▎ 摘　　要

NOVELTY - A graphene derivative has an amount of component derived from ester bond to the sum total of amount of a component derived from carbon-carbon single bond, a component derived from carbon-carbon double bond, a component derived from carbon-oxygen single bond, a component derived from ether bond and a component derived from ester bond of 8-20%, calculated by waveform separation of C-1s spectrum in X-ray photoelectron spectroscopy. USE - Graphene derivative is used in composite used as fiber, filtering material, adsorbent and ion exchange resin, used in system for treating water (all claimed). ADVANTAGE - The derivative has high protein adsorption capacity. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for composite, which comprises the graphene derivative and antibacterial protein or its derivative. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of water treatment system. To-be-processed water inflow tube (10) Water treatment unit (20) Treated-water outflow tube (30) Water treatment system (100)