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The goal of predictive science is to establish structure−function relations for a system of interest. The obvious first step is to determine the structure of the system. Predictions in asphaltene science have been greatly inhibited, because of disagreement regarding molecular weight and molecular structure. With substantial progress on both structural fronts, structure−function relationships can be explored. Here, high quality factor (high-Q) ultrasonics is used to demonstrate asphaltene nanoaggregation at ∼100 mg/L. Fluorescence quenching measurements corroborate these results. Simple concepts regarding asphaltene molecular structure can be used to understand asphaltene nanoaggregation. These relations are seen to apply for asphaltene samples of very different origin. The implications of this understanding on larger-scale asphaltene aggregation and solubility are discussed.

Around the world, there is a growing increase in biofuels consumption, mainly ethanol and biodiesel as well as their blends with diesel that reduce the cost impact of biofuels while retaining some of the advantages of the biofuels. This increase is due to several factors like decreasing the dependence on imported petroleum; providing a market for the excess production of vegetable oils and animal fats; using renewable and biodegradable fuels; reducing global warming due to its closed carbon cycle by CO2 recycling; increasing lubricity; and reducing substantially the exhaust emissions of carbon monoxide, unburned hydrocarbons, and particulate emissions from diesel engines. However, there are major drawbacks in the use of biofuel blends as NOx tends to be higher, the intervals of motor parts replacement such as fuel filters are reduced and degradation by chronic exposure of varnish deposits in fuel tanks and fuel lines, paint, concrete, and paving occurs as some materials are incompatible. Here, fuel additives become indispensable tools not only to decrease these drawbacks but also to produce specified products that meet international and regional standards like EN 14214, ASTM D 6751, and DIN EN 14214, allowing the fuels trade to take place. Additives improve ignition and combustion efficiency, stabilize fuel mixtures, protect the motor from abrasion and wax deposition, and reduce pollutant emissions, among other features. Two basic trends are becoming more relevant:  the progressive reduction of sulfur content and the increased use of biofuels. Several additives' compositions may be used as long as they keep the basic chemical functions that are active.

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Recebido em 9/1/09; aceito em 5/3/09; publicado na web em 25/3/09 BIODIESEL CHAIN FROM THE LAB BENCH TO THE INDUSTRY: AN OVERVIEW WITH TECHNOLOGY ASSESMENT, R&D&I OPPORTUNITIES AND TASKS. Contextualized overview of the Biodiesel Production Chain, from the lab bench to the industry, with critical evaluation of state-of-art and technological development through scientific articles and patents, focusing on feedstock, reaction/production, first and second generation processes, specification and quality, transport, storage, co-products (effluents and sub-products), and emissions. Challenges are identified and solutions are proposed based on the Brazilian feedstock, edaphoclimatic conditions, process monitoring in remote regions, state policy, and environment preservation, among others. Forecasts are made based on the technology assessment, identifying future trends and opportunities for R&D&I.Keywords: biofuels production chain; technology assessment; forecasting. introduçãoA cadeia produtiva do biodiesel pode ser vista de modo integrado (Figura 1) compreendendo matérias-primas e insumos, reação (transformação), processo de produção e purificação, controle de qualidade, transporte, armazenamento e estocagem, coprodutos (efluentes e subprodutos), uso e emissões. A Química permeia toda a cadeia do biodiesel, sendo indispensável para sua viabilização econômica, ambiental e tecnológica, tanto nas áreas rurais como industriais.A busca pela inserção do biodiesel na matriz energética tem sido um dos focos de vários países e blocos comerciais.1-4 Esta intensificação do uso do biodiesel se alicerça num tripé: (1) ambiente (melhoria das condições climáticas por redução das emissões e utilização de CO 2 pela matéria-prima); (2) social (desenvolvimento rural associado à produção de matéria-prima); (3) energia (independência de fornecedores, consumidores produzindo sua própria energia).Para que o biodiesel seja classificado como fonte renovável de energia é essencial considerar não só o balanço de energia da sua produção, mas também as proporções de energia alocadas aos seus coprodutos e ao seu reaproveitamento.5 Além de renovável, o biodiesel tem ainda a vantagem de redução das emissões reguladas. Adicionalmente, permite melhorar o fechamento do ciclo do carbono (carbon neutral) e, quando de origem vegetal, intensifica o sequestro de CO 2 da atmosfera, impactando favoravelmente nas mudanças climáticas do planeta, ao retirar CO 2 no crescimento das plantas geradoras de óleo, deste modo compensando a adição de CO 2 à atmosfera durante a sua queima. O biodiesel é ainda biodegradável e, adicionado ao diesel, tem efeito sinérgico de biodegradação por cometabolismo. 5A maior desvantagem tecnológica do biodiesel é a relação inversa entre a estabilidade oxidativa (favorecida pela maior concentração de ácidos graxos saturados) e as propriedades a baixa temperatura, como ponto de névoa e ponto de entupimento (favorecidos pela maior concentração de ácidos graxos insaturados). 6 Economicamente, para que o biodiesel tenha um papel ativo no m...

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Microbial enhanced oil recovery (Meor) is an incontestably efficient alternative to improve oil recovery, especially in mature fields and in oil reservoirs with high paraffinic content. This is the case for most oil fields in the Recôncavo basin of Bahia, Brazil. Given the diverse conditions of most oil fields, an approach to apply Meor technology should consider primarily: (i) microbiological studies to select the appropriate microorganisms and (ii) mobilization of oil in laboratory experiments before oil field application. A total of 163 bacterial strains, selectively isolated from various sources, were studied to determine their potential to be used in Meor. A laboratory microbial screening based on physiological and metabolic profiles and growth rates under conditions representative for oil fields and reservoirs revealed that 10 bacterial strains identified as Pseudomonas aeruginosa (2), Bacillus licheniformis (2), Bacillus brevis (1), Bacillus polymyxa (1), Micrococcus varians (1), Micrococcus sp. (1), and two Vibrio species demonstrated potential to be used in oil recovery. Strains of B. licheniformis and B. polymyxa produced the most active surfactants and proved to be the most anaerobic and thermotolerant among the selected bacteria. Micrococcus and B. brevis were the most salt‐tolerant and polymer producing bacteria, respectively, whereas Vibrio sp. and B. polymyxa strains were the most gas‐producing bacteria. Three bacterial consortia were prepared with a mixture of bacteria that showed metabolic and technological complementarity and the ability to grow at a wide range of temperatures and salinity characteristics for the oil fields in Bahia, Brazil. Oil mobilization rates in laboratory column experiments using the three consortia of bacteria varied from 11.2 to 18.3 % [v/v] of the total oil under static conditions. Consortia of B. brevis, B. icheniformis and B. polymyxa exhibited the best oil mobilization rates. Using these consortia under anaerobic conditions could be an interesting alternative for Meor technology because their growth could be easily controlled through the administration of phosphate and inorganic electron acceptors. Bacterial strains selected in this work could be valuable for further application in oil recovery at productive and mature oil well sites as well as for the prevention and control of paraffin deposits.