Comparison of fuel and emission properties of petro diesel and sunflower biodiesel prepared by optimized production variables

► In this research, the values of the major factors affecting the transesterification of sunflower oil were optimized by response surface methodology. ► Biodiesel was derived from transesterification of sunflower oil with methanol and KOH was used as catalyst. It was assumed that the yield of biodiesel (dependent variable, Y) was mainly affected by the following variables: (1) the molar ratio of methanol to oil, (2) the weight percent of the catalyst, (3) the reaction time and (4) the temperature of the reaction. ► Using the obtained optimum values of the independent variable, samples of biodiesel were prepared and tested for some common fuel properties, including: flash point, cloud and pour point, kinematic viscosity, copper strip corrosion and ash content. ► Regular diesel fuel and the biodiesel prepared using the optimum values were used in a single cylinder diesel engine for exhaust emission analysis. ► The resulting optimized values for molar ratio of oil to methanol, weight percent of catalyst, reaction time and temperature of the medium were 1:5.5, 1.0%, 65.5 min and 51.7 °C, respectively. Using these optimum values, the yield of biodiesel was 83.4% which was higher than the runs based on experimental design. Most measured fuel properties of optimally produced biodiesel were within the specified range recommended for biodiesel. The emission property test indicated that exhaust emissions of the prepared biodiesel contained lower pollutant than petro diesel.