1000 resultados para Técnicas de remediação


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El fracaso renal agudo afecta a un 25% de los pacientes hospitalizados en las unidades de cuidados intensivos. A pesar de los avances tecnológicos, la mortalidad de estos pacientes sigue siendo elevada debido a las complicaciones asociadas. Uno de los tratamientos del fracaso renal agudo son las técnicas continuas de reemplazo renal ya que permiten tratar las complicaciones y disminuir la mortalidad. El conocimiento y la habilidad de la enfermera en relación con estas técnicas serán decisivos para el éxito de la terapia. Para ello, la formación y la experiencia de la enfermera son el componente clave. El presente artículo tiene como objetivo actualizar los conocimientos sobre las técnicas continuas de reemplazo renal. Para ello, se realiza una revisión de los principios físico-químicos, como la difusión y la convección, entre otros, una descripción de las modalidades de las técnicas continuas de reemplazo renal, una presentación de los principales accesos vasculares y una descripción de los cuidados enfermeros y de las complicaciones relacionadas con las técnicas utilizadas.

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Extraction and clean-up are essential points in polycyclic aromatic hydrocarbon (PAHs) analysis in a solid matrix. This work compares extraction techniques and clean-up procedures for PAH analysis. PAH levels, their toxicological significance and source were also evaluated in the waters of the Cocó and Ceará rivers. The efficiency of PAH recovery was higher for the soxhlet and ultrasonic techniques. PAH recovery varied from 69.3 to 99.3%. Total PAH concentration (ΣHPA) varied from 720.73 to 2234.76 µg kg-1 (Cocó river) and 96.4 to 1859.21 µg kg-1 (Ceará river). The main PAH sources are pyrolytic processes and the levels were classified as medium so that adverse effects are possible.

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This work deals with paint decomposition methods for major, minor and trace elements determination. Three methods were investigated: (1) decomposition in closed quartz vessel and heating in microwave oven; (2) decomposition in open vessel using HNO3 and ashing, following the ASTM D 3335-85a method; and (3) decomposition in open vessel using HNO3 + HF and ashing. Paints of different types and colours were analyzed, in which several elements were determined using inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP OES). It was observed that method (1) is appropriate for trace, minor and major elements determination, while method (3) is appropriate for Ti.

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Glass ionomer cements (GICs) are products of the acid-base setting reaction between an finely fluoro-alumino silicate glass powder and poly(acrylic acid) in aqueous solution. The sol gel method is an adequate route of preparation of the glasses used to obtain the GICs. The objective of this paper was to compare two powders: a commercial and an experimental and to investigate the structural changes during hardening of the cements by FTIR and Al MAS NMR. These analyses showed that the experimental glass powder reacted with organic acid to form the GICs and it is a promising material to manufacture dental cements.

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In this work the potentiality of reductive-oxidative processes based on zero-valent iron was studied aiming the degradation of nitroaromatic compounds and the remediation of residues from the explosive industry. The reductive process was applied as a continuous treatment system, using steel-wool as zero-valent iron source. The process permitted an almost total degradation of nitrobenzene, nitrophenol, nitrotoluene, dinitrotoluene and trinitrotoluene, probably with generation of the respective amine-derivative. The yellow-water residue, containing soluble trinitrotoluene, was notably modified by the reductive process, a fact that permitted a substantial enhancement of its biodegradability. Furthermore, the subsequent photo-Fenton process allowed TOC removal of about 80%.

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The use of the Fenton's reagent process has been investigated for the remediation of a Brazilian soil contaminated by diesel. Laboratory experiments were conducted in batch experiments. Slurries, consisting of 10 g of diesel-contaminated soil and 30 mL of Fenton's Reagent (0.41 mol L-1 H(2)0(2) and 0.18 mol L-1 FeSO4). The experiments were monitored during 24, 48 and 72 h. The efficiency of the Fenton treatment was dependent on the time of contact between soil and Fenton's reagents and matrix characteristics, probably iron content. Data suggested that no iron addition is needed for the application of Fenton-like treatment for the remediation of diesel-contaminated iron rich soils after 72 h reaction.

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An analytical comparison of three different techniques for quantitative profile of esters in cachaça is reported. The Ministério da Agricultura Pecuária e Abastecimento (MAPA) recommends the use of GC/FID or volumetry. Despite being laborious and lacking in chemical speciation, the volumetric technique for total ester content shows to be appropriate, reproducible, and accurate for the analysis of cachaça. However, the GC/FID suggested by MAPA, considering only ethyl acetate, shows inaccuracy, underestimating the total ester content by a median factor of 72%, mainly due to the absence of ethyl lactate analysis. On the other hand, the GC/MS technique that comprises the analysis and speciation of nine esters, including ethyl lactate, proved to be reproducible, simple, fast and accurate for the analysis of total ester content in cachaça. Thus, the total ester content results obtained using GC/FID must be considered with precaution.

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Direct infusion electrospray ionization mass spectrometry in the negative ion mode, ESI(-)-MS and Fourier transform infrared spectroscopy (FTIR) were used together with partial least squares (PLS) as a tool to determine B3 adulteration (B3 - mixture of 3% v/v of biodiesel in diesel) with kerosene and residual oil.

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The determination of pesticide residues in water samples by Liquid Chromatography require sample preparation for extraction and enrichment of the analytes with the minimization of interferences to achieve adequate detection limits. The Solid Phase Extraction (SPE), Solid Phase Microextraction (SPME), Stir Bar Sorptive Extraction (SBSE) and Dispersive Liquid-Liquid Microextraction (DLLME) techniques have been widely used for extraction of pesticides in water. In this review, the principles of these sample preparation techniques associated with the analysis by Liquid Chromatography with Diode Array Detection (LC-DAD) or Mass Spectrometry (LC-MS) are described and an overview of several applications were presented and discussed.

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High-throughput screening (HTS) and virtual screening (VS) are useful methods employed in drug discovery, allowing the identification of promising hits for lead optimization. The efficiency of these approaches depends on a number of factors, such as the organization of high quality databases of compounds and the parameterization of essential components of the screen process. This brief review presents the basic principles of the HTS and VS methods, as well as a perspective of the utility and integration of these drug design approaches, highlighting current opportunities and future challenges in medicinal chemistry.

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In this work the degradation of textile dyes were evaluated, using Fenton, photo-Fenton and electro-Fenton processes. Under optimized conditions Fenton and photo-Fenton processes showed high decolorization capacity of the model dyes. The electro-Fenton process was carried out in an undivided electrochemical reactor (1000 mL) equipped with a carbon-felt cathode (253 cm²) and a platinum gauze anode (6 cm²). Under optimal conditions (J: 1.6 mA cm-2, Na2SO4: 0.075 mol L-1, pH: 3) H2O2 concentration of about 60 mg L-1 was observed. The addition of Fe2+ (15 mg L-1) induces Fenton reactions that permit almost total decolorization of textile dyes.

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TiO2 nanotubes were synthesized by hydrothermal method and doped with three nitrogen compounds to enhance photocatalytic activity under visible light. Catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS) and specific surface area and pore volume determined by BET and BJH methods, respectively. Photocatalytic activity was evaluated by photodegradation of rhodamine B under visible and UV radiations. Results showed doped-nanotubes were more efficient under visible light. The best photocatalytic activity was for sample NTT-7-600/NH3I, being 30% higher than the non-doped sample.

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In this paper studies based on Multilayer Perception Artificial Neural Network and Least Square Support Vector Machine (LS-SVM) techniques are applied to determine of the concentration of Soil Organic Matter (SOM). Performances of the techniques are compared. SOM concentrations and spectral data from Mid-Infrared are used as input parameters for both techniques. Multivariate regressions were performed for a set of 1117 spectra of soil samples, with concentrations ranging from 2 to 400 g kg-1. The LS-SVM resulted in a Root Mean Square Error of Prediction of 3.26 g kg-1 that is comparable to the deviation of the Walkley-Black method (2.80 g kg-1).

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The determination of veterinary drug residues in foods of animal origin is an important issue because of the risk these compounds pose to human health in addition to their persistence and tendency to bioaccumulate. In recent years, significant progress has been made in the area and this review presents the state of the art in sample preparation procedures associated with chromatographic techniques coupled to mass spectrometry for multiresidue determination of veterinary drugs in food of animal origin at concentration levels suitable for the control of residues and contaminants in food.

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This paper describes the development of methods in micro-scale for the determination of K, Mg, Na and Zn in meat by atomic spectrometry techniques. The limits of detection (LOD) for K and Na by microdigestion were 0.18 and 0.20 mg g-1, respectively whereas LOD for Mg and Zn by microsolubilization with TMAH were 2.40 and 18.4 µg g-1, respectively. The RSD values were lower than 6.0% and the CRMs analyzed showed values with 95% agreement. The proposed methods are simple, fast and use small amounts of sample (around 10 mg) yet do not require special equipment for sample preparation.