Lipase-Catalysed In Situ Transesterification of Waste Rapeseed Oil to Produce Diesel-Biodiesel Blends

Egle Sendzikiene,Violeta Makareviciene,Migle Santaraite

doi:10.3390/pr8091118

Abstract

Rapeseed oil of high acidity, an agricultural industry by-product unsuitable for food, was used as an inexpensive raw material for the production of biodiesel fuel. The use of rapeseed oil that is unsuitable for food and lipase as a catalyst makes the biodiesel production process environmentally friendly. Simultaneous oil extraction and in situ transesterification using diesel as an extraction solvent was investigated to obtain a diesel-biodiesel blend. The diesel and rapeseed oil blend ratio was 9:1 (w/w). The enzymatic production of biodiesel from rapeseed oil with high acidity and methanol using eleven different lipases as biocatalysts was studied. The most effective biocatalyst, lipase—Lipozyme TL IM (Thermomyces lanuginosus), which is suitable for in situ transesterification—was selected, and the conversion of rapeseed oil into fatty acid methyl ester was evaluated. The influence of the amount of methanol and lipase, the reaction temperature and the reaction time were investigated to achieve the highest degree of transesterification. The optimal reaction conditions, when the methanol to oil molar ratio was 5:1, were found to be a reaction time of 5 h, a reaction temperature of 25 °C and a lipase (Lipozyme TL IM) concentration of 5% (based on oil weight). Under these optimal conditions, 99.90% (w/w) of the rapeseed oil was extracted from the seed and transesterified. The degree of transesterification obtained was 98.76% (w/w). Additionally, the glyceride content in the biodiesel fuel was investigated and met the requirements perfectly.

Highlights

Biodiesel fuel, produced from renewable raw materials such as animal fats or vegetable oils, is a better choice diesel fuel
When the lipase concentration in the reaction media is 3% or 4%, the glyceride concentration of the biological fraction of reaction product do not meet the requirements for glyceride content in biodiesel fuel
It can be concluded that a 5% lipase concentration is the most appropriate for the lipase-catalysed in situ transesterification process because of a high yield of rapeseed oil and rapeseed methyl ester (99.90% (w/w)), a high degree of transesterification (98.76% (w/w)), and optimal glyceride content in biodiesel fuel

Summary

Introduction

Biodiesel fuel, produced from renewable raw materials such as animal fats or vegetable oils, is a better choice diesel fuel. Beginning with the first published research on the production of biodiesel from oil-containing raw materials, more than 350 oil-containing materials were explored as potential raw materials for biodiesel production [2]. These raw materials can be classified into five main classes: Oilseeds, agricultural waste, microbial biomass, microalgae, and biological waste [1]. It is important to widely investigate oil-containing raw materials that have no competition with the food industry and are suitable for the in situ transesterification process. The following non-edible raw materials have already been investigated: Jatropha seeds [3], Karanja seeds [4], Castor seeds [5], Cynara

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Conclusion