Milda Gumbytė

The influence of Oxidation on Tribological Properties of Rapeseed Oil

Abstract Approximately a half of all consumed lubricants, in one or another way, end up in the environment. Some countries put forward recommendations or even requirements for the use of environmentally friendly bio-lubricants the purpose of which is to reduce a negative influence of lubricants. The priority areas of using environmentally friendly lubricants cover water transport, hydraulic systems in forestry machinery, railway applications, road building machines etc. Particularly it is the case when an increased possibility of putting a lubricant in the environment occurs. Regarding good lubricity and excellent biodegradability, vegetable oils are widely used as environmentally friendly lubricants. The biggest disadvantage of vegetable oils as base stock for lubricants is pure oxidation stability. This article deals with the influence of thermal oxidation on tribological properties of rapeseed oil. The obtained results show that oxidation decreases lubrication ability due to structural changes in oil. ...

Enzymatic microalgae oil transesterification with ethanol in mineral diesel fuel media

This article examines opportunities of enzyme application during the production of biodiesel from microalgae oil by its transesterification in the mixture with mineral diesel fuel. The oil and mineral diesel fuel ratio in the reaction mixture enabled a yield of 7% ester content in the mixture. Effectiveness tests were conducted on seven industrial lipases, and Lipozyme TL IM was selected as the most effective lipase for further optimization. The process of algae oil transesterification with ethanol was optimized by applying response surface methodology. The interactions and impacts of the following independent variables on the transesterification yield were evaluated: ethanol and oil molar ratio, process duration, lipase content, and temperature. Optimum conditions were determined: a temperature of 30 °C, 13.26% biocatalyst (from the oil content), an ethanol and oil molar ratio of 4.54:1, and a process duration of 13 h. The transesterification yield of the product under the above conditions reached 98%.

BIODIESEL FUEL PRODUCTION FROM MICROALGAE OIL BY APPLYING ENZYMATIC TRANSESTERIFICATION WITH ETHANOL

Rapeseed is currently the main raw material for biodiesel production in Europe. The search for new raw materials is very important for the increase of biodiesel fuel production volume. Microalgae are one of alternatives for biodiesel fuel production. In this research, transesterification of microalgae Chlorella sp . oil with ethanol by applying the biotechnological method has been studied. The effectiveness of seven commercial lipases was evaluated. The most effective lipase Lipolase 100 L was selected for optimization of reaction conditions. The influence of main process parameters, including the ethanol to oil molar ratio, lipase amount and process duration on transesterification yield was evaluated. The results revealed, that process duration and amount of lipase affected the transesterification yield mostly. The biodiesel yield higher than 96.5 % could be obtained when ethanol and oil molar ratio in reaction mixture is 8:1, process duration – 24 hours, lipase amount – 8 %. Keywords: biodiesel, enzymatic transesterification, ethanol, microalgae oil Article DOI: http://doi.org/10.15544/RD.2015.002