Snail (Helix pomatia) Shells as a Catalyst for Biodiesel Synthesis

Biodiesel is an alternative to conventional diesel. The use of heterogeneous catalysts in biodiesel production is promising, as it is easier to separate them from the product than homogeneous ones. It was determined that the calcined grape snail (Helix pomatia) shells show good catalytic efficiency in the rapeseed oil transesterification process with methanol. It was determined that the CaO concentration in calcined grape snail (Helix pomatia) shells was 97.74 ± 0.12%. Using the response surface methodology, the biodiesel production process was optimized. The influence of the interaction of independent variables and optimal conditions for the synthesis of rapeseed oil methyl ester was determined: an alcohol-to-oil molar ratio of 10.6:1, a catalyst concentration of 5.7 wt%, and a reaction duration of 7.8 h at a temperature of 64 °C. The physical and chemical properties of the produced biodiesel at optimal process conditions are presented, and their compliance with the requirements of the biodiesel standard is discussed. The produced biodiesel using snail shells, which are food processing waste, meets the requirements of the standard and can be used in diesel engines during the summer period.