CT - DEQ - Artigos publicados em periódicos

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Influência do método de síntese sobre propriedades da peneira molecular SAPO-11
(Associação Brasileira de Química, 1997) Medeiros, Gilson Gomes de; Cardoso, Dilson
Samples of SAPO-11 were synthesized by hydrothermal crystallization, with the objective of investigating the influence of the method of synthesis on the properties such as crystallinity, morphology, and catalytic activity. Solid products were analyzed by X-ray diffraction, scanning electronic microscopy and plasma emission spectroscopy. Catalytic evaluation of the samples in ethylbenzene disproportionation was realized using a continuous flow fixed bed reactor connected on-line with a gas cromatograph. The results with regard to percentual conversion of ethylbenzene and para-selectivity are given
Preparartion and characterization of terbium over paligorsquite clay as acid catalyst
(Elsevier, 2000-08-01) Melo, Marcus Antônio de Freitas; Ruiz, Juan Alberto Chavez; Melo, Dulce Maria de Araújo; Vitor Sobrinho, Eledir; Schmall, M.
Palygorskite clays containing 5% and 10% terbium (W/W) were prepared by ion exchange from acid-leached naturalclay. Samples were calcined at 523, 573, 623 and 673 K to verify the e ect of the temperature over the physical±chemicalproperties. Characterization was using X-ray di raction, infrared spectroscopy (n-butylamine adsorption), UV±visibledi use reØectance spectroscopy and N2adsorption. Isopropyl alcohol (IPA) transformation was also performed inorder to improve the acid behavior. TB3áintroduction does not change the palygorskite structure, albeit leading to anincrease in the surface area and generation of Lewis acid sites. Results from the DRS spectra along with a decrease inthe catalytic activity suggested the formation of terbium oxide for relatively high TB3ácontents
Avaliação química e sensorial de linguiças de pescado tipo frescal
(Boletim Centro de Pesquisa de Processamento de Alimentos, 2001) Correia, Roberta Targino Pinto; Mendonça, Silvana Correia de; Lima, Maria Lucilda; Silva, Priscilla Diniz da
A presente pesquisa teve por objetivo caracterizar quimicamente e investigar a aceitabilidade de três tipos de lingüiça preparadas a partir da associação dos seguintes ingredientes cárneos: camarão e peixe, camarão e bacon, camarão, bacon e peixe. As análises químicas incluíram determinação do teor de umidade, gordura, proteína e cinzas, enquanto a análise sensorial envolveu os testes de aceitabilidade e de preferência. A composição química mostrou-se adequada, com teores de umidade, cinzas e proteína similares a de produtos existentes no mercado e percentual lipídico reduzido, configurando produto cárneo com baixo teor de gordura. Todas as preparações analisadas tiveram boa aceitação e a formulação obtida a partir de camarão e bacon foi considerada a preferida pelo painel sensorial.
α Function for a series of hydrocarbons to peng−robinson and van der waals equations of state
(ACS Publications, 2001) Chiavone Filho, Osvaldo; Amaral Filho, Pedro G.; Silva, Douglas do Nascimento; Terron, Luiz Roberto
This paper reports estimated coefficients for the α function based on vapor pressure data to a series of 438 components, mainly hydrocarbons, for both van der Waals and Peng−Robinson equations of state (EoS). The α function utilized for the attractive term is the one proposed by Mathias and Copeman in 1983, and it improves the cubic EoS calculations. Accurate vapor-pressure correlations and critical data required for the estimation of the constants were retrieved from two databases, i.e., AIChE DIPPR and the Reid et al. (The Properties of Gases and Liquids; McGraw-Hill: New York, 1987) reference book. The method of calculation is described, and the constants are tested with respect of their representation of thermodynamic properties, mainly in terms of the vapor-pressure deviations. The behavior of density and enthalpy EoS predictions is also evaluated. The estimated coefficients for the α function are reported in the Supporting Information and may be applied as a data bank in a simulator, providing more accurate thermodynamic property calculations in the recommended temperature range, as demonstrated
Escoabilidade de leitos de partículas inertes com polpa de frutas tropicais: efeitos na secagem em leito de jorro
(Departamento de Engenharia Agrícola - UFCG, 2001-12) Medeiros, Maria de Fátima Dantas de; Alsina, O. L. S.; Rocha, Sandra C.; Jerônimo, Carlos E. de M.; Mata, Ana Lúcia de Medeiros Lula da; Medeiros, Uliana Karina Lopes de; Furtunato, Andréa A.
Neste trabalho, foram caracterizados seis tipos de material inerte, utilizados na secagem de polpa de frutas em leito de jorro. Determinou-se o ângulo de repouso das partículas, com e sem adição de água e de polpa de diversas frutas tropicais. Correlacionou-se a escoabilidade com as propriedades das partículas e com a composição química das polpas. Analisou-se a influência do ângulo de repouso sobre o desempenho do secador, no que se refere à produção. Os resultados mostraram que, em geral, as polpas com elevadas concentrações de gordura e sólidos insolúveis e baixos teores de açúcares redutores, facilitam a escoabilidade. Uma análise dos resultados obtidos na secagem de polpa de frutas tropicais, utilizando-se partículas de poliestireno de baixa densidade, como material inerte, mostrou que, embora a escoabilidade permita a obtenção de menores vazões de jorro mínimo, em relação ao desempenho do secador, pode não favorecer uma produção maior de pó
Preparative chromatography of xylanase using expanded bed adsorption
(Elsevier, 2002-01) Santos, Everaldo Silvino dos; Guirardello, Reginaldo; Franco, Telma Teixeira
Expanded bed adsorption was used to purify a marketable xylanase often used in the kraft pulp bleaching process. Experiments in packed and expanded beds were carried out mainly to study the adsorption of xylanase on to a cationic adsorbent (Streamline SP) in the presence of cells. In order to study the presence of cells, a Bacillus pumilus mass (5% wet mass) was mixed with the enzyme extract and submitted to an expanded bed adsorption system. One xylanase was purified to homogeneity in the packed bed. However, the 5% cell content hampered purification
Determination of the solubility of extracts from vegetable raw material in pressurized CO2: a pseudo-ternary mixture formed by cellulosic structure+solute+solvent
(Elsevier, 2002-01) Chiavone Filho, Osvaldo; Rodrigues, Vera Maria; Sousa, Elisa Maria Bittencourt Dutra de; Monteiro, Alcilene Rodrigues; Marques, Márcia Ortiz Mayo; Meireles, Maria Angela A.
This paper discusses the application of the dynamic method to measure the solubility in pseudo-ternary systems formed by vegetable raw materials (cellulosic structure+solute) and CO2. For aromatic, medicinal, and spice plants, the soluble portion of the solid is formed of essential oils, oleoresins, pigments, and various substances from several other classes of organic compounds. The experimental data were measured in two independent laboratories, using three experimental set-ups, and three vegetable species: clove buds, eucalyptus, and ginger. The solubility for the system clove buds/CO2 varied from 0.220 to 0.277 kg-extract/kg-CO2 for the isotherm of 288.15 K. The ginger extract solubility varied from 2.01×10−3 to 7.20×10−3 kg-extract/kg-CO2 for pressures of 100–300 bar, and temperatures of 298.15–313.15 K. The eucalyptus solubility for the isobar of 66.7 bar varied from 3.95×10−3 to 4.07×10−3 kg-extract/kg-CO2. © 2002 Elsevier Science B.V. All rights reserved
Experimental results for the extraction of essential oil from Lippia sidoides cham. using pressurized carbon dioxide
(Scielo, 2002-04) Chiavone Filho, Osvaldo; Sousa, E. M. B. D.; Moreno, M. T.; Silva, Douglas do Nascimento; Marques, M. O. M.; Meireles, M. A. A.
The odoriferous species Lippia sidoides Cham. is abundant in the Brazilian Northeast. Its essential oil possesses antiseptic activity due to the presence of thymol. In this work, thermodynamic and kinetic data were experimentally determined for the CO2 + L. sidoides system. Solubility was determined using the dynamic method at pressures of 66.7 and 78.5 bar and temperatures of 283.15, 288.15, 293.15, 295.15, and 298.15 K. SFE kinetic data were obtained at 288.15 K and 66.7 bar. The composition of the multicomponent solute mixture was determined by GC-MS and compared to the composition of both the volatile oil obtained by steam distillation and the oleoresin obtained using ethanol. The SFE process yield was higher than the yield of either the steam distillation or the ethanol extraction. The solubilities were correlated using the Peng-Robinson equation of state with one binary interaction parameter for the attractive term, considering the essential oil as a pseudo-component. Sovov·ís model quantitatively described the overall extraction curve
Operational intensification by direct product sequestration from cell disruptates: application of a pellicular adsorbent in a mechanically integrated disruption-fluidised bed adsorption process
(Wiley, 2002-08-19) Santos, Everaldo Silvino dos; Jahanshahi, Mohsen; Sun, Yan; Pacek, Andrzej; Franco, Telma Teixera; Nienow, Alvin; Lyddiatt, Andrew
A novel prototype adsorbent, designed for in-tensi®ed ¯uidised bed adsorption processes, was as-sembled by the emulsi®cation coating of 4% (w/v)porous agarose upon a zirconia-silica solid core. Theadsorbent, designated ZSA (particle density 1.75 g/ml,maximum pellicle depth 40 lm), was subjected tophysical and biochemical comparison with the perfor-mance of two commercial adsorbents (Streamline andMacrosorb K4AX). Bed expansion qualities and hydro-dynamic characteristics (N, Daxland Bo) of ZSA demon-strated a marked robustness in the face of elevatedvelocities (up to 550 cm/h) and biomass loading (up to30% (ww/v)) disrupted yeast cells. Cibracron Blue deriv-atives of the pellicular prototype (ZSA-CB), evaluated inthe batch and ¯uidised bed recovery of glyceraldehyde3-phosphate dehydrogenase (G3PDH) from unclari®edyeast disruptates, exhibited superior capacities and ad-sorption/desorption performance to the commercial derivatives. These advanced physical and biochemicalproperties facilitated a demonstration of the direct, mechanical coupling of bead-milling and ¯uidised bed ad-sorption in a fully integrated process for the acceleratedrecovery of G3PDH from yeast. The generic applicationof such pellicular adsorbents and integrated processesto the recovery of labile, intracellular products is dis-cussed
Preparation and characterization of lanthanum palygorskite clays as acid catalysts
(Elsevier, 2002-10-07) Melo, Dulce Maria de Araújo; Ruíz, Juan Alberto Chavez; Melo, Marcus Antônio de Freitas; Vitor Sobrinho, Eledir; Martinelli, Antonio Eduardo
Palygorskite clays containing 2, 4, 6 or 10% lanthanum (w/w) were prepared by ion-exchange from acid-leached natural clays. Samples were characterized by chemical and thermogravimetric analysis, X-ray diffraction, infrared spectroscopy, and N2 adsorption. Isopropyl alcohol was transformed in order to improve the acid behavior of the material. The introduction of La3+ did not change the structure of the palygorskite. Surface areas as high as 177.6 m2 g−1 were measured for catalysts containing 2% lanthanum. This material also showed a very good activity for alcohol dehydration
Vapor-Liquid Equilibria for Pentane + Dodecane and Heptane + Dodecane at Low Pressures
(ACS Publications, 2002-10-25) Chiavone Filho, Osvaldo; Oliveira, Humberto Neves Maia de; Lopes, Francisco W. Bezerra; Dantas Neto, Afonso Avelino
A Fischer recirculating still has been used to measure isobaric vapor-liquid equilibrium data for pentane + dodecane and heptane + dodecane at 70 and 100 kPa and 40, 70, and 100 kPa, respectively. The concentrations of the vapor and liquid mixtures have been determined with the aid of an oscillating tube densimeter. The excess volume behavior has also been found on the basis of density-composition calibration curves. Vapor pressure data of the pure components as function of the temperature have also been measured and indicated the reliability of the experimental procedure. Thermodynamic consistency tests of the vapor-liquid data have been checked using a maximum likelihood data reduction and the UNIQUAC model
Cor e propriedades mecânicas de algumas argilas do Rio Grande do Norte para uso em cerâmica branca
(Cerâmica - Associação Brasileira de Cerâmica, 2002-12) Melo, Marcus Antônio de Freitas; G. Neto, S.; Melo, Dulce Maria de Araújo; Carvalho, L. P.; Galdino, José Nildo; Silva, S. A. G.
O interesse crescente no uso de argilas para a produção de cerâmica no Rio Grande do Norte requer a caracterização técnica das matérias primas. Este trabalho mostra algumas propriedades de cinco argilas encontradas nesta região, tais como coloração após queima a 950 oC, 1250 oC e 1450 oC, retração linear e resistência à flexão. A queima de argilas regionais resultaram em uma variedade de faixas de tonalidades do branco ao creme. As propriedades gerais dos produtos da queima são melhores que as reportadas na literatura, demonstrando o potencial tecnológico das argilas da região estudada
Caracterização e usos de argilas bentonitas e vermiculitas para adsorção de cobre (II) em solução
(Cerâmica - Associação Brasileira de Cerâmica, 2002-12) Melo, Marcus Antônio de Freitas; Santos, C. P. F. dos; Melo, Dulce Maria de Araújo; Vitor Sobrinho, Eledir
Vários trabalhos tratam da remoção de metais por argilas e argilominerais. O processo de remoção geralmente ocorre por precipitação, troca iônica e adsorção. Neste trabalho estudou-se a adsorção de solução de Cu (II) em vermiculita, bentonitas sódica e cálcica, proveniente de Campina Grande-PB , tendo-se como variáveis pH, tempo de contato e concentração do adsorvente. Os ensaios foram realizados à temperatura ambiente e as medidas de Absorção Atômica foram feitas no sobrenadante e no resíduo sólido. As argilas bentonitas cálcicas, provenientes de Campina-Grande (PB), sódica de Wyoming (Wyoming-USA) e sódicas (preparadas em laboratório) e as vermiculitas (provenientes do Piauí) foram caracterizadas antes e após o processo de adsorção de Cu (II) em solução através das técnicas, análise química, TG e DTA, área superficial (BET), espectroscopia na região de infravermelho, difração de raios X e medidas de pH. Os resultados mostram que as argilas estudadas adsorvem metais pesados através da troca iônica e que a vermiculita foi mais eficaz no processo, adsorvendo 40,9% de cobre da solução em estudo, em relação às outras argilas envolvidas no processo
Determination of relative acid strength of La/paligorskyte by n-butylamine
(Elsevier, 2003-03-01) Melo, Dulce Maria de Araújo; Ruiz, Juan Alberto Chavez; Vitor Sobrinho, Eledir; Melo, Marcus Antônio de Freitas; Martinelli, Antonio Eduardo; Zinner, Léa Barbieri
The relative acid strength of lanthanum catalysts supported on paligorskyte was determined by thermodesorption of n-butylamine and infrared absorption spectroscopy. The results indicated that the desorption reaction took place in four temperature ranges. The catalyst containing 2% lanthanum particularly showed a considerable number of acid sites probably as a result of the relatively high specific area of the material
Influência da dessalga e cozimento sobre a composição química e perfil de ácidos graxos de charque e jerked beef
(Food Science and Technology, 2003-04) Correia, Roberta Targino Pinto; Biscontini, Telma Maria Barreto
O objetivo deste trabalho foi o de investigar o efeito da dessalga e cozimento úmido sobre o teor de umidade, cinzas, lipídios, proteína e perfil de ácidos graxos de dois produtos cárneos amplamente consumidos no Brasil, charque e jerked beef. Os resultados observados revelaram níveis de retenção de 76% e 65% de umidade, 10 e 11% de cinzas, 71 e 87% de proteína e 60 e 65% de lipídios respectivamente em relação ao charque e jerked beef estudados. O perfil de ácidos graxos manteve-se praticamente inalterado após processamento, entre os dois produtos.
Adsorption of crude oil on anhydrous and hydrophobized vermiculite
(Elsevier, 2003-04-15) Melo, Marcus Antônio de Freitas; Farias, Robson Fernandes de; Silva Júnior, Umberto Gomes da; Silva, Adaı́lton F. da
This publication reports the adsorption of crude oil on vermiculite samples, expanded and hydrophobized with carnauba (CoperníciaCerífera) wax. The adsorption studies were performed by using columns filled with the vermiculite matrices and by dispersion of the vermic-ulite samples in an oil–water (50 ppm of oil) emulsion. The hydrate vermiculite exhibits a very low adsorption capacity against crude oil. Onthe other hand, anhydrous (expanded) and hydrophobized matrices show a high adsorption capacity. The 10% hydrophobized matrix show a50% increased adsorption capacity, in comparison with the expanded one. For adsorption performed in the water–oil emulsion, saturation ofthe solid hydrophobized matrix is achieved after 60 min. The hydrophobized samples exhibit adsorption factors in the 0.7–1.0 range
Heavy metals extraction by microemulsions
(Elsevier, 2003-06) Dantas, Tereza Neuma de Castro; Dantas Neto, Afonso Avelino; Moura, Maria Carlenise Paiva de Alencar; Barros Neto, Eduardo Lins de; Forte, K. R.; Leite, R. H. L.
The objective of this study is the heavy metal extraction by microemulsion, using regional vegetable oils as surfactants. Firstly, the main parameters, which have influence in the microemulsion region, such as: nature of cosurfactant, influence of cosurfactant (C)/surfactant (S) ratio and salinity were studied, with the objective of choosing the best extraction system. The extraction/reextraction process by microemulsion consists of two stages. In the first one, the heavy metal ion present in the aqueous phase is extracted by the microemulsion. In a second step, the reextraction process occurs: the microemulsion phase, rich in metal, is acidified and the metal is recovered in a new aqueous phase, with higher concentration. The used system had the following parameters: surfactant—saponified coconut oil; cosurfactant—n-butanol; oil phase—kerosene; C=S ratio=4; salinity—2% (NaCl); temperature of 2771 C; water phase—aqueous solution that varied according to the heavy metal in study (Cr, Cu, Fe, Mn, Ni and Pb). A methodology of experimental planning was used (Scheff! e Net) to study the behavior of the extraction in a chosen domain. The extraction was accomplished in one step and yielded extraction percentage higher than 98% for all metals. In the reextraction HCl—8M was used as reextraction agent and the influence of the pH and time were verified. This work showed the great efficiency of the microemulsion, indicating that it is possible to extract selectively the heavy metals from the aqueous phase
Evaluation of CoAl2O4 as ceramic pigments
(Elsevier, 2003-09-02) Melo, Dulce Maria de Araújo; Cunha, Jardel Dantas da; Fernandes, Joana D. G.; Bernardi, Maria Inês Basso; Melo, Marcus Antônio de Freitas; Martinelli, Antonio Eduardo
CoAl2O4 powder was obtained from a mixture of Co and Al oxalates at a ratio of 1:8 (Co:Al). The material was calcinated at different temperatures, established from TG data, and characterized using FTIR spectroscopy, X-ray diffraction, BET surface area, and thermal analysis. The dyeing characteristics of CoAl2O4 were established by coating ceramic substrates with different concentrations of the powder
Rheological properties of a new surfactant-based fracturing gel
(Elsevier, 2003-09-15) Dantas, Tereza Neuma de Castro; Santanna, Vanessa Cristina; Dantas Neto, Afonso Avelino; Barros Neto, Eduardo Lins de; Moura, Maria Carlenise Paiva de Alencar
Surfactant-based fracturing gels are considered as clean gels due to the absence of insoluble residues in their composition. This kind of fluid has been developed to minimize or eliminate damages to fractures. Therefore, new studies about gel rheological properties become more and more important, namely viscosity, the most important property of fracturing gels. This research was accomplished with the purpose of evaluating a new anionic surfactant based gel. Steady and oscillatory shear experiments were carried out in order to evaluate the inner structure of the developed gel with variable composition, within the gel region in a pseudoternary diagram. It could be observed that small variations in gel composition resulted in changes in micellar structure
Treatment of saline wastewater contaminated with hydrocarbons by the photo-fenton process
(ACS Publications, 2004-01-03) Chiavone Filho, Osvaldo; Moraes, José Ermírio Ferreira de; Quina, Frank H.; Nascimento, Cláudio Augusto Oller do; Silva, Douglas do Nascimento
The application of the photo-Fenton process to the treatment of saline wastewater contaminated with hydrocarbons is investigated. Aqueous saline solutions containing raw gasoline were used as a model oil-field-produced water. The dependence on concentrations of the following reagents has been appropriately evaluated: hydrogen peroxide (100−200 mM), iron ions (0.5−1 mM), and sodium chloride (200−2000 ppm). The reactions were monitored by measurement of the absorption spectra and total organic carbon (TOC). Experimental results demonstrate that the photo-Fenton process is feasible for the treatment of wastewaters containing hydrocarbons, even in the presence of high concentrations of salt. The effect of the salt in this process is described through a series of reactions. A simple feedforward neural network model was found to correlate well the observed data for the degradation process

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