Optimisation of Second-Generation Biodiesel Production from Australian Native Stone Fruit Oil Using Response Surface Method

Nanjappa Ashwath,Mohammad Anwar,Md Rahman,Mohammad Rasul

doi:10.3390/en11102566

Abstract

In this study, the production process of second-generation biodiesel from Australian native stone fruit have been optimised using response surface methodology via an alkali catalysed transesterification process. This process optimisation was performed varying three factors, each at three different levels. Methanol: oil molar ratio, catalyst concentration (wt %) and reaction temperature were the input factors in the optimisation process, while biodiesel yield was the key model output. Both 3D surface plots and 2D contour plots were developed using MINITAB 18 to predict optimum biodiesel yield. Gas chromatography (GC) and Fourier transform infrared (FTIR) analysis of the resulting biodiesel was also done for biodiesel characterisation. To predict biodiesel yield a quadratic model was created and it showed an R2 of 0.98 indicating the satisfactory performance of the model. Maximum biodiesel yield of 95.8% was obtained at a methanol: oil molar ratio of 6:1, KOH catalyst concentration of 0.5 wt % and a reaction temperature of 55 °C. At these reaction conditions, the predicted biodiesel yield was 95.9%. These results demonstrate reliable prediction of the transesterification process by Response surface methodology (RSM). The results also show that the properties of the synthesised Australian native stone fruit biodiesel satisfactorily meet the ASTM D6751 and EN14214 standards. In addition, the fuel properties of Australian native stone fruit biodiesel were found to be similar to those of conventional diesel fuel. Thus, it can be said that Australian native stone fruit seed oil could be used as a potential second-generation biodiesel source as well as an alternative fuel in diesel engines.

Highlights

Global climate change and the resulting desire for renewable energy sources has generated the interests for using biofuel in the transport sector [1]
It is clear that Australian native stone fruit oil (SFO) oil have similar fuel properties including fatty acid, calorific value and viscosity with the data of other researchers, it is expected that Australian native SFO may serve as a good feedstock for biodiesel production
Optimum operating parameters for transesterification of stone fruit seed oil were found to be methanol: oil molar ratio of 6:1, catalyst concentration 0.5 wt %, and a reaction temperature of 55 ◦ C, considering both reaction time and reaction agitation speed were fixed at 60 min and 600 rpm

Summary

Introduction

Global climate change and the resulting desire for renewable energy sources has generated the interests for using biofuel in the transport sector [1]. Due to the higher production of biofuel in recent years, it currently contributes 1.5% global transportation fuel. Of the total worldwide biofuel supply comes from emerging and developing countries. The expansion of biofuel production around the world has raised major concerns, for example the existence of several first-generation biofuels. Biofuels that are produced from edible sources are termed first-generation biofuels [2], and these have been increasingly questioned over some concerns such as food-fuel controversy, environmental pollution, and climate change. The increasing concern regarding the sustainability of several first-generation biofuels has led to investigations into the potential of producing biodiesel from non-food crops which are termed as second-generation biodiesel

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Conclusion