Transesterification of postfrying oils and utilization of the glycerol phase

Methyl esters synthesis using spent frying oils and subsequent utilization of the glycerol phase have been described. Potassium hydroxide (basic transesterification) at 25°C and sulfuric acid (acidic transesterification) at 60 °C were used. The conditions of the transesterification reaction which affect the yield and purity of the product esters, including the oil quality (acid number, peroxide number), were considered. It was found that dipper thermal oil degradation during frying resulted in FAME of inferior calorific value. The glycerol fraction from methanolysis was purified and used for the production of triacetin with the 76% yield.