Steryl glucosides recovered from biodiesel tank deposits are an excellent source of phytosterols

Abstract

Over the biodiesel production process some minor components are produced and being accumulated on the storage tanks where precipitate, having a negative impact on the quality of the final product. The identity of the main component of the tank deposits have been unequivocally identified as steryl glucosides (SG). Looking for new repurposed and revalued byproducts from waste of biodiesel production, SG were recognized as potential candidates. Starting from biodiesel tank deposits, a purification procedure was proposed and optimized providing highly pure SG (99%). The procedure allowed the biodiesel recovery, and applied solvents that are commonly used on the vegetable oil and biodiesel factories. Finally, looking to demonstrate the potential of SG as a biorefinery valuable raw material, a process to produce phytosterols was investigated. The proposed circular procedure uses mineral acid and water as reaction media, without extractions with organic solvents. The reaction proved to be very efficient with yields as high as 95%, providing a highly pure raw product (99%). Moreover, the batch process allowed reusing the acidified water at least nine times.