A F��sica aplicada �� qualidade alimentar: identifica����o de metais por ���pixe��� em castanhas

A concentra����o na castanha de minerais como o c��lcio, pot��ssio, o magn��sio e outros tem sido estudada tradicionalmente por absor����o at��mica ou por espectrofotometria de UV-VIS [1-2]. Neste trabalho foi estudada a composi����o elementar de duas variedades (Longal e Judia) de castanha europeia (Castanea sativa Mill.) com a t��cnica PIXE (Proton Induced X-ray Emission). Os resultados preliminares mostram que a composi����o difere de acordo com a variedade, nos elementos maiorit��rios e nos minorit��rios. Este estudo �� parte de um projecto mais amplo, que visa avaliar o efeito do processamento p��s-colheita de alimentos com feixe de electr��es e raios-X.

Determina����o de metais em ��leos lubrificantes utilizando a t��cnica de espectrometria de emiss��o ��ptica com plasma induzido por laser

IPEN/D

Uso do bivalve l��mnico Anodontites tenebricosus (LEA, 1834) no biomonitoramento de metais do Rio Ribeira de Iguape

This study investigated the contamination of the Ribeira de Iguape River - RIR by Cd, Zn, Cr and Pb, using the bivalve Anodontites tenebricosus as a biomonitor. Metal concentrations in tissue samples were measured by HR-ICPMS. Bivalve tissues exhibited mean levels of 1.00 ��g/g Cd; 152.89 ��g/g Zn; 14.79 ��g/g Cr and 4.40 ��g/g Pb. Lead concentrations were comparable to those reported for moderately contaminated sites. The results showed that Pb is bioavailable to the bivalves, exhibiting high concentrations and exceeding both natural and reference values for human consumption. The freshwater bivalve Anodontites tenebricosus is a suitable biomonitor of contamination by metals.

Adi����o do res��duo de biomassa da cana-de-a����car em pastas para cimenta����o de po��os petrol��feros produtores de ��leos pesados

The Potiguar basin has large fields of viscous oil where the used method for recovering is based on vapor injection; this operation is carried out by injecting vapor in the oilwell directly, without the protection of a revetment through thermal insulation, what causes its dilation and, consequently, cracks in the cement placed on the annular, and lost of hydraulic insulation; this crack is occasioned by the phenomenon of retrogression of the compressive resistance due to the conversion of the hydrated calcium silicate in phases calcium-rich, caused by the high temperatures in the wells, subjected to thermal recuperation. This work has evaluated the application of composite pastes with addition of residue of biomass of ground sugar-cane bagasse as anti-retrogression mineral admixture for cementation of oil-wells subjected to thermal recuperation. The addition of the mineral residue was carried out considering a relative amount of 10, 20, 30, 40 and 59% in relation to cement mass, trying to improve the microstructure of the paste, still being developed a reference paste only with cement and a paste with addition of 40% of silica flour - renowned material in the oil industry as anti-retrogression additive. Pozzolanic activity of the ash was evaluated through XRD, TG/DTG, as the resistance to compression, and it was also determined the physical and mechanical behavior of the pastes when submitted to cure at low temperatures (22 and 38�� C); besides it was evaluated the behavior of the pastes when submitted to two cycles of cure at high temperature (280��C) and pressure (7 MPa). It was verified that the ash of the sugar-cane biomass presents pozzolanic reaction and has great efficiency in decrease the permeability of the paste by filler effect, as well as that addition of ash in a relative amount of 10, 20 e 30% increases cured compressive resistance at low temperatures. It was also showed that the ash in a relative amount of 40% and 59% has very significant efficiency as anti-retrogression additive, since it prevents the decrease of compressive resistance and forms hydrated calcium silicate type xenotlita and tobermorita which have more resistance and stability in high temperatures

Remoci��n de metales pesados con carb��n activado como soporte de biomasa

El incremento en los niveles de contaminaci��n del agua por metales pesados ha resultado en un aumento en la investigaci��n y el desarrollo de m��todos m��s efectivos para su eliminaci��n

Determinaci��n de metales pesados y evaluaci��n de la biotransferencia de especies inorg��nicas de ars��nico en leche bovina cruda

Prop��sito y m��todo de estudio: En el presente estudio se evalu�� el factor de biotransferencia (FBT) de ars��nico (As) inorg��nico en leche bovina cruda a trav��s de agua de consumo en zonas contaminadas con este metaloide en M��xico. Las muestras de leche y agua fueron colectadas en municipios de Durango, San Luis Potos�� y Zacatecas zonas lugares donde se lleva a cabo la miner��a y con antecedente de contaminaci��n por As. Para el an��lisis de As total fue empleado el m��todo de digesti��n acida asistido por microondas (EPA 3052). La extracci��n de especies inorg��nicas de As fue asistida por microondas empleando H3PO4 0.3 M a 90 ��C durante 30 min, para su posterior separaci��n en una resina de intercambio ani��nico fuerte (SAX). La determinaci��n de As total y de especies de ars��nico se llev�� a cabo por Espectrometr��a de Masas con Fuente de Plasma de Acoplamiento Inductivo (ICP-MS). Adicionalmente en las muestras leche previamente digeridas se analiz�� el contenido total de Pb, Cd, Cu, Zn y Fe por ICP-MS con la finalidad de evaluar el grado de contaminaci��n por estos metales y establecer una correlaci��n con la concentraci��n de As en leche y el posible origen de la contaminaci��n. Contribuciones y conclusiones La concentraci��n de As total en el agua de la mayor��a de las zonas de estudio super�� el l��mite permisible para agua de consumo seg��n la norma oficial NOM-127-SSA1-1994-2000 (25 ��g/L). En cuanto a las muestras de leche, las concentraciones de As se encontraron entre el l��mite de detecci��n y 472.80 ��g/kg, siendo los estados de Durango y San Luis Potos�� los que presentaron las concentraciones mayores. Las concentraciones de los otros metales analizados en leche mostraron que el promedio de Pb en leche en Zacatecas y San Luis Potos��, super�� el l��mite permisible de acuerdo a la Comisi��n Europea. As�� mismo para el caso del Cd la concentraci��n media en el estado de San Luis Potos�� super�� los niveles ya reportados. Las zonas de San Luis Potos��, Durango y Zacatecas presentaron niveles altos de metales esenciales (Zn, Cu y Fe). Adem��s se encontr�� que para los metales analizados (Pb, Cd, Cu, Zn y Fe) se present�� una correlaci��n positiva estad��sticamente significativa (p < 0.05) con As en leche, lo cual sugiere una fuente de contaminaci��n com��n la minera que se realiza en los sitios de estudio. En cuanto a la concentraci��n de especies de As inorg��nico en leche, las concentraciones para la especie de As (V) fueron mayores (79.60-242.20 ��g/kg) que las de As (III) (31.00-96.81 ��g/kg); dado que la especie de As (V) presenta un menor grado de toxicidad podr��a indicar menor riesgo para la poblaci��n que ingiere este alimento. Por ��ltimo, se determin�� el FBT de especies de As inorg��nicas a trav��s del agua de consumo, obteni��ndose valores superiores a los ya reportados para As total (2.6 x 10-6 a 6 x 10-4); sin embargo, no se encontr�� una correlaci��n significativa entre As en leche y ars��nico en agua (p ��0.05), lo cual sugiere que el agua no es la ��nica v��a de exposici��n de este metaloide. Para una posterior evaluaci��n del factor de biotransferencia se sugiere el analizar el contenido de As en alimento y el suelo donde habita el organismo e incorporar estas fuentes de contaminaci��n al modelo del FBT.

Impregna����o de metais em xisto retortado para uso como adsorventes

Concern with the environment has lead to an increase in the research for new adsorption techniques, low cost adsorvent materials and with high availability. Many works search the development of higher selectivity modified adsorvents. The Brazil has the second world reserve of oiled shale, because of it, the use of that reject is of great interest. This study has the goal of characterize and analyze the retorted shale, reject of the pirobetuminous shale pyrolysis, and the retorted shale modified through the humid impregnation method, wich the precursors were the metals nitrates ( Cobalt, Nickel and Copper), to the usage has adsorvent materials. The samples were characterized chemically, textually and structurally by the X ray fluorescence (XRF), BET, X ray diffraction (XRD) and scanning electronic microscopy (SEM) techniques. The impregnated samples showed a reduction in the superficial area and in the pore volume when compared with the retorted shale. Besides that, diffractions referred to the impregnated metals where observed in the XRD analysis, wich were the same metals detected in the XRF and SEM analysis. The materials showed homogeneity in it s composition. The results shows that the materials presents adequate adsorption characteristics

Estudo param��trico do processo de inje����o de solventes em po��os horizontais para reservat��rios de ��leos pesados

The world has many types of oil that have a range of values of density and viscosity, these are characteristics to identify whether an oil is light, heavy or even ultraheavy. The occurrence of heavy oil has increased significantly and pointing to a need for greater investment in the exploitation of deposits and therefore new methods to recover that oil. There are economic forecasts that by 2025, the heavy oil will be the main source of fossil energy in the world. One such method is the use of solvent vaporized VAPEX which is known as a recovery method which consists of two horizontal wells parallel to each other, with a gun and another producer, which uses as an injection solvent that is vaporized in order to reduce the viscosity of oil or bitumen, facilitating the flow to the producing well. This method was proposed by Dr. Roger Butler, in 1991. The importance of this study is to analyze how the influence some operational reservoir and parameters are important in the process VAPEX, such as accumulation of oil produced in the recovery factor in flow injection and production rate. Parameters such as flow injection, spacing between wells, type of solvent to be injected, vertical permeability and oil viscosity were addressed in this study. The results showed that the oil viscosity is the parameter that showed statistically significant influence, then the choice of Heptane solvent to be injected showed a greater recovery of oil compared to other solvents chosen, considering the spacing between the wells was shown that for a greater distance between the wells to produce more oil

Avalia����o de metodologia de preparo de amostra de petr��leo por digest��o ��cida auxiliada por microondas para determina����o de metais por ICP-OES

This project describes a methodology optimization that would allow for a more efficient microwave assisted digestion process for petroleum samples. With the possible chance to vary various factors at once to see if any one factor was significant enough in the answers, experimental planning was used. Microwave assisted digestion allows, through the application of potency, an increasing number of collisions between the HNO3 and H2O2 molecules, favoring sample opening for complex matrixes. For this, a 24 factorial experimental planning was used, varying potency, time and the volumes for HNO3 65% and H2O2 30%. To achieve the desired answers, several elements were monitored (C, Cu, Cr, Fe, Ni, Zn and V) through Inductively coupled plasma atomic emission spectroscopy (ICP-OES). With this initial study it was noticed that the HNO3 was not a significant factor for any of the statistical studies for any of the analytes and the other 3 factors and their interactions showed statistical significance. A Box Behnken experimental planning was used taking in consideration 3 factors: H2O2 volume, time (min) and Potency (W), Nitric Acid kept at 4mL for a mass of 0,1g of petroleum. The results were extremely satisfying showing higher efficiency in the digestion process and taking in a responsibility between the answers for each analyte and the carbon monitoring was achieved in the following conditions: 7mL of H2O2, 700 Watts of potency and a reaction time of 7 minutes with 4mL de HNO3 for a mass of 0,1g of petroleum. The optimized digestion process was applied to four different petroleum samples and the analytes determined by ICP-OES

Extra����o de metais (K, Mg, Ba, Ca, Cr, Mn, Li, Fe) de ��gua produzida utilizando sistema microemulsionado

The produced water is a byproduct formed due to production of petroleum and carries with it a high amount of contaminants such as oil particles in suspension, organic compounds and metals. Thus, these latter pollutants are very difficult to treat because of its high solubility in water. The objective of this work is to use and evaluate a microemulsioned system to remove metals ( K , Mg , Ba , Ca , Cr , Mn , Li , Fe ) of synthetic produced water. For the extraction of metals, it was used a pseudoternary diagram containing the following phases: synthetic produced water as the aqueous phase (AP), hexane as organic phase (OP), and a cosurfactant/surfactant ratio equal to four (C/S = 4) as the third phase, where the OCS (saponified coconut oil) was used as surfactant and n-butanol as cosurfactant. The synthetic produced water was prepared in a bench scale and the region of interest in the diagram for the removal of metals was determined by experimental design called. Ten points located in the phase Winsor II were selected in an area with a large amount of water and small amounts of reagents. The samples were analyzed in atomic absorption spectrometer, and the results were evaluated through a statistical assesment, allowing the efficiency analysis of the effects and their interactions. The results showed percentages of extraction above 90% for the metals manganese, iron, chromium, calcium, barium and magnesium, and around 45% for metals lithium and potassium. The optimal point for the simultaneous removal of metals was calculated using statistical artifact multiple response function (MR). This calculation showed that the point of greatest extraction of metals occurs was the J point, with the composition [72% AP, 9% OP, 19% C/S], obtaining a global extraction percentage about 80%. Considering the aspects analyzed, the microemulsioned system has shown itself to be an effective alternative in the extraction of metals on synthetic produced water remediation

Determinaci��n de metales pesados (plomo y ars��nico) y oligoelementos (hierro, cobre y zinc) en hojas de Crotalaria longirostrata (chipilin) por el m��todo de absorci��n at��mica

La presente investigaci��n tuvo como finalidad analizar esta especie vegetal cultivada en la zona Central y Occidental del territorio salvadore��o; para ello, se llev�� a cabo una investigaci��n de campo visitando los Municipios de Col��n y Ciudad Arce ubicados en el Departamento de la Libertad; y los Municipios de Izalco y Nahuizalco, ambos pertenecientes al Departamento de Sonsonate; donde se recolectaron las muestras (hojas de C. longirostrata); Se elaboraron encuestas dirigidas a T��cnicos �� Ingenieros agr��nomos que laboraran en Agroservicios de mayor afluencia en el pa��s y a los productores de los cultivos seleccionados; con la finalidad de conocer los productos agroqu��micos aplicados al tratamiento del cultivo de esta hortaliza. Se realiz�� un an��lisis qu��mico e instrumental para determinar elementos met��licos como metales pesados (plomo y ars��nico) y oligoelementos (hierro, cobre y zinc) utilizando las t��cnicas de Espectrofotometr��a de Absorci��n At��mica (EAA): - Horno de graf��to para plomo. - Generador de Hidruros para ars��nico. - Llama para hierro, cobre y zinc. Los resultados se compararon con los l��mites m��ximos establecidos por la normativa de JECFA - Comit�� Mixto FAO/OMS de Expertos en Aditivos Alimentarios y Codex Alimentarius; y se evaluaron estad��sticamente a trav��s del an��lisis de varianza de un factor (ANOVA), las pruebas de comparaci��n DMS y Bonferroni; para evaluar el comportamiento de los datos experimentales obtenidos en el an��lisis. Seg��n los resultados obtenidos se encontraron trazas de plomo y ars��nico en algunas muestras analizadas; as�� como un alto contenido de hierro, cobre y zinc en todas las muestras de C. longirostrata. Se recomienda que se analicen muestras de suelos, agua de riego y otros cultivos de C. longirostrata ubicados en diversas zonas geogr��ficas de El Salvador; con la finalidad de evaluar la calidad de las distintas hortalizas de esta especie vegetal existentes en el pa��s.