Among various heterogeneous catalysts proposed for biodiesel
production, CaO is well known for its high activity, high alkalinity
and poor solubility in methanol which makes it an ideal solid base
catalyst for biodiesel production[11]. In literature, there are many
studies that investigate the silent or US assisted biodiesel production using CaO, giving detailed information about CaO activity[13–
17]. On the other hand, dolomite is an anhydrous carbonate mineral with the formula CaMg(CO3)2[18]. Except some few studies,
biodiesel production using dolomite is not thoroughly investigated
and also there is not a detailed study on US assisted biodiesel production by transesterification using dolomite as solid catalyst.
Thus, the aim of this work was to investigate the effects of ultrasound on the heterogeneously catalyzed transesterification reaction. For this purpose, two different catalysts namely dolomite
and CaO were used and herewith the catalytic activities of CaO
and Dolomite were compared under ultrasonic irradiation
45 50
Temperature (C) 25 45 55
a
60
a
Initial experimental conditions.
I. Korkut, M. Bayramoglu / Fuel 180 (2016) 624–629 625
sonochemical reactor, magnetic stirring was applied at 600 rpm.
Due to the heating effect of US in the reaction medium, cooling
was applied by circulating water in the reactor jacket. In this
way, the reaction temperature was kept at the set point within
±1C. At the end of the reaction, the solid catalyst was separated
by centrifuge and then the liquid mixture was filtered by blue band
filter paper under vacuum. After filtration, the excess methanol
remaining in the heterogeneous liquid mixture was separated by
rotary evaporator under vacuum (100 mbar). The product liquid
was put into a separating funnel and was kept at room temperature for one day, to separate into an upper layer (biodiesel phase)
and a lower layer (glycerol phase). The FAME content of the biodiesel phase was determined by Agilent
6890 Gas Chromatogram
(GC) equipped with a flame ionization detector (FID) and capillary
column (CARBOWAX 20M) following European regulated procedure EN 14103. A typical biodiesel GC spectrum is given inFig. 2