Navegando por Autor "Souza, A. G."

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Antioxidative properties of hydrogenated cardanol for cotton biodiesel by PDSC and UV/VIS
(Springer, 2009-04-27) Bicudo, Tatiana de Campos; Rodrigues Filho, M. G.; Souza, A. G.; Santos, I. M. G.; Silva, M. C. D.; Sinfrônio, F. S. M.; Vasconcelos, A. F. F.
Biodiesel is a non-toxic biodegradable fuel that consists of alkyl esters produced from renewable sources, vegetal oils and animal fats, and low molecular mass alcohols, and it is a potential substitute for petroleum-derived diesel. Depending on the raw materials used, the amount of unsaturated fatty acids can vary in the biodiesel composition. Those substances are widely susceptible to oxidation processes, yielding polymeric compounds, which are harmful to the engines. Based on such difficulty, this work aims to evaluate the antioxidant activity of cashew nut shell liquid (cardanol), as additive for cotton biodiesel. The oxidative stability was investigated by the pressure differential scanning calorimetry (PDSC) and UV/Vis spectrophotometer techniques. The evaluated samples were: as-synthesized biodiesel – Bio T0, additivated and heated biodiesel – Bio A (800 ppm L –1 of hydrogenated cardanol, 150°C for 1 h), and a heated biodiesel – Bio B (150°C, 1 h). The oxidative induction time (OIT) analyses were carried out employing the constant volume operation mode (203 psi oxygen) at isothermal temperatures of 80, 85, 90, 100°C. The high pressure OIT (HPOIT) were: 7.6, 15.7, 22.7, 64.6, 124.0 min for Bio T0; 41.5, 77.0, 98.6, 106.6, 171.9 min for Bio A and 1.7, 8.2, 14.8, 28.3, 56.3 min for Bio B. The activation energy (E) values for oxidative processes were 150.0 1.6 (Bio T0), 583.8 1.5 (Bio A) and 140.6 0.1 kJ mol –1 (Bio B). For all samples, the intensities of the band around 230 nm were proportional to the inverse of E, indicating small formation of hyper conjugated compounds. As observed, cardanol has improved approximately four times the cotton biodiesel oxidative stability, even after the heating process
Characterization of gypsum using TMDSC
(Springer, 2007-03-07) Dantas, H. F.; Mendes, R. A. S.; Pinho, R. D.; Soledade, Luiz Edmundo Bastos; Paskocimas, Carlos Alberto; Lira, B. B.; Schwartz, M. O. E.; Souza, A. G.; Santos, Ieda Maria Garcia dos
Gypsum is a dihydrated calcium sulfate, with the composition of CaSO4⋅2H2O, with large application interest in ceramic industry, odontology, sulfuric acid production, cement, paints, etc. During calcination, a phase transformation is observed associated to the loss of water, leading to the formation of gypsum or anhydrite, which may present different phases. The identification of the phases is not so easy since their infrared spectra and their X-ray diffraction patterns are quite similar. Thus, in this work, temperature modulated differential scanning calorimetry (TMDSC) was used to identify the different gypsum phases, which can be recognized by their different profiles
Influence of soybean biodiesel content on basic properties of biodiesel–diesel blends
(Elsevier BV, 2009-04) Bicudo, Tatiana de Campos; Candeia, R. A.; Silva, M. C. D.; Carvalho Filho, J. R.; Brasilino, M. G. A.; Santos, I. M. G.; Souza, A. G.
The world tendency in last years is to restrict the use of fossil fuels and replace them partially or totally by renewable fuels. Accordingly, biodiesel is being studied as one of the main alternatives and the production and consumption of this pure biofuel and its binary blends with fossil diesel have been markedly grown. Thus, the present work evaluated the influence of biodiesel concentration on such blends when mixed to diesel in 5, 15, 25 and 50 volume percentages. For each blend, both methanol and ethanol biodiesels were investigated. The biodiesel samples were physicochemically characterized. Their rheological behavior was analyzed. It was observed that the biodiesel enrichment leads to an acceptable increase in the viscosity and to a decrease in the volatilization of the binary blends. The viscosity was also shown to be temperature-dependent, as well as the fatty acids chain length and unsaturation
Influence of the storage on the thermo-oxidative stability of methyl and ethyl esters by PDSC
(Springer, 2011-02-14) Bicudo, Tatiana de Campos; Candeia, R. A.; Sinfrônio, F. S. M.; Queiroz, N.; Barros Filho, A. K. D.; Soledade, Luiz Edmundo Bastos; Santos, I. M. G.; Souza, A. L.; Souza, A. G.
Biodiesel oxidation is a complex process widely influenced by the chemical composition of the biofuel and storage conditions. Several oxidation products can be formed from these processes, depending on type and amount of the unsaturated fatty acid esters. In this work, fatty acid methyl and ethyl esters were obtained by basecatalyzed transesterification of soybean oil and physicochemically characterized according to standards from ASTM, EN, and ABNT. The thermal and oxidative stabilities of biodiesel samples were investigated during the storage process by pressure differential scanning calorimetry (PDSC) and by viscosity measurements. Absolute viscosities of biodiesels after accelerated aging were also determined. The viscosity increased as the aging temperature and time were raised. The results showed that oxidation induction can occur during storage, decreasing the biodiesel stability. PDSC analysis showed that during storage under climate simulation the values of high-pressure oxidative induction times (HPOIT) were reduced for both FAEE and FAME
Processamento de cerâmicas reticuladas a partir de matérias-primas naturais
(ABCERAM, 2006-04) Albuquerque, F. R.; Lima, S. J. G.; Paskocimas, Carlos Alberto; Silva, Elson Longo da; Souza, A. G.; Santos, Ieda Maria Garcia dos
Foram produzidas cerâmicas porosas reticuladas a partir de uma matéria-prima natural (AF) empregada na produção de telhas e tijolos, misturando-a com caulim (AC). A matéria-prima AF é constituída basicamente de quartzo e feldspatos. O método empregado para confecção das peças cerâmicas foi o da impregnação em espuma polimérica. Foram otimizadas as viscosidades de barbotinas contendo 70% m/m, utilizando poliacrilato de sódio (PAA-Na) como defloculante. As suspensões com 70% m/m de AF apresentaram viscosidade em torno de 600 mPa.s, reduzindo para 300 mPa.s após adição de 20% m/m de AC. O teor de PAA-Na empregado para a fabricação das cerâmicas porosas foi 2,0% m/m. A tixotropia e a pseudoplastia das barbotinas facilitaram a impregnação de espumas poliméricas com 5, 10 e 40 poros/cm. As cerâmicas reticuladas foram obtidas após sinterização a 1100 e 1200 oC. Os difratogramas de raios X indicaram a dissolução do quartzo a 1200 oC, com uma peça apresentando basicamente mulita e fase vítrea. As cerâmicas reticuladas com porosidade 10 poros/cm apresentaram estrutura suficientemente rígida com resistência mecânica superior a 1,70 MPa e com constante de permeabilidade darciana na ordem de 3,58.10-9 (±10,0%) m2
Propiedades ópticas del pigmento α-Fe2 O3 /SiO2
(Sociedad Española de Cerámica y Vidrio, 2005) Spinelli, A.; Oliveira, A. P. N.; Soledade, Luiz Edmundo Bastos; Paskocimas, Carlos Alberto; Silva, Elson Longo da; Souza, A. G.; Chicariano, C. A.; Flores, J. A.
En el presente trabajo describimos la síntesis del pigmento α-hematites/SiO2 según el método de mezcla de óxidos. El color rojo del pigmento corresponde a las transiciones electrónicas 6A1g→ 4T1g y 6A1g→ 4T2g del ion Fe+3 que presenta la configuración estructural d5 y está enlazado a seis oxígenos en la estructura de la hematites. Los cambios en el matiz del color rojo del pigmento están relacionados con la entropía del sistema y con la disminución consecuente del gap. El compuesto α-hematites/SiO2 se mostró como un pigmento cerámico promisorio para aplicación a la temperatura de 1100°C
Rheology and MT-DSC studies of the flow properties of ethyl and methyl babassu biodiesel and blends
(Springer, 2011-02-27) Bicudo, Tatiana de Campos; Santos, N. A.; Rosenhaim, R.; Dantas, M. B.; Cavalcanti, E. H. S.; Barro, A. K.; Santos, I. M. G.; Souza, A. G.
Biodiesel is an increasingly attractive alternative to diesel fuel. The main component of Babassu biodiesel is lauric acid (C12:0), which is a saturated fatty acid with a high melting point. Controlling flow properties, such as viscosity and the cold filter plugging point, is critical because viscosity affects atomization, and crystal formation resulting from decreases in temperature can negatively affect engine starting and performance. To evaluate its flow characteristics more fully, the rheological properties of babassu biodiesel were analyzed, taking into account variations in temperature. The crystallization temperature was determined by modulated temperature differential scanning calorimetry (MT-DSC). The curve of biodiesel viscosity as a function of the biodiesel refrigeration temperature contained an inflection point (corresponding to a steep increase in viscosity) that was coincident with both the transition from a Newtonian-type flow to a pseudoplastic-type flow and the crystallization temperature obtained by MT-DSC, indicating that the appearance of crystals in the biodiesel increased its viscosity. The rheological properties of fatty acid methyl and ethyl mixtures (FAME and FAEE) with metropolitan diesel were also evaluated; a higher FAME percentage reduced viscosity in blends up to B100
Themo-oxidative stability ald cold flow properties of babassu biodiesel by PDSC ans TMDSC techniques
(Springer, 2009-04-27) Bicudo, Tatiana de Campos; Santos, N. A.; Santos, J. R. J.; Sinfrônio, F. S. M.; Santos, I. M. G.; Antoniosi Filho, N. R.; Fernandes Jr, V. J.; Souza, A. G.
The babassu (Orbignya PhalerataMart.) biodiesel has lauric esters as main constituents, resulting in high oxidative stability and low cloud and freezing points. In order to reduce these side effects, the saturated ethyl esters content was reduced by means of winterization process. The TMDSC and PDSC techniques were used to verify the thermal and oxidative stabilities of the ethyl babassu biodiesel. During the heating stage, the winterized solid phase of ethyl esters presented an endothermic transition associated to the solidification process. This behavior was not observed for the liquid winterized FAEE, confirming the efficiency of the winterization process
Thermal investigation of oil and biodiesel fromJatropha curcasL.
(Springer, 2009-06-19) Bicudo, Tatiana de Campos; Freire, L. M. S.; Rosenhaim, R.; Sinfrônio, F. S. M.; Botelho, J. R.; Carvalho Filho, J. R.; Santos, Ieda Maria Garcia dos; Fernandes Júnior., V. J.; Antoniosi Filho, N. R.; Souza, A. G.
Biodiesel is susceptible to autoxidation if exposed to air, light and temperature, during its storage. Physic nut (Jatropha curcas L.) seeds show potential application for biodiesel production since its oil yields high quality biodiesel. This work aims to evaluate the thermal behavior of the physic nut oil and biodiesel, from several Brazilian crops, by means of thermoanalytical techniques. Thermogravimetry (TG) and pressurized-ifferential scanning calorimetry (PDSC) were used in order to determine the applicability of physic nut biodiesel as fuel. Results suggest that physic nut biodiesel is a practical alternative as renewable and biodegradable fuel able to be used in diesel motors

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Navegando por Autor "Souza, A. G."