Artigos Científicos - FEQ/ITEC

URI Permanente para esta coleçãohttps://repositorio.ufpa.br/handle/2011/2456

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Acesso aberto (Open Access)
Adsorção de cromo (VI) por carvão ativado granular de soluções diluídas utilizando um sistema batelada sob pH controlado
(Instituto Nacional de Pesquisas da Amazônia, 2009-09) SOUZA, Renata dos Santos; CARVALHO, Samira Maria Leão de; GARCIA JÚNIOR, Márcio Ronald de Lima; SENA, Rafael dos Santos Fernandes
In Amazonia, chromium is mainly used in the leather and wood industries. It is responsible for many health problems, because of its toxicity. These industries remove chromium waste by various processes, such as adsorption. This work shows the results of Cr(VI) adsorption by commercial granular activated carbon (GAC) as adsorbent from diluted solutions, and batch systems with controlled pH. The functional groups on the CAG surface was carried out by the Boehm method. In addition, effect of pH on the Cr(VI) adsorption, adsorption equilibrium, and kinetic were studied under experimental conditions (pH = 6, MA = 6g, for 90min.). On the GAC surface, carboxylic groups were found to be in higher concentrations (MAS=0,43 mmol/gCAG), which increase the Cr(VI) adsorption, principally in acidic pH values. The adsorption capacity is dependent on the pH of the solution, due to its influence on the surface properties of the CAG and different ionic forms of the Cr(VI) solutions. The adsorption equilibrium data was adjusted satisfactorily by the Langmuir isotherm (R2=0,988), favorable type. From kinetics adsorption of 20 mg/L and 5 mg/L, the results were compatible with the national legislation (Res. nº 357/05). Therefore, the experimental system using (CAG) was efficient in removing the Cr(VI) from liquid streams containing low concentrations of the metal.
Acesso aberto (Open Access)
Alkaloids and volatile constituents from the stem of Fusaea longifolia (Aubl.) Saff. (Annonaceae)
(2005-06) TAVARES, Josean Fechine; BARBOSA FILHO, José Maria; SILVA, Marcelo Sobral da; MAIA, José Guilherme Soares; CUNHA, Emidio Vasconcelos Leitão da
A phytochemical study of the ethanol extract and an extraction of the volatile compounds, performed by means of Clevenger apparatus were carried out with the stem of Fusaea longifolia (Aubl.) Saff. (Annonaceae). The ethanol extract yielded O-methylmoschatoline, isolated for the first time in this species, and stepholidine, reported for the first time in genus Fusaea. The structural identification of the alkaloids was made based on the analysis of their NMR spectra. Through the use of GC and GC-MS, two sesquiterpenoids, a-cadinol (12.5%) and spatulenol (12.0%) were identified as the major constituents of the essential oil.
Acesso aberto (Open Access)
Alumina para utilização cerâmica, obtida a partir do rejeito de beneficiamento de caulim
(1997-12) FLORES, Silvia Maria Pereira; NEVES, Roberto de Freitas
The kaolin processing for paper covering produces a great volume of residues formed primarily by kaolinite claymineral, here the starting material for the synthesis of ammonium alumen aiming to obtain free sodium alumina with fine grade for ceramic manufacturing. The synthesis process to obtain ammonium alumen consisted of the following procedures: residues calcination and sulphuric leaching of metakaolinite followed by neutralization/crystallisation of aluminum sulphate solution with ammonium hydroxide concentrated solution. The effect of calcination temperature (650 °C, 700 °C and 750 °C), calcination time of residues (30 min, 60 min and 120 min), sulphuric acid concentration as well as leaching temperature (70 °C, 80 °C and 90 °C) on the kinetics of aluminum leaching were studied. The influence of pH on ammonium alumen crystallization was also studied. Data on chemical analysis, XRD, DTA, TGA and granulometry of the material utilized and synthesized are presented and discussed.
Acesso aberto (Open Access)
Antioxidant capacity and biological activity of essential oil and methanol extract of Conobea scoparioides (Cham. & Schltdl.) Benth
(2009) REBELO, Monaliza Maia; SILVA, Joyce Kelly do Rosário da; ANDRADE, Eloisa Helena de Aguiar; MAIA, José Guilherme Soares
The essential oils of the sub-aquatic plant Conobea scoparioides (fresh and dried previously) showed yields of 3.4 and 3.3%, respectively. The main identified constituents were thymol methyl ether (39.6 and 47.7%), thymol (40.0 and 26.4%), α-phellandrene (12.1 and 14.3%) and p-cymene (1.5 and 1.7%), totalizing more than 90% of the oils. The DPPH radical scavenging activity (EC50) of the oils and extract was 46.7 ± 3.6 µg mL-1 in the fresh plant (CsO-f), 56.1 ± 2.4 µg mL-1 in the dried plant (CsO-d), and 23.0 ± 2.2 µg mL -1 in the methanol extract. The extract (CsE-d)value is comparable to BHT (19.8 ± 0.5 µg mL-1) used as antioxidant standard. The mean value of the oils is twice smaller but equally important as antioxidant agent. The mean amount of Total Phenolics (TP, 124.6 ± 8.7 mg GAE per g) and the Trolox Equivalent (TEAC, 144.1 ± 4.9 mg TE per g) of the methanol extract confirmed the significant antioxidant activity of C. scoparioides. Similarly, in the brine shrimp bioassay (Artemia salina) the mean value of the lethal concentration for the oils (CL50, 7.7 ± 0.3 µg mL-1) was ten times higher than the methanol extract (CL50, 77.6 ± 7.1 µg mL-1) showing important biological activity.
Acesso aberto (Open Access)
Antioxidant capacity and biological activity of essential oil and methanol extract of Hyptis crenata Pohl ex Benth
(2009-03) REBELO, Monaliza Maia; SILVA, Joyce Kelly do Rosário da; ANDRADE, Eloisa Helena de Aguiar; MAIA, José Guilherme Soares
The essential oils of fresh and dried leaves and fine stems of Hyptis crenata furnished the following yields: 1.4% and 0.9%. The main volatile constituents were α-pinene (22.0%; 19.5%), 1,8-cineole (17.6%; 23.2%), β-pinene (17.0%; 13.8%), camphor (4.7%; 11.6%), limonene (5.4%; 4.4%) and γ-terpinene (3.5%; 2.4%), totalizing more than 70% in the oils. The DPPH radical scavenging activity (EC50, 16.7 + 0.4 µg/mL) of the methanol extract was comparable to BHT (19.8 ± 0.5 µg/mL) showing a significant antioxidant activity. The oils showed low activities. The amount of total phenolics (TP, 373.0 + 15.9 mg GAE/g) and trolox equivalent (TEAC, 226.8 + 0.5 mg TE/g) confirmed the antioxidant activity of the methanol extract that can be attributed to the presence of polar phenolic compounds. In the brine shrimp bioassay the lethal concentrations (LC50) for the oil and methanol extract were 6.7 + 0.2 µg/mL and 13.0 + 3.7 µg/mL, respectively, providing important evidence of their biological activities.
Acesso aberto (Open Access)
Características físicas e físico-química da casca de mangostão em três períodos da safra
(2009-06) CHISTÉ, Renan Campos; FARIA, Lênio José Guerreiro de; LOPES, Alessandra Santos; MATTIETTO, Rafaella de Andrade
In this work, it was evaluated the physical characteristics of fruit and physiochemical of the mangosteen peel, harvested in different periods (beginning, middle and end). The physical characteristics of fruits range significantly (p≤0.05) from the beginning to the end, and it was observed that the fruits average weight, ranged from 91.33 to 50.82 g and the peel consists of an average from 72.12 to 76.86% of the total fruit weight. The physiochemical characterization shows that the peel possesses high moisture content (64.5 to 66%), total fibers (24.9 to 29.1%), high water activity (0.96 – 0.98), low energy value (24.8 to 34.7 Kcal/100g) and expressive content of total anthocyanins (25.9 to 63.9 mg/100g), mainly in the intermediate harvest period.
Acesso aberto (Open Access)
Collecting and evaluation of germplasm of spiked pepper from Brazilian Amazon
(2010-06) GAIA, José Maria Demetrio; MOTA, Milton Guilherme da Costa; CONCEIÇÃO, Carmen Célia Costa da; MAIA, José Guilherme Soares
Spiked pepper (Piper aduncum L.) is an aromatic plant species with high essential oil production. It is a species that occurs abundantly in the Brazilian Amazon. Its essential oil has exploitable biological properties in the human health and agriculture. Aiming to study its germplasm toward future use in genetic breeding programs, collecting was carried out (inflorescences, cuttings, leaves and thin branches) in ten provenances from the Brazilian Amazon. Twelve morphoagronomic traits were determined to take the data: number of leaves by branch, length of leaf, width of the leaf, circumference of the older branch, height of the plant, number of orthotropic branches, number of plageotropic branches, length of the internodes, number of spikes per branches, yielding of oil, content and production of dillapiole, as well as data on the environment and populations of spiked pepper. The inflorescences and cuttings were encoded and sent for the Federal Rural University from Pará State (UFRA), Brazil, for propagation. The leaves and thin branches were sent for the Emílio Goeldi Museum, from Pará State (MPEG) for extraction of essential oil (hydrodistillation). Estimators of amplitude of variation, mean, standard deviation and coefficient of variation were utilized to study the phenotypical variability. The morphoagronomic traits of largest variability were number of orthotropic branches, number of spikes per branch, circumference of the older branch and the content and production of dillapiole. This species has adapted to many different environments of vegetation, soil, climate, relief and drainage becomming easy the domestication and cropping. There is morphoagronomic variability pleasing the selection and genetic breeding.
Acesso aberto (Open Access)
Comportamento higroscópico de partes aéreas de pimenta-de-macaco (Piper aduncum L.)
(2015-04) SILVA, Carolina de Lourdes Oliveira Cruz e; FARIA, Lênio José Guerreiro de; COSTA, Cristiane Maria Leal
Desorption isotherms of monkey pepper were determined by static gravimetric method at temperatures 35, 45, and 55 ºC, over a relative humidity range of 5.5-81%. Three mathematical models were applied to analyse the experimental data. The modified GAB model showed the best adjustment of the experimental data. The isosteric heat and differential entropy were determined by applying Clausius-Clapeyron and Gibbs-Helmholtz equations, respectively. The isosteric heat and the entropy of desorption isotherm presented similar behavior. The enthalpy-entropy compensation theory was applied to the isotherms, indicating that the aerial parts desorption mechanism are enthalpy-controlled.
Acesso aberto (Open Access)
Database of the Amazon aromatic plants and their essential oils
(2009) MAIA, José Guilherme Soares; ANDRADE, Eloisa Helena de Aguiar
The aromatic flora of the Amazon has been inventoried for 30 years. In this sense, were made over 500 field trips to collect over 2500 plants and to obtain more than 2000 essential oils and aroma concentrates, all of them submitted to GC and GC-MS. This work led to the creation of a database for the aromatic plants of the Amazon, which catalogs general information about 1250 specimens. The database has allowed the publication of the chemical composition of the oils and aromas of more than 350 species, associated with a larger number of chemical types. The essential oils of many species offer optimum conditions for economic exploitation and use in national and international market of fragrances, cosmetics, agricultural and household pesticides.
Acesso aberto (Open Access)
Desorption of heavy metals from ion exchange resin with water and carbon dioxide
(2006-06) SILVA, Denilson Luz da; BRUNNER, Gerd
Adsorption and regeneration of ion exchange resins were studied using a subcritical solution of a CO2-H2O mixture and a fixed bed column. The commercial Amberlite IRC-50/IRC-86 cation exchange resins and Amberlite IRA-67 anion exchange resin were tested for heavy metals (Pb, Cu, Cd) adsorption from a solution with different initial metal concentrations at different temperatures. After adsorption, the loaded resins were regenerated with water and carbon dioxide at different temperatures and a pressure of 25 MPa. The efficiency of the IRC-50 resin was lower than that of the IRC-86 resin for the adsorption of metals like Cd, Cu and Pb. Results obtained for desorption of these metals indicated that the process could be used for Cd and in principle for Cu. Sorption of metal ions depended strongly on feed concentration. Mathematical modeling of the metal desorption process was carried out successfully as an extraction process. For this purpose, the VTII Model, which is applied to extraction from solids using supercritical solvents, was used in this work.
Acesso aberto (Open Access)
Determinação do ponto de carga zero da bauxita da região nordeste do Pará
(2012-12) PINTO, Rayssa Luana da Silva; SILVA, Kelly Cristina Sarmento da; CARDOSO, Dilson Nazareno Pereira; MACÊDO, Emanuel Negrão; FELIPE, Augusta Maria Paulain Ferreira
In the northeast of Pará, Brazil, the transport of bauxite pulp is through pipeline, being the viscosity a parameter which can interfere in the pumping. This study illustrates the influence of pH on pulp rheology through of determination of the zero point of charge. Were done particle size analysis, SEM, EDS, potentiometric tests testing ammonia chloride as indifferent electrolyte and rheological tests at different pH values. The results revealed that ammonia chloride can be used as indifferent electrolyte and showed a decrease in viscosity when there is far of the zero point of charge.
Acesso aberto (Open Access)
Extraction of oil from pressed palm oil (Elaes guineensis) fibers using supercritical CO2
(1997-12) FRANÇA, Luiz Ferreira de; MEIRELES, Maria Angela de Almeida
Residual fibers from palm oil production are a good source of carotene, since they contain more than 5% of the original oil, with about 5000 ppm of carotenoids. As carotenoids are thermosensitive molecules, supercritical CO2 can be used for oil recovery, because this technique employs low temperatures. In this work results of oil extraction experiments from pressed palm oil fibers are shown. Fibers were from AGROPALMA, an industry which is located in Tailândia (Pará, Brazil). Extractions were carried out at 200, 250 and 300 bar and at temperatures of 45 and 55oC. Oil was analyzed by UV/vis spectrophotometry for total carotene determination. Results showed a large increase in extraction rate from 200 to 250 bar and a small variation from 250 to 300 bar. The total amount of carotenes did not increase in the course of extraction at 300 bar, but it showed a large increase at 200 and at 250 bar. Free fatty acids are present in amounts larger than those found in commercial oils.
Acesso aberto (Open Access)
Generalized integral transform solution for hydrodynamically developing non-Newtonian flows in circular tubes
(2006-03) NASCIMENTO, Shirley Cristina Cabral; MACÊDO, Emanuel Negrão; QUARESMA, João Nazareno Nonato
The Generalized Integral Transform Technique (GITT) is applied to the solution of the momentum equations in a hydrodynamically developing laminar flow of a non-Newtonian power-law fluid inside a circular duct. A primitive variables formulation is adopted in order to avoid the singularity of the auxiliary eigenvalue problem in terms of Bessel functions at the centerline of the duct when the GITT approach is applied. Results for the velocity field and friction factor-Reynolds number product are computed for different power-law indices, which are tabulated and graphically presented as functions of the dimensionless coordinates. Critical comparisons with previous results in the literature are also performed, in order to validate the numerical codes developed in the present work and to demonstrate the consistency of the final results.
Acesso aberto (Open Access)
High pressure vapor-liquid equilibria of palm fatty acids distillates-carbon dioxide system
(1997-12) MACHADO, Nélio Teixeira de; BRUNNER, Gerd
Vapor-Liquid equilibria of palm fatty acids distillates/carbon dioxide system has been investigated experimentally at temperatures of 333, 353, and 373 K and pressures of 20, 23, 26, and 29 MPa using the static method. Experimental data for the quasi-binary system palm fatty acids distillates/carbon dioxide has been correlated with Redlich-Kwong-Aspen equation of state. Modeling shows good agreement with experimental data. Selectivity obtained indicates that supercritical carbon dioxide is a reasonable solvent for separating saturated (palmitic acid) and unsaturated (oleic+linoleic acids) fatty acids from palm fatty acids distillates in a continuous multistage countercurrent column.
Acesso aberto (Open Access)
Influence of the sodium content on the reactivity of carbon anodes
(2008-09) BATISTA, Jefferson dos Santos; SILVEIRA, Benedito Inácio da
Spent anodes, denominated butts in the aluminum industry, are recycled as part of the raw material used to produce new anodes. The fragmentation of the butt generates some sodium-rich powder, which is captured and included in the recycled material. This paper evaluates the influence of sodium content on anode reactivity. Six formulations with 0 to 25% butt powder were used. An average increase of 48 ppm of sodium from one to another formulation caused average increments of 3.38 and 2.72% for air and CO2 reactivity, respectively. The quality-related figures varied from 1.34 to 1.12 for CO2 and from 1.10 to 0.62 for air, showing quality loss in higher sodium content and higher impact on air reactivity. The Fischer formula predicted a carbon specific consumption of - 48.47 kg.t-1 Al for baked carbon anodes with 127 ppm to 367 ppm of sodium content, showing that the sodium can cause relevant carbon losses and increase costs of the aluminum production.
Acesso aberto (Open Access)
Inibição e reversão da agregação plaquetária de eqüinos in vitro com o uso de ketoprofeno, fenilbutazona e flunixim meglumine
(2009-10) LEME, Fabiola de Oliveira Paes; WURZINGER, Laurenz; ALVES, Geraldo Eleno Silveira; BICALHO, Adriane Pimenta da Costa-Val; BARBOSA, Marcos Pinott; PAES, Paulo Ricardo de Oliveira; OLIVEIRA, Marcos Enê Chaves
Several diseases may lead to platelet pre-activation and hypercoagulability states in horses. The activity of many drugs against platelet aggregation may, not only contribute to the evaluation of a disease but also its response to the therapy. With the aim to study in vitro prevention and reversion of platelet aggregation, the non steroidal anti-inflammatory drug (NSAID): ketoprophen, phenylbutazone and flunixin-meglumin were evaluated. The comparison demonstrated that phenylbutazone and ketoprophen prevented platelet aggregation induced by ADP better than flunixin-meglumin, in a superior manner to the monoclonal antibody Reopro, and in a better way than the membrane receptor blockers Ro-438857 and RGDS. The reversion of platelet aggregation demonstrated that even phenylbutazone or ketoprophen have a dose-dependent effect.
Acesso aberto (Open Access)
Integral transform method for laminar heat transfer convection of herschel-bulkley fluids within concentric annular ducts
(2001-12) VIANA, Marcos Jose Gomes; NASCIMENTO, Udilma da Conceição Serrão; QUARESMA, João Nazareno Nonato; MACÊDO, Emanuel Negrão
Related momentum and energy equations describing the heat and fluid flow of Herschel-Bulkley fluids within concentric annular ducts are analytically solved using the classical integral transform technique, which permits accurate determination of parameters of practical interest in engineering such as friction factors and Nusselt numbers for the duct length. In analyzing the problem, thermally developing flow is assumed and the duct walls are subjected to boundary conditions of first kind. Results are computed for the velocity and temperature fields as well as for the parameters cited above with different power-law indices, yield numbers and aspect ratios. Comparisons are also made with previous work available in the literature, providing direct validation of the results and showing that they are consistent.
Acesso aberto (Open Access)
Integral transform solution for the forced convection of herschel-bulkley fluids in circular tubes and parallel-plates ducts
(1998-03) QUARESMA, João Nazareno Nonato; MACÊDO, Emanuel Negrão
The thermal entry region in laminar forced convection of Herschel-Bulkley fluids is solved analytically through the integral transform technique, for both circular and parallel-plates ducts, which are maintained at a prescribed wall temperature or at a prescribed wall heat flux. The local Nusselt numbers are obtained with high accuracy in both developing and fully-developed thermal regions, and critical comparisons with previously reported numerical results are performed.
Acesso aberto (Open Access)
Investigação do processo de corrosão causado pela polpa de bauxita em mineroduto de aço carbono
(2015-03) SANTOS, Marcelo Costa; PINHEIRO, Clairon Lima; CARDOSO FILHO, José Carlos de Araújo
The corrosion caused by the ore slurry transported plays a fundamental role in the lifetime of a pipeline. Thus, the corrosion of API 5L-X70 carbon steel was investigated using process water and bauxite pulp (5% w./v.) as solution and electrochemical techniques. The results of open circuit potential (OCP), polarization and electrochemical impedance spectroscopy (EIS) showed that presence of bauxite caused changes when it compared to water process results and the corrosion rate increased in the bauxite presence. The micrographs of specimens surface obtained by scanning electron microscopy (SEM) showed cracks formation in the oxide in the metal surface and this phenomenon may be responsible for increased corrosion in bauxite presence. The methodology described in this work show to be useful for the investigation of corrosion in pipelines.
Acesso aberto (Open Access)
A mass transfer model applied to the supercritical extraction with CO2 of curcumins from turmeric rhizomes (Curcuma longa L)
(2000-09) CHASSAGNEZ MÉNDEZ, Angel Luis; CORRÊA, Nádia Cristina Fernandes; FRANÇA, Luiz Ferreira de; MACHADO, Nélio Teixeira de; ARAÚJO, Marilena Emmi
Increasing restrictions on the use of artificial pigments in the food industry, imposed by the international market, have increased the importance of raw materials containing natural pigments. Of those natural substances with potential applications turmeric rhizomes (Curcuma longa L), are one of the most important natural sources of yellow coloring. Three different pigments (curcumin, desmetoxycurcumin, and bis-desmetoxycurcumin) constitute the curcuminoids. These pigments are largely used in the food industry as substitutes for synthetic dyes like tartrazin. Extraction of curcuminoids from tumeric rhizomes with supercritical CO2 can be applied as an alternative method to obtain curcuminoids, as natural pigments are in general unstable, and hence degrade when submitted to extraction with organic solvents at high temperatures. Extraction experiments were carried out in a supercritical extraction pilot plant at pressures between 25 and 30 MPa and a temperature of 318 K. The influence of drying pretreatment on extraction yield was evaluated by analyzing the mass transfer kinetics and the content of curcuminoids in the extracts during the course of extraction. The chemical identification of curcuminoids in both the extract and the residual solid was performed by spectrophotometry. Mass transfer within the solid matrix was described by a linear first-order desorption model, while that in the gas phase was described by a convective mass transfer model. Experimental results showed that the concentration profile for curcuminoids during the supercritical extraction process was higher when the turmeric rhizomes were submitted to a drying pretreatment at 343 K.