Scheme 1: First remove peroxide and then dehydrate, qualitatively determine the amount of peroxide, determine the amount of peroxide, remove peroxide, distill, distill twice, remove fractions, and save. Actual measurement: Take the polyurethane prepolymer waste liquid and add 1% sodium borohydride and stir for 15 minutes, measure the peroxide, completely remove it, and then distill it in a water bath. The test result shows that the distilled liquid only accounts for 47.15%, while the remaining liquid accounts for 52.85. The recovery rate is too low and unreasonable.

Scheme 2: Dehydrate first and then remove peroxide azeotropic dehydration-adding calcium oxide dehydration-reducing oxide with calcium hydride and further dehydrating-distilling-preserving. Since the polyurethane prepolymer forms an azeotropic mixture with water under one atmosphere, the boiling point is 63.4°C and the moisture content is 5%. Therefore, when the water content is greater than 5%, azeotropic dehydration can be carried out first. Since the measured water content of the waste polyurethane prepolymer used in this experiment is 4.9%, azeotropic dehydration is not required.