Percorrer por autor "Gomes, Maria Carolina Sérgi"
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- Biodiesel production from residual cooking oils and its purification by adsorption processes based on adsorbents of natural originPublication . Garção, Maria Isabella Lima; Gomes, Maria Carolina Sérgi; Queiroz, Ana; Ribeiro, António E.; Brito, PauloTotal global energy consumption has increased significantly in recent decades, and nowadays the main sources of world energy are oil, coal and natural gas. In addition to environmental concerns, the limited availability of fossil fuels has increased the interest in exploring alternative energy sources. In this quest, biofuel is a promising renewable energy source with low carbon emissions, also, it can be produced from a variety of resources, including waste cooking oil (WCO). Biodiesel is renewable, biodegradable, non-toxic, sulfur-free and free of aromatic carcinogens
- Biodiesel production from residual cooking oils and its purification through adsorption processes using activated carbon prepared from cork wastePublication . Garção, Maria Isabella Lima; Queiroz, Ana; Brito, Paulo; Ribeiro, António E.; Gomes, Maria Carolina SérgiBiodiesel is a renewable fuel that can be produced from waste cooking oil mainly through transesterification. However, from its production results a contaminant called glycerol, which must be removed. Wet washing is the most common method for biodiesel purification, but it has several drawbacks, including high costs and the generation of large amounts of aqueous effluent. This study proposes using activated carbon obtained from industrial cork waste in adsorption as an alternative method for glycerol removal. This approach could potentially reduce the environmental impact and cost of producing biodiesel, while also providing an alternative for the valorization of industrial cork waste. The highest value of removal of 89% of glycerol occurred with a cork chemically activated carbon with KOH at a load of 2%wt at 25°C for 6 hours of contact. After the biodiesel washing using adsorption process, the remaining glycerol content was 0.016%wt, below the maximum value of 0.02%wt specified by the EN14214:2012 standard.
- Biodiesel production from residual cooking oils and its purification through adsorption processes using activated carbon prepared from cork wastePublication . Garção, Maria Isabella Lima; Queiroz, Ana; Brito, Paulo; Ribeiro, António E.; Gomes, Maria Carolina SérgiBiodiesel is a renewable fuel that can be produced from waste cooking oil mainly through transesterification . However, from its production results a contaminant called glycerol, which must be removed. Wet washing is the most common method for biodiesel purification, but it has several drawbacks,including high costs and the generation of large amounts of aqueous effluent. This study proposes using activated carbon obtained from industrial cork waste in adsorption as an alternative method for glycerol removal. This approach could potentially reduce the environmental impact and cost ofproducing biodiesel, while also providing an alternative for the valorization of industrial cork waste.
- Biodiesel production from residual cooking oils and purification by adsorption processes based on adsorbents of natural originPublication . Garção, Maria Isabella Lima; Gomes, Maria Carolina Sérgi; Queiroz, Ana; Ribeiro, António E.; Brito, PauloTotal global energy consumption has increased significantly in recent decades. International Energy Agency predicts that from 2012 to 2040, and also the International Energy Agency (IEA), by 2030, the world's demand for energy will increase by 50%. Nowadays, the main sources of energy supply in the world are oil, coal and natural gas. In addition to the environmental problems, the supply of fossil fuels is limited, which makes many researchers increasingly interested in exploring alternative energy sources [1]. In this pursuit, biofuels are promising renewable energy sources with lower carbon emissions, besides the possibility of being made from a variety of resources, including residues such as waste cooking oil (WCO), oily sludge from factories, and discarded animal fats [2]. In contrast to petroleum-derived diesel, biodiesel is renewable, biodegradable, non-toxic, sulphur-free and aromatic carcinogen-free [3]. The cost of biodiesel is now 10% to 50% higher than petroleum diesel. A more possible way to increase biodiesel production is to use WCO as a feedstock, which is 25% to 40% of the price of edible oil. This way, WCO gets a better destination than its discard [3]. Biodiesel is produced through transesterification/esterification which are reactions that convert oils or free fatty acids into alkyl esters. Through transesterification, the triglycerides react with small chain alcohol in order to obtain methyl or ethyl esters of fatty acids and glycerol. The process occurs in three reversible and consecutive reactions, which produce molecules of diglycerides and monoglycerides as intermediates [4]. The properties of biodiesel will depend on the feedstock used in its production, and it should be similar to petroleum diesel in order to be functional in motors without any changes. All parameters, such as cetane number, fatty acid methyl esters content, density, and acid value, are defined by standards and vary depending on the location. For example, in Europe, they are defined by the European Biodiesel Standard EN 14214, whose last version was published in 2008. It is set to specify characteristics that define the behaviour of biodiesel combustion in an engine and also the methods that have to be used to determine those parameters
- Cork waste-based adsorbents for glycerol removal from biodiesel: a sustainable alternative to wet washingPublication . Garção, Maria Isabella Lima; Milani, Eduardo C.; Camilo, Gabriel L.; Díaz de Tuesta, Jose Luis; Gomes, Maria Carolina Sérgi; Ribeiro, António E.; Queiroz, Ana; Brito, PauloThis work aims to use activated carbon from industrial cork waste as a novel method for glycerol removal from crude biodiesel produced using waste cooking oil, combining two residues to obtain both high-quality biodiesel and highly adsorbent activated carbon. The study first optimizes the biodiesel production conditions, achieving the highest ester yield at 30 degrees C, with a 1:9 oil-to-ethanol molar ratio, 1 wt.% NaOH catalyst, and a reaction time of 1 h. Additionally, activated carbons were prepared and characterized from cork waste, showing significantly higher BET surface areas than the raw material. The most promising cork-based materials were then applied to optimize glycerol removal from crude biodiesel through adsorption. A preliminary study identified milled raw cork and its KOH-activated carbon (SBET = 2057 m2/g) as the most effective. Kinetic and equilibrium studies demonstrated that optimal glycerol removal was achieved after 6 h at 25 degrees C using 2 wt.% of KOH-activated cork-based adsorbent, resulting in 88% glycerol removal and a final glycerol content of 0.017 wt.%. These findings demonstrate that cork waste-derived activated carbon is highly effective for biodiesel purification, successfully meeting the quality specifications required by European Standard EN 14214:2012+A2:2019 and offering an innovative solution for waste valorization and sustainable fuel production.
- Dry purification of ethanolic biodiesel through adsorption using almond shell based materialsPublication . Mezzalira, Melissa Giacomet; Gomes, Maria Carolina Sérgi; Queiroz, Ana; Ribeiro, António E.; Brito, PauloPetroleum-based fuels and non-renewable sources remain dominant in the global energy supply, meeting 80% of global energy demand in 2023. However, using these non-renewable fuels results in significant emissions of pollutants into the atmosphere, including greenhouse gases such as carbon dioxide (CO2). In this context, biodiesel is a potential alternative to meet global energy demand as a substitute for non- renewable fuels, as itis considered one of the best alternatives to diesel due to its comparable properties, not requiring majoramendments in machines with combustion motors, biodegradability, and renewable advantages. Biodiesel is usually produced through a transesterification reaction using different sources of triglycerides, primarily edible vegetable oils. However, waste cooking oil (WCO) is an excellent feedstock alternative, as it is a waste product generated in significant quantities by the food industry, often improperly discarded, causing environmental harm. Biodiesel purification is another important step in the process, as contaminants such as glycerol can damage engines, requiring their removal before the fuel can be commercialized. Several purification methods can be applied, the most common being wet washing, which uses large amounts of water to solubilize glycerol and other impurities in biodiesel. However, more sustainable methods like dry washing involving adsorbent materials are currently under extensive study. Hence, this study aims to produce and characterize activated carbon derived from almond shells, evaluating its use in purifying the ethanolic biodiesel produced from WCO. In this work, biodiesel was produced via an ethanolic route with a 1:7.5 oil/ethanol molar ratio and NaOH catalyst load of 0.5%(w/w). Furthermore, the activated carbon was chemically activated with phosphoric acid (H3PO4) and carbonized at 550°C for 1 hour, achieving a carbonization yield of 59.4%(w/w). The materials were characterized by the determination of the point of zero charge (pHPZC) and the quantification of functional groups present on the material's surface. Activation with H₃PO₄ had an impact on the materials’ characteristics, as evidenced by the decrease, from 6.48 to 4.96, in the pHPZC value compared to that of the raw material, given that the number of acid groups on the surface of the materials exhibits higher values after activation. The activated carbon materials will be tested for their capacity to remove glycerol from crude ethanolic biodiesel, aiming to meet the quality standard specified by EN14214, which sets the maximum biodiesel free glycerol content at 0.02%(w/w).
- Evaluation and kinetic study of alkaline ionic liquid for biodiesel production through transesterification of sunflower oilPublication . Lima, Ana Carolina Coelho; Hachemane, Khadidja; Ribeiro, António E.; Queiroz, Ana; Gomes, Maria Carolina Sérgi; Brito, PauloBiodiesel production is performed in the industry by alkaline transesterification of oils with a low amount of free fatty acids. In order to reduce the disposal of conventional catalysts used industrially, ionic liquids (ILs) have been studied to be applied as catalysts in transesterification since they can be recovered and reused in subsequent reaction cycles. In this work, the ionic liquid choline hydroxide (ChOH) was successfully applied as a catalyst for the transesterification reaction of triacylglycerols present in sunflower oil with methanol. A kinetic modeling study under the specific conditions of 2 wt% catalyst dosage, 1:10 oil/methanol molar ratio, for 0–120 min at 35–65 ℃ was conducted, and liquid–liquid extraction with water/butanol was evaluated as a process to recover the IL. A 95.0% ester yield content was achieved in this work for a short reaction time (30 min). Furthermore, the results of the kinetic study demonstrated that a first-order model was the best fit for the reaction with a rate constant (k) estimated as 0.1182 min 1 and activation energy (Ea) of 13.64 kJ/mol. For the tested conditions, the complete recovery of the IL using liquid–liquid extraction did not occur since it is noted the presence of ChOH in both phases.
- Purificação a seco do biodiesel etanólico através de adsorção utilizando materiais à base de casca de amêndoaPublication . Mezzalira, Melissa Giacomet; Gomes, Maria Carolina Sérgi; Queiroz, Ana; Ribeiro, António E.; Brito, PauloA demanda global de energia continua crescendo, devido, principalmente, ao crescimento populacional, ao desenvolvimento econômico e a urbanização acelerada, ocorrendo majoritariamente nas economias emergentes [1]. Os combustíveis baseados em petróleo e fontes não renováveis continuam dominando a fonte de energia global. Porém, a distribuição desigual dos recursos de combustíveis fósseis pode resultar em tensões geopolíticas, além de que o uso destes combustíveis promove uma grande emissão de poluentes na atmosfera, incluindo gases com efeito de estufa como o dióxido de carbono [2]. Nesse contexto, o biodiesel é uma possível alternativa para satisfazer a demanda de energia global em substituição dos combustíveis não renováveis, já que é considerado uma das melhores alternativas para substituir o diesel, devido a suas propriedades compatíveis, biodegradabilidade e origem renovável [3]. O biodiesel é produzido, normalmente, através da reação de transesterificação, utilizando, principalmente, óleos vegetais comestíveis como fonte de triglicerídeos. Por outro lado, o óleo alimentar usado (OAU) é uma ótima alternativa de matéria prima, já que é um resíduo produzido em grandes quantidades por indústrias alimentares, sendo descartado, geralmente, de maneira incorreta prejudicando o meio ambiente. Dessa maneira, o uso de OAU na produção do biodiesel, além de ser benéfico ambientalmente, por ser um resíduo doméstico ou industrial, possui um custo mais baixo em relação aos óleos vegetais [4]. A purificação do biodiesel é uma etapa importante do processo, já que os contaminantes presentes no biodiesel bruto, como o glicerol, trazem prejuízos aos motores, sendo necessário retirá-los, possibilitando, assim, a comercialização do combustível. Diversos métodos de purificação podem ser aplicados, sendo o mais comum alavagem com água, que implica a geração de grandes quantidades de efluentes aquosos. Porém, a fim de solubilizar o glicerol e outras impurezas contidas no biodiesel, métodos mais sustentáveis como a lavagem a seco, envolvendo a utilização de materiais adsorventes, são atualmente objeto de estudo, nomeadamente através do aproveitamento de resíduos agrícolas como precursores na produção dosmateriais adsorventes, tornando o processo ainda mais significante ambientalmente [5].
- Purificação a seco do biodiesel etanólico através de adsorção utilizando materiais à base de casca de amêndoaPublication . Mezzalira, Melissa Giacomet; Gomes, Maria Carolina Sérgi; Queiroz, Ana; Brito, Paulo; Ribeiro, António E.O crescente interesse por fontes de energia sustentáveis tem impulsionado a busca por alternativas aos combustíveis fósseis. Nesse contexto, o biodiesel surge como uma possível alternativa ao diesel, devido às suas propriedades compatíveis.1 Esse biocombustível pode ser obtido a partir de diversas matérias-primas, incluindo o óleo alimentar usado (OAU), promovendo o reaproveitamento eficiente de resíduos.2 A purificação do biodiesel é geralmente realizada por lavagem com água, embora eficaz, gera grandes volumes de efluentes. Dessa forma, o uso de materiais adsorventes surge como uma alternativa mais limpa e sustentável para a remoção de contaminantes como o glicerol. Neste trabalho, o processo foi dividido em três fases: produção do biodiesel, preparação e caracterização do adsorvente a partir de cascas de amêndoa e estudos de adsorção.
- Purificação a seco do biodiesel etanólico através de adsorção utilizando materiais à base de casca de amêndoaPublication . Mezzalira, Melissa Giacomet; Gomes, Maria Carolina Sérgi; Queiroz, Ana; Brito, Paulo; Ribeiro, António E.O crescente interesse por fontes de energia sustentáveis tem estimulado a substituição dos combustíveis fósseis1. Nesse contexto, o biodiesel surge como alternativa viável ao diesel convencional, podendo ser produzido a partir de diversas matérias-primas, como o óleo alimentar usado (OAU), promovendo o reaproveitamento eficiente de resíduos. A purificação convencional do biodiesel via lavagem com água, embora eficiente, gera elevados volumes de efluentes. Como alternativa ambientalmente mais sustentável, têm sido investigados materiais adsorventes para a remoção de contaminantes, como o glicerol, com o objetivo de atender à norma EN 14214, que estabelece um limite máximo de glicerol de 0,02% (m/m) no biodiesel.
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