Recovery and purification method of glycerol as by-product of biodiesel production prepared by Jatrohpa curcas seed oil

The invention discloses a recovery and refining method for a diesel byproduct, glycerin produced by barbadosnut seed oil, wherein the glycerin can finally reach the medical-grade standard. The concrete method comprises the following steps: methanol is vaporized under pressure reduction in a waste liquid obtained after the barbadosnut seed oil uses potassium hydroxide as a catalyst to produce biodiesel through a methanol or alcohol ester exchange reaction, an aqueous solution of acid is added into a remaining liquid for reaction, a crude fatty acid is removed through liquid separation, then an aqueous solution of alkali is used to neutralize to be neutral, a filtrate is added with absolute ethyl alcohol after the filtration, kept stand for one night, and is refiltered, inorganic salt is further removed, and alcohol is removed through vaporization. Finally, the molecular distillation is performed to obtain medical-grade high-purity glycerin. The medical-grade glycerin is produced by utilizing the barbadosnut seed oil to produce the biodiesel byproduct, the obtained product has the advantages of excellent performance, suitability for industrialized production and so on, and the method greatly reduces the production cost for the biodiesel and has remarkable economical and social benefits.