Simultaneous oil extraction and trans-esterification of high acidity rapeseed oil

Abstract

Simultaneous extraction and trans-esterification of high-acidity (3 mgKOH/g) rapeseed oil, using a mineral diesel (as an extraction solvent) and methanol mixture, have been investigated aiming to obtain a mixture of mineral diesel and biodiesel fuel which can currently be used as fuel. Mineral diesel and rapeseed oil ratio in mixture was 9:1 (w/w). Effectiveness of different biocatalysts-lipases (Lipozyme RM IM, Lipozyme TL IM, Novozyme 435, Lipozyme 435, Lipolase 100 L, Lecitase Ultra, Resinase A 2X, Palatase 20000 L, Lipozyme CALB, Liopozyme TL 100 L, Lipex 100L), suitable for in-situ processes, were studied and the most effective was selected. The conversion of rapeseed oil to biodiesel fuel was evaluated in the presence of a lipase from Lipozyme TL IM (Thermomyces lanuginosus). We aimed to extract the maximum amount of rapeseed oil, as well as to fully convert the oil to methyl esters. At the optimal conditions the 99.9% of the rapeseed oil was extracted from rapeseed. The maximum methyl esters yield was 98.99% (degree of trans-esterification more than 96.5%) after 5 h of reaction. The quantities of monoglycerides (0.38%), diglycerides (0.06%) and triglycerides (0.00%) remaining in the product comply with the requirements of standard for biodiesel fuel. It was found that the optimum conditions for simultaneous oil extraction and trans-esterification using methanol and lipase-Lipozyme TL IM were the following: molar ratio of methanol to oil-5:1, amount of lipase preparation Lipozyme TL IM-7%, duration of reaction-5h, temperature-23±2°C.