To determine the influence of the calcination temperature on
the activity of the eggshell-derived catalyst, eggshell was calcined
at different temperatures between 200 C and 1000 C and then
tested for the transesterification of soybean oil to produce biodiesel.
These results showed that eggshell sample calcined above
800 C was the most active catalyst. A yield of 97–99% was obtained
in the presence of eggshell sample calcined above 800 C.
When the calcination temperature was 700 C, a yield of 90% was
achieved, whereas, a low level of activity was observed when the
calcination temperature was