Reusability of the Egg shell-CaO-900-600
One of the most important features for a heterogeneous catalyst is the ability to be recycled. Reusability of the Egg shell-CaO-900-600 catalyst obtained by the calcination–hydration–dehydration treatment of egg shells was examined for 6 cycles with 5 wt% catalyst (based on oil weight), a methanol to oil ratio of 12:1, a reaction temperature of 65 °C and a reaction time of 1 h and it is shown in Fig. 4. After each cycle, the solid catalyst was separated from the reaction mixture by filtration and washed with methanol to remove the adsorbed stains and recalcined at 600 °C for further use. The results indicate that a high biodiesel conversion of above 90% was achieved for all the 6 tested runs