Dissertações em Engenharia Química (Mestrado) - PPGEQ/ITEC

URI Permanente para esta coleçãohttps://repositorio.ufpa.br/handle/2011/2309

O Mestrado Acadêmico iniciou-se em 1992 e pertence ao Programa de Pós-Graduação em Engenharia Química (PPGEQ) do Instituto de Tecnologia (ITEC) da Universidade Federal do Pará (UFPA).

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Agora exibindo 1 - 19 de 19

Acesso aberto (Open Access)
Absorção de gases da queima de combustíveis fósseis em torre de recheio estruturado utilizando lama vermelha
(Universidade Federal do Pará, 2013-03-11) SANTOS, Iara Ferreira; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968; SOUZA, Célio Augusto Gomes de; http://lattes.cnpq.br/0800747860976046
The production of alumina from the Bayer process produces 1-3 tons of waste per ton of aluminum. This residue is known red mud, compound of minerals insoluble in concentrated sodium hydroxide, hematite and other iron oxides, quartz and titanium oxides. The red mud has in its composition varied levels of NaOH, depending on the specific industrial plant used. The purpose of this study is to evaluate the process of absorption of gases from a boiler countercurrent with a suspension of red mud, in a spray tower and a packed column. Experiments were performed varying the type of absorption tower, temperature of the liquid phase and solids content in liquid phase to evaluate the reduction in content of gases of combustion in the output of absorption tower and pH variation with time of operation, it was possible to identify the time required for the occurrence of red mud neutralization, and also a reduction in the content of carbon dioxide, thereunto were performed measurements of the concentrations of gasesin the input and output packed column, and also measurements of temperature and pH. The absorption of CO2 existing in the gases of combustion for suspension of red mud occurs by the carbonation process, where the gas reacts with NaOH present in red mud, with water as catalyst. The results obtained after the experiments were satisfactory, and it was concluded that the process performed in absorption towers is efficient for pH reduction of red mud and reducing the content of CO2 freed to atmosphere, providing a double profit for the environment.
Acesso aberto (Open Access)
Análise experimental do comportamento fluidodinâmico e da secagem de sementes de linhaça (Linum usitatissimum L.) em leito de jorro
(Universidade Federal do Pará, 2011-09-30) SANTANA, Elza Brandão; PINTO, Cláudio Roberto Orofino; http://lattes.cnpq.br/4833991906165550; COSTA, Cristiane Maria Leal; http://lattes.cnpq.br/0581730621014796
Flaxseed is the seed of the flax plant (Linum usitatissimum L.) is polymorphic native flax, and is considered one of the six plants currently recognized by the National Cancer Institute of the United States (U.S. National Cancer Institute - NCI) for their properties specific anti-cancer. Part of this recognition should be the remarkable characteristic of being the richest source of lignin precursors (vegetable steroid action analogous to the mammalian estrogen) in the human diet. The variety used in this work was the "Linseed" brown and objective of this study was to analyze the fluid-dynamics of spouted bed. The fluid-dynamics was defined by the measurements of the bed pressure drop as a function of the flow rate for different seeds loads, so getting information to determine parameters related to the process, such as: minimum spouting velocity, maximum pressure drop, stable spout pressure drop and minimum spouted pressure drop. These values were compared with the values obtained by empirical equations found in the literature. It was also studied the drying of raw material, through a full factorial design 22 with com three central point and the statistical analysis of the results were realized and the effects of independent variables spouting air temperature (Tg) and time (t) on the responses humidity ratio (Xr, adim.), germination (G, %) and germination speed index (GSI, t-1) were evaluated. The optimal operational point was determined as function of the entrance variables applying the concept of global desirability. The kinetics of drying was performed at temperatures of 45, 55 and 65 °C, and the Midilli et al. model showed the best fitting to the experimental data. For the fluid-dynamic parameters showed that the correlation of Gorshtein and Mukhlenov (1965) showed the lowest deviations for minimum spouted pressure drop and pressure drop in the steady spouted, Abdelrazek (1969) showed the smallest deviation to the minimum spouting velocity and Pallai and Németh (1969) described adequately the maximum pressure drop. It was observed that the mass of seeds processed and air-spouted temperature exerted a significant influence on fluid-dynamic. Based on the statistical analysis of experimental noticed that all variable Tg e t are statistically significant for the responses: humidity ratio, germination and germination speed index, proposing models representative of these parameters with the presence of curvature, obtaining the coefficient of determination (R2) greater than 99 %.
Acesso aberto (Open Access)
Ativação alcalina para a produção de geopolímeros a partir de resíduo industrial
(Universidade Federal do Pará, 2018-02-02) BRITO, Woshington da Silva; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968
The sustainable construction of the future, and has low energy consumption and greenhouse gas emissions must also adopt the principle of reuse of wastes impacting the environment generated by the productive chain. The aluminum production chain has as one of the leading waste impact on the environment the gray generation. The present study focused on the research and development of a cement-based material. Refers to an inorganic polymer, formed by the activation of amorphous aluminosilicates (Al2O3. SiO2), which react in a strongly alkaline medium, called geopolymer. As a raw material furnace fly ash, mineral residue from the combustion of the boilers of the company of the municipality of Barcarena-PA; As a source of aluminosilicate, and the kaolin that underwent the process of burning at 800 ºC that became metakaolin; And the alkaline medium of sodium silicate (Na2SiO3) and sodium hydroxide (NaOH), used as activators. As fly ash partially crystallizes during burning and loses some of its amorphous state, so are its reactive properties to chemically combine during the geopolymerization reaction are reduced. To increase reactive properties of fly ash and added metakaolin. As the main analyzes, no X-ray diffraction (XRD), X-ray fluorescence (FRX), scanning electron microscopy (SEM) and EDS. Tests of resistance to compression of the traces in the hardened state were also carried out and the rheological test of the geopolymer was carried out at the start of the reaction in the fresh state. For Davidovits ratios in the range of 2.5 to 3.23, the best geopolymers with compressive strength were obtained reaching 25 MPa in 24 hours of cure. For 60 days of cure at room temperature the geopolymers reached a resistance of 45, 36 MPa. The research carried out through the characterization analysis of the samples and the mechanical and rheological tests were presented in a satisfactory way and demonstrated that the residues of fly ash and metakaolin, when activated with sodium silicate and sodium hydroxide, are an alternative for the possible application of Geopolymer materials in construction.
Acesso aberto (Open Access)
Avaliação das condições de secagem no rendimento e na qualidade do óleo de linhaça (Linum usitatissimum L.)
(Universidade Federal do Pará, 2011-06-20) VALENTE, Maria da Conceição da Costa; COSTA, Cristiane Maria Leal; http://lattes.cnpq.br/0581730621014796; SOUZA, Célio Augusto Gomes de; http://lattes.cnpq.br/0800747860976046
From Asian origin flaxseed (Linum usitatissimum L.) and belongs to the linaceae family and it is obtained from flax. It is considered a functional food, because it contains substances that may prevent diseases such as degenerative and cardiovascular diseases. Flaxseeds are still a major lignans source, that are photochemical compounds similar estrogen, which it may performs cancer-preventative. In addition to being one of the richest sources of α-linolenic acid oil and soluble fibre. The drying is a unit operation, in general, usually means removal of relatively small amounts of water from material by evaporation or by sublimation, applying heat under control conditions. Aiming to analyze the behavior of flax seeds during the drying operation, this study aimed to perform the experimental design and statistically analyze the results used to quantify the influence of air temperature (T), drying time (t) fluidization air velocity (Uf) and solids loading (Cs) on the humidity ratio (Xr), oil yield (Rend.) and the parameters oleochemicals. The estimate of the optimal point of operation was determined according to the input variables by applying the concept of global desirability. Among the conditions set out in this work, the optimal value of the function you want and when T is shifted to high level (72 oC), Uf is shifted to high level (0,83 m/s), t you for the minimum (3h ) and Cs for the secondary level (500 g), thus obtaining: 0.126 to Xr, 36,92 % for Rend.; 4.51 mg KOH/g for IA, 22,52meq O2/g IP and 0,31% for DC. We obtained the sorption isotherms of flaxseed at temperatures 40, 60 and 80 °C. Six mathematical models were applied to analyze the experimental data. The enthalpy and differential entropy were determined by appying Clausius-Clapeyron and Gibbs-Helmholtz equation, respectively. Peleg model and GAB model showed the best fit to experimental data. The enthalpy-entropy compensation theory was applied to the isotherms, indicating that they are enthalpy - controlled. The flaxseed Drying were evaluated in a fixed and fluidized bed dryer, the experimental runs were done at temperatures 40, 60 and 80 °C. Five mathematical models were evaluated and the Midilli et al. model was found to be the best model for describing the flaxseeds drying behavior. It was observed that the effective diffusivity for the flaxseeds increased with increasing drying air temperature. The diffusivity dependence by temperature was described by the Arrhenius equation. It was estimated the activation energy.
Acesso aberto (Open Access)
Avaliação do processo de produção de etanol pela fermentação do caldo de mandiocaba (Manihot esculenta Crantz)
(Universidade Federal do Pará, 2013-02-28) SOUZA, Leiliane do Socorro Sodré de; FRANÇA, Luiz Ferreira de; http://lattes.cnpq.br/6545345391702172
The physico-chemical characteristics identified at sweet cassava root, was: moistures (%), fiber (%), protein (%), ash (%), total lipids (%), reducing sugars and total reducing sugars (%); the sap extract from sweet cassava root was characterized by pH, soluble solids (%), glucose and titratable acidity. This study used the yeast Saccharomyces cerevisiae PE-2. Was realized 15 tests that followed the conditions determined by the experimental design of Box- Behnken, with 3 independent variables: temperature (oC) (X1), pH (X2) and concentration of inoculum (g/L) (X3). The statistical analysis was performed with p>0,05. Through the analysis of variance (ANOVA) was proposed a second order polynomial model to the alcohol content (ºGl), and by analysis of response surfaces it was determined the optimum condition to the fermentation of sap extract from sweet cassava root without addition of nutrients, on original substrate concentration of it (6,46 g/L): 28ºC (temperature), 4,88 (pH) and 10 g/L (inoculum concentration). Under these conditions a test was conducted, which aimed to raise the curves of cell growth (yeast), CO2 production, consumption of sugars and ethanol production, to better understand the process of fermentation broth of sweet cassava. Through the cellular growth curve was determined the duration of the exponential phase, using the method of linear regression; this step in this study occurred at different time intervals. The value found to μm was 0,05 h-1.
Acesso aberto (Open Access)
Destilação fracionada do óleo essencial de P. aduncum L. rico em dilapiol
(Universidade Federal do Pará, 2011-09-30) MARTINS, Gisele Luciana Domont; FARIA, Lênio José Guerreiro de; http://lattes.cnpq.br/7428609361678173
The species Piper aduncum L. is a shrubby plant, popularly known in the Amazon as monkey-pepper (spiked pepper). An essential oil, rich in dillapiol, can be extracted from this plant, which is of great economic interest for its insecticidal and pesticide action in agriculture. This biopesticide is an alternative to replace synthetic insecticides as it is from natural origin and does not cause damage to the environment and human health. In this paper the physical properties of the essential oil of spiked pepper were analyzed. The oil was obtained by steam distillation which showed mean values of refractive index of 1.516 and specific mass 1.08 g/cm³. The fractional distillation of the essential oil was studied, in order to concentrate the compound of interest, thus, adding greater economic value and enabling its use in the production of new products. In this process a high purity compound is obtained. The assessment was performed using a mathematical model to evaluate the concentration of dillapiol at the bottom of the distillation flask by regression analysis as a function of operating time which set the experimental data very well. The analysis of the results suggests that the process of fractional distillation can be used to separate the useful constituents from the essential oils. This is only possible because the essential oils are constituted of several volatile organic compounds with different boiling points and steam pressures, making the separation viable. The highest content of dillapiol obtained experimentally by the method of fractional distillation was 95 %, operating under vacuum conditions (40 mmHg) and mean temperature of the column of 122 ºC, and the average yield obtained was 41 % (v/v).
Acesso aberto (Open Access)
Efeito da adição de lama vermelha como carga nas propriedades mecânicas de compósitos de poliéster insaturado reforçado com fibra natural de curauá (Ananas erectifolius)
(Universidade Federal do Pará, 2013-06-11) OLIVEIRA, Mauro Júnior Aires de; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968
Nowadays, due to the increasing need for good mechanical performance and due to the environmental issues, researchers have tried to replace synthetic fibers used in composites (such as glass fiber) for natural fibers. A natural fiber that has already been used in the automobile industry is the curaua fiber (Ananas erectifolius) which shows excellent tensile strength. Expecting to enhance some properties of the composites and to minimize the usage of resin, and this way minimize costs, it has been researched the utilization of fillers incorporated to composites matrices. In recent papers, it has been studied the utilization of red mud (waste of the bauxite industry) as filler due to the great availability, low cost and for being potentially dangerous to the environment. The objective of this work was to evaluate effects of red mud addition on the mechanical properties of Curaua fiber (Ananas erectifolius) reinforced composites. The results showed that the using of red mud as filler in volume fractions equal or higher than 20% and Curaua fiber in volume fraction of 5% was improved significantly the reinforcing effect.
Acesso aberto (Open Access)
Equilíbrio líquido-líquido dos sistemas biodiesel de castanha do Brasil + metanol + (glicerina ou água): determinação experimental e modelagem termodinâmica
(Universidade Federal do Pará, 2013-12-18) GONÇALVES, Jefferson Dias; AZNAR, Martín; http://lattes.cnpq.br/5798321645560791; SANTOS, Geormenny Rocha dos; http://lattes.cnpq.br/0844662601945669
Biodiesel is defined as being a mixture of fatty esters derived of animal fats or vegetable oils, obtained through the process of transesterification with short chain alcohols. During the production is used a quantity in excess of alcohol and a catalyst to propitiate the formation reaction of esters; in this way the output flow of the reactor contains the catalyst, the unreacted alcohol and products obtained by transesterification, biodiesel and glycerin, forming a biphasic system; depending on the solubility of these compounds, will may there be amounts of biodiesel and glycerin-rich phase and quantities of glycerin in biodiesel-rich phase. During the process of purification of biodiesel it is necessary to accomplish a washing with water, to promote removal of the catalyst and impurities of the product of interest. Due to the amount of compounds involved in the production and purification is essential to know the liquid-liquid equilibrium data in order to predict the proportions in which the compounds coexist and subsequently, to proceed with purification under suitable conditions for obtaining biodiesel with greatest efficiency and to assist in the design of the reactor and tanks. The objectives of this work were to produce biodiesel from oleaginous plants native to the region, the Brazil nut (Bertholletia excelsa H. B. K.) and to establish liquid-liquid equilibrium data (ELL) to ternary systems: biodiesel of Brazil nut + methanol + glycerin and biodiesel of Brazil nut + methanol + water at temperatures of 30° C and 50° C. The biodiesel produced was initially characterized in accordance with the standards of the National Petroleum Agency (ANP) using physicochemical methods. The data obtained were afterward correlated with NRTL and UNIQUAC thermodynamic models for the calculation of the coefficient of activity of each component in the liquid phase, with new energetic interaction parameters obtained. The results obtained from the modeling were satisfactory, and was observed that the NRTL model represented better the experimental data.
Acesso aberto (Open Access)
Estudo cinético e das isotermas de adsorção dos óleos de palma (Elaes guineensis, Jacq.) e andiroba (Carapa guianensis, Aubl.) em y-alumina e modelagem da dessorção com dióxido de carbono supercrítico
(Universidade Federal do Pará, 2013-11-08) AMARAL, Anderson Rocha; MACHADO, Nelio Teixeira; http://lattes.cnpq.br/5698208558551065
In this work, the variables of the batch adsorption process of palm (Elaeis guineensis, Jacq.) and andiroba (Carapa guianensis, Aubl.) vegetables oils on thermally activated alumina at 723,15 K and 923,15 K (y-alumina) has been investigated by analyzing the influence of temperature, time, mass of vegetable oil, mass of adsorbent on the adsorbent capacity. A kinetic model of second-order was proposed to modeling the adsorption capacity of free fatty acids (FFA). Capacity results of FFA of the crude palm oil on y-alumina AG.450 at 328.15 K and of the crude andiroba oil on y-alumina AG.650 at 323.15 K were obtained from the consecutive adsorption experiments and adjusted by isotherms of Langmuir e BET. The transfer mass model of TAN & LIOU (1989) was used to modeling the kinetic desorption of the palm oil from y-alumina AG.650 and of the andiroba oil on y-alumina AG.450 with supercritical carbon dioxide, evaluating the yields, errors, correlation coefficients and the residues of the desorbed oil mass versus predicted by the model.The study of the variables influence, over the adsorption capacity, presented negative correlation (with exponential behavior) to the variable mass of oil. The adsorbent mass influence, presented a positive correlation (with a linear behavior) and the temperature increase is favorable to the adsorption process. The total reduction of the FFA after three consecutive adsorptions of the crude palm oil on y-alumina AG.450 and after four consecutive adsorptions on -alumina AG.650 with andiroba oil, were 21.07 % and 40.29 %, respectively. The modeling of the FFA capacity to the palm oil with Langmuir model, presented a high experimental data prediction ability (R² = 0.9610), as well as to the andiroba oil with the BET model, which presented a high adjustment (R² = 0.9140). Tan & Liou model evidenced high prediction capacity of the desorption oil mass from γ-alumina for all experiments, minimum correlation coefficient of 0.9230 and magnitude residues of 10-1 grams. The yields, based on adsorbate initial mass, of the palm oil desorbed from y-alumina AG.650 at 20 MPa up to 30 MPa and 323.15 K up to 328.15 K were 28.880 % up to 34.563 %, while to the andiroba oil on y-alumina AG.450 at 15 MPa up to 25 MPa at 323.15 K were 14.108 % up to 27.972 %. The yields results shows that the increase of pressure and temperature are favorable to the supercritical desorption.
Acesso aberto (Open Access)
Estudo da influência da granulometria no comportamento reológico de polpa de bauxita e no fator de atrito
(Universidade Federal do Pará, 2011-09-14) BRUM, Sebastião Martins; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968; MACÊDO, Emanuel Negrão; http://lattes.cnpq.br/8718370108324505
This paper presents studies of the rheological characterization and determination of friction factors in three bauxite slurries originating in Miltonia Mine, Paragominas - Para, resulting from operating conditions with different degrees of grinding. Thus, the basic difference between them lies in the size distribution. The goal is to make a proposal to revise the specification of the product particle size (for the bauxite slurry pipeline), allowing a comparison with the slurries of the project (pilot plant) and the current operation (processing plant) and the response to changes, especially, viscosity and friction factors. The slurry proposal incorporates a higher percentage of fines (<10 microns) compared with other slurries. The benefits can earn recovery with the incorporation of this portion of fines, which currently is discarded to the tailings pond. The material was characterized by size analysis of the series Tyler, physical and physical-chemical, electron microscopy (SEM) and X-ray spectrometry energy dispersive (EDS). Testes were conducted in coaxial cylinder viscometer, Searle type, in order to determine the rheological behavior of these slurries, depending on the size distribution and varying the concentration of solids. The rheological properties were measured viscosity, yield stress and also behaviors that show the dependence of viscosity with the time of application of a constant shear rate, verifying through the hysteresis curve, the presence or absence of thixotropy and reopexia. The experimental results showed that for the slurries tested, the particle size and solids concentration are important parameters in determining the viscosity. Tests with these three bauxite slurries of different sizes, were performed at predetermined concentrations, to determine the model whose rheological parameters showed the best correlation coefficients (R2), and the best fits were found using the Herschel-Bulkley model. The friction factors were obtained for formulations involving a logarithmic relationship, using the Law of the Wall as a method of obtaining these expressions apply to non-Newtonian viscoplastic fluid, and compared with those calculated by Dodge and Metzner correlation and found that in general there is agreement between the model studied in the three slurries. The factor analysis of friction in the concentration of 50% solids, which is the concentration of pumping by pipeline, shows that the behavior of the slurries studied is similar, with the best settings for the range from 10,000 to 100,000 Reynolds (average work range for the turbulent flow of the ore pulp, homogeneous and heterogeneous).
Acesso aberto (Open Access)
Estudo da utilização de polímeros naturais como auxiliares de floculação no tratamento de água para fins industriais
(Universidade Federal do Pará, 2012-09-27) SILVA, Juliane da Silva e; SILVA, Denilson Luz da; http://lattes.cnpq.br/4241759369873376
This work is to evaluate the effectiveness of new alternatives for use with natural species of okra (Abelmoschus esculentus) seed angico red (Anadenanthera peregrina (L.) Speng) and seed-eye dragon (Adenanthera pavonina L.) also known as ‘falso angico’, sprayed with a particle size of 0.074 mm, sieving for water treatment as natural polymers, helping the flocculation on removal of main parameters in turbidity and color through tests in the scanner equipment using Jar Test static bench adding a chemical coagulant (aluminium sulfate). The powder of polymers were obtained after washing, drying, crushing, grinding, sieving, and used in the coagulation process, flocculation and sedimentation to test the efficiency of each one, when used alone and when used in conjunction with the chemical coagulant, followed by the analysis of physical-chemical parameters pH, turbidity, apparent color, true color and temperature. The results showed that the polymer of okra presented better efficiency in removing turbidity and color compared to the same doses used with other polymers considered and when reducing the dosage of coagulant used in conjunction with the polymers, it was observed a great removal of turbidity, especially with the conjunction of coagulant and polymer of okra, with the removal efficiency of 94% of turbidity and 98% of color with optimum dosage of okra equal to 1.0 mg/L and coagulant equal to 10 mg/L. Therefore it is possible to reduce the dosage of the coagulant when used in conjunction with the auxiliary flocculation, as the polymer of okra can be used for water treatment and facing the possibility of multiple economic and ecological uses in industry.
Acesso aberto (Open Access)
Estudo de misturas de enzimas (complexo celulásico, complexo enzimático, xilanase, β-glucanase e xilanase, β-glucosidase e Glucoamilase) na bioconversão do bagaço da cana-de-açúcar em etanol
(Universidade Federal do Pará, 2015) MOREIRA, Rosiane Fernandes; MACHADO, Nelio Teixeira; http://lattes.cnpq.br/5698208558551065
This work, it was proposed to evaluate mixtures of commercial enzymes by supplier Novozymes A / S. The enzymes used in this work were: celulase complex, xylanase, β-glucosidase, enzymático complex, xylanase and β-glucanase and glucoamylase in the glucose production from sugarcane bagasse subjected to treatment with alkali hydroxide solution sodium at room temperature, 70 ° C, 90 ° C and 120 ° C. The BCA yield on a dry basis after treatment with NaOH solution 6 (w / v) were 30.64% ± 1.395 (PACTA), 44.00% ± 1.787 (PAC70), 65.91% ± 1.096 (PAC90), and 95.25% ± 1.461 (CAP 120), respectively. The ash content for the BCA were 2.05% ± 0.027 (PACTA), 0.62% ± 0.013 (PAC70), 0.48% ± 0.007 (PAC90) and 0.18% ± 0.008 (PAC120). The lignin contents were 20.67 ± 0.603 (PACTA), 13.03 ± 0.711 (PAC70), 6.05 ± 0.196 (PAC90) and 5.49 ± 0.151 (PAC120). The results suggest that the conversion rates of cellulosic waste into glucose are strongly dependent on temperature in the alkaline pulping process. The kinetic parameters obtained in kinetic adjustments enzymatic hydrolysis of the BCA for PACTA, PAC70, PAC90 and PAC120 were: Vmax (g/h) equal to 7.20; 5.12; 4.54 and 0.87 respectively; Km (g) equal to 3.6; 2.56; 2.27 and 2.56 respectively; Kcat (h) equal to 1.44; 1.02; 0.91 and 0.17 respectively; Km/Vmax equal to 0.5 for all samples and Kcat/Km of 0.4 for all samples.
Acesso aberto (Open Access)
Estudo eletroquímico de ligas metálicas alumínio-silício em meio ácido
(Universidade Federal do Pará, 2012-03-30) SANTOS, Luana Santana dos; CARDOSO FILHO, José Carlos; http://lattes.cnpq.br/7033790503322903
The alloys based on aluminum-silicon have low specific weight, good mechanical strength and corrosion resistance, have been widely used as substitutes for some ferrous alloys in manufacturing parts for various industries. In this research we studied the electrochemical behavior of aluminum and aluminum-silicon alloys 0.3 and 0.7% by mass in electrolytes sulfuric acid and hydrochloric acid, both at 0.1 mol/L. The results of electrochemical techniques showed that the Si caused a shift to more positive values corrosion potential was observed a region of passivity anodic curves of the electrodes in sulfuric acid, this phenomenon was not observed in hydrochloric acid. The Nyquist diagrams show two arcs, a capacitive region of high frequencies related to the formation of the layer oxidizes and an inductive at low frequencies attributed to adsorption of anions on the metal surface, the similarities in the diagrams show that the electrochemical phenomena are identical and independent addition of Si. The impedance diagrams also showed low polarization resistance of the alloys Al-Si. Considering only the electrochemical studies it can be stated that the electrodes did not show significant differences between themselves and susceptibility to corrosion in these acidic solutions does not imply a negative feature to your application.
Acesso aberto (Open Access)
Modelagem e simulação do processo de separação por membrana difusa polimérica para a extração de metais
(Universidade Federal do Pará, 2007-02-16) CARDOSO, Simone de Aviz; QUARESMA, João Nazareno Nonato; http://lattes.cnpq.br/7826389991864785
Metal extraction process using polymeric membranes is analyzed by using the lines-Gear method in the solution of the related equations of specie conservations. The mathematical modeling of the physical problem is done by considering the diffusion process of metals in polymeric membranes in order to extract metals, such as Cd (II), Au (III) and Pd (II) from acid solutions. Therefore, the behavior of concentration profiles of metals to be extracted from the feeding phase is discussed in the light of the influence of relevant parameters in the extraction process, such as, composition and thickness of the membrane, diffusion coefficient and constant extraction. Comparisons with previously reported results in the literature for typical situations are also performed. The obtained results were very satisfactory when they were compared with other found results in the literature.
Acesso aberto (Open Access)
Obtenção e caracterização de carvão ativado de caroço de buriti (Mauritia flexuosa L. f.) para avaliar o processo de adsorção de uma solução de Cu (II)
(Universidade Federal do Pará, 2013-09-30) PINTO, Marcos Vinicios de Souza; SILVA, Denilson Luz da; http://lattes.cnpq.br/4241759369873376
Buriti core carbon (CCB) was produced from the reject of artisanal production of its fruit for the extraction of oil, heated to 400ºC. Then, the CCB was activated at temperatures of 800ºC and 900ºC. Adsorption tests were performed to evaluate the discharge of these activation temperatures in the adsorption of a solution of copper (II) to a known initial concentration of 50 mg/L. After having examined the results, it was decided by the activation of coal to 900ºC. The activated carbon of the buriti core (CACB) to 900ºC was characterized according to commercial properties such as specific area, porosimetry, apparent and real densities, porosity of a bed fix, scanning electron microscopy, ash content, pH, moisture, fixed carbon and acid surface functional groups present in the CACB. The results showed a higher removal efficiency of copper (II) to the diameter D < 0.595 mm, for the contact time of 300 minutes, for the pH of 4.01 and the initial concentrations of copper (II) 50 and 80 mg/L. Mathematical models of Langmuir and Freundlich were applied to the data of adsorption equilibrium. The mathematical model of Langmuir was the best fit to the data of balance. The Langmuir’s mathematical model was the best fit to the data of balance. According to data from the kinetic equilibrium, it was observed that from the contact time of 15 minutes all the equilibrium concentrations were below the allowed maximum of 1,0 mg/L under the law CONAMA nº 357/2005 for release effluent into aqueous environments. The experimental results obtained are indicative that it is possible to remove copper (II) from industrial effluent using CACB activated physically at 900ºC for a period of 60 minutes.
Acesso aberto (Open Access)
Partição de antocianinas de açaí utilizando equilibrio líquido-líquido a base de solventes eutéticos profundos
(Universidade Federal do Pará, 2021-02-04) SABOYA, Adriana Marcela Moreno; COSTA, Mariana Conceição da; http://lattes.cnpq.br/5415527829271587; SANTOS, Geormenny Rocha dos; http://lattes.cnpq.br/0844662601945669
The anthocyanin in the acai fruit is one of the most attractive industrial compounds. It is used as a natural dye due to its violet pigment and its antioxidant power. An alternative technique for the extraction of biomolecules is extraction using Liquid Liquid Equilibrium (LLE) systems, composed of Deep Eutectic Solvents (DESs) characterized by being economical, efficient and of low toxicity to the environment and human body. Therefore, this study aimed to determine liquid-liquid equilibrium data of DES-based systems: ChCl:GLI (choline chloride:glucose) + isopropanol + water and ChCl:SAC (choline chloride:saccharose) + isopropanol + water at temperatures of 25oC and 35oC, and to assess its application in the partition of the acai anthocyanins. First, the physical-chemical characterization of the lyophilized acai was carried out. Second, Box Behnken factorial design was applied to analyze and optimize the extraction process to evaluate the influence of experimental conditions on the extraction of anthocyanin and total polyphenols from the lyophilized acai. Once the optimization conditions were found, the DESs that would be used in the LLE system were prepared. Furthermore, the thermal and structural properties for each DESs were determined with DSC and FTIR respectively. Third, aiming to research DESs behavior with water and isopropanol mixtures in equilibrium phases, the LLE data at 25 oC and 35oC were determined. The binodal curves were obtained by cloud point titration, and the tie lines were determinate for gravimetrical and analytical (HPLC and Karl-fischer) methods. The systems studied were characterized as quaternary systems and the experimental LLE data were correlated by NRTL obtaining a mean quadratic deviation (RMSD) of 0.438%. The anthocyanin partition in ELL was carried out using the anthocyanin extract obtained in optimal conditions. Finally, it was proven that the individual components of DESs have a high affinity with the anthocyanins, showing the total migration of the biomolecules in the bottom phase. The partition coefficients of total polyphenols (KPT) were higher than 1, showing the preference of biomolecules in the bottom phase and the extraction efficient (%EE) of 70% with ChCl + Glucose + isopropanol + water system. This result confirmed xithe potential of using these systems to extract natural pigments aiming at a probable use of the separation of nonpolar biomolecules (acai lipids) in the alcohol-rich phase.
Acesso aberto (Open Access)
Produção de biodiesel da gordura de murumuru (Astrocaryum murumuru) via catálise heterogênea
(Universidade Federal do Pará, 2010-09-24) TEIXEIRA, Louise Carolina Gonçalves; FRANÇA, Luiz Ferreira de; http://lattes.cnpq.br/6545345391702172; CORRÊA, Nádia Cristina Fernandes; http://lattes.cnpq.br/5763999772352165
This work investigated the feasibility of Murumuru oilseed (Astrocaryum murumuru) as raw material for biodiesel production through the use of heterogeneous catalysis in the basic transesterification. Murumuru is a fruit composed of pulp and kernel, producing about 50% of white fat, odorless, with the advantage of not be tasteless easily because it is rich in saturated fatty acids of short-chain such as for lauric and myristic. The biodiesel is conventionally production through the basic homogeneous catalysis. However this catalysis presents a few inconvenients, such as saponification of esters and the difficulty of removing the catalyst. On the otter hand, the heterogeneous catalytic route avoids the drawbacks of homogeneous catalysis, reducing the amount of aqueous effluent generated during the process and reuse of catalysts. The heterogeneous catalyst hydrotalcite, was synthesized and evidenced by analysis of X-ray fluorescence, X – ray diffraction, thermal analysis, textural analysis (BET method) and electronic scanning microscopy. A complete factorial planning was conducted using methanol as reacting product. Independent variables were temperature, molar ratio and catalyst concentration and the response variable was the conversion, measured through spectrophotometric method. These reactions were conducted in to a pressurized batch reactor. The best conversion found through factorial planning was 88,97% for molar ratio of methanol/oil worth 12, temperature of 200ºC and catalyst concentration equaling 6% in 1 hour of reaction. For this condition, kinetic studies were performed and tested the use of ethanol; through the kinetic study a good correlation can be achieved between the kinetic constants and conversion when using the model that considers reversible reaction, chemical reaction as controlling stage following the Eley Rideal mechanism.
Acesso aberto (Open Access)
Produção de carvão ativado a partir da biomassa residual da castanha do Brasil (Bertholletia excelsa L.) para adsorção de cobre (II)
(Universidade Federal do Pará, 2012-09-20) MELO, Selma dos Santos; SILVA, Denilson Luz da; http://lattes.cnpq.br/4241759369873376
Activated carbon was produced from the Brazil nut bark (Bertholletia excelsa l.) to be used in the cooper (II) removing, in adsorption process in bath system. The bark is a waste material from the chestnut improvement which was collected, selected, washed in running water and then it was dried up in stove at 150 °C in 24 h. The carbons were charred at 400 °C for 3h and thermally activated at 800 °C in 1, 2 and 3 hours time when they received its encodings CA1, CA2 and CA3 respectively. Then they were characterized as: the specific superficial area, volume and pores size, X-ray diffraction, scanning electron microscopy (SEM) coupled to EDS (energy dispersive X-ray system) and Fourier transformed infrared spectroscopy FTIR). Preliminary tests were performed to assess the carbon efficiency as cooper (II) removing in synthetic solution of 50 mg L-1 initial concentration. As the results were satisfactory to CA1, CA2 and CA3 (93,43, 97,23 and 96,92 % to those carbons), decided by what had higher removing percentage of. The CA2 was produced and characterized as: the real and apparent densities, porosity in fixed bed, pH, moisture (wet basis), ashes, fixed carbon and functional groups by Boehm method. There were preformed tests to determine the cooper (II) efficiency removing concerning the carbon particle diameter influence, pH of the solution, contact time influence and variation of the initial concentration. The results of higher removing percentage were to diameter 0,595≤D≤1,19 mm, pH 5,09, in time of 5 min and concentrations of 50, 100 e 150 mg L-1. The adsorption kinetic study that best fit according to data was pseudo-second order model. The experimental data that presented good fit according to mathematical models of Langmuir and Frendlich isotherm. In this sense, was obtained activated carbon at a low cost from the Brazil nut bark which one showed a good efficiency in cooper (II) removing process and also allowing the using in the effluents treatment.
Acesso aberto (Open Access)
Simulação computacional da adsorção dos poluentes benzeno, tolueno e p-xileno sobre carvão ativado
(Universidade Federal do Pará, 2013-12-27) COSTA, Wanessa Almeida da; MARTELLI, Marlice Cruz; http://lattes.cnpq.br/1213009262936026; BRASIL, Davi do Socorro Barros; http://lattes.cnpq.br/0931007460545219
The greatest problems of groundwater and soil contamination are assigned to monoaromatic hydrocarbons which are the most soluble and the most mobile constituents of the fraction of certain substances, such as gasoline. To remove these contaminants, adsorption by activated carbon is the most widely used method, for it presents a significant ability to adsorb organic low molecular weight components, such as benzene, toluene and p-xylene. In this work, we verified the adsorption on activated carbon thereof via computer simulation. As base, we used the postulated model of charcoal prepared by Bourke et al. (2007). Several steps have been completed since the design of the structures of carbon and pollutants to the molecular dynamics phase. For the conformational analysis of the coal’s structure, it was used the semi-empirical method PM3 and for the molecular dynamics technique, the AMBER force field FF99SB. The structure went through a heating at constant pressure until it reaches a final temperature of 298K (25ºC), being its information collected every 50 ps. Subsequently, the structure was submited to equilibrium system at a constant temperature of 298K (25ºC) for 500ps for its information can be analyzed. Finally, the system was then submited to molecular dynamics during 30ns. After analyzing the results, it was found that the ether, lactone and carbonyl (ketone) groups present in the structure of activated carbon provide to it acid feature and because of this and its consequent negative surface charge, adsorption has become viable once the pollutants had positive surface charge, which supports the view that is already known about this type of phenomenon.

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