A green and low-cost room temperature biodiesel production method from waste oil using egg shells as catalyst

Egg shells were used as catalyst for biodiesel production from waste cooking oil at room temperature. High FAME yield (97 wt.%) was obtained after 11 h of regular stirring and the catalyst was reused five times. The catalyst was stored for at least three months without decrease in its activity and for a year with only 10% decrease in FAME yield.93