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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Comparison of electric vehicles, hybrid vehicles & LPG vehicles

Ngan, Shing-kwong., 顔成廣. January 1999 (has links)
published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management
42

A influência da implantação de um terminal aquaviário na dinâmica sedimentar local da Baía de Guanabara / The influence of the implantation of an aquaviary terminal in local dynamics sedimentary f the Guanabara Bay, RJ

Hurtado, Shanty Navarro 06 November 2008 (has links)
A Baía da Guanabara vem sofrendo alterações na sua bacia de drenagem desde o início do século XIX que resultaram em acentuada degradação ambiental. O presente trabalho discute a influência da implantação de um Terminal Aquaviário de Gás Natural Liquefeito (GNL) na Baía, e suas possíveis influências nos processos de sedimentação local e/ou re-disponibilização de sedimentos de fundo, e possíveis contaminantes associados. Os resultados dos modelos matemáticos mostram que as maiores velocidades das plumas termicas que atingem o fundo são em média 0,46 m3/s para as simulações de verão e 0,47 m3/s para as simulações de inverno, sendo que são necessários pelo menos de 0,50 m3/s para uma corrente erodir o fundo, porem velocidades na faixa de 20 a 50 m3/s são suficientes para causar erosão de sedimentos finos inconsolidados. Sendo assim, a influência das plumas térmicas geradas no processo de re-gaseificação do GNL é de pequena magnitude, e suas correntes só conseguem exportar estes sedimentos para distancias inferiores a 1000 m. Em relação a re-disponibilização de contaminantes associados aos sedimentos de fundo se mostrou pouco provável, dado o fato da qualidade dos sedimentos apresentarem, diferente da água, baixa concentração de contaminantes e da baixa competência de erosão, que eles tenham competência para erodir sedimentos consolidados. / Since the beginning of the XIX century, interventions on the Guanabara\'s Bay drainage basin result in severe environmental degradation. This work aimed to analyze the implementation of an Aquaviary Terminal of Liquefied Natural Gas (LNG), and its putative consequences on the local sedimentation processes, and the availability and possible associated contaminants of the bottom sediments. According to the mathematical models developed, the means of the greatest speeds of the thermal plumes that reach the bottom are 0.46m3/s for the summer simulations and 0.47m3/s for the winter. However, for a current to be able to erode the bottom it must be of at least 50m3/s. Currents with speeds ranging from 20 to 50m3/s are sufficient only to cause the erosion of fine and non-consolidated sediment. Therefore, the thermal plumes generated in the process of re-gasification of the LNG are of little magnitude, and will not be able to export these sediments to any distance greater than 1000 meters. The re-availability of the contaminants associated with the bottom sediments is not likely, once these sediments, differently from the water, showed little concentration of contaminants. In addition, with the low erosion capacity of the currents generated, the consolidated sediments are not likely to be eroded.
43

A influência da implantação de um terminal aquaviário na dinâmica sedimentar local da Baía de Guanabara / The influence of the implantation of an aquaviary terminal in local dynamics sedimentary f the Guanabara Bay, RJ

Shanty Navarro Hurtado 06 November 2008 (has links)
A Baía da Guanabara vem sofrendo alterações na sua bacia de drenagem desde o início do século XIX que resultaram em acentuada degradação ambiental. O presente trabalho discute a influência da implantação de um Terminal Aquaviário de Gás Natural Liquefeito (GNL) na Baía, e suas possíveis influências nos processos de sedimentação local e/ou re-disponibilização de sedimentos de fundo, e possíveis contaminantes associados. Os resultados dos modelos matemáticos mostram que as maiores velocidades das plumas termicas que atingem o fundo são em média 0,46 m3/s para as simulações de verão e 0,47 m3/s para as simulações de inverno, sendo que são necessários pelo menos de 0,50 m3/s para uma corrente erodir o fundo, porem velocidades na faixa de 20 a 50 m3/s são suficientes para causar erosão de sedimentos finos inconsolidados. Sendo assim, a influência das plumas térmicas geradas no processo de re-gaseificação do GNL é de pequena magnitude, e suas correntes só conseguem exportar estes sedimentos para distancias inferiores a 1000 m. Em relação a re-disponibilização de contaminantes associados aos sedimentos de fundo se mostrou pouco provável, dado o fato da qualidade dos sedimentos apresentarem, diferente da água, baixa concentração de contaminantes e da baixa competência de erosão, que eles tenham competência para erodir sedimentos consolidados. / Since the beginning of the XIX century, interventions on the Guanabara\'s Bay drainage basin result in severe environmental degradation. This work aimed to analyze the implementation of an Aquaviary Terminal of Liquefied Natural Gas (LNG), and its putative consequences on the local sedimentation processes, and the availability and possible associated contaminants of the bottom sediments. According to the mathematical models developed, the means of the greatest speeds of the thermal plumes that reach the bottom are 0.46m3/s for the summer simulations and 0.47m3/s for the winter. However, for a current to be able to erode the bottom it must be of at least 50m3/s. Currents with speeds ranging from 20 to 50m3/s are sufficient only to cause the erosion of fine and non-consolidated sediment. Therefore, the thermal plumes generated in the process of re-gasification of the LNG are of little magnitude, and will not be able to export these sediments to any distance greater than 1000 meters. The re-availability of the contaminants associated with the bottom sediments is not likely, once these sediments, differently from the water, showed little concentration of contaminants. In addition, with the low erosion capacity of the currents generated, the consolidated sediments are not likely to be eroded.
44

Highly selective mesoporous sorbents for mercury removal from industrial wastewater

Godongwana, Ziboneni Governor January 2011 (has links)
The results of this study show that novel mesoporous carbons were obtained as inverse replica of SBA-15, HMS and MCM-41 silica templates, with a large pore diameter (2-4 nm), a BET surface area of 1867, 874 and 910 m2g –1 respectively for CA_SBA-15_LPG_105, CA_HMS_LPG_80 and CA_MCM- 41_LPG_80 with bimodal pore size distribution (PSD) in the mesopores range. The results obtained show that mesoporous carbon with graphitic structures can be synthesized via the LPG route.
45

Highly selective mesoporous sorbents for mercury removal from industrial wastewater

Godongwana, Ziboneni Governor January 2011 (has links)
The results of this study show that novel mesoporous carbons were obtained as inverse replica of SBA-15, HMS and MCM-41 silica templates, with a large pore diameter (2-4 nm), a BET surface area of 1867, 874 and 910 m2g –1 respectively for CA_SBA-15_LPG_105, CA_HMS_LPG_80 and CA_MCM- 41_LPG_80 with bimodal pore size distribution (PSD) in the mesopores range. The results obtained show that mesoporous carbon with graphitic structures can be synthesized via the LPG route.
46

Chemical and physical characterization of aerosols from the exhaust emissions of motor vehicles

Lim, McKenzie C. H. January 2007 (has links)
The number concentration and size distribution of particles in Brisbane have been studied extensively by the researchers at The International Laboratory for Air Quality and Health, Queensland University of Technology (Morawska et al., 1998, 1999a, 1999b). However, the comprehensive studies of chemical compositions of atmospheric particles, especially with regard to the two main classes of pollutants (polycyclic aromatic hydrocarbons and trace elements), that are usually of environmental and health interest, have not been fully undertaken. Therefore, this thesis presents detailed information on polycyclic aromatic hydrocarbons (PAHs) and elemental compositions of vehicle exhausts and of urban air in Brisbane. The levels of polycyclic aromatic hydrocarbons (PAHs) and elements in three of Brisbane's urban sites (Queensland University of Technology, Woolloongabba and ANZ stadium sites) were measured. The most common PAHs found in all sites were naphthalene, phenanthrene, anthracene, fluoranthene, pyrene and chrysene while Al, Cd, Co, Cr, Cu, Fe, Mn, Mo, Si, Sn, Sr and Zn were the most common elements detected in the total suspended particles and fine particle (PM2.5). With the aid of multivariate analysis techniques, several outcomes were obtained. For example: -- Major human activities such as vehicular and industrial sources were the most contributing pollution sources in Brisbane. However, these two sources have different influential strength on the compositions of the polycyclic aromatic hydrocarbons and trace inorganic elements found in the urban air. -- Woolloongabba bus platform was the most polluted site on the basis of the elemental and PAH compositions in its air samples while QUT site was the worst polluted site in terms of PM2.5 elemental contents. These results demonstrated that the impact of traffic related pollutants on Brisbane's urban air is significant. This led to the investigations of the direct emissions of pollutants from exhaust vehicular source in the second part of this research work. The exhaust studies included the investigations of PAHs, trace inorganic elements and particles. At the time of the study, the majority of vehicles in Brisbane used low sulfur diesel (LSD) fuel or unleaded petrol (ULP). However, the importance of vehicles using ultra low sulfur diesel (ULSD) and liquefied petroleum gas (LPG) is constantly growing. Therefore, the exhaust emission studies on chassis dynamometer from heavy duty non-catalyst-equipped buses powered by LSD and ULSD with 500 ppm and 50 ppm sulfur contents respectively as well as passenger cars powered by ULP and LPG were explored. The outcomes of such studies are summarized as follows: -- Naphthalene, acenaphthene, acenaphthylene, anthracene, phenanthrene, fluorene, fluoranthene and pyrene were frequently emitted by the buses powered by LSD and ULSD. However, buses powered by ULSD emitted 91% less PAHs than those powered by LSD. On the other hand, Mg, Ca, Cr, Fe, Cu, Zn, Ti, Ni, Pb, Be, P, Se, Ti and Ge were found in measurable quantities in the exhaust of the buses. The emissions of the elements were found to be strongly influenced by the engine driving conditions of the buses and fuel parameters such as sulfur content, fuel density and cetane index. -- Naphthalene, fluorene, phenanthrene, anthracene, pyrene, chrysene, benzo(a)anthracene and benzo(b)fluoranthene were predominantly emitted by ULP and LPG cars. On the average, the total emission factors of PAHs from LPG cars were generally lower than those of ULP cars, but given the large variations in the emission factors of cars powered by the same type of fuel, differences in the emission factors from both car types were statistically insignificant. In general, platinum group elements and many other elements were found in the exhausts of cars powered by both fuels. Emissions of inorganic elements from the cars were dependent on the type and the mileage of the cars. For example, ULP cars generally emitted higher levels of Cu, Mg, Al and Zn while LPG cars emitted higher level of V. In addition, cars with higher mileages were associated with higher emissions of the major elements (Zn, Al, Fe, V and Cu). -- Buses powered by ULSD usually emitted fewer particles, which were generally 31% to 59% lower than those emitted by LSD powered buses. Similarly, cars powered by LPG emitted less particles from those powered by ULP fuel. However, more nanoparticles (those with aerodynamic diameters of less than 50 nm) were emitted by LPG powered cars than their ULP counterparts. Health effect assessment of the exhaust PAHs was evaluated in terms of benzo(a)pyrene toxicity equivalent (BAPeq). The potential toxicities of PAHs emitted by ULSD powered buses were generally lower than those emitted by their LSD counterparts. A similar trend with lower emissions of PAHs from LPG cars than from ULP cars was observed when otherwise identical passenger cars were powered by LPG and ULP fuels. In summary, this thesis has shown that the majority of airborne particles found around Brisbane have anthropogenic origins, particularly vehicle emissions, and that fuel or lubricant formulations and engine operating conditions play important roles in the physical and chemical characteristics of pollutants emitted by vehicles. The implications of these results on worldwide strategies to reduce the environmental and health effects of particles emitted by motor vehicles were discussed. In this regard, direct emission measurements from vehicles powered by LSD, ULSD, ULP and LPG unveiled the relative environmental benefits associated with the use of ULSD in place of LSD to power diesel engines, and of LPG in place of ULP to power passenger cars.
47

An?lise do desempenho de um queimador infravermelho funcionando com g?s liquefeito de petr?leo e glicerina

Dantas, Marcello Ara?jo 31 May 2010 (has links)
Made available in DSpace on 2014-12-17T14:08:39Z (GMT). No. of bitstreams: 1 MarcelloAD_DISSERT.pdf: 3032114 bytes, checksum: 1b49aa6af338e06fe387bb398cc85b4b (MD5) Previous issue date: 2010-05-31 / The use of infrared burners in industrial applications has many advantages in terms of technical-operational, for example, uniformity in the heat supply in the form of radiation and convection, with greater control of emissions due to the passage of exhaust gases through a macro-porous ceramic bed. This paper presents an infrared burner commercial, which was adapted an experimental ejector, capable of promoting a mixture of liquefied petroleum gas (LPG) and glycerin. By varying the percentage of dual-fuel, it was evaluated the performance of the infrared burner by performing an energy balance and atmospheric emissions. It was introduced a temperature controller with thermocouple modulating two-stage (low heat / high heat), using solenoid valves for each fuel. The infrared burner has been tested and tests by varying the amount of glycerin inserted by a gravity feed system. The method of thermodynamic analysis to estimate the load was used an aluminum plate located at the exit of combustion gases and the distribution of temperatures measured by a data acquisition system which recorded real-time measurements of the thermocouples attached. The burner had a stable combustion at levels of 15, 20 and 25% of adding glycerin in mass ratio of LPG gas, increasing the supply of heat to the plate. According to data obtained showed that there was an improvement in the efficiency of the 1st Law of infrared burner with increasing addition of glycerin. The emission levels of greenhouse gases produced by combustion (CO, NOx, SO2 and HC) met the environmental limits set by resolution No. 382/2006 of CONAMA / A utiliza??o de queimadores infravermelhos em aplica??es industriais apresenta muitas vantagens do ponto de vista t?cnico-operacional, como por exemplo, homogeneidade no fornecimento de calor, na forma de radia??o e convec??o, apresentando um maior controle das emiss?es devido ? passagem dos gases de exaust?o atrav?s de um leito cer?mico macroporoso. O presente trabalho apresenta um queimador infravermelho comercial, no qual foi adaptado um ejetor experimental, capaz de promover uma mistura de g?s liquefeito de petr?leo (GLP) e glicerina. Atrav?s da varia??o de percentuais de combust?vel dual, foi avaliado o desempenho do queimador infravermelho mediante a realiza??o de um balan?o de energia e das emiss?es atmosf?ricas. Foi introduzido um controlador de temperatura com termopar modulando dois est?gios (fogo baixo/alto), utilizando v?lvulas solen?ides para cada combust?vel. O queimador infravermelho foi submetido a testes e ensaios variando-se a quantidade de glicerina inserida por um sistema de alimenta??o por gravidade. Como m?todo de an?lise termodin?mica para estimativa de carga foi utilizada uma placa de alum?nio localizada na sa?da dos gases de combust?o, sendo a distribui??o de temperaturas medida por um sistema de aquisi??o de dados que registrou em tempo real as medidas dos termopares afixados. O queimador apresentou uma combust?o est?vel para os n?veis de 15, 20 e 25 % de adi??o de glicerina em raz?o m?ssica de GLP, aumentando o fornecimento de calor para a placa. Pelos dados obtidos, observou-se que houve uma melhora na efici?ncia de 1? Lei do queimador infravermelho quando ocorre o aumento de adi??o da glicerina na mistura. Os n?veis de emiss?es de gases poluentes produzidos pela combust?o (CO, NOx, SO2 e HC) atenderam aos limites estabelecidos pela resolu??o ambiental n? 382/ 2006 do CONAMA.
48

Estrutura de capital, estratégia e competição de mercado na indústria de gás liquefeito de petróleo (GLP) no período 1995-2003

Oliveira, Cláudio Alexandre Figueiredo de January 2004 (has links)
Made available in DSpace on 2009-11-18T19:01:01Z (GMT). No. of bitstreams: 0 Previous issue date: 2004 / A indústria brasileira de gás liquefeito de petróleo, GLP, tem sido alvo freqüente, nos últimos anos, da atenção de órgãos reguladores, mídia e público em geral. Muitas têm sido as especulações a respeito de seu padrão de conduta publicados na imprensa, variando desde práticas predatórias até a formação disciplinada de cartel. A presente pesquisa, baseada em depoimentos de executivos da indústria e no acesso a dados das firmas dessa indústria tomado públicos - dados financeiros e operacionais - explora qual seja, afinal, o padrão de competição desse oligopólio. O estudo parte da Teoria da Estrutura de Capital aplicada para decisões de competição e mercado - preços e quantidades a ofertar para constatar que, dadas suas escolhas de estrutura de capital, as firmas esta indústria específica simplesmente adotam um padrão tradicional de arrefecimento da competição a partir de sua dívida. A dívida, nesta indústria, é utilizada para a criação de barreiras de entrada. Ainda assim, casos de acirramento da competição e de concentração de mercado foram encontrados, indicando que não haja uma disciplina formal de conduta por parte de suas firmas as quais devem, eventualmente, encontrar dificuldades - ou falta de interesse - na convivência em um mercado em fase de transformação. / The Brazilian industry of liquefied petroleum gas, LPG, has been calling, in the late years, the attention of the media, regulatory agencies and the general publico Many speculations have emerged, in the press, over its pattems of behaviour, which have been ranging from predatory practices up to a formal cartel operating under collusion. The present research, based in statements from industry executives as well as in data publicly disclosed by those firms - financiaI and operational ones - explores what their competitive behaviour would be, after alI. The study starts from the Theory of Capital Structure applied to product market competition decisions - output and price decisions - to realize that, given their capital structure choices, the firms within that particular industry simply adopt a classical behaviour of sofier competition. Debt, in this industry, has the role of an entry barrier. Even though, cases of tougher competition have been found, indicating the lack of a formal discipline among its members which ones, eventually, may find it very difficult - or of no interest - to coexist together in a fast changing industrial environment.
49

Extração e caracterização de compostos bioativos de Lupinus albescens utilizando fluidos pressurizados / Extraction and characterization of bioactive compounds from Lupinus albescens using pressurized fluids

Confortin, Tássia Carla 17 July 2017 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The use of chemicals, in excessive doses or inadequately, in the control of pests and diseases in agriculture, has promoted environmental damage, contamination of animals, intoxication of farmers, among others. Looking for less aggressive control alternatives, plant extracts have been successfully used and are a differentiated and a promising option for the integrated management in plant protection. These products are considered an alternative for the control of phytopathogens. They do not cause harm to the environment and to living beings. One of the techniques for extracting plant extracts is the extraction wiyh supercritical/pressurized fluids. This thechnology appears as a great option which is economically viable and ecologically correct. Therefore, the main objective of this work was to investigate the potential of extraction of extracts from flowers, leaves, stalks and roots of Lupinus albescens, using pressurized fluids as liquefied petroleum gas (LPG) or supercritical carbon dioxide (CO2). Furthermore, the objective was to evaluate the kinetic parameters, adjusting to a mathematical spline model. Characterization of extracts and evaluation of their potential in biological control, was performed. In the supercritical fluid extraction with CO2 (SFE-CO2) pressure ranged between 150 to 250 bar and temperature ranged between 40 and 60ºC. In the extraction with compressed LPG, these parameters were fixed between 15 and 35 bar and 25 and 45ºC, respectively. The yield of extraction, kinetic parameters, chemical profile and antifungal effect were evaluated. Maximum yield of extract obtained from different matrices was 1.28% in leaves with solvent LPG under 45°C and 15 bar. The chemical profiles were similar for all matrices and solvents investigated, highlighting stigmasterol. With respect to minimum inhibitory concentration, it rang ed from 29.248 to 192.965 μg mL-1. For antifungal tests, all extracts showed inhibitory powers for Fusarium oxysporum and Fusarium verticillioides. Plant extract obtained from roots showed superior inhibition power, as 70.12% (CO2) and 65.12% (LPG) for Fusarium oxysporum, and 67.76% CO2) anda 61.15% (LPG) for Fusarium verticillioides. From the results obtained in this work, it is possible confirm that the supercritical extraction or using pressurized fluid is a promising methodology for obtaining bioactive compounds from Lupinus albescens, which presented antifungal potential for both fungi investigated in this work. / A utilização de produtos químicos, em doses excessivas ou de forma inadequada, no controle de pragas e doenças na agricultura, tem promovido grandes danos ambientais, contaminação de animais, intoxicação de agricultores, entre outros. Buscando alternativas de controle menos agressivas, extratos vegetais têm sido utilizados com sucesso e ressurgem como uma opção diferenciada e promissora para o manejo integrado em proteção de plantas. Estes produtos são considerados uma alternativa de controle de fitopatógenos, demonstrando prósperos resultados, não causando malefícios ao meio ambiente e aos seres vivos. Uma das técnicas de obtenção dos extratos vegetais é a extração por fluidos supercríticos/pressurizados que também aparece como ótima opção de tecnologia economicamente viável e ecologicamente correta. Portanto, o objetivo principal deste trabalho foi investigar o potencial da extração das flores, folhas, caules e raízes de Lupinus albescens, a partir da técnica da extração por fluidos pressurizados ou em condições supercríticas utilizando gás liquefeito de petróleo (GLP) e dióxido de carbono (CO2) como solventes, bem como avaliar os parâmetros cinéticos, adequando ao ajuste matemático. Realizou-se também a caracterização dos extratos obtidos e avaliação do seu potencial no controle biológico. Na extração supercrítica foram utilizados dióxido de carbono no estado supercrítico (EFS-CO2) e gás liquefeito de petróleo pressurizado. Na EFS-CO2 os valores de pressão investigadas foram fixados entre 150 a 250 bar e os valores da temperatura entre 40 e 60ºC; já para a extração com GLP pressurizado, estes parâmetros foram fixados entre 15 e 35 bar e 25 e 45ºC, respectivamente, sendo avaliados o rendimento de extração, os parâmetros cinéticos, o perfil químico e efeito antifúngico. O rendimento máximo de extrato obtido nas diferentes matrizes foi de 1,28% na folha com o solvente GLP nas condições de 45°C e 15 bar. Os perfis químicos foram semelhantes para todas as matrizes e solventes investigados, destacando-se o composto estigmasterol, em relação à concentração inibitória mínima que variou de 29,248 à 192,965 μg/ml-1. Para os testes antifúngicos, todos os extratos apresentaram poderes inibitórios para Fusarium oxysporum e Fusarium verticillioides. O extrato vegetal obtido a partir da raiz apresentou poder de inibição superior, para Fusarium oxysporum de 70,12% (CO2) e 65,12% (GLP) de inibição, e para Fusarium verticillioides de 67,76% (CO2) e 61,15% (GLP). A partir dos resultados obtidos neste trabalho, os mesmos confirmam que a extração supercrítica ou utilizando fluido pressurizado é uma metodologia promissora na obtenção de compostos bioativos de Lupinus albescens, sendo que o extrato apresentou potencial antifúngico para ambos os fungos investigados neste trabalho.
50

AVALIAÇÃO DE DIFERENTES PROCESSOS DE EXTRAÇÃO NA OBTENÇÃO DE ÓLEO DE FARELO DE ARROZ / EVALUATION OF DIFFERENT EXTRACTION PROCESSES ON THE OBTAINMENT OF RICE BRAN OIL

Soares, Juliana Ferreira 19 February 2015 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Rice bran oil (RBO) is a natural rich source of antioxidants and contains a balanced fatty acids composition, which is of great interest for application in food, cosmetic and pharmaceutical industries. Therefore, the objective of this study was to investigate the rice bran oil extraction using supercritical fluid extraction with carbon dioxide (SFE-CO2), SFE-CO2 assisted by ultrasound (US) and with compressed liquefied petroleum gas (LPG). Also, the antioxidant activity and chemical composition of extracts were evaluated. In the SFE, pressure (150 250 bar) and temperature (40 80 °C) conditions were studied, while in the SFE + US the variables studied were power (160 320 W) and time of ultrasound application (40 120 min). In the extraction using LPG, the pressure (5 25 bar) and the temperature (20 30°C) effects were investigated. The antioxidant activity of the extracts was assayed by DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging method and the chemical composition by gas chromatography mass spectrometry (GC-MS). The maximum yields achieved of RBO were 12.68%, at 250 bar and 40 °C, in the SFE, 12.65%, using 160 W for 40 min in the SFE assisted by US, and 12.07% at 25 bar and 40°C in the extraction with compressed LPG. The antioxidant activity of the extracts ranged from 54.55 71.67% in the SFE, 69.26 72.42% in the SFE + US and 63.55 67.49% in the extraction with compressed LPG. The main antioxidant compound found in different processes was the β-sitosterol, which is one of sterols that compose the γ-oryzanol. The US application in SFE accelerated the process and increased the RBO yield in approximately 27%. In the SFE and SFE + US processes were spent 120 min to obtain 81.93% and 64.38%, respectively, while extraction with compressed LPG took only 5 minutes to extract 78.17% of oil, showing high oil solubility in this solvent. In general, the processes performed well in the recovery of rice bran oil, being considered as technically viable alternatives to conventional processes. / O óleo do farelo de arroz (RBO) é uma fonte natural rica em antioxidantes e contém uma composição balanceada de ácidos graxos, o que é de grande interesse para aplicação na indústria alimentícia, cosmética e farmacêutica. Nesse sentido, o objetivo deste trabalho foi estudar a extração do óleo de farelo de arroz pelos processos de extração supercrítica utilizando dióxido de carbono (ESC-CO2), ESC-CO2 assistida por ultrassom (US) e extração com gás liquefeito de petróleo comprimido (GLP), além de avaliar a atividade antioxidante e a composição química dos extratos obtidos. Na ESC foram estudadas as condições de pressão (150 250 bar) e temperatura (40 80 °C), enquanto na ESC + US as variáveis estudadas foram potência (160 320 W) e o tempo de aplicação (40 120 min) do ultrassom. Nas extrações com GLP foi investigado o efeito da pressão (5 25 bar) e da temperatura (20 30 °C). A atividade antioxidante dos extratos foi determinada pelo método do radical DPPH (2,2-difenil-1-picrilhidrazila) e a composição química por cromatografia gasosa acoplada a espectrometria de massas (CG-EM). Os rendimentos máximos alcançados de RBO foram de 12,68%, a 250 bar e 40°C, na ESC, 12,65%, utilizando 160 W por 40 min na ESC assistida por US, e de 12,07% a 25 bar e 40°C na extração com GLP comprimido. A atividade antioxidante dos extratos variou de 54,55 71,67% na ESC, de 69,26 72,42% na ESC + US e de 63,55 67,49% na extração com GLP. O principal composto antioxidante encontrado nos diferentes processos foi o β-sitosterol, que é um dos esteróis que compõem o γ-orizanol. A aplicação do US na ESC acelerou o processo e aumentou em aproximadamente 27% o rendimento de RBO. Nos processos de ESC com e sem aplicação de US foram dispendidos 120 minutos para obtenção de 81,93% e 64,38% de rendimento, respectivamente, enquanto que a extração com GLP comprimido levou apenas 5 minutos para extrair 78,17% de óleo, mostrando a elevada solubilidade do óleo nesse solvente. De um modo geral, os processos obtiveram um bom desempenho na recuperação do óleo do farelo de arroz, sendo consideradas alternativas tecnicamente viáveis aos processos convencionais.

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