Peanut oil biodiesel production by methyl transesterification and application of the response surface

Abstract

Biodiesel is an environmentally friendly fuel alternative and a renewable energy source. According to the National Agency of Petroleum (NAP), biodiesel is a fuel composed of esters of long chain alkyl acids, produced by transesterification and/or esterification of vegetable oils or animal fats. The peanut oil presents a high oil content, becoming a promising alternative for biodiesel production. Nevertheless, due to the high viscosity of this oil, a previous step of transesterification is needed. The chemical transformation of transesterification involves diverse factors that need to be optimized to produce a biodiesel with higher quality. In this study, a study of the biodiesel production process by methyl transesterification in basic medium was accomplished following an experimental design associated with response surface methodology. As independent variables, two factors were selected (molar ratio alcohol/oil and temperature) in terms of the response variables that represent the quality of the biodiesel produced (acid index, specific mass, and kinematic viscosity), and the process performance (mass yield). The results have shown that most of the conditions applied have resulted in the production of a biodiesel with quality parameters within the limits specified by NAP. Additionally, statistical analyses have led to optimal molar ratio alcohol/oil and temperature ranges by which it is possible to obtain a maximum mass yield of 90-100%, corresponding to 6.7:1 to 8.7:1 and 47 °C to 60 °C, respectively.