Chinese tallow tree (TT) seeds are a rich source of lipids and have the potential to be a biodiesel feedstock, but currently, its invasive nature does not favor large scale cultivation. Being a nonfood material, they have many advantages over conventional crops that are used for biodiesel production. The purpose of this study was to determine optimal oil extraction parameters in a batch-type and laboratory scale continuous-flow microwave system to obtain maximum oil recovery from whole TT seeds using ethanol as the extracting solvent. For the batch system, extractions were carried out for different time-temperature combinations ranging from 60 to 120 degrees C for up to 20 min. The batch system was modified for continuous extractions, which were carried out at 50, 60, and 73 degrees C and maintained for various residence times of up to 20 min. Control runs were performed under similar extraction conditions and the results compared well, especially when accounting for extremely short extraction times (minutes vs hours). Maximum yields of 35.32% and 32.51% (by weight of dry mass) were obtained for the continuous and batch process, respectively. The major advantage of microwave assisted solvent extraction is the reduced time of extraction required to obtain total recoverable lipids, with corresponding reduction in energy consumption costs per unit of lipid extracted. This study indicates that microwave extraction using ethanol as a solvent can be used as a viable alternative to conventional lipid extraction techniques for TT seeds.
The use of microwaves as a heating medium to drive the transesterification of vegetable oils into ethyl esters was investigated. A continuous-flow microwave-assisted transesterification of soybean and rice bran oil was carried out in the presence of ethanol, using a molar ratio alcohol/oil of 5:1, and 0.6% w/w of sodium hydroxide as catalyst. The reactions were performed at atmospheric pressure, using a flow rate of 100 mL/min at temperatures of 50 and 73 °C for different reaction times (1, 5, and 10 min). At all tested parameters, the ethyl ester biodiesel produced conformed with ASTM specifications, with conversion rates between 96.7 and 99.3%, indicating a good quality biodiesel. The results indicated that microwave heating can be used effectively to obtain high ethyl esters of fatty acids (biodiesel) yields at lower alcohol/oil ratios, effectively reducing the reaction time, even under continuous-flow reactions due to a reduction in activation energy and an increase in Arrhenius pre-exponential factor. The results indicate that this heating process has potential to be scaled up for use in the industry to produce good quality biodiesel using ethanol as the alcohol of choice.
The Chinese tallow tree (TT) has been widely considered to be an invasive species in the US without potential benefits. However, the literature on TT seeds is scarce and the effect of storage conditions on seed oil quality in particular has not been published to our knowledge. Prior research revealed that TT has a very high yield of seeds containing large percentages of long and short chain fatty acids (mainly palmitic fatty acid, along with some oleic, linoleic and linolenic fatty acids), which can be base transesterified into biodiesel. This study aims to address the issue of the quality of the kernel oil of TT seeds stored at different temperatures (4°C and room temperature) and under controlled atmosphere storage conditions (3% CO 2 , 6% CO 2 , vacuum, normal headspace). The total storage time was 3 months with the oil quality being analyzed weekly. Extracted oil was analyzed by titratable acidity, peroxide value, oxidative stability index and fatty acid composition. These experiments provided evidence that, after 12 weeks of storage, a controlled atmosphere did not produce any remarkable advantage over low cost air storage. The results validate the belief that no elaborate storage conditions are required to store this economically promising high oil content biofuel feedstock.
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