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1.
Chemphyschem ; 23(5): e202100856, 2022 03 04.
Artículo en Inglés | MEDLINE | ID: mdl-34995018

RESUMEN

Sulphur, not phosphorus, is the only known third-row element capable of experiencing an electrostatic gauche effect with fluorine. Some six-membered rings containing an endocyclic phosphorus atom and a ß-fluorine substituent that can interconvert to axial (gauche relative to phosphorus) and equatorial positions were then analysed. While phosphines do not establish an electrostatic attraction between fluorine and phosphorus, some oxidised forms exhibit surprising stability for the sterically disfavoured axial orientation. Because the nature of this behaviour was not obvious, since an intramolecular hydrogen bond can appear, a phosphonium derivative was further studied and its axial conformation was found to be highly stable. A preference for the gauche arrangement appears even for the acyclic and sterically hindered (2-fluoroethyl)triphenylphosphonium cation. On the other hand, (ethane-1,2-diyl)bis(phosphonium) cations are exclusively in anti conformation due to an (+/+)-electrostatic repulsion between the positively charged phosphonium groups.


Asunto(s)
Flúor , Flúor/química , Enlace de Hidrógeno , Conformación Molecular , Electricidad Estática , Rayos X
2.
J Environ Sci (China) ; 57: 312-320, 2017 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-28647251

RESUMEN

This work describes the synthesis of catalysts based on red mud/polyethylene terephthalate (PET) composites and their subsequent heat treatment under N2 atmosphere. The materials were characterized by scanning electron microscopy (SEM), temperature programmed reduction (TPR), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric (TG) analysis and N2 adsorption/desorption. The catalysts were evaluated in the oxidative desulfurization reaction of dibenzothiophene (DBT) in a biphasic system. The results indicated that the PET impregnation on red mud increased the affinity of the catalyst with the nonpolar phase (fuel), in which the contaminant was dissolved, allowing a higher conversion (up to 80%) and selectivity to the corresponding dibenzothiophene sulfone. The sulfone compound is more polar than DBT and diffused into the polar solvent as indicated by the data obtained via gas chromatography-mass spectrometry (GC-MS).


Asunto(s)
Modelos Químicos , Tereftalatos Polietilenos/química , Adsorción , Catálisis , Oxidación-Reducción , Espectroscopía Infrarroja por Transformada de Fourier , Tiofenos
3.
Int Braz J Urol ; 39(3): 335-42; discussion 343, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-23849566

RESUMEN

UNLABELLED: Integrins are transmembrane glycoprotein receptors that regulate cell-matrix interactions, thus functioning as sensors from the environment. They also act as cell adhesion molecules that are responsible for the maintenance of the normal epithelial phenotype. Some studies have reported a correlation between carcinogenesis and changes in integrin expression, especially ß1 integrin, however its role in prostate cancer (PC) is unclear. The aim of our study was to evaluate the expression of ß1 integrin in localized PC and to correlate the pattern of expression with recurrence after surgical treatment. Methods For this case-control study, we retrospectively selected surgical specimens from 111 patients with localized PC who underwent radical prostatectomy. Recurrence was defined as a PSA level exceeding 0.2 ng/mL after surgery, and the median follow-up was 123 months. Integrin expression was evaluated by immunohistochemistry in a tissue microarray containing two samples from each tumor. We employed a semiquantitative analysis and considered a case as positive when the expression was strong and diffusely present. RESULTS: There was a loss of 11 cases during the tissue micro array assembling. ß1 expression was positive in 79 of the 100 evaluated cases (79%). The univariate and multivariate analyses showed that the negative expression of ß1 integrin was associated with biochemical recurrence (p = 0.047) and time to recurrence after radical prostatectomy (p = 0.023). When ß1 was negative, the odds ratio for recurrence was 2.78 times higher than that observed in the positive cases [OR = 2.78, p = 0.047, IC 95% (1.01-7.66)]. CONCLUSIONS: The loss of ß1 integrin immune expression was correlated with biochemical recurrence in patients treated with radical prostatectomy for localized PC.


Asunto(s)
Biomarcadores de Tumor/análisis , Integrina beta1/análisis , Recurrencia Local de Neoplasia/química , Neoplasias de la Próstata/química , Adulto , Anciano , Humanos , Inmunohistoquímica , Estimación de Kaplan-Meier , Masculino , Persona de Mediana Edad , Clasificación del Tumor , Recurrencia Local de Neoplasia/patología , Pronóstico , Antígeno Prostático Específico/sangre , Neoplasias de la Próstata/patología , Factores de Tiempo
4.
Environ Sci Pollut Res Int ; 28(31): 42093-42106, 2021 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-33791966

RESUMEN

Water contamination is a common problem, especially considering dyes and drugs disposal. A possible and effective treatment method to remove these organic pollutants from water is photocatalytic reaction. This study aimed to improve the photocatalytic properties of TiO2 using iron oxides (Ti/Fe composite). Different magnetic photocatalysts based on commercial TiO2 were obtained with 30, 50, and 80% (wt./wt.) of TiO2 supported on maghemite. X-ray diffraction with Rietveld refinement confirms the presence of γ-Fe2O3, α-Fe2O3, anatase, and rutile, as well as the relative percentages of the phases present in each photocatalyst. The magnetic properties were certified by VSM and sedimentation kinetics in the presence of a magnetic field. Besides their magnetic properties, UV-vis DRS shows that the obtained photocatalysts presented lower bandgap values when compared with TiO2. These factors allowed the materials to absorb radiation in the visible-light region and the separation from the reaction medium by the application of magnetic field. It was observed an enhancement of photodegradation reaction of methylene blue (MB) and paracetamol (PC). For example, when the content of TiO2 increased from 30 to 80% (wt./wt.), the efficiency increased from 58 to 99% (for MB) and 39 for 80% (for PC) under UV (λ = 254 nm). The reactions carried out with solar radiation showed 56 to 95% efficiency to discolor MB. In addition, the results of sedimentation kinetics and characterization confirmed the goals of the synthesis.


Asunto(s)
Azul de Metileno , Luz Solar , Acetaminofén , Catálisis , Titanio
5.
Environ Sci Pollut Res Int ; 28(5): 5714-5730, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-32968906

RESUMEN

Environmental contamination has been a cause of concern worldwide, being aggravated by anthropogenic activities carried out without the correct disposal of toxic products in the various habitats on our planet. In Brazil, mining companies are responsible for the contamination of large river basins with toxic elements from mining activities. Among these elements, arsenic draws attention because it is highly carcinogenic and found in waters in concentrations above those recommended by regulatory agencies. Here, Fe2(MoO4)3 nanoparticles are synthesized and used as a filter medium in water purification systems contaminated with arsenic. The adsorption kinetics of arsenic by Fe2(MoO4)3 nanoparticles is fast, showing pseudo-second-order rate constants of 0.0044, 0.0080, and 0.0106 g mg-1 min-1 for As3+, As5+, and MMA, respectively. The adsorption isotherms are better adjusted with the Langmuir and Redlich-Peterson models, indicating that the arsenic adsorption occurs in monolayers on the Fe2(MoO4)3 surface. The Fe2(MoO4)3 adsorption capacities determined for the As3+, As5+, and MMA species are 16.1, 23.1, and 23.5 mg g-1, respectively. The Fe2(MoO4)3 filter is efficient in purifying arsenic-contaminated water, reducing its initial concentration from 1000 µg L-1 to levels close to zero. Biological tests indicate that Fe2(MoO4)3 nanoparticles and filtered water have no cytotoxic, genotoxic, and mutagenic risks to human life. Those results suggest that the Fe2(MoO4)3 filter can be used as an efficient and safe technology for the purification of water contaminated by arsenic.


Asunto(s)
Arsénico , Contaminantes Químicos del Agua , Purificación del Agua , Adsorción , Arsénico/análisis , Bioensayo , Brasil , Daño del ADN , Humanos , Concentración de Iones de Hidrógeno , Hierro , Cinética , Molibdeno , Mutágenos , Agua , Contaminantes Químicos del Agua/análisis
6.
Int Braz J Urol ; 36(3): 348-54, 2010.
Artículo en Inglés | MEDLINE | ID: mdl-20602828

RESUMEN

PURPOSE: Tumor banks have the primary responsibility for collecting, cataloging, storing and disseminating samples of tissues, cells and fluids, which are used by researchers to identify diagnostic molecular markers, prognostic indicators and therapeutic targets. The objective of this review was to describe a simple, reliable and reproducible protocol for obtaining and storing samples of urological tumors. MATERIALS AND METHODS: Urogenital tumor tissues were collected by the surgeons from the Urology Division of University of Sao Paulo Medical School. The obtained surgical specimens were immediately placed in liquid nitrogen, dry ice or in a tube containing RNAlater, and then stored by cryopreservation (-80 degrees C). A mirror fragment was fixed in 10% formalin processed routinely and embedded in Paraplast. RESULTS: We developed a protocol for the collection, cataloging, storage, conservation and use of tumor samples. During a period of one year the Urological Tumor Bank of the Urology Division stored 274 samples of prostate, bladder, kidney, penis and testicle tumors of different histological types, 74 urine and 271 serum samples. CONCLUSIONS: Having biological materials characterized and available along with the clinical patient information provides an integrated portrait of the patients and their diseases facilitating advances in molecular biology. It also promotes the development of translational research improving methods of diagnosis and cancer treatment.


Asunto(s)
Investigación Biomédica , Manejo de Especímenes/métodos , Bancos de Tejidos/organización & administración , Neoplasias Urogenitales/patología , Brasil , Criopreservación , Comités de Ética en Investigación , Humanos , Bancos de Tejidos/ética , Bancos de Tejidos/estadística & datos numéricos , Recolección de Tejidos y Órganos/métodos , Investigación Biomédica Traslacional , Neoplasias Urogenitales/cirugía
7.
ACS Omega ; 5(34): 21392-21400, 2020 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-32905303

RESUMEN

Furfural chemistry is one of the most promising platforms directly derived from lignocellulose biomass. In this study, a niobium-based catalyst (mNb-bc) was synthesized by a new fast and simple method. This new method uses microemulsion to obtain a catalyst with a high specific surface area (340 m2 g-1), defined mesoporosity, and high acidity (65 µmol g-1). Scanning electron microscopy revealed that mNb-bc has a rough surface. The mNb-bc was used to catalyze the conversion reaction of xylose into 2-furfuraldehyde in a monophasic system using water as a green solvent. This reaction was investigated using a 23 experimental design by varying the temperature, time, and catalyst-to-xylose ratio (CXR). The responses evaluated were xylose conversion (X c), reaction yield (Y), and selectivity to 2-furfuraldehyde (S). The optimized reaction conditions were used to evaluate the reaction kinetics. At milder reaction conditions of 140 °C, 2 h, and a CXR of 10%, mNb-bc led to an X c value of 41.2%, an S value of 77.1%, and a Y value of 31.8%.

8.
Biol Trace Elem Res ; 194(2): 502-513, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-31313244

RESUMEN

The aim of the study was to evaluate if gold-coated superparamagnetic iron oxide nanoparticles (AuSPION) magnetic-targeted to the arthritic articulation of collagen induced arthritis (CIA) rats are able to ameliorate rheumatoid arthritis without producing significant biological adverse effects in comparison to colloidal Au nanoparticles (AuC) and metotrexate (MTX). Male Wistar rats were divided into control; arthritic; AuSPION (150 µg kg-1); AuC (150 µg kg-1) and MTX (2.5 µg kg-1). Treatments were administered thrice every other day by the intraperitoneal route 15 min after all groups had a neodymium magnet coupled to the right ankle joint (kept for 1 h). Paw edema and body weight were measured weekly. Joint sections were evaluated by Haematoxylin & Eosin and immunohistochemistry (TNF-α, IL-1ß). Biomarkers of oxidative stress were used to evaluate toxicity. Among the evaluated treatments, AuSPION led to significant clinical improvements (decreased edema and infiltration by leukocytes as well as less positively immunostained cells for both TNF-α and IL-1ß in synovium) accompanied by a lack of toxicity as indicated by redox state and genotoxicity assays. Our results clearly indicate that the magnetic targeting of AuSPION suppresses joint edema and inflammation, cytokine expression as well as the redox imbalance, thereby contributing to an amelioration of arthritis severity in CIA rats. The results demonstrate for the first time the potentiality of AuSPION administration under a magnetic field as an attractive alternative for future treatments of rheumatic diseases.


Asunto(s)
Artritis Experimental , Nanopartículas del Metal , Animales , Artritis Experimental/tratamiento farmacológico , Citocinas , Oro , Nanopartículas Magnéticas de Óxido de Hierro , Fenómenos Magnéticos , Masculino , Ratas , Ratas Wistar
9.
Chemosphere ; 215: 422-431, 2019 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-30336319

RESUMEN

l-Cystine functionalized δ-FeOOH nanoparticles (Cys-δ-FeOOH) were prepared by a cheap and straightforward method for using as an adsorbent of Hg(II) in aqueous solution. X-ray diffraction (XRD), attenuated total reflectance infrared spectroscopy (ATR-IR), and Raman spectroscopy confirmed that Cys-δ-FeOOH was successfully synthesized. Cys-δ-FeOOH with 14 nm crystal size, 34 m2 g-1 surface area, and 9 nm pore size were produced. The functionalization of the δ-FeOOH surface with cysteine decreases the point of zero charge of the iron oxyhydroxide from 8.4 in δ-FeOOH to 5.7 in Cys-δ-FeOOH, which is beneficial for the adsorption of Hg(II) near neutral pH. The maximum Hg(II) adsorption capacity of the δ-FeOOH and Cys-δ-FeOOH at pH 7 were found to be 35 mg g-1 and 217 mg g-1, respectively. The kinetics data were best fitted by a pseudo-second-order model, suggesting chemical adsorption on the surface and pores of Cys-δ-FeOOH nanoparticles. Finally, δ-FeOOH and Cys-δ-FeOOH filters were constructed for purifying mercury-contaminated water. The filters were highly efficient to treat mercury-contaminated water from a Brazilian river, reducing the concentration of mercury in water to values below the allowed limits by the current legislation.


Asunto(s)
Cistina/química , Compuestos Férricos/química , Mercurio/aislamiento & purificación , Contaminantes Químicos del Agua/aislamiento & purificación , Purificación del Agua/métodos , Adsorción , Brasil , Concentración de Iones de Hidrógeno , Cinética , Mercurio/análisis , Ríos/química , Contaminantes Químicos del Agua/análisis
10.
J Hazard Mater ; 151(1): 280-4, 2008 Feb 28.
Artículo en Inglés | MEDLINE | ID: mdl-18078712

RESUMEN

This study evaluated the feasibility of using a solid waste from the leather industry as an adsorbent for removal of Cr(VI) and As(V) from aqueous media. The adsorbent material was characterized by chemical analyses, infrared spectroscopy, and scanning electronic microscopy (SEM) prior to reaction in order to assess its surface properties. Langmuir and Freundlich equations were used for analyzing the experimental data, which showed a better fit to the Langmuir model, thus suggesting a monolayer adsorption process in the surface of the adsorbent. The high amounts of Cr(VI)-133 mg g(-1) and As(V)-26 mg g(-1) adsorbed demonstrates the great potential for using this solid waste from the leather industry as a low-cost alternative to the traditionally used adsorbent materials.


Asunto(s)
Arsénico/aislamiento & purificación , Cromo/aislamiento & purificación , Residuos Industriales , Eliminación de Residuos Líquidos/métodos , Contaminantes Químicos del Agua/aislamiento & purificación , Adsorción , Arsénico/química , Cromo/química , Contaminantes Químicos del Agua/química
11.
Int J Biol Macromol ; 106: 1218-1234, 2018 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-28851645

RESUMEN

This study focused on the synthesis and comprehensive characterization of environmentally friendly hydrogel membranes based on carboxymethyl cellulose (CMC) for wound dressing and skin repair substitutes. These new CMC hydrogels were prepared with two degrees of functionalization (DS=0.77 and 1.22) and chemically crosslinked with citric acid (CA) for tuning their properties. Additionally, CMC-based hybrids were prepared by blending with polyethylene glycol (PEG, 10wt.%). The results demonstrated that superabsorbent hydrogels (SAP) were produced with swelling degree typically ranging from 100% to 5000%, which was significantly dependent on the concentration of CA crosslinker and the addition of PEG as network modifier. The spectroscopical characterizations indicated that the mechanism of CA crosslinking was mostly associated with the chemical reaction with CMC hydroxyl groups and that PEG played an important role on the formation of a hybrid polymeric network. These hydrogels presented very distinct morphological features depended on the degree of crosslinking and the surface nanomechanical properties (e.g., elastic moduli) were drastically affected (from approximately 0.08GPa to 2.0GPa) due to the formation of CMC-PEG hybrid nanostructures. These CMC-based hydrogels were cytocompatible considering the in vitro cell viability responses of over 95% towards human embryonic kidney cells (HEK293T) used as model cell line.


Asunto(s)
Vendajes/microbiología , Materiales Biocompatibles/química , Carboximetilcelulosa de Sodio/química , Polietilenglicoles/química , Materiales Biocompatibles/uso terapéutico , Carboximetilcelulosa de Sodio/uso terapéutico , Reactivos de Enlaces Cruzados/química , Reactivos de Enlaces Cruzados/uso terapéutico , Células HEK293 , Humanos , Hidrogeles/química , Hidrogeles/uso terapéutico , Polietilenglicoles/uso terapéutico , Cicatrización de Heridas/efectos de los fármacos
12.
Environ Sci Pollut Res Int ; 25(14): 13857-13867, 2018 May.
Artículo en Inglés | MEDLINE | ID: mdl-29512010

RESUMEN

The high toxicity and potential arsenic accumulation in several environments have encouraged the development of technologies for its removal from contaminated waters. However, the arsenic released into aquatic environment comes mainly from extremely acidic mining effluents, making harder to find stable adsorbents to be used in these conditions. In this work, K-jarosite particles were synthesized as a stable adsorbent in acidic medium for eliminating arsenic from contaminated water. The adsorption capacities of K-jarosite for As3+, As5+, and monomethylarsonic acid were 9.45, 12.36, and 8.21 mg g-1, respectively. Most arsenic in water was adsorbed within the first 10 min, suggesting the fast arsenic adsorption kinetics of K-jarosite particles. Because of that, a K-jarosite filter was constructed for purifying water at a constant flow. The K-jarosite filter was highly efficient to treat arsenic-contaminated water from a Brazilian river, reducing the concentration of arsenic in water to near zero. These data suggest the K-jarosite filter can be used as a low-cost technology for purifying arsenic-contaminated water in acidic medium.


Asunto(s)
Arsénico/análisis , Arsenicales/análisis , Compuestos Férricos/química , Potasio/química , Sulfatos/química , Contaminantes Químicos del Agua/análisis , Purificación del Agua/métodos , Adsorción , Filtración/instrumentación , Iones/análisis , Purificación del Agua/instrumentación
13.
Environ Technol ; 39(22): 2856-2872, 2018 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-28805161

RESUMEN

In this study, new eco-friendly hydrogel adsorbents were synthesized based on carboxymethylcellulose (CMC, degree of substitution [DS] = 0.7) chemically cross-linked with citric acid (CA) using a green process in aqueous solution and applied for the adsorption of methylene blue (MB). Spectroscopic analyses demonstrated the mechanism of cross-linking through the reaction of hydroxyl functional groups from CMC with CA. These CMC hydrogels showed very distinct morphological features dependent on the extension of cross-linking and their nanomechanical properties were drastically increased by approximately 300% after cross-linking with 20% CA (e.g. elastic moduli from 80 ± 15 to 270 ± 50 MPa). Moreover, they were biocompatible using an in vitro cell viability assay in contact with human osteosarcoma-derived cells (SAOS) for 24 h. These CMC-based hydrogels exhibited adsorption efficiency above 90% (24 h) and maximum removal capacity of MB from 5 to 25 mg g-1 depending on the dye concentration (from 100 to 500 mg L-1), which was used as the model cationic organic pollutant. The adsorption of process of MB was well-fit to the pseudo-second-order kinetics model. The desorption of MB by immersion in KCl solution (3 mol L-1, 24 h) showed a typical recovery efficiency of over 60% with conceivable reuse of these CMC-based hydrogels. Conversely, CMC hydrogels repelled methyl orange dye used as model anionic pollutant, proving the mechanism of adsorption by the formation of charged polyelectrolyte/dye complexes.


Asunto(s)
Contaminantes Ambientales , Contaminantes Químicos del Agua , Adsorción , Carboximetilcelulosa de Sodio , Colorantes , Humanos , Hidrogeles
14.
Environ Sci Pollut Res Int ; 25(28): 27737-27747, 2018 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-29700754

RESUMEN

Semiconductors based on Fe/Nb oxides can present both solar sensitivity and high catalytic activity. However, there is still a lack regarding the comparison between different routes to produce Fe/Nb-based solar photocatalysts and the evaluation of the impact of the synthesis operating conditions on the material properties. In this work, Fe/Nb2O5 ratio, type of precipitating agent, presence/absence of washing stage, and temperature of calcination were verified to be the most relevant parameters in the synthesis by the co-precipitation method. These factors led to remarkable differences in the properties and performance of the photocatalysts produced by each distinct synthesis route. Composition, iron species present in the materials, crystallinity characteristics, and pH of the catalysts were affected, leading to different photocatalytic activities under UV-Vis light. Due to their characteristics, the synthesized materials are potential photocatalysts for application in solar processes. Graphical abstract ᅟ.


Asunto(s)
Hierro/química , Niobio/química , Óxidos/química , Óxidos/síntesis química , Semiconductores , Rayos Ultravioleta , Purificación del Agua/métodos , Catálisis , Precipitación Química , Procesos Fotoquímicos
15.
Dalton Trans ; 47(32): 10976-10988, 2018 Aug 14.
Artículo en Inglés | MEDLINE | ID: mdl-30020278

RESUMEN

In this work, a two-dimensional coordination polymer was synthesized and the structure was determined by single-crystal X-ray diffraction. The crystal structure belongs to the space group Pna21 and was characterized by Raman and FT-infrared spectroscopy, powder X-ray diffraction and Brunauer-Emmett-Teller surface area analysis. Catalyst activities were evaluated through the synthesis of glycerol carbonate from glycerol and urea using a batch reactor. After the optimization of both reaction and reaction conditions, the activity results showed that the coordination polymer used as a heterogeneous catalyst has good values of conversions and selectivity for the manufacturing of glycerol carbonate in a fine-chemical process. The analysis of powder X-ray diffraction and spectroscopy for the coordination polymer employed, before and after the reaction, shows that some changes have taken place in the crystal structure during the process, in spite of a recovery at the end of the reaction. The advantages and limitations of the coordination polymer were discussed and compared with those of the previous heterogeneous catalysts in the literature.

16.
RSC Adv ; 8(19): 10310-10313, 2018 Mar 13.
Artículo en Inglés | MEDLINE | ID: mdl-35540472

RESUMEN

A new class of polyoxoniobate complex has been synthesized and characterized as a novel anticancer agent for photodynamic therapy. The complex inhibits the growth of chronic myelogenous leukemia cells with an IC50 value of 30 µM, in the dark. However, upon exposure to light (365 nm) there is a fivefold increase in the cytotoxic activity. Light radiation activate the complex with the formation of radical species capable of interacting with DNA according to our experimental and theoretical data.

17.
J Hazard Mater ; 141(1): 344-7, 2007 Mar 06.
Artículo en Inglés | MEDLINE | ID: mdl-16901630

RESUMEN

The industrial tanning of leather usually produces considerable amounts of chromium-containing solid waste and liquid effluents and raises many concerns on its environmental effect as well as on escalating landfill costs. Actually, these shortcomings are becoming increasingly a limiting factor to this industrial activity that claims for alternative methods of residue disposals. In this work, it is proposed a novel alternative destination of the solid waste, based on the removal of organic contaminants from the out coming aqueous-residue. The adsorption isotherm pattern for the wet blue leather from the Aurea tanning industry in Erechim-RS (Brazil) showed that these materials present high activity on adsorbing the reactive red textile dye as well as other compounds. The adsorbent materials were characterized by IR spectroscopy and SEM and tested for the dye adsorption (reactive textile and methylene blue dyes). The concentrations of dyes were measured by UV-vis spectrophotometry and the chromium extraction from leather waste was realized by basic hydrolysis and determined by atomic absorption. As a low cost abundant adsorbent material with high adsorption ability on removing dye methylene blue (80mgg(-1)) and textile dye reactive red (163mgg(-1)), the leather waste is revealed to be a interesting alternative relatively to more costly adsorbent materials.


Asunto(s)
Cromo/química , Colorantes/química , Residuos Industriales , Curtiembre , Eliminación de Residuos Líquidos/métodos , Adsorción
18.
Nanoscale Res Lett ; 12(1): 443, 2017 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-28683540

RESUMEN

Quantum dots (QDs) are colloidal semiconductor nanocrystals with unique properties that can be engineered by controlling the nanoparticle size and chemical composition by doping and alloying strategies. However, due to their potential toxicity, augmenting their biocompatibility is yet a challenge for expanding to several biomedical and environmentally friendly applications. Thus, the main goal of this study was to develop composition-tunable and biocompatible Zn x Cd1 - x S QDs using carboxymethylcellulose polysaccharide as direct capping ligand via green colloidal aqueous route at neutral pH and at room temperature for potential biomedical and environmental applications. The ternary alloyed QDs were extensively characterized using UV-vis spectroscopy, photoluminescence spectroscopy (PL), transmission electron microscopy (TEM), X-ray diffraction (XRD), electron energy loss spectroscopy (EELS), and X-ray photoelectrons spectroscopy (XPS). The results indicated that Zn x Cd(1 - x)S QDs were surface stabilized by carboxymethylcellulose biopolymer with spherical morphology for all composition of alloys and narrow sizes distributions ranging from 4 to 5 nm. The XRD results indicated that monophasic ternary alloyed Zn x Cd1 - x S nanocrystals were produced with homogenous composition of the core as evidenced by EELS and XPS analyses. In addition, the absorption and emission optical properties of Zn x Cd1 - x S QDs were red shifted with increasing the amount of Cd2+ in the alloyed nanocrystals, which have also increased the quantum yield compared to pure CdS and ZnS nanoparticles. These properties of alloyed nanomaterials were interpreted based on empirical model of Vegard's law and chemical bond model (CBM). As a proof of concept, these alloyed-QD conjugates were tested for biomedical and environmental applications. The results demonstrated that they were non-toxic and effective fluorophores for bioimaging live HEK293T cells (human embryonic kidney cells) using confocal laser scanning fluorescence microscopy. Moreover, these conjugates presented photocatalytic activity for photodegradation of methylene blue used as model organic industrial pollutant in water. Hence, composition-tunable optical properties of ternary Zn x Cd1 - x S (x = 0-1) fluorescent alloyed QDs was achieved using a facile eco-friendly aqueous processing route, which can offer promising alternatives for developing innovative nanomaterials for applications in nanomedicine and environmental science and technology.

19.
Environ Sci Pollut Res Int ; 24(7): 6114-6125, 2017 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-27040545

RESUMEN

Fe2O3-SiO2 composites were prepared by impregnation (sample FeIMP) or doping (sample FeDOP) in the structure of porous silica. The dye removal capacity of the materials was investigated through adsorption and oxidation studies of methylene blue and rhodamine B. N2 adsorption/desorption measurements on FeIMP and FeDOP resulted in specific areas of 27 and 235 m2 g-1, respectively. Mössbauer spectroscopy and XRD data detected hematite and maghemite as the iron phases in the samples FeIMP and FeDOP, respectively. Adsorption isotherms and kinetic studies of the dyes were better fitted in DKR model for FeDOP, where the process follows a pseudo-second order with the interparticle diffusion step being the rate-limiting step. On the other hand, FeIMP has better fit in the Langmuir model. Photocatalytic activity was observed in FeDOP under UV irradiation by the presence of reaction-hydroxylated intermediates for MB (m/z = 301) and RhB (m/z = 459). However, the photocatalytic activity was strongly influenced by the adsorption affinity between dye/catalyst. Photogenerated holes are the species responsible for the dye degradation when the adsorption is too strong, while hydroxyl radical action will be favored when the adsorption is not vigorous as detected by ESI-MS. Graphical Abstract Action of photogenerated holes and free electrons into the photocatalytically mechanism of methylene blue degradation over a semiconductor.


Asunto(s)
Compuestos Férricos/química , Imanes/química , Dióxido de Silicio/química , Contaminantes Químicos del Agua , Purificación del Agua/métodos , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/química , Contaminantes Químicos del Agua/aislamiento & purificación
20.
Sci Rep ; 6: 24348, 2016 Apr 14.
Artículo en Inglés | MEDLINE | ID: mdl-27076349

RESUMEN

The goal of this work was to investigate the relevant dosimetric and luminescent properties of MgO:Li3%,Ce0.03%,Sm0.03%, a newly-developed, high sensitivity Optically Stimulated Luminescence (OSL) material of low effective atomic number (Zeff = 10.8) and potential interest for medical and personal dosimetry. We characterized the thermoluminescence (TL), OSL, radioluminescence (RL), and OSL emission spectrum of this new material and carried out a preliminary investigation on the OSL signal stability. MgO:Li,Ce,Sm has a main TL peak at ~180 °C (at a heating rate of 5 °C/s) associated with Ce(3+) and Sm(3+) emission. The results indicate that the infrared (870 nm) stimulated OSL from MgO:Li,Ce,Sm has suitable properties for dosimetry, including high sensitivity to ionizing radiation (20 times that of Al2O3:C, under the measurement conditions) and wide dynamic range (7 µGy-30 Gy). The OSL associated with Ce(3+) emission is correlated with a dominant, practically isolated peak at 180 °C. Fading of ~15% was observed in the first hour, probably due to shallow traps, followed by subsequent fading of 6-7% over the next 35 days. These properties, together with the characteristically fast luminescence from Ce(3+), make this material also a strong candidate for 2D OSL dose mapping.


Asunto(s)
Cerio/metabolismo , Óxido de Magnesio/metabolismo , Dosimetría con Luminiscencia Ópticamente Estimulada/métodos , Samario/metabolismo , Relación Dosis-Respuesta en la Radiación , Temperatura
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