Researchers from the University of Porto, Portugal, are now looking at water-free methods for purifying biofuels, including those made from waste cooking oils, animal fats and other fatty wastes derived from industrial activities, according to the Institute of Chemical Engineers.

Traditional methods of biodiesel production use high volumes of water to remove impurities or ‘soaps’ to meet stringent quality standards. Fifty percent of water used in palm oil production becomes palm oil mill effluent. That is the largest pollutant of rivers in Malaysia.

Researchers used catalysts to pre-treat and target impurities such as calcium ‘soaps’ in the biodiesel instead of water. The impurities were then removed by absorption into resins or passing through ceramic membranes.

The researchers were able to produce good quality biodiesel from both virgin vegetable oil and, importantly, waste oils used for frying. The new process could provide significant economic and environmental benefits compared to other more energy intensive water-based production methods.

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