Optimization of Biodiesel Production from Spent Palm Cooking Oil Using Fractional Factorial Design Combined with the Response Surface Methodology

Abstract

Fractional Factorial Design (FFD) of the experiments combined with the response surface methodology was used to determine the optimum conditions for the production of biodiesel from Used Cooking Oil (UCO) in a batch reactor. Spent palm olein cooking oil was used as a raw material for biodiesel production as it is commonly used in most of the restaurants in Bahrain. The data indicate that the catalyst (NaOH) concentration and reaction temperature are the most influential factors, while the reaction time and molar ratio of methanol to oil (M:O) have only modest effects on the biodiesel yield. A 2nd order polynomial model was used to predict the biodiesel yield as a function of the catalyst amount and temperature. For the production of alkyl esters, the optimum conditions are 50°C, 0.30 wt % of NaOH catalyst, 1h reaction time and 9:1 feed molar ratio. These optimum values agree well with the literature values. At these optimum values, the alkyl esters content is 89.3 vol%, which is in good agreement with the predicted biodiesel yield (~ 91% by volume). Also, the biodiesel produced was characterized based on the flashpoint, viscosity, density, pH, percentage conversion of oil and yield.