▎ 摘　　要

NOVELTY - Separation of graphene oxide involves centrifuging for X1 times by satisfying specific relation, and separating graphene oxide after each centrifugation process. USE - Separation of graphene oxide used for forming graphene oxide layer in surface-treated steel sheet (claimed). ADVANTAGE - The graphene oxide is effectively separated with high yield. DETAILED DESCRIPTION - Separation of graphene oxide involves centrifuging for X1 times by satisfying relation: Y1=a.X1+b, where a is -200 to -100, b is 500-900, X1 is centrifugation order and Y1 is difference between the centrifugation condition (centrifugation time in minutes) and centrifugation speed (1000 rpm), and separating graphene oxide after each centrifugation process. INDEPENDENT CLAIMS are included for the following: (1) centrifugation system; and (2) surface-treated steel sheet.