Navegando por Assunto "Ferro"

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Acesso aberto (Open Access)
Avaliação do uso da casca do fruto e das folhas de Caesalpinia ferrea Martius como suplemento nutricional de Fe, Mn e Zn
(2010-09) SILVA, Clelivaldo Santos da; NUNES, Patrícia de Oliveira; MESCOUTO, Cleide Samara Tavares; MÜLLER, Regina Celi Sarkis; PALHETA, Dulcidéia da Conceição; DANTAS, Kelly das Graças Fernandes
Medicinal plants can be used as alternative sources of mineral nutrients in the alimentary diet. Elements such as iron, manganese, and zinc present variable bioavailability due to their chemical form (species) present in foods. This work has the objective of evaluating the concentration and bioavailability of iron, manganese, and zinc in extracts of the peel and leaves of Caesalpinia ferrea Martius by Flame Atomic Absorption Spectrometry (FAAS). The extraction agents tested were 0.05 mol.L-1 NaOH, 0.05 mol.L-1 Tris-HCl buffer (pH 8.0), 0.05 mol.L-1 Tris-HCl buffer (pH 8.0) containing 1% (m/v) sodium dodecylsulfate (SDS), 0.05 mol.L-1 HCl, and hot water at 60 ºC. The peel and leaves of Caesalpinia ferrea Martius presented higher levels of iron and manganese when compared to other medicinal plants. The elements studied showed predominant association with compounds of high and low molecular weight and soluble and insoluble species in water. Among the analyzed elements, the iron presented the best bioavailability in the peel and leaves of the fruit. Manganese and zinc presented higher bioavailability in the leaves. The peel and leaves of Caesalpinia ferrea Martius can be an alternative source of iron, manganese, and zinc in the alimentary diet.
Acesso aberto (Open Access)
Desenvolvimento de processo para obtenção de zeólita do tipo faujasita a partir de caulim de enchimento, caulim duro e tube press: aplicação como adsorvente.
(Universidade Federal do Pará, 2015-03-31) ROCHA JUNIOR, Carlos Augusto Ferreira da; NEVES, Roberto de Freitas; http://lattes.cnpq.br/9559386620588673; 9559386620588673
The main purpose of this work is zeolite synthesis of faujasite type (X and Y) from kaolin from the beneficiation process for paper coating, hard kaolin or Flint (mining of waste), tube press kaolin and filler kaolin. For each process zeolitização kaolin used in a chemical reactor a product of calcination of each material (metakaolin), sodium metasilicate, solid sodium hydroxide and distilled water, subjected at 110 ° C, reaction time 13 h Si / Al ratio of 2, 4 and 6. The products of each zeolite synthesis as well as the starting kaolin were characterized by chemical, physical and mineralogical analyzes such as X-ray diffraction, X-ray fluorescence, electron microscopy scan and thermal analysis. From these tests, it was observed that all the kaolin showed the formation of faujasite zeolite, but with differences in the peak intensities and their associations with other zeolite phases. Hard kaolin showed a lower potential zeolitization into the Si / Al ratio equal to 2 compared with the other two supposedly related to the iron present in its composition, thus made was a removal process of this constituent, by Mehra and Jackson method to verify a possible maximization in the synthesis process. New results indicated a complete modifications to the area and degree of structural order of faujasita phase, now moving into a major phase and there is an increase in the degree of structural order. As this reaction condition for consumption and a lower cost of raw materials and energy for calcination This medium was used as a starting point for an experimental design to evaluate the best reaction conditions. This design was varied some parameters of the synthesis as temperature, reaction time, Si / Al ratio and H2O / Na2O. The results of the statistical design showed the formation of faujasite in 32 points of study, as well as a great region with 8 points of planning, in this region point 13 proved the best reaction conditions. The zeolite synthesized at this point, showed an increase of ammonium adsorption capacity and percentage near 85 % efficiency up to 60 ppm. The Langmuir model was more suitable than the Freundlich and Sips in agreement with experimental data. The thermodynamic parameters showed that adsorption of NH4 + is a spontaneous and exothermic process, in which the temperature rise from 25 to 60 ° C promotes a small decrease in the adsorption capacity.
Acesso aberto (Open Access)
Efeitos do quelante de ferro, a deferoxamina, sobre as alterações oxidativas e cognitivas induzidas pela dapsona, em modelo animal
(Universidade Federal do Pará, 2020-11-17) MENDES, Paulo Fernando Santos; MAIA, Cristiane do Socorro Ferraz; http://lattes.cnpq.br/4835820645258101; MONTEIRO, Marta Chagas; http://lattes.cnpq.br/6710783324317390; https://orcid.org/ 0000-0002-3328-5650
Dapsone (DDS) is an antibiotic that works by inhibiting folate synthesis, showing good bacteriostatic action. However, it can lead to severe adverse events such as neurological disorders, methemoglobinemia and hemolysis. These hematological disorders lead to the alteration of iron homeostasis and thereby increase the formation of ROS that can lead to cellular and tissue damage. This change plays an important role in neurodegenerative diseases, whether as a causative and / or intensifying agent in these diseases. In this context, we used an iron chelator, deferoxamine (DFX), to evaluate its effects on the formation of ROS triggered by the increase in free iron induced by the use of DDS. For this, the alteration of iron homeostasis was induced in Swiss mice, using DDS, followed by the administration of DFX. After that, oxidative stress parameters were measured in the hippocampus and plasma, in addition to the measurement of iron levels. Our results showed that DDS decreased TEAC and that DFX treatment was restored. In addition, DDS decreased GSH and DFX treatment was restored. It increased the LPO and the treatment with DFX reduced this effect, increased the concentration of iron and that was reversed by the treatment with DFX. Additionally, the animals were submitted to the Morris water maze, where our results showed that animals treated with DDS showed a reduction in mnemonic capacity and that treatment with DFX was able to inhibit loss. These results suggest that the use of iron chelators may be an alternative to reduce the effects of iron accumulation on the nervous system observed in neurodegenerative diseases.
Acesso aberto (Open Access)
Influência da temperatura de calcinação na redução da hematita e na liberação do titânio na lama vermelha (resíduo do processo bayer)
(Universidade Federal do Pará, 2016-12-26) VIEGAS, Bruno Marques; MAGALHÃES, Edilson Marques; CV: http://lattes.cnpq.br/1570353513360972; MACÊDO, Emanuel Negrão; http://lattes.cnpq.br/8718370108324505
In this work a technological route was proposed aiming at the reduction of hematite to magnetite and the release of titanium present in red mud from Hydro Alunorte. The fluorescence and x ray diffraction analysis showed that the red mud presents in their composition approximately 5% of titanium oxide as anatase and 28% of iron oxide in the forms of hematite and goethite. Therefore, the proposed route will enable the obtainment of a material with magnetic characteristics which can be used as source of titanium after extraction of iron compounds in magnetic form. So, the reduction of the hematite to the magnetite was carried out by thermal treatment in a reducing atmosphere. To accomplish this, mixtures were made in different concentrations of red mud and charcoal. These mixtures were calcined at temperatures of 500, 600 and 1000 ° C for two hours. Then, X ray diffraction analysis were performed, which showed that the hematite was reduced to magnetite in all experimental conditions and, for the mixtures calcined at 1000 ° C, besides the formation of the magnetite, there was also the formation of maghemite. Through analysis of Raman spectroscopy and scanning electron microscopy, it was verified that for calcination temperatures of 500 to 600° C titanium remained in the free form of anatase, but for the calcination carried out at 1000° C this passed to the combined form with iron (ilmenite). The technological route allowed the formation of magnetite from the red mud, which can be extracted with the use of a magnetic separator.
Acesso aberto (Open Access)
Ironstones da base da Formação Pimenteiras, borda noroeste da bacia do Parnaíba, região Xambioá-Colinas do Tocantins
(Universidade Federal do Pará, 2011-01-05) AMARO, Gabriel de Jesus Lavareda; VILLAS, Raimundo Netuno Nobre; http://lattes.cnpq.br/1406458719432983
The present study deals with the ironstones that occur at the base of the Devonian Pimenteiras Formation in the northwestern border of the Parnaíba basin. Samples were collected along the Xambioá-Vanderlâdia and Colinas do Tocantins-Couto Magalhães sections about 180 km away from each other. In both sections the sedimentary package lies unconformably over the Proterozoic basement represented by rocks of the Araguaia belt. The ironstones consist of discontinous decimeter-thick layers intercalated in sandstones and shales. The ironstones of the Xambioá-Vanderlândia show abundant oölites immersed in an iron-oxide/hydroxide-rich matrix. The size of the oölites ranges from 0.2 to 0.5 mm, reaching exceptionally 1.0 mm, while the shape is generally spherical to ellipsoidal. Most oolites present concentric internal structure and only a few are broken. Their nucleus is commonly occupied by detrital grains of quartz, zircon or monazite around which iron-oxide/hydroxide concentric lamellae were formed. Locally some laminae are composed of chemically precipitated monazite. Goethite/hematite (75-80%), quartz (5-15%) and smectite /kaolinite (0-10%) are the main mineral constituents. Chemically the oolithic ironstones are made up of SiO2 (3-15%), Al2O3 (4.4-7.7%), Fe2O3 (62.5-79%), P2O5 (0.5-3,2%), TiO2 (0.2-0.8%); other components total less than 0,2% and LOI values vary from 9.4 to 13.5%. P2O5 contents are high enough to be accounted for the amounts of the phosphate minerals (monazite and goyasite), so that some P was most likely adsorbed on the iron oxides-hydroxides. Regarding the trace elements, the higher average concentrations were determined for V (780-1990 ppm), Zr (125-600 ppm), Sr (15-296 ppm), Ba (25-266 ppm), Ni (22-225 ppm),Y (39-181ppm) and REE (144-1630 ppm, with Ce>NdLa), which reflect the variable amounts of zircon, monazite and goyasite. The vanadium values in particular may be due to the presence of interbedded clay minerals and /or adsorption on the iron oxides-hydroxides. When normalized to the North American Shale Composite (NASC), the oölithic ironstone samples are enriched in REE by factors greater than 2 few of them exhibiting discrete positive Ce anomalies. In general, the distribution pattern for REE is convex between La and Dy, but towards Lu it tends to become sub-horizontal resembling a “capsized spoon”. Unlike the ironstones described above, those of Colinas do Tocantins-Couto Magalhães area do not present oolithic texture, although they are also basically composed of iron oxides-hydroxides, which not only imparts them a dark red coloration but also acts as a cement for the randomly distributed detrital grains of several minerals. These non-oölithic ironstones consist of hematite/goethite, quartz, clay minerals, muscovite and accessory amounts of monazite and zircon. Their chemical composition reveals Fe2O3 (41-60%), SiO2 (16-39%), Al2O3 (6-11%), K2O (0.5-1,2%), P2O5 (0.32%) and H2O (6-11%) recorded as LOI. MgO, CaO, Na2O, MnO and Cr2O3 are minor components and represent less than 0.4% of the rock. V (83-3.488 ppm), Zr (62-372ppm), Ba (166-347 ppm), Rb (26-62 pm), Zn (19-868 ppm), Ni (3-106 ppm) e Sr (31-51 ppm) are the trace elements with more expressive contents. REE values range from 100 to 300 ppm. LREE (Ce> La> Nd) contents are usually >15 ppm whereas the other REE are in general below of 5 ppm. Although the chemical composition of these ironstones is largely controlled by the amounts of minerals present, the high concentrations of some trace elements may indicate incorporation in the phyllosilicate lattice (Ni and Ba) and adsorption on the iron oxides-hydroxides (V). Comparatively to NASC, the nonoölithic ironstone samples are poorer in REE, whose distribution pattern is dominantly concave and marked by the fractionation of the IREE in relation to both LREE and HREE. The Xambioá-Vanderlândia ironstones are texturally and chemically quite distinct from those of the Colinas do Tocantins-Couto Magalhães area. Besides the presence of oolites, the former show smaller amounts of terrigenous material (especially quartz) and higher iron oxide-hydroxides proportions. They also are more enriched in V, Sr, Zr and REE, and poorer in Al2O3 e Rb. The NASCnormalized REE distribution pattern is also different, especially concerning the IREEN values which, being higher in the oölithic ironstones, display convex curves and, being lower in the nonoolithic ironstones, display concave curves. In the field, however, spatial relationships could not be defined between the two ironstones types. It is then suggested that they represent different lithological facies of the same iron formation. Probably, the deposition of the non-oölith facies occurred in deeper and quieter waters away from the continental border, where larger amounts of detrital sediments were discharged, whereas the deposition of the oölith facies took place in shallower and more agitated waters, with less supply of terrigenous material. Iron was largely derived from the erosion of continental areas where reduced environments favored its mobilization and transported by rivers along with suspended particles, colloids, and organic complexes.
Acesso aberto (Open Access)
O Refinamento de Rietveld como um método para o controle de qualidade de minérios de ferro
(2002-04) KONIG, Uwe; POELLMANN, Herbert; ANGÉLICA, Rômulo Simões
The Rietveld method is an innovative technique for quality control and processing. A Quantification of iron ores with 2 and more phases is possible in a fraction of the time needed till now. This paper shows the most essential bases to the conditioning, preparation and quantification of simple mixtures of hematite, magnetite, goethite and quartz as principle ingredients of iron ores. Special preparation methods are necessary due to the anisotropic hematite crystals. Different sample preparations parameters must be evaluated prior to Rietveld quantification, for instance, "side loading" or "back loading" are recommended. The duration of grinding depends on the respective ore and hematite variety, usually between 4 and 12 minutes. A quantification of a 3 phases mixture turned out well with a maximum relative standard deviation of 3%.
Acesso aberto (Open Access)
Teores de cobre, zinco e ferro no fígado de búfalos (Bubalus bubalis) com paratuberculose
(Universidade Federal do Pará, 2016-01) BELO REIS, Alessandra dos Santos; BRITO, Marilene de Farias; BOMJARDIM, Henrique dos Anjos; FAIAL, Kelson do Carmo Freitas; SALVARANI, Felipe Masiero; UBIALI, Daniel Guimarães; OLIVEIRA, Carlos Magno Chaves; BARBOSA NETO, José Diomedes
In order to study copper, zinc and iron concentration in the liver of buffaloes with paratuberculosis (PTB), 13 buffalo cows above three years of age of the Murrah and Mediterranean races or their crosses were used. They originated from two farms in the municipalities of São Luís and São Mateus, state of Maranhão, Brazil. The animals were selected according to clinical signs of paratuberculosis, as diarrhea, dehydration and submandibular edema. Rectal biopsies for detection of Mycobacterium avium subsp. paratuberculosis (Map) through PCR in real time (qPCR) and Ziehl-Neelsen (ZN) stain were performed on all animals. Seven buffaloes revealed positive and six were negative for PTB. They were separated into two groups: Group 1 contained seven buffaloes positive for paratuberculosis, and Group 2 contained six animals negative for paratuberculosis. They were euthanized and postmortem examination was performed for the collection of various tissue samples to be fixed in 10% formalin for histopathology; also liver tissue samples were collected to be frozen for chemical analysis of trace minerals (Cu, Zn and Fe). Postmortem showed that all buffaloes with PTB had brown colored mesenteric lymphnodes, indicating hemosiderosis. One buffalo had brown spots on the mucosa of the small intestine. Histopathology revealed moderate to severe hemosiderosis of the spleen in buffaloes of Group 1. All animals positive for PTB showed micromineral levels below the reference values. The average Cu concentration in buffaloes with PTB was only 18.0ppm and the one of Zn only 68.6ppm. In Group 2, negative for PTB, the average Cu concentration was 113.7ppm and the one of Zn 110.0ppm. Fe concentrations in buffaloes of both groups were high (>669ppm). The analysis of trace elements in the liver confirmed copper deficiency, but also showed low levels of zinc and high levels of iron. Based on clinical and pathological findings, and the micromineral concentrations found in the liver, it is concluded that paratuberculosis could lead to mineral deficiency and worsen the clinical condition of the buffaloes.
Acesso aberto (Open Access)
Thermal decomposition and stability in a series of heterobimetallic carbonyl compounds of the type [Fe(CO)4(HgX)2] (X=Cl, Br, I)
(2000) ZAMIAN, José Roberto; MAURO, Antônio Eduardo; NUNES, Carolina Coimbra; ALMEIDA, Eduardo Tonon de
Foram preparados compostos carbonílicos heterobimetálicos do tipo [Fe(CO)4(HgX)2] ( X= Cl, Br, I), contendo ligação metal-metal, objetivando investigar suas estabilidades térmicas em função do halogênio coordenado aos átomos de mercúrio. A caracterização destes complexos foi feita usando-se de técnicas espectroscópicas de infravermelho e ressonância magnética nuclear, além de análise elementar. O produto final das termodecomposições foi identificado através de espectroscopia no infravermelho e difratograma de raios-X, método de pó.