BIODIESEL PRODUCTION USING CONTINUOUS ULTRASONICATION OF NON-EDIBLE OILS

Abstract

The present work focuses on biodiesel production from non-edible oils using continuous ultrasonication. The use of non-edible oils as a feedstock improves the economy of biodiesel production. Further, the process intensification techniques, such as ultrasonic irradiation enhances the mass transfer rate between the reactants which are immiscible and thereby reduces the reaction time and improves production yield. When compared to batch process, using continuous ultrasonication assisted transesterification process improves the overall economic effect, providing a lower production cost, uniform product quality and easier control of the process and decreases the reactor volume by reducing retention time required to achieve the desired degree of triglycerides conversion. In the present work, jatropha curcas oil was converted to biodiesel in a two-step process. In the first step, esterification of jatropha curcas oil was carried out with methanol in the presence of sulphuric acid catalyst in batch process. Second step involves transesterification of esterified jatropha curcas oil with methanol in continuous process using ultrasonication at a temperature of 35- 40 0C. Sodium methoxide with 1 wt. % of oil was used as base catalyst and 6:1 methanol to oil molar ratio was taken. Experiments were designed using Central Composite Design (CCD) in Response Surface Methodology (RSM) in Design Expert software to determine the optimized process parameters. Amplitude, pulse ratio and flowrate are taken as process variables. Maximum FAME conversion was determined to be 77.21 % and was obtained at 80 % amplitude, 80 % pulse ratio and 4 mL/min total flowrate. Highest biodiesel yield obtained was 70.82 % at same operating conditions. Parameter optimization is done and optimized conditions were determined to be 64 % amplitude, 80 % pulse ratio and 3.5 mL/min total flowrate where FAME conversion and biodiesel yield were found to be 76.84 % and 70.25 % respectively and were in good agreement with the predicted values. Properties of produced biodiesel such as specific gravity, flash point and fire point, cloud point and pour point at these conditions were matching with the EN 14214 specifications for standard biodiesel. Energy consumed per gram of biodiesel produced is less using ultrasonication process which makes the process energy efficient.