M.P. Dorado

Evaluation of by-products from the biodiesel industry as fermentation feedstock for poly(3-hydroxybutyrate-co-3-hydroxyvalerate) production by Cupriavidus necator

Utilization of by-products from oilseed-based biodiesel production (crude glycerol, rapeseed meal hydrolysates) for microbial polyhydroxyalkanoate (PHA) production could lead to the replacement of expensive carbon sources, nutrient supplements and precursors for co-polymer production. Batch fermentations in shake flasks with varying amounts of free amino nitrogen led to the production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P(3HB-co-3HV)) with a 2.8-8% 3HV content. Fed-batch fermentations in shake flasks led to the production of 10.9g/L P(3HB-co-3HV) and a 55.6% P(3HB-co-3HV) content. NaCl concentrations between 2 and 6g/L gradually became inhibitory to bacterial growth and PHA formation, whereas in the case of K(2)SO(4), the inhibitory effect was observed only at concentrations higher than 20g/L. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and nuclear magnetic resonance ((13)C NMR) demonstrated that the incorporation of 3HV into the obtained P(3HB-co-3HV) lowered glass transition temperature, crystallinity and melting point as compared to polyhydroxybutyrate. Integrating PHA production in existing oilseed-based biodiesel plants could enhance the viability and sustainability of this first generation biorefinery.

Multiple response optimization of vegetable oils fatty acid composition to improve biodiesel physical properties.

The effect of fatty acids chain length (LC) and its interaction with unsaturation degree (UD) on important biodiesel quality parameters was studied. Low calorific value, kinematic viscosity, flash point, cetane number and cold filter plugging point of biodiesel blends covering a wide range of fatty acids were analyzed. Analytical results were processed with statistical regression to obtain a prediction model for each property, combining LC and UD. Due to the antagonistic effects of the chemical composition over quality properties, the Derringer desirability function was proposed to allow the most suitable fatty acid composition. This target was achieved considering an average of 1.26 double bounds and 17 carbon atoms. A set of combinations of LC and UD values that provides a biodiesel that fits the European standard EN 14214 was proposed. It was found that a reduction of FAME LC allows a lower UD while keeping biodiesel specifications under the standard limits.

Influence of vegetable oils fatty-acid composition on biodiesel optimization.

Biodiesel is an alternative fuel for diesel engines produced through transesterification of oleaginous feedstocks. To analyze the influence of the fatty-acid composition on biodiesel optimization, transesterification of several vegetable oils has been studied. Reactions were carried out in flasks filled with vegetable oils, heated to the reaction temperature and stirred at 1100 rpm. The reactions started when the methanol and potassium hydroxide solutions were added to the flasks. Concentration of catalyst, amount of methanol, reaction temperature and time were optimized using a factorial design and a surface response design. Also, a kinetics study was carried out to optimize the reaction time. Results showed that reaction parameters optimal values depend on the oil chemical and physical properties. It can be concluded from this field trial that the effect of both catalyst concentration and reaction time over the transesterification yield is greatly influenced by the saturation degree and fatty-acid chain length.

Influence of vegetable oils fatty acid composition on reaction temperature and glycerides conversion to biodiesel during transesterification.

Presence of unreacted glycerides in biodiesel may reduce drastically its quality. This is why conversion of raw material in biodiesel through transesterification needs to readjust reaction parameter values to complete. In the present work, monitoring of glycerides transformation in biodiesel during the transesterification of vegetable oils was carried out. To check the influence of the chemical composition on glycerides conversion, selected vegetable oils covered a wide range of fatty acid composition. Reactions were carried out under alkali-transesterification in the presence of methanol. In addition, a multiple regression model was proposed. Results showed that kinetics depends on chemical and physical properties of the oils. It was found that the optimal reaction temperature depends on both length and unsaturation degree of vegetable oils fatty acid chains. Vegetable oils with higher degree of unsaturation exhibit faster monoglycerides conversion to biodiesel. It can be concluded that fatty acid composition influences reaction parameters and glycerides conversion, hence biodiesel yield and economic viability.

Response surface modeling to predict biodiesel yield in a multi-feedstock biodiesel production plant.

For economic reasons, multi-feedstock plants are preferred to produce biodiesel. However, the optimal conditions of the transesterification reaction depend on the raw material, thus making difficult the achievement of a high yield of biodiesel when different types of feedstock are used under the same operational settings. In the present work, a response surface methodology is proposed to both predict biodiesel yield when different raw materials are used to produce biodiesel and to determine the optimal operational conditions of a multi-feedstock plant. The optimization of the transesterification reaction of five vegetable oils consisting in a wide range of fatty acid profiles has been carried out. Results provided a compromise zone where all the experimental responses satisfied the imposed specifications to achieve the goals, where the best optimal combination of parameters was selected. According to this model, the tested properties of the produced biodiesel are within the limits of the EN 14214 standard. It can be concluded that this methodology provides the most suitable operational conditions to achieve the highest biodiesel yield in a multi-feedstock biodiesel plant, also considering the economics of the process.

Biorefinery development through utilization of biodiesel industry by-products as sole fermentation feedstock for 1,3-propanediol production

Rapeseed meal (RSM) hydrolysate was evaluated as substitute for commercial nutrient supplements in 1,3-propanediol (PDO) fermentation using the strain Clostridium butyricum VPI 1718. RSM was enzymatically converted into a generic fermentation feedstock, enriched in amino acids, peptides and various micro-nutrients, using crude enzyme consortia produced via solid state fermentation by a fungal strain of Aspergillus oryzae. Initial free amino nitrogen concentration influenced PDO production in batch cultures. RSM hydrolysates were compared with commercial nutrient supplements regarding PDO production in fed-batch cultures carried out in a bench-scale bioreactor. The utilization of RSM hydrolysates in repeated batch cultivation resulted in a PDO concentration of 65.5 g/L with an overall productivity of 1.15 g/L/h that was almost 2 times higher than the productivity achieved when yeast extract was used as nutrient supplement.

Flow injection analysis-based methodology for automatic on-line monitoring and quality control for biodiesel production

An automated on-line approach based on determination of free and bound glycerol was here proposed to monitor biodiesel production. The method was based on liquid-liquid extraction of glycerol from the biodiesel to an aqueous ethanolic phase in which glycerol is oxidized to formaldehyde with meta periodate with subsequent reaction with acetylacetone. The reaction product was photometrically measured at 410 nm. Free and bound glycerol were differentiated by glycerides hydrolysis with potassium ethylate. The experimental set-up consisted of a flow-injection manifold for liquid-liquid extraction without phase separation and iterative change of the flow direction that enabled: (a) filling the flow manifold with a meta periodate-acetylacetone acceptor phase; (b) sampling of small amounts (microl) from the reactor; (c) determination of free glycerol by extraction from biodiesel to the aqueous phase with simultaneous oxidation-reaction with acetylacetone in the acceptor phase; (d) continuous monitoring of the aqueous phase by passage through a photometric detector; (e) filling the flow manifold with a potassium ethylate-meta periodate-acetylacetone new acceptor phase; (d) repetition of steps b-to-d to determine total glycerol after saponification of the bound glycerol by potassium ethylate; and (f) determination of bound glycerol by difference between the second and first analyses. The results showed that the proposed automated on-line method is a suitable option in routine analysis during biodiesel production.

Ultrasound-assisted biodiesel production from Camelina sativa oil.

The main drawbacks of biodiesel production are high reaction temperatures, stirring and time. These could be alleviated by aiding transesterification with alternative energy sources, i.e. ultrasound (US). In this study, biodiesel was obtained from Camelina sativa oil, aided with an ultrasonic probe (20kHz, 70% duty cycle, 50% amplitude). Design of experiments included the combination of sonication and agitation cycles, w/wo heating (50°C). To gain knowledge about the implications of the proposed methodology, conventional transesterification was optimized, resulting in higher needs on catalyst concentration and reaction time, compared to the proposed reaction. Although FAME content met EN 14103 standard, FAME yields were lower than those provided by US-assisted transesterification. Energy consumption measurements showed that ultrasound assisted transesterification required lower energy, temperature, catalyst and reaction time.

Molecular beam depletion by homogeneous and oscillating electric fields

Abstract As was suggested by a theoretical study made by one of us [An. Fis. 93 (1997) 105] the attenuation of a N 2 O supersonic beam was observed when molecules interact with both a homogeneous electric field and a radiofrequency resonant with the Stark N 2 O(1,±1)→(1,0) transition. The experimental observation of the new phenomenon opens interesting possibilities not only for fundamental research but also for technological applications, as for example the development of new analytical techniques based on such a molecular beam depletion.

Vegetable-based feedstocks for biofuels production

Abstract: This chapter presents the most frequent vegetable-based feedstocks to biodiesel and bioethanol production. The chapter focuses on first- and second-generation biofuels with special emphasis on low-cost feedstocks. Finally, raw materials for developing technologies, including anaerobic digestion to produce biogas, Fischer-Tropsch from biomass, pyrolysis and biological production of bio-hydrogen are discussed.