Purification of residual glycerol obtained in biodiesel production from waste oils

Abstract

Domestic production of biodiesel is becoming increasingly widespread, via transesterification processes; it generates a significant amount of glycerol that can become available in various sectors of national industry providing that it has a level of compatible purity. This paper presents a purification route for glycerin obtained in alkaline methyl transesterification of waste oils and soybean oils of animal origin obtained from commercial rotissery processes. The residual oils were characterized as acid , peroxide, saponification and iodine values, as well as viscosity and ash contents; after obtaining the residual glycerine from biodiesel it was subjected to processes of pre-purification through washing with solvent, acidification and neutralization, followed by purification with active charcoal and cationic and anionic resins. After the process of purification the glycerin samples were characterized by glycerol content, alkalinity, ash, chloride, color and moisture, obtaining as the best result for glycerol content 94.19 ± 1.46 for glycerin obtained from soybean oil used.