▎ 摘　　要

NOVELTY - Graphene oxide adsorbent comprises graphene oxide layers overlapping each other, an interlayer material arranged between the graphene oxide layers, and pores composed of the graphene oxide layers and the interlayer material. USE - The graphene oxide adsorbent is used for adsorbing the same substance as the interlayer substance, and for separating a substance (all claimed), preferably as a light water adsorbent for separating light water and heavy water. ADVANTAGE - The graphene oxide adsorbent has a large maximum adsorption amount of a substance to be adsorbed. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) a method for separating a substance, comprising contacting the graphene oxide adsorbent with a gas containing a substance to be adsorbed and another substance to adsorb the substance to be adsorbed; and (2) a method for producing the graphene oxide adsorbent, comprising freeze-drying a graphene oxide dispersion containing a solvent containing a substance to be an interlayer substance and layered graphene oxide, and reducing the content of the solvent to obtain the product.