Mejora del rendimiento del biodiesel a partir de aceite de oliva no comestible pre-esterificado mediante transesterificación asistida por microondas

In the present research, biodiesel production from olive oils with different initial free fatty acid concentrations (2.5, 5.0, and 10.0%) was evaluated. A two-stage acid-catalyzed esterification and alkaline-catalyzed transesterification (ACT) process using the microwave heating method was compared with the traditional heating method. Free fatty acid was reduced to less than 2.0% in the first stage. Although no significant difference was observed between microwave and traditional esterification methods in terms of fatty acid reduction, the microwave treatment significantly decreased reaction time by 92.5%. Comparing microwave ACT results with those of the traditional heating method showed that the microwave can significantly increase methyl ester yield and purity, and simultaneously decrease reaction time. Physical constants of methyl esters were also improved using the microwave heating method. Therefore, the microwave heating method can be regarded as an efficient method instead of the two-stage method for biodiesel production. This method is capable of using inedible olive oil with high concentrations of free fatty acids.En la presente investigación, se evaluó la producción de biodiesel a partir de aceites de oliva con diferentes concentraciones iniciales de ácidos grasos libres (2,5, 5,0 y 10,0%). Se comparó un proceso de esterificación en dos etapas catalizada con ácido y transesterificación catalizada alcalina (ACT) usando microondas con el método de calentamiento tradicional. Los ácidos grasos libres se redujeron a menos del 2,0% en la primera etapa. Aunque no se observaron diferencias significativas entre los métodos de esterificación, por microondas y tradicional, en términos de reducción de ácidos grasos, sin embargo, el microondas disminuyó significativamente el tiempo de reacción en un 92,5%. La comparación de los resultados de ACT de microondas con los del método de calentamiento tradicional mostró que el microondas puede aumentar significativamente el rendimiento y la pureza del éster metílico, y simultáneamente disminuir el tiempo de reacción. Las constantes físicas de los ésteres metílicos también se mejoraron usando el método de calentamiento por microondas. Por lo tanto, el método de calentamiento por microondas puede considerarse como un método eficiente en lugar de la producción de biodiésel en dos etapas. Este método es capaz de usar aceite de oliva no comestible con altas concentraciones de ácidos grasos libres

Producción de biodiésel mejorada por esterificación y transesterificación asistida por ultrasonidos de aceite de oliva no comestible

In the first phase of this study, inedible olive oil with different initial free fatty acid concentrations (2.5, 5.0, and 10.0%) was processed through acid-catalyzed esterification. Various heating methods were used for this purpose. The ultrasound-assisted esterification and traditional magnetic stirrer-assisted esterification methods were similar to each other in terms of their effects on free fatty acid reduction. However, the ultrasound reaction time was significantly shorter than that of the traditional magnetic stirrer. In the second phase of this study, biodiesel production was carried out through the ultrasound-assisted transesterification of inedible olive oil. Independent variables were, namely, ultrasound power level (30, 90, and 150 W), methanol/oil mole ratio (3, 9, and 15), catalyst concentration (0.5, 1.0, and 1.5%), ultrasound time (15, 30, and 45 min), and reaction temperature (45, 55, and 65 °C), which affected the yield indices and physicochemical constants of the produced biodiesel. The purest biodiesel (98.95%) and the highest amount of yield (92.69%) were observed when using an ultrasound power level of 90 W, a methanol/oil mole ratio of 9, a catalyst concentration of 1.0%, an ultrasound time of 30 min, and a reaction temperature of 55 °C. Optimizing the reaction conditions of the ultrasound operation can effectively increase the biodiesel yield (92.69%), while reducing the energy consumption (4.775 kWh/kg) and shortening the reaction time (30 min), compared to the traditional magnetic stirrer (77.28%, 2.17 kWh/kg, and 120 min, respectively). Therefore, ultrasound-assisted transesterification can serve as an effective alternative because of its fast and economic operation for making biodiesel out of inedible olive oil.En la primera fase de este estudio, el aceite de oliva no comestible tenía diferentes concentraciones iniciales de ácidos grasos libres (2,5, 5,0 y 10,0%) y se procesó mediante esterificación catalizada por ácido. Se utilizaron varios métodos de calentamiento para este propósito. La esterificación asistida por ultrasonido y los métodos tradicionales de esterificación asistida por agitador magnético fueron similares entre sí en términos de sus efectos sobre la reducción de ácidos grasos libres. Sin embargo, el tiempo de reacción usando ultrasonidos fue significativamente más corto que el de agitador magnético tradicional. En la segunda fase de este estudio, la producción de biodiesel, a partir de aceite de oliva no comestible, se llevó a cabo mediante transesterificación asistida por ultrasonidos. Las variables independientes fueron, nivel de potencia de ultrasonido (30, 90 y 150 W), relación molar metanol/aceite (3, 9 y 15), concentración de catalizador (0,5, 1,0 y 1,5%), tiempo de ultrasonido (15, 30 y 45 min) y temperatura de reacción (45, 55 y 65 °C) que afectaron al rendimiento y a las constantes fisicoquímicas del biodiesel producido. El biodiésel más puro (98,95%) y el mayor rendimiento (92,69%) se observaron cuando se utilizó un nivel de potencia de ultrasonido de 90 W, una relación molar de metanol / aceite de 9, una concentración de catalizador del 1,0%, un tiempo de ultrasonido de 30 min, y una temperatura de reacción de 55 °C. La optimización de las condiciones de reacción de la operación de ultrasonido puede aumentar efectivamente el rendimiento de biodiésel (92,69%), al tiempo que reduce la cantidad de consumo de energía (4,775 kWh/kg) y acorta el tiempo de reacción (30 min), en comparación con el agitador magnético tradicional (77,28 %, 2,17 kWh/kg y 120 min, respectivamente). Por lo tanto, la transesterificación asistida por ultrasonido puede servir como una alternativa eficaz debido a su operación rápida y económica en la producción de biodiesel a partir de aceite de oliva no comestible

Mejora de la estabilidad oxidativa del aceite de oliva: Incorporación de Espirulina y evaluación de su sinergismo con ácido cítrico

The effects of different Spirulina concentrations used alone and in combination with citric acid on the oxidative stability of olive oil were assessed. The amounts of primary and secondary oxidation products produced in Spirulina samples were lower than that of the control. The improved oxidative stability indices of Spirulina samples with and without citric acid were in the range of 85.20–94.47% and 258.10–260.21%, respectively. In comparison with the control, Spirulina samples manifested significantly higher carotenoid and chlorophyll contents at the beginning and end of the storage period. The presence of these bioactive compounds results from the presence of Spirulina in the medium and can thus retard the oxidation of olive oil. A higher oxidative stability was reached using BHT in comparison with Spirulina samples. Furthermore, no synergistic action was observed in possible connections between citric acid and Spirulina. In conclusion, Spirulina can enhance oxidative stability and improve the shelf life of olive oil.Se evaluaron los efectos de diferentes concentraciones de Espirulina usadas solas y en combinación con ácido cítrico sobre la estabilidad oxidativa del aceite de oliva. Las cantidades de productos de oxidación primarios y secundarios producidos en muestras de Espirulina fueron menores que las del control. Además, la estabilidad oxidativa de muestras de Espirulina con y sin ácido cítrico estaban en el intervalo de 85,20–94,47% y 258,10–260,21%, respectivamente. En comparación con el control, las muestras de Espirulina mostraron un contenido significativamente mayor de carotenoides y clorofila al inicio y al final del período de almacenamiento. La presencia de estos compuestos bioactivos y la presencia de Espirulina en el medio pueden retardar la oxidación del aceite de oliva. Se obtuvo una mayor estabilidad oxidativa usando BHT en comparación con muestras de Espirulina. Además, no se observó ninguna acción sinérgica en las posibles combinaciones entre el ácido cítrico y la Espirulina. En conclusión, la Espirulina puede mejorar la estabilidad oxidativa y la vida útil del aceite de oliva

Experimental and numerical investigation of tensile and flexural behavior of nanoclay wood-plastic composite

In this study, the effect of wood powder and nanoclay particle content on composites’ mechanical behavior made with polyethylene matrix has been investigated. The wood flour as a rein-forcer made of wood powder was at levels of 30, 40, and 50 wt.%, and additional reinforcement with nanoclay at 0, 1, 3, and 5 wt.%. Furthermore, to make a composite matrix, high-density polyethylene was used at levels of 70, 60, and 50% by weight. Wood-plastic composite (WPC) specimens were manufactured in injection molding. After preparing the specimens, tensile and bending tests were performed on samples. The mechanical properties such as tensile and flexural strength and flexural modulus were measured. Results showed that nanoclay particle content increases flexural modulus, flexural strength, modulus of elasticity, and tensile strength. The experimental test results show that Young’s moduli increased with the volume of wood flour. The biggest modulus of elasticity was achieved in the samples having 50 wt.% of wood powder. Furthermore, the highest value of tensile strength was achieved at the level of 30 wt.%. The highest flexural strength was for the sample containing 50% wood powder by weight. Additionally, a numerical model was made utilizing the Abaqus software using the finite element method (FEM). Comparing the numerical and experimental results, it was found that they are compatible in the linear-elastic and plastic state of the material. There are no crucial differences between experiment and FEM

Estabilidad oxidativa del aceite de soja conteniendo aceite de rosa e irradiado con UV y rayos X

The effects of UV radiation and X-ray on the oxidative stability of soybean oil were investigated. Also, rose oil was incorporated into soybean oil and its antioxidant activity was compared with that of α-tocopherol during accelerated storage. Treating the samples with radiation (UV and X-ray) stimulated the oxidation process in soybean oil in comparison with samples that did not receive radiation. X-rayed samples had significantly higher amounts of oxidation products than UV irradiated samples. The X-ray caused more oxidation in the samples due to its higher energy content. Also, the antioxidant activity of rose oil was comparable with that of α-tocopherol.Se investigaron los efectos de la radiación UV y los rayos X sobre la estabilidad oxidativa del aceite de soja. Además, el aceite de rosa se incorporó al aceite de soja y su actividad antioxidante se comparó con la del α-tocoferol durante el almacenamiento acelerado. El tratamiento de las muestras con radiación (UV y rayos X) fomentó el proceso de oxidación del aceite de soja en comparación con las muestras que no recibieron radiación. Las muestras con rayos X tenían cantidades significativamente más altas de productos de oxidación que las muestras irradiadas con UV. Los rayos X causaron más oxidación en las muestras debido a su mayor contenido de energía. Además, la actividad antioxidante del aceite de rosa fue comparable con la del α-tocoferol

Optimización de la extracción de ácido γ linolenico de spirulina mediante nuevos disolventes verdes

2 páginas, 1 tabla.-- Trabajo presentado al "Flucomp 2011: V Reunión de Expertos en Tecnologías de Fluidos Comprimidos" celebrada en Burgos (España) del 15 al 17 de junio de 2011.En el presente trabajo se ha optimizado, a través métodos quimiométricos, la obtención de ácidos grasos de alto valor añadido empleando técnicas de extracción con disolventes presurizados y/o subcríticos.Peer reviewe

Effect of <em>Thymus vulgaris</em> and <em>Bunium persicum</em> essential oils on the oxidative stability of virgin olive oil

Natural antioxidants are becoming a major focus because natural food ingredients are safer than synthetic types. The aim of this study was to investigate the protective effects of Thymus vulgaris and Bunium persicum essential oils (EO) on the oxidation of virgin olive oil (VOO) during accelerated storage. The antioxidant activities of EOs were compared with those of α-tocopherol and BHT. GC/MS analyses revealed that thymol (28.50%), p-cymene (27.14%), carvacrol (18.36%), and γ-terpinene (4.97%) are the main components of T. vulgaris EO, while cuminaldehyde (32.81%), γ-terpinene (16.02%) and p-cymene (14.07%) are the main components of B. persicum EO. Both EOs provided protection for the VOO, inhibiting the formation of primary and secondary oxidation products although T. vulgaris EO showed greater protection against the oxidation process than B. persicum EO. The effect of T. vulgaris essential oil on the oxidation inhibition of VOO was similar to that of BHT. α-Tocopherol showed no measurable effect on improving the oxidative stability of VOO. This study suggests that T. vulgaris and B. persicum EOs can be used to improve the oxidative stability of VOO

Limonene: Green non polar solvent for sample preparation

Trabajo presentado a la XIII Reunión Científica de la Sociedad Española de Cromatografía y Técnicas Afines celebrada en Tenerife (España) del 8 al 11 de octubre de 2013.Traditional non polar solvents like alkanes are obtained from non-renewable sources. The idea of Green Chemistry has its roots in sustainable development. Green Analytical Chemistry emerged from green chemistry in 2000. The principles of Green Analytical Chemistry emphasize the importance of using reagents obtained from renewable sources, eliminate toxic reagents and increase safety of the operator. The use of limonene as non-polar extracting agent in order to replace hexane has been slightly studied. Limonene is obtained from citrus peel residues, being the main compound in the terpene fraction of citrus peel oil. This compound possesses a dielectric constant close to hexane and has thus been suggested as a valuable green alternative to n-alkanes and halogenated hydrocarbons. In the present work a fast method for the isolation of high value lipids is presented involving the use of limonene, a green biodegradable solvent, as an alternative to traditional hexane extraction. The optimized process is based on pressurized liquid extraction (PLE) at 180°C for 15 min using limonene:ethanol (1:1). To prove the method efficacy, the extraction of lipids from marine microorganisms was selected. One green alga (Stigeoclonium) and four cyanobacteria (Spirulina, Nostoc, Anabaena and Phormidium) were tested. After extraction, lipids were analyzed by a Fast-GC-MS method.This work has been financed by the Spanish Ministry of Science (Project AGL2011-29857-C03-01). M.-T. Golmakani wishes to thank Iran Ministry of Science, Research, and Technology (# 42/4/52566) and Research council of the University of Tehran for supporting his stay in CIAL-CSIC, Spain. Authors would like to thank Spanish Bank of Algae (BEA) at University of Las Palmas de Gran Canaria, Spain (http://bea.marinebiotechnology.org) for the donation of samples.Peer Reviewe

Greener Solvents for Old Challenges

Trabajo presentado al 10th International Symposium on Supercritical Fluids celebrado en San Francisco (US) del 13 al 16 de mayo de 2012.At present, there is a clear need for alternative non-toxic solvents able to meet the Principles of Green Chemistry and Green Engineering and preferentially obtained from renewable sources. In the present work, three green solvents have been used, namely ethanol, ethyl lactate and limonene, to obtain high value lipids from the cyanobacteria Spirulina (Arthrospira platensis). Among the lipids found in Spirulina, γ-linolenic acid (GLA) is the most valuable, and is found at high concentration. Moreover, considering that Spirulina is easy to grow, and that the syntheses of different compounds mainly depend on growing conditions, the interest of obtaining lipids from algae and microalgae is increasing every day. Ethyl lactate and limonene are from natural origin and easily biodegradable; they can be found traditionally in consumed foodstuff like wine or beer (ethyl lactate) or fruits (limonene). These solvents have polarities in the range of acetonitrile and hexane, respectively. Therefore, these solvents, together with ethanol, can be used to cover a wide range of polarities. In order to achieve greener extractions, pressurized liquid extraction (PLE) with ethanol, ethyl lactate, limonene and their binary mixtures, together with ethanol-expanded CO2 (gas-expanded liquid; GXL) extraction were selected. Advantages of PLE are mainly the low solvent consumption, short extraction times and improved kinetics. On the other hand, the use of GXLs has, over SFE, the advantage of milder pressures and can be considered as an extraction liquid media ranging from the neat organic solvent to supercritical-CO2 (SC-CO2). Optimization of extraction conditions was carried out using chemometric approaches, namely: a Taguchi L9 design for the gas expanded liquid extractions (ethanol:CO2) and a central composite (43) for PLE experiments. The responses elected for the optimization were: total yield, fatty acid content and γ-linolenic acid in extracts. For its quantification GC-MS was used previous derivatization by ethylation.This work has been financed by the Ministry of Science and Innovation CSD2007-00063 FUN-CFOOD (Programa CONSOLIDER INGENIO 2010) project and by Comunidad Autónoma de Madrid (2009/AGR-1469). M.-T. Golmakani wishes to thank Iran Ministry of Science, Research, and Technology (42/4/52566) for supporting his stay in CIAL-CSIC, Spain.Peer Reviewe