Transesterification reactions were carried out in a 300 ml threenecked cylindrical glass reactor equipped with a reflux condenser.
Known weights of methanol and catalysis were poured into the
reactor and the mixture was stirred magnetically. Then, canola
oil was added to the mixture. At the start of each run, the heterogeneous mixture was sonicated at continuous mode to generate an
initial homogeneous mixture until the reaction mixture reached to
the set temperature by the heating effect of ultrasound and hotplate heating as well. In all experiments, the heterogeneous mixture was sonicated at pulsed mode (pulse ratio 0.9) which is
beneficial for low electrical energy consumption and for easier control of reactor temperature and also for cooling the transducer[9].
To maintain stable and uniform cavitational activity in the
Fig. 1.Scheme of experimental setup.
Table 1
Variables and numeric values.
Variables Low level High level
Catalyst amount (wt.% of oil) 3 4 5
a
67
Methanol/oil ratio (mol/mol) 4 6 9a
12 15
Time (min) 60 75 90
a
105 120
Ultrasound power (W) 30 35 40
a
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