Navegando por Assunto "Synthesis"

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Acesso aberto (Open Access)
Desenvolvimento de aplicativos usando reconhecimento e síntese de voz
(Universidade Federal do Pará, 2006-08-30) SAMPAIO NETO, Nelson Cruz; KLAUTAU JÚNIOR, Aldebaro Barreto da Rocha; http://lattes.cnpq.br/1596629769697284
Speech is a natural mechanism for human-machine interaction. Speech (or voice) technology is a well-developed field when one considers the international community. There is a wide variety of academic and industrial software. The majority of them assumes a recognizer or synthesizer is available, and can be programmed through an API. In contrast, there are no such resources in public domain for Brazilian Portuguese. This work discusses some of these issues and compares SAPI and JSAPI, which are APIs promoted by Microsoft and Sun, respectively. We also present two examples: a CALL application using SAPI-based speech synthesis in English and Portuguese, recognition in English, and visual agents; and a JSAPI-based software that incorporates speech synthesis and recognition to IRC through Java APIs.
Acesso aberto (Open Access)
Desenvolvimento de processo de zeólita A utilizando o caulim da Amazônia e aplicação na adsorção de Cu+2
(Universidade Federal do Pará, 2014-08-22) MORAES, Cristiane Gomes; MACÊDO, Emanuel Negrão; http://lattes.cnpq.br/8718370108324505; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968
Around the world millions of tons of inorganic waste are produced every day in mining and mineral processing. These wastes are stored in sedimentation basins or discarded in landfills, and very often are thrown directly into the environment without any treatment process. However, alternative recycling and/or reuse should be investigated and, where possible. This work shows studies in order to reuse the kaolin waste from Amazon, from a kaolin processing company for paper covering. For the synthesis of the zeolite in static and dynamic hydrothermal processes, was used as the silicon source and the aluminum kaolin waste, which passed through the calcination procedure in a muffle at 600°C to obtain metakaolin; and as sodium source chose to 5M sodium hydroxide solution. In the static method was used stainless steel autoclaves, in an oven at 110°C, using 1,75g of metakaolin, varying the time of synthesis and the mass of sodium hydroxide and the dynamic process, we used 100g of metakaolin, mass 34,5g sodium hydroxide; at 95°C under stirring system, varying the time of synthesis, in order to determine the optimal conditions in the synthesis of the zeolite in the process. Matches materials and zeolitic products obtained in the syntheses were characterized by: X-ray diffraction (XRD), scanning electron microscopy (SEM), differential thermal analysis and thermogravimetric (DTA/TG), X-ray fluorescence (XRF) and particle size analysis. There is the possibility of scale-up, since the zeolite obtained, the dynamic process in time of 30 min. Data from adsorption experiments determined by iodometric technique copper alloys and metal and minerals, adjusted by Langmuir and Freundlich suggest that the static and dynamic zeolitic materials have good adsorptive capacity reached 95% efficiency for concentrations in the range of 50 to 100mg/L, thereby demonstrating that these materials are efficient and cost effective alternative when used for the removal of heavy metals, in the case of copper, the treatment of industrial effluents.
Acesso aberto (Open Access)
Produção de material zeolítico a partir de caulim da Amazônia em escala semi piloto: aplicação na adsorção de cobre
(Universidade Federal do Pará, 2019-06-27) RODRIGUES, Emerson Cardoso; MACÊDO, Emanuel Negrão; http://lattes.cnpq.br/8718370108324505; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968
This work aims to synthesize a zeolite product composed of zeolite type "A" plus sodalite using as filler kaolin starting material. The synthesis of Zeolites was carried out in a short time and in a system with agitation, in a reactor of stainless steel with a volume of approximately 0.001 m3, that is, in semi-pilot scale. The system was heated by steam from a boiler. The X ray diffraction (XRD), X ray Fluorescence Spectrometry, Scanning Electron Microscopy (SEM), Granulometric Analysis and Differential and Gravimetric Thermal Analysis (DTA and TG) were identified and characterized. In the synthesis process the metakaolin was used as the source of silica and alumina, which was obtained at 600 ° C for 2 hours of calcination in a muffle furnace. A 5M sodium hydroxide solution was used as the sodium source. Several syntheses were carried out for a maximum duration of 180 minutes. Every 30 minutes aliquots of the product were taken for the study of reaction kinetics. The results of the zeolite syntheses were satisfactory and the product obtained was applied to the adsorption of Cu2+ ions, in which the influence of the variables: time, temperature, pH and adsorbent quantity were evaluated. The determination of the best adsorption model was performed by the Monte Carlo method via Markov Chain and through the Akaike Information Criterion the isotherms that were closest to the presented results were established. The results obtained were compared with other studies available in the literature and showed significant values, which characterize the process of zeolite production and adsorption as promising and efficient.
Acesso aberto (Open Access)
Rejeito de caulim e caulim estéril amazônicos como fontes de Si e Al na obtenção de SAPO-34: síntese, otimização, influência de impurezas e aplicação em adsorção de corante
(Universidade Federal do Pará, 2021-05-27) PINHEIRO, Darllan do Rosário; PAZ, Simone Patrícia Aranha da
Kaolin waste from kaolin industry sedimentation ponds for paper and sterile kaolin or flint belonging to the same mine, in the Capim region, in northeastern Pará, were used in the synthesis of the SAPO-34 molecular sieve. The precursor materials and those produced were characterized by: DRX, FRX, TG-DSC-DTG, FTIR, ASEBET and MEV. First, the use of R-metakaolin as a precursor was evaluated, varying the SiO2 / Al2O3 ratio in the formulation of the SAPO-34 molecular sieve. The adjustment in the value of this molar ratio showed a positive effect on the formation of the desired zeolite, which showed formation of the CHA structure, in less time and with good thermal stability. In relation to the use of F-metakaolin, the effect of the amount of SDA and crystallization time (nucleation and crystal growth) on the formation of the CHA structure was evaluated and, later, that zeolitic product formed with less amount of SDA was used for a detail evaluation, in which the influence of Fe and Ti ions type impurities was studied. The results revealed a positive effect of the greater amount of SDA in the formation of SAPO-34 (CHA), but in a shorter time and, consequently, contribution in the Si distribution in the structure. When comparing the zeolitic products derived from F-metakaolin and a high purity kaolinitic pattern, the zeolitic product obtained from the kaolinitic sterile showed thermal resistance where the calcined product's DRX pattern maintained the CHA diffractometric profile, but with reduced crystallinity. It was also observed that before calcination, the zeolitic product obtained with F-metakaolin showed a smaller displacement to a 2θ (º) angle, indicating an increase in the interplanar distance with reference to the d101 plane, possibly due to interferences of the present impurities (Fe and ions). Ti), however after the calcination for decomposition of the SDA this displacement was not evidenced, thus indicating interference of the SDA used. That product considered the best, based on crystallochemical parameters, was used in the performance evaluation in methylene blue adsorption, which showed good adsorption capacity. In the evaluation of the adsorption kinetics, the pseudo-second order model (R2 = 0.998) was the one that best fit the experimental data. The optimization of the synthesis using tailings through the planning of Box-Behnken experiment and response surface methodology. It was concluded that the use of Amazon waste and/or flint kaolin is viable for the production of SAPO-34 zeolite (CHA).
Acesso aberto (Open Access)
Sinterização de pelotas de argila, carvão vegetal e cinza volante de caldeira em uma célula de combustão de leito fixo: análise da propagação da frente de reação de combustão no leito
(Universidade Federal do Pará, 2016-05-20) MELO, Alvino Oliveira; MACÊDO, Emanuel Negrão; http://lattes.cnpq.br/8718370108324505; MARTINS, Marcio Ferreira
A great preoccupation of humanity turns around the preservation of the environment, seeking to constantly through studies and search, alternatives to find a balance of coexistence between man and nature. Normally, industries in general, produce waste at its majority toxic which damage the environment, humans being and other diversities of life inserted in it. Looking up, insert itself in this context, this work makes a study of evolution of the temperature of combustion of a mixture, in predefined proportions of fly ash from boiler industries located in the State of Pará, clay from the banks of the Guamá River and charcoal acquired in metropolitan region of Belem-Pa, Brazil. The experiments were performed in a combustion reactor, acquired by Programa de Pós - Graduação em Engenharia de Recursos Naturais da Amazônia in order to assess the temperature profile of each experiment during the combustion process and if the values of these temperatures would be sufficient to initiate the process of sintering of the pellets. For the experiments performance, parameters such as inlet velocity of the fluid (air), diameters of the pellets (mixture of charcoal, ash and clay) and grain size of charcoal were varied and the effect of variations of these parameters were analyzed for each experiment. The historical temperatures were recorded by a data acquisition instrument named Paperless Recorder - PHL and subsequently plotted for analysis. Temperatures varying in the range of 800°C - 1290°C, were obtained and these values are sufficient to initiate the process of sintering of the pellets. Data generated by the combustion reactor were recorded by "Paperless Recorder" and compared with numerical results computational.