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The kinetics of the sunflower oil methanolysis process was studied at lower temperatures (10-30 degrees C). The sigmoidal kinetics of the process was explained by the mass transfer controlled region in the initial heterogenous regime, followed by the chemical reaction controlled region in the pseudo-homogenous regime. A simple kinetic model, which did not require complex computation of the kinetic constants, was used for simulation of the TG conversion and the FAME formation in the latter regime: the fast irreversible second-order reaction was followed by the slow reversible second-order reaction close to the completion of the methanolysis reaction. The mass transfer was related to the drop size of the dispersed (methanol) phase, which reduced rapidly with the progress of the methanolysis reaction. This was attributed to the formation of the emulsifying agents stabilizing the emulsion of methanol drops into the oil.

The kinetics of Ca(OH)(2)-catalyzed methanolysis of sunflower oil was studied at a moderate temperature (60 degrees C), a methanol-to-oil molar ratio (6:1) and different catalyst amounts (from 1% to 10% based on oil weight). The methanolysis process was shown to involve the initial triglyceride (TG) mass transfer controlled region, followed by the chemical reaction controlled region in the latter period. The TG mass transfer limitation was caused by the low available active specific catalyst surface due to the high adsorbed methanol concentration. Both the TG mass transfer and chemical reaction rates increased with increasing the catalyst amount.

Biodiesel, an alternative to fossil fuels, consists of alkyl, usually methyl, esters of fatty acids (FAME). Conventionally, it is mostly obtained by homogeneous base catalyzed methanolysis of edible oils. Despite the significant advantages, the main drawbacks of this process are the high requirements in terms of the quality of the raw materials and environmentally unfavorable processes of catalyst separation and products purification. For these reasons, the researches of biodiesel synthesis are aimed at developing new processes that are economically and environmentally acceptable. In this paper processes of FAME synthesis, their advantages, disadvantages and opportunities for improving are analyzed, in order to develop processes suitable for industrial applications. The main aim was to present an overview of the researches in developing biodiesel synthesis providing a high FAME yield, which are environmentally-friendly and economically acceptable. Heterogeneously catalyzed process has most often studied, aiming at developing catalytic active, stable and cheap catalysts as well as at process improvement. The developments of enzyme and noncatalytic processes are mainly aimed at reducing production costs and increasing the FAME yield under mild reaction conditions, respectively. Generally, the perspectives of biodiesel synthesis include the use of continuous processes and suitable reactor systems.

The kinetics of the sunflower oil ethanolysis process using NaOH as a catalyst was studied at different reaction conditions. The reaction system was considered as a pseudo-homogeneous one with no mass transfer limitations. It was also assumed that the chemical reaction rate controlled the overall process kinetics. A simple kinetic model consisting of the irreversible second-order reaction followed by the reversible second-order reaction close to the completion of the ethanolysis reaction was used for the simulation of the triglyceride conversion and the fatty acid ethyl ester formation. The proposed kinetics model fitted the experimental data well.

Abstract In the present work, the sodium hydroxide-catalyzed synthesis of fatty acid ethyl esters (FAEE) from sunflower oil and ethanol was optimized using a 33 full factorial design of experiments with two replications and the response surface methodology (RSM). The effects of temperature, ethanol-to-oil molar ratio and catalyst loading on the FAEE were studied. The ANOVA results shows that at the 95% confidence level all three factors and the 2-way interactions of reaction temperature with ethanol-to-oil molar ratio and catalyst loading significantly affect the FAEE formation. A second-order polynomial equation is developed to relate the FAEE purity and the operational variables (temperature, ethanol-to-oil molar ratio and catalyst loading). The fitted model shows a good agreement between predicted and actual FAEE purities (R2 = 0.937; mean relative percentage deviation ±1%), demonstrating the validity of the regression analysis in the process optimization. The optimal process conditions were: ethanol-to-oil molar ratio of 12:1, reaction temperature of 75 °C and catalysts loading of 1.25%. The RSM is proved to be suitable method for optimizing the operating conditions in order to maximize the FAEE purity.

Abstract Biodiesel has been studied in last few decades because of limited energy resources and a huge increase of the energy demand. The basic feedstocks for the production of biodiesel are vegetable oils and animal fats that contain primarily triacylglycerols while the main reaction is transesterification. This reaction is most frequently conducted at commercial scale in the presence of the homogeneous alkali catalyst. Previous studies on biodiesel were mainly focused on its production and fuel properties, while its environmental management is rarely considered. The present work is a review of the previous studies on treating wastewaters generated by the biodiesel production processes involving alkali-catalyzed transesterification. The attention is focused on physical, chemical, physico-chemical, electrochemical, biological and integrated treatment processes of biodiesel wastewaters. Both advantages and disadvantages of different biodiesel wastewater treatment processes are discussed. Since different input biodiesel wastewaters are employed in different studies, it is difficult to compare different treatments with respect to their contaminant removal efficiencies. Proper acidification and chemical coagulation/flocculation or electrocoagulation remove grease and oil successfully but they are unsuccessful in removing COD. The combinations of acidification, coagulation and the electrochemical treatment improve the removal efficiencies of COD and BOD. Advanced oxidation technologies appear not to be effective in removing the contaminants from raw biodiesel wastewaters. The performance of biological processes is improved by the pretreatment of biodiesel wastewater with acidification, chemical coagulation, electrocoagulation or photo-Fenton. When selecting a treatment process, it should be evaluated with respect to its treatment efficiency and operational requirements. The right choice is probably an integration treatment involving acidification, coagulation/flocculation or electrocoagulation and a biological process. The reuse of the pretreated wastewater is also an interesting alternative.

Abstract This paper overviews the technological, technical, economic, environmental, social, toxicological and human health risk considerations of biodiesel production and use. The future efforts in the technological domain should be directed towards low–cost and non–edible feedstocks, advanced technologies with reduced overall production costs and profitable production capacity. Process innovations that include new more active and stable catalysts, advanced reactors, continuous operation, lower energy inputs, better energy balance and lower GHG emissions and produce low or no wastes can lead to more efficient biodiesel production. Environmentally sustainable biodiesel production requires that sustainability standards cover direct and indirect impacts on the environment, i.e. soil, water and air. The combination of technological with economic, social and environmental issues will increase biodiesel benefits and may lead to integrated biorefineries capable of producing sustainable biodiesel and other valuable chemicals. Government policies will be the primary driving force for further increases in biodiesel production. Increased cooperation among governments and various stakeholders is needed to develop and apply corresponding sustainability criteria in a consistent way worldwide as soon as possible.

Abstract This paper deals with biodiesel production from corn oil as a feedstock via the transesterification and esterification reactions. To date, corn oil has not been considered a viable biodiesel feedstock because of its high edible value and relatively high price, but some industrial corn processing co-products, such as corn germ and dried distillers grains with solubles (DDGS), have potential for this application after the extraction of corn distillers oil (CDO). Here, after brief discussion of the issues related to corn botany, cultivation, and use, as well as the corn germ and oil composition, properties and use, the methods of corn processing for germ and DDGS recovery are presented. In addition, the mechanical and solvent extraction techniques for oil recovery from whole ground corn kernels, germs, and DDGS are considered. Furthermore, biodiesel production from corn oil, waste frying corn oil, and CDO is critically analyzed. It is expected that further investigation will be directed toward developing simpler, more effective and energy-saving technologies for biodiesel production from corn oil-based feedstocks, especially from CDO. The integration of biodiesel production directly into corn-based ethanol production will advance the overall economy of industrial plants. Furthermore, the fuel properties, performances and exhaust gas emissions of corn-based biodiesel and its blends with diesel fuel are discussed, taking into account the biodiesel quality standards. Finally, issues related to the environmental and socio-economic impacts of corn-based biodiesel production and use are also tackled.