical desorption experiments were also conducted to assess their potential mobility to groundwater. Results revealed that digestate amendment increased metformin and lamotrigine adsorbed amounts by 210% and 240%, respectively, increasing organic matter content. Metformin adsorption kinetics were best described by Langmuir model and those of lamotrigine by Elovich and intraparticle diffusion models. Trace metals did not significantly affect the adsorption of metformin in amended soil while significantly decreased that of lamotrigine by 12-39%, with exception for Cu2+ that increased both pharmaceuticals adsorbed amounts by 5 - 8%. This study highlighted the influence of digestate amendment on pharmaceutical adsorption and fate in soil, which must be considered in the circular economy scenario of waste-to-resource.


Asunto(s)
Metales Pesados , Metformina , Contaminantes del Suelo , Oligoelementos , Suelo , Metales Pesados/análisis , Lamotrigina , Anticonvulsivantes , Contaminantes del Suelo/análisis , Adsorción , Preparaciones Farmacéuticas
10.
J Acoust Soc Am ; 134(6): 4681, 2013 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-25669280

RESUMEN

The acoustical macro-behavior of mineral open-cell foam samples is modeled from microstructure morphology using a three-dimensional idealized periodic unit-cell (3D-PUC). The 3D-PUC is based on a regular arrangement of spheres allowed to interpenetrate during the foaming process. Identification and sizing of the 3D-PUC is made from x-ray computed microtomography and manufacturing process information. In addition, the 3D-PUC used allows to account for two scales of porosity: The interconnected network of bubbles (meso-porosity) and the inter-crystalline porosity of a gypsum matrix (micro-porosity). Transport properties of the micro- and the meso-scales are calculated from first principles, and a hybrid micro-macro method is used to determine the frequency-dependent visco-thermal dissipation properties. Olny and Boutin found that the double porosity theory provides the visco-thermal coupling between the meso- and micro-scales [J. Acoust. Soc. Am. 114, 73-89 (2003)]. Finally, the results are successfully compared with experiments for two different mineral foam samples. The main originality of this work is to maintain a direct link between the microstructure morphology and the acoustical macro-behavior all along the multi-scale modeling process, without any adjusted parameter.

11.
Inorg Chem ; 51(23): 12988-3000, 2012 Dec 03.
Artículo en Inglés | MEDLINE | ID: mdl-23150940

RESUMEN

Alzheimer's disease is characterized by senile plaques in which metallic ions (copper, zinc, and iron) are colocalized with amyloid-ß peptides of different sequences in aggregated forms. In addition to the full-length peptides (Aß1-40/42), N-terminally truncated Aß3-40/42 forms and their pyroglutamate counterparts, Aßp3-40/42, have been proposed to play key features in the aggregation process, leading to the senile plaques. Furthermore, they have been shown to be more toxic than the full-length Aß, which made them central targets for therapeutic approaches. In order to better disentangle the possible role of metallic ions in the aggregation process, copper(II) coordination to the full-length amyloid peptides has been extensively studied in the last years. However, regarding the N-terminally modified forms at position 3, very little is known. Therefore, copper(I) and copper(II) coordination to those peptides have been investigated in the present report using a variety of complementary techniques and as a function of pH. Copper(I) coordination is not affected by the N-terminal modifications. In contrast, copper(II) coordination is different from that previously reported for the full-length peptide. In the case of the pyroglutamate form, this is due to preclusion of N-terminal amine binding. In the case of the N-terminally truncated form, alteration in copper(II) coordination is caused by second-sphere effects that impact the first binding shell and the pH-dependent repartition of the various [Cu(peptide)] complexes. Such second-sphere effects are anticipated to apply to a variety of metal ions and peptides, and their importance on changing the first binding shell has not been fully recognized yet.


Asunto(s)
Péptidos beta-Amiloides/química , Cobre/química , Compuestos Organometálicos/síntesis química , Concentración de Iones de Hidrógeno , Estructura Molecular , Compuestos Organometálicos/química
12.
Inorg Chem ; 51(14): 7897-902, 2012 Jul 16.
Artículo en Inglés | MEDLINE | ID: mdl-22765389

RESUMEN

Self-assembly of amyloidogenic peptides and their metal complexes are of multiple interest including their association with several neurological diseases. Therefore, a better understanding of the role of metal ions in the aggregation process is of broad interest. We report pH-dependent structural and aggregation studies on Zn(II) binding to the amyloidogenic peptide Ab11-28. The results suggest that coordination of the N-terminal amine to Zn(II) is responsible for the inhibition of amyloid formation and the overall charge for amorphous aggregates.


Asunto(s)
Péptidos beta-Amiloides/química , Compuestos Organometálicos/química , Fragmentos de Péptidos/química , Zinc/química , Concentración de Iones de Hidrógeno , Cinética , Espectroscopía de Resonancia Magnética , Modelos Moleculares , Estructura Molecular , Compuestos Organometálicos/síntesis química , Espectroscopía de Absorción de Rayos X
13.
Acta Crystallogr Sect E Struct Rep Online ; 68(Pt 4): m474-5, 2012 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-22589837

RESUMEN

The title compound, [Cu(2)(C(14)H(10)Cl(2)NO(2))(4)(C(2)H(6)OS)(2)], comprises a Cu(II) (2) core that is quadruply bridged by four carboxyl-ate ligands with the dimethyl sulfoxide ligands binding along the Cu⋯Cu axis. The four carboxyl-ate ligands bind in a bidentate syn-syn bridging mode. Mol-ecules reside on crystallographic inversion centres bis-ecting the mid-point of the Cu⋯Cu axis. There are no inter-molecular inter-actions of note.

14.
Environ Toxicol Chem ; 41(11): 2700-2707, 2022 11.
Artículo en Inglés | MEDLINE | ID: mdl-35899978

RESUMEN

The (bio)availability of pharmaceuticals at solid/water interfaces is governed by their sorption, which determines their concentrations in groundwaters and surface waters in contact with biota, and can be affected by the presence of other contaminants such as metallic trace elements likely to compete for adsorption sites and form complexes with pharmaceuticals. We studied the adsorption of the pharmaceuticals propranolol and sotalol-two ß-blockers-on one soil and one sediment using batch experiments to assess their (bio)availability. The influence of contact time, pH, and concentration was studied. As in the real environment these contaminants are not alone but in mixtures, and they were studied alone, simultaneously added, and in the presence of Cu2+ , which is known to form coordination complexes with propranolol and sotalol, but their presence in mixtures did not alter their adsorption properties. Sotalol was more mobile in water and thus more bioavailable for organisms than propranolol. The mobility in surface waters of both ß-blockers and thus their bioavailabity for organisms is more important than their risk of transfer to groundwater during rainwater infiltration and to surface water due to runoff. Environ Toxicol Chem 2022;41:2700-2707. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.


Asunto(s)
Complejos de Coordinación , Oligoelementos , Contaminantes Químicos del Agua , Suelo , Adsorción , Cobre/química , Oligoelementos/análisis , Propranolol , Sotalol , Antagonistas Adrenérgicos beta , Contaminantes Químicos del Agua/química , Agua/química , Preparaciones Farmacéuticas
15.
J Biol Inorg Chem ; 16(2): 333-40, 2011 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-21061029

RESUMEN

Metal ions such as zinc and copper can have dramatic effects on the aggregation kinetics of and the structures formed by several amyloidogenic peptides/proteins. Depending on the identity of the amyloidogenic peptide/protein and the conditions, Zn(II) and Cu(II) can promote or inhibit fibril formation, and in some cases these metal ions have opposite effects. To better understand this modulation of peptide aggregation by metal ions, the impact of Zn(II) binding to three amyloidogenic peptides (Aß14-23, Aß11-23, and Aß11-28) on the formation and structure of amyloid-type fibrils was investigated. Zn(II) was able to accelerate fibril formation for all three peptides as measured by thioflavin T fluorescence and transmission electron microscopy. The effects of Zn(II) on Aß11-23 and Aß11-28 aggregation were very different compared with the effects of Cu(II), showing that these promoting effects were metal-specific. X-ray absorption spectroscopy suggested that the Zn(II) binding to Aß11-23 and Aß11-28 is very different from Cu(II) binding, but that the binding is similar in the case of Aß14-23. A model is proposed in which the different coordination chemistry of Zn(II) compared with Cu(II) explains the metal-specific effect on aggregation and the difference between peptides Aß14-23 and Aß11-23/Aß11-28.


Asunto(s)
Amiloide/química , Péptidos/química , Zinc/química , Amiloide/ultraestructura , Microscopía Electrónica , Nefelometría y Turbidimetría , Espectrometría de Fluorescencia , Espectroscopía de Absorción de Rayos X
16.
Chemistry ; 17(36): 10151-60, 2011 Aug 29.
Artículo en Inglés | MEDLINE | ID: mdl-21780203

RESUMEN

The Gly-His-Lys (GHK) peptide and the Asp-Ala-His-Lys (DAHK) sequences are naturally occurring high-affinity copper(II) chelators found in the blood plasma and are hence of biological interest. A structural study of the copper complexes of these peptides was conducted in the solid state and in solution by determining their X-ray structures, and by using a large range of spectroscopies, including EPR and HYSCORE (hyperfine sub-level correlation), X-ray absorption and (1)H and (13)C NMR spectroscopy. The results indicate that the structures of [Cu(II)(DAHK)] in the solid state and in solution are similar and confirm the equatorial coordination sphere of NH(2), two amidyl N and one imidazole N. Additionally, a water molecule is bound apically to Cu(II) as revealed by the X-ray structure. As reported previously in the literature, [Cu(II)(GHK)], which exhibits a dimeric structure in the solid state, forms a monomeric complex in solution with three nitrogen ligands: NH(2), amidyl and imidazole. The fourth equatorial site is occupied by a labile oxygen atom from a carboxylate ligand in the solid state. We probe that fourth position and study ternary complexes of [Cu(II)(GHK)] with glycine or histidine. The Cu(II) exchange reaction between different DAHK peptides is very slow, in contrast to [Cu(II)(GHK)], in which the fast exchange was attributed to the presence of a [Cu(II)(GHK)(2)] complex. The redox properties of [Cu(II)(GHK)] and [Cu(II)(DAHK)] were investigated by cyclic voltammetry and by measuring the ascorbate oxidation in the presence of molecular oxygen. The measurements indicate that both Cu(II) complexes are inert under moderate redox potentials. In contrast to [Cu(II)(DAHK)], [Cu(II)(GHK)] could be reduced to Cu(I) around -0.62 V (versus AgCl/Ag) with subsequent release of the Cu ion. These complete analyses of structure and redox activity of those complexes gave new insights with biological impact and can serve as models for other more complicated Cu(II)-peptide interactions.


Asunto(s)
Cobre/química , Oligopéptidos/química , Compuestos Organometálicos/química , Cristalografía por Rayos X , Resonancia Magnética Nuclear Biomolecular , Oxidación-Reducción , Conformación Proteica
17.
Environ Sci Pollut Res Int ; 28(30): 40264-40274, 2021 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-33387313

RESUMEN

Bioreduction of selenium oxyanions to elemental selenium is ubiquitous; elucidating the properties of this biogenic elemental selenium (BioSe) is thus important to understand its environmental fate. In this study, the magnetic properties of biogenic elemental selenium nanospheres (BioSe-Nanospheres) and nanorods (BioSe-Nanorods) obtained via the reduction of selenium(IV) using anaerobic granular sludge taken from an upflow anaerobic sludge blanket (UASB) reactor treating paper and pulp wastewater were investigated. The study indicated that the BioSe nanomaterials have a strong paramagnetic contribution with some ferromagnetic component due to the incorporation of Fe(III) (high-spin and low-spin species) as indicated by electron paramagnetic resonance (EPR). The paramagnetism did not saturate up to 50,000 Oe at 5 K, and the hysteresis curve showed the coercivity of 100 Oe and magnetic moment saturation around 10 emu. X-ray photoelectron spectroscopy (XPS) and EPR evidenced the presence of Fe(III) in the nanomaterial. Signals for Fe(II) were observed neither in EPR nor in XPS ruling out its presence in the BioSe nanoparticles. Fe(III) being abundantly present in the sludge likely got entrapped in the extracellular polymeric substances (EPS) coating the biogenic nanomaterials. The presence of Fe(III) in BioSe nanomaterial increases the mobility of Fe(III) and may have an effect on phytoplankton growth in the environment. Furthermore, as supported by the literature, there is a potential to exploit the magnetic properties of BioSe nanomaterials in drug delivery systems as well as in space refrigeration.


Asunto(s)
Nanoestructuras , Selenio , Compuestos Férricos , Fenómenos Magnéticos , Aguas del Alcantarillado
18.
Sci Total Environ ; 664: 188-202, 2019 May 10.
Artículo en Inglés | MEDLINE | ID: mdl-30743112

RESUMEN

Application of anaerobically digested sludges and manure (digestates) to agricultural fields reduces the need for fertilizer application, but might also pose environmental risks due to the introduction of various pollutants -including metal trace elements and pharmaceuticals- to amended soils. The simultaneous presence of different contaminants can affect plant uptake, altering the performance of phytoremediation. This work aims to investigate and compare the single and combined effects of Enrofloxacin (Enro) and Cu on their plant uptake from digestate solutions. Plant uptake experiments were carried out by exposing, for 5 days, Phragmites australis to three different concentrations of a liquid digestate doped with Cu and/or Enro. Contaminant concentrations were afterward determined in both plant tissues and digestate solutions. Contaminant speciation in solution and Cu speciation in plant roots were also assessed. Cu plant uptake (mostly in plant roots, Cu concentration varied between 55 and 254 µg·g-1) was observed, especially at low concentration of digestate. At high digestate concentration, Cu uptake decreased due to the formation of Cu-DOC complexes rendering Cu less bioavailable. The presence of the antibiotic slightly further reduced Cu plant uptake due to the formation of Cu-Enro complexes. Plant roots also accumulated Enro, an accumulation also higher for the lowest concentration of digestate (an increase of 40%), and that slightly increased in the presence of Cu (up to 226 µg·g-1). However, proportion of free Enro in solution decreased (up to 70%) in the presence of Cu due to complexation. Cu speciation in plant roots confirmed the implication of the complexation in the uptake of Cu and Enro when they are simultaneously present in solution. Thus, the presence of amendments (such as digestates) increasing the DOC content, in addition to the interactions between contaminants, should be taken into account for field crop soils as well as for phytoremediation technologies.


Asunto(s)
Biodegradación Ambiental , Cobre/análisis , Enrofloxacina/análisis , Poaceae/química , Contaminantes del Suelo/análisis , Eliminación de Residuos Líquidos , Suelo
19.
J Environ Qual ; 37(2): 631-8, 2008.
Artículo en Inglés | MEDLINE | ID: mdl-18396550

RESUMEN

A lignocellulosic substrate (LS) obtained from our local agroindustry was used as a low-cost and effective adsorbent for the removal of pesticides from wastewaters. The studied pesticides were terbumeton (N-(1,1-dimethyl)-Nethyl-6-methoxy-1,3,5-triazine-2,4-diamine), desethyl terbumeton (N-(1,1-dimethylethyl)-6-methoxy-1,3,5-triazine-2,4-diamine), dimetomorph (4-[3-(4-chlorophenyl)-3-(3,4-dimethoxyphenyl)acryloyl]morpholine), and isoproturon (3-(4-isopropylphenyl)-1,1-dimethylurea). Batch and column experiments were conducted as a function of pH and pesticide concentration under laboratory and industrial conditions. The concentration range studied for the pesticides varied from 2 x 10(-7) to 3 x 10(-4) mol L(-1). The influence of organic and inorganic pollutants was assessed by studying the retention of pesticide in the presence of copper(II) and a surfactant. These experiments indicated that LS is an efficient adsorbent toward the investigated pesticides and has little influence of the other pollutants. The kinetic adsorptions are fast, and the amounts of adsorbed pesticide varied from 1 to 8 g kg(-1) of LS. These retention capacities show that LS can provide a simple, effective, and cheap method for removing pesticides from contaminated waters. Thus, this biomaterial may be useful for cleaning up polluted waters.


Asunto(s)
Celulosa/química , Lignina/química , Plaguicidas/química , Eliminación de Residuos Líquidos/métodos , Contaminantes Químicos del Agua/química , Adsorción , Cobre/química , Costos y Análisis de Costo , Fibras de la Dieta , Cinética , Tensoactivos/química , Purificación del Agua/métodos
20.
Sci Total Environ ; 639: 841-851, 2018 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-29803054

RESUMEN

The bioavailability of pharmaceuticals is governed by their sorption in soils/sediments, as the retention processes determine their concentration in surface- and ground-water. The adsorption of these contaminants can involve various solid components such as organic matter, clays and metallic oxides, and their distribution among these solid components depends on contaminant and solid properties. In this paper we studied the adsorption of the pharmaceutical propranolol - a beta-blocker - on eight different solids (six soils, one sediment and one kaolinite-based sample) by batch experiments. The influence of contact time, propranolol concentration and pH was considered, as well as the presence of copper(II). The investigated solids displayed a wide variability in terms of CEC (cationic exchange capacity) and organic carbon and carbonates contents. The influence of pH was negligible in the pH range from 5.5 to 8.6. The adsorbed amounts were greatly dependent on the solid and two groups of solids were evidenced: three soils of high CEC and organic carbon contents which retained high amounts of propranolol, and three soils, the sediment and the kaolinite-based sample (low CEC and organic carbon content) displaying a low adsorption capacity for the beta-blocker. A linear model enabling the determination of the sorption parameters Kd and Koc was pertinent to describe the adsorption isotherms but the Koc values showed a great variability. It was shown that organic carbon content alone could not explain propranolol adsorption. The CEC value was identified as influent parameter and a simple empirical model was proposed to describe propranolol adsorption. At microscopic and molecular scales, ToF-SIMS experiments indicated (i) a decrease of potassium on the surface upon propranolol adsorption with a distribution of the beta-blocker similarly to alumino-silicates, iron and organic carbon on the surface confirming a cation exchange mechanism and (ii) the absence of degradation products and copper-propranolol complexes.


Asunto(s)
Cobre/química , Modelos Químicos , Propranolol/análisis , Contaminantes del Suelo/análisis , Espectrometría de Masa de Ion Secundario/métodos , Adsorción , Concentración de Iones de Hidrógeno , Suelo
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