Research Highlights

doi:10.1038/nindia.2018.102 Published online 9 August 2018

Biodiesel from waste cooking oil

Catalysts made from discarded chicken eggshells can convert waste cooking oil into biodiesel, a study reveals1. This is a promising green process to produce biodiesel, an alternative to fossil fuels that emit greenhouse gases.

Commonly used catalysts such as potassium hydroxide and sodium hydroxide are known to corrode the industrial equipment that helps churn out biodiesel. Besides being expensive, such catalyst-based processes produce large volumes of wastewater.

To find an eco-friendly process, scientists from the Institute of Chemical Technology in Mumbai, India, synthesised two catalysts (calcium oxide and calcium diglyceroxide) from chicken eggshells. They then compared and tested these catalysts’ efficiency in converting waste cooking oil into biodiesel. 

Both catalysts contained nanocrystals. Calcium diglyceroxide helped produce more biodiesel than the calcium oxide. Increasing amounts of the catalysts also enhanced biodiesel yield considerably.

The chemical reaction that makes the biodiesel requires enough energy in the form of heat. An increase in temperature from 500C to 650C increased biodiesel yield from 60% to 93%. At 600C, however, the biodiesel yield reached 96%, indicating it to be an optimal temperature for the reaction.   

The catalysts can be reused. The biodiesel made from the waste cooking oil is not potentially corrosive to the fuel tank, linings and pipelines of a car. It can even fuel an engine at an extremely low temperature, showing that it has all the properties of a good biofuel. 


1. Gupta, A. R. et al. Waste cooking oil and waste chicken eggshells derived solid base catalyst for the biodiesel production: optimization and kinetics. Waste. Manag. 79, 169-178 (2018)