Transesterification of triglycerides in a new ultrasonic-assisted mixing device

Abstract

We adapted a media mill to house an ultrasonic horn to transesterify triglycerides to biodiesel. This configuration combines enhanced mass transfer from the acoustic cavitation of the ultrasonic probe with nonconventional mixing from the media mill. It ensures oil and methanol circulates in the vicinity of the ultrasonic tip. We tested methanol, ethanol and isopropanol as alcohols and KOH as a catalyst to transesterify canola oil. The branched isopropanol lowers the biodiesel cloud point by 10 °C compared to biodiesel produced with methanol (fatty acid methyl ester). We withdrew samples at regular intervals and analysed them in a GC according to EN14103-2011. The ultrasonic-assisted mixing device that we designed converts most of the triglycerides with methanol within one minute of pulsed ultrasonic irradiation. The reaction with ethanol and isopropanol is faster than in classical batch reactors.