2.3. Catalyst characterization
Scanning Electron Microscopy (SEM) analysis was performed
to confirm the morphology of the catalyst using a High Resolution
Scanning Electron Microscope (Model: F E I Quanta
FEG 200).
The surface areas of Egg shell-CaO-900, Egg
shell-CaO-900-600 and commercial CaO were determined by
BET analysis using an ASAP 2020 surface area analyzer
(Micromeritics).
Basic strength of the catalyst was measured
using the Hammett Indicator Titration.
2.4. Transesterification process
The transesterification reactions were carried out in a 250 ml
3-necked round bottomed flask. The middle neck was used
to insert a mechanical stirrer (BioLab BL 232 D), one of the
side necks was fitted with a water-cooled condenser, and the
other neck was fitted with a temperature indicator. The speed
of the mechanical stirrer was monitored by using an analog
tachometer (Fuji Kogyo Co. Ltd., Kyoto). The desired amount
of catalysts, methanol and waste frying oil was introduced into
the round bottomed flask and the reactions were carried out at
65 _C for 1 h. After the reaction is completed, the catalyst was
separated by filtration and the transesterification products
were allowed to settle overnight for the clear separation of biodiesel
and glycerol. The conversion of oil to fatty acid methyl
esters was analyzed by 1H Nuclear Magnetic Resonance Spectroscopy
(1H NMR) using a Bruker Avance III 500 MHz (AV 500) spectrometer. CDCl3 was used as solvent. An equation has been given by Knothe [12] to calculate the percentage conversionof methyl esters C 100 _2AME
3AaCH2 ๐1 where C= percentage conversion of triglycerides to methyl
esters, AME = integration value of the methoxy protons of
the methyl esters and Aa–CH2 = integration value of the a-methylene
protons.
reaction.
Commercial CaO was treated in the muffle furnace
at 600 _C for 3 h before use.