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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.
1

Qualitative and Quantitative Assessment of Fatty Acids of Buddleja asiatica by GC-MS

Ali, F., Ali, I., Bibi, H., Malik, A., Stern, Ben, Maitland, Derek J. 03 2013 (has links)
No / To analyze the fatty acid contents of Buddleja asiatica Lour, both the non-volatile oil and fat obtained from the n-hexane soluble sub-fraction were subjected to GC/MS using BSTFA (N,O-bis(trimethylsilyl) trifloroacetamide) derivatization. The oil showed the presence of six fatty acids including palmitic acid (46.75 %), linoleic acid (37.80 %), stearic acid (10.98 %), arachidic acid, margaric acid and lignoceric acid (< 3 %). Analysis of the fat revealed nine fatty acids including lignoceric acid (43.12 %), behenic acid (26.39 %), arachidic acid (9.29 %) and stearic acid (5.3 %). Cerotic acid, montanic acid, melissic acid and palmitic acid were found in low amounts (< 5 %) while trycosylic acid (4.83 %) was the only fatty acid with odd number of carbon atoms. The oil showed a low thermal stability. / Higher Education Commission Pakistan
2

Estudo do processo enzimático de produção de biodiesel a partir de óleos e gorduras residuais de fritura / Study of the enzymatic process of biodiesel production from waste frying oils and fats

Silva, Albanise Enide da 03 1900 (has links)
The use of biodiesel as a fuel has showed a high potential all over the world. In spite of the possible environmental benefits of the vegetable oil use to conversion into biodiesel as a substitute for the diesel, barrels in the economic and ethic points of view, as soil and water use in competition with food cultures and to other technical purposes, motivated the search of alternative raw material for biodiesel production. Among the studied alternatives, the reutilization of residual animal and vegetable oils and fats from food frying processes has shown to be attractive, because the consumption of fried and pre fried food has increased in the last years, causing rise in production of OGRF´s ( Fried Residual Fats and Oils). In this work transesterification reactions of vegetables oils and fats used in frying processes was studied for biodiesel production with immobilized lipases. The samples of OGRF´s were collected in commercial establishments in Maceió city. These samples were characterized concerning its acidity index, iodine index, cinematic viscosity, specific mass, fat acid composition. A study on temperature in which the lipase (Novozym 435) presents better enzymatic activity, in the range between 40-60ºC, was carried out. The alcoholysis reaction was catalyzed by immobilized commercial lipase Novozym 435, the experiments were done according to an factorial experimental design 24-1 where the variables study were: temperature (40-60°C), reaction time (24-72h), enzyme concentration (5-10%) and oil-ethanol rate (1:3-1:9). The determination of yield in ethyl esters (biodiesel) was accomplished by gas chromatography. Among these results, the higher yield was obtained in higher conditions of temperature, enzyme concentration, reaction time and oil: ethanol rate. / A utilização de biodiesel como combustível tem apresentado um potencial promissor no mundo inteiro. Apesar dos possíveis benefícios ambientais no emprego de óleos vegetais para conversão em biodiesel como substituto ao diesel, barreiras do ponto de vista econômico e ético, como concorrência do uso do solo e água com culturas alimentares e para outros fins técnicos, motivaram a busca de matérias-primas alternativas para produção deste biocombustível. Dentre as alternativas estudadas, a reutilização de óleos e gorduras vegetais e animais residuais de processos de fritura de alimentos tem se mostrado atraente, pois o consumo de alimentos fritos e pré-fritos tem aumentado nos últimos anos, provocando um aumento na produção de OGRF’s (Óleos e Gorduras Residuais de Fritura). Neste trabalho estudaram-se reações de alcoólise de óleos e gorduras comestíveis usados em frituras para produção de biodiesel catalisada por lipase imobilizada. As amostras de OGRF’s foram coletadas em estabelecimentos comerciais da cidade de Maceió. Estas amostras foram então caracterizadas quanto aos índices de acidez e de iodo, viscosidade cinemática, massa específica e composições em ácidos graxos. Um estudo para se determinar a temperatura em que a enzima (Novozym 435) apresenta melhor atividade, na faixa compreendida entre 40-60°C, foi realizado. A reação de alcoólise foi catalisada pela lipase comercial imobilizada Novozym 435. Os experimentos foram realizados de acordo com um planejamento experimental fatorial fracionário 24-1 onde as variáveis estudadas foram temperatura (40-60°C), tempo de reação (24-72h), concentração de enzimas (5-10%) e razão óleo:etanol (1:3-1:9). A determinação do rendimento em ésteres etílicos (biodiesel) foi realizada por cromatografia gasosa. Dentre os resultados, o maior rendimento (87,3%) foi obtido nas condições de maiores temperatura, concentração enzimas, tempo reacional e razão óleo:etanol.
3

Aplica??o de catalisadores a base de SiO2-SO3H na s?ntese de biodiesel: estudo cin?tico do processo de transesterifica??o de triacilglicerideos

Oliveira Junior, Gelson Cerqueira de 10 September 2015 (has links)
Data de aprova??o retirada da vers?o impressa do trabalho. / Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2017-08-30T18:13:36Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) gelson_cerqueira_oliveira_junior.pdf: 2578577 bytes, checksum: 83cb8ab9378ea856fed151a0f1c1992d (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2017-08-30T18:51:12Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) gelson_cerqueira_oliveira_junior.pdf: 2578577 bytes, checksum: 83cb8ab9378ea856fed151a0f1c1992d (MD5) / Made available in DSpace on 2017-08-30T18:51:12Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) gelson_cerqueira_oliveira_junior.pdf: 2578577 bytes, checksum: 83cb8ab9378ea856fed151a0f1c1992d (MD5) Previous issue date: 2015 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Neste trabalho s?lica gel foi preparada a partir de areia de constru??o e carbonato de s?dio, apresentando uma ?rea de superf?cie de 378,68 m2/g, e volume de poro de 1,59x10-2 cm3/g. A fim de preparar diferentes catalisadores a base do mesmo material uma al?quota foi previamente aquecida a 400? C e outra a 700? C, as quais foram denominadas S400 e S700 que ap?s tratamento com H2SO4, deram origem a dois diferentes catalisadores, chamados de C400 e C700. Os catalisadores apresentaram volume total dos mesoporos de 0,23 cm3/g (C400) e 0,20 cm3/g (C700) e ?rea superficial de 31,06 m2/g (C400) e 23,10 m2/g (C700). Pela primeira vez foi utilizado ?cido de Bronsted imobilizado em s?lica para a convers?o de OGR em biodiesel. Ambos C400 e C700 apresentaram alta atividade na convers?o do ?leo e gordura residuais altamente ?cidos (13,7 mg de KOH) e com teor de ?gua de 0,58%, a biodiesel (?steres met?licos de ?cido graxo) em aproximadamente 99,4 %. As rea??es foram repetidas 4 vezes antes do catalisador perder sua atividade catal?tica. / Disserta??o (Mestrado) ? Programa de P?s-gradua??o em Biocombust?veis, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2015. / In this work, silica gel was prepared from building sand and sodium carbonate, having a surface area of 378.68 m2/g and pore volume of 1,59x10-2 cm3/g. In order to prepare different catalysts the basis of the same material aliquot was preheated to 400? C and another at 700? C, which were referred to as S400 and S700 which upon treatment with H2SO4, gave rise to two different catalysts, called C400 and C700. The catalysts showed total volume of mesopores of 0.23 cm3/g (C400) and 0.20 cm3/g (C700) and surface area of 31.06 m2/g (C400) and 23.10 m2/g (C700). For the first time was used Bronsted acid immobilized on silica OGR for conversion into biodiesel. Both C400 and C700 showed high activity in the oil conversion and highly acidic waste fat (13.7 mg of KOH) and 0.58% water content, biodiesel (fatty acid methyl esters) by approximately 99.4% . Reactions were repeated four times before the catalyst to lose its catalytic activity.
4

Sustainable alternatives to fish meal and fish oil in fish nutrition : effects on growth, tissue fatty acid composition and lipid metabolism

Karalazos, Vasileios January 2007 (has links)
Traditionally, fish meal (FM) and fish oil (FO) have been used extensively in aquafeeds, mainly due to their excellent nutritional properties. However, various reasons dictate the use of sustainable alternatives and the reduction of the dependence on these commodities in fish feeds. Hence, the aim of the present thesis was to investigate the effects of the replacement of FM and FO with two vegetable oils (VO) and an oilseed meal on the growth performance, feed utilization, nutrient and fatty acids (FA) digestibility and tissue FA composition and metabolism in three commercially important European fish species. Specifically, in Experiment I crude palm oil (PO) was used to replace FO in diets for rainbow trout. In Experiments II and III FO was replaced with rapeseed oil (RO) in diets for Atlantic salmon at various dietary protein/lipid levels aiming also at further reductions of FM by using low protein (high lipid) diet formulations. In Experiments II and III the fish were reared at low and high water temperatures, respectively, in order to elucidate, also, the potential effects of temperature. Lastly, the effects of the replacement of FM with full fat soya meal (FFS) in Atlantic cod were investigated in Experiment IV. The results of the present thesis showed no negative effects on growth performance and feed utilization in rainbow trout when FO was replaced with PO. The dietary inclusion of RO improved the growth of Atlantic salmon, possibly, due to changes in the nutrient and FA digestibilities and FA catabolism while, the growth and feed utilization were unaffected by the dietary protein/lipid level. However, the growth of Atlantic cod was affected negatively by the replacement of FM with FFS. The proximate composition of the fish whole body was in most cases unaffected by dietary treatments. The changes in dietary formulations affected the dietary FA compositions and resulted in significant changes in the fish tissue FA compositions. It was clearly shown that the fish tissue total lipid FA composition reflects the FA composition of the diet, although specific FA were selectively utilized or retained in the tissues by the fish. These may have serious implications not only for fish metabolism and growth but also for the quality of the final product, especially in terms of possible reductions of n-3 HUFA.

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