TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: The hydrochloric acid in the step (i) is 30% of hydrochloric acid. The mass ratio of hydrochloric acid to poultry feather is 2-1. The heating temperature is 100-110 degrees C and heating time is 4-6 hours. In the step (ii), the method for separating for the first time is plate frame pressing and filtering separation. In the step (iii), the volume ratio of the added pure alkali to the first hydrolyzed separated solution is 1-30, heating temperature is 70 degrees C, heating time is 4 hours, and neutralizing time is 30 minutes. In the step (iv), the method for separating for the second time is plate frame pressing and filtering separation. The method for decoloring for the first time is a method for separating active carbon and the first decolored solution by using plate frame pressing and filtering method after decoloring the active carbon. The second neutralization comprises adding pure alkali, heating and neutralizing. The volume ratio of the pure alkali to the first decolored solution is 1-4, heating temperature is 70 degrees C, and heating time is 2 hours. In the step (v), the method for separating the third time is plate frame pressing and filtering separation. The method for decoloring for the second time is a method for separating active carbon and the second decolored solution by using plate frame pressing and filtering method after decoloring the active carbon. The third neutralization comprises adding pure alkali, heating and neutralizing. The volume ratio of the pure alkali to the second decolored solution is 1-6, heating temperature is 70 degrees C, and heating time is 1 hour. In the step (vi), the method for separating for the fifth time is plate frame pressing and filtering separation. The third decoloring process uses active carbon to decolor. The fourth neutralization comprises adding pure alkali, heating and neutralizing. The volume ratio of the pure alkali to the fifth decolored solution is 1-6, heating temperature is 70 degrees C, and heating time is 1 hour. In the step (vii), the method for separating for the sixth time is plate frame pressing and filtering separation. In the step (viii), the volume of the condensed solution is 2/3 of the fourth neutralized separation solution. The crystallization has the amino neutralizing method which is neutralized by using ammonia whose concentration is 40% until pH value is 2.5. The separation process has the centrifugal separation method. The drying temperature is 120 degrees C.