Methods for decolorizing colored polymer material and preparing regenerated polymer, and decolorizing solution

A method for decolorizing a colored polymer material, comprising:

• subjecting the colored polymer material to a first decolorizing treatment with a first decolorizing solution to remove a colorant from the colored polymer material, so as to obtain a first decolorized polymer material and a first used decolorizing solution;
• wherein the first decolorizing treatment is conducted at a temperature of not less than 100° C. for a time period of not less than 30 minutes;
• wherein the first decolorizing solution is selected from the group consisting of an unused decolorizing solution, a used decolorizing solution, and a decolorized solution, the first decolorizing solution including water, a ketone solvent, and a base;
• wherein in the first decolorizing solution, the base is present in an amount ranging from 2 g to 10 g, the ketone solvent is present in an amount not lower than 30 mL, based on 1 L of water;
• wherein a weight ratio of water to the colored polymer material is not lower than 5;
• wherein the used decolorizing solution is obtained by subjecting the colored polymer material to at least one decolorizing treatment with the unused decolorizing solution or the decolorized solution;
• and
• wherein the decolorized solution is obtained by subjecting the used decolorizing solution to a distillation treatment to obtain a distillate containing water and a ketone solvent, followed by mixing with a component containing a base.