▎ 摘　　要

NOVELTY - A graphene/metal oxide composite material comprises a divalent and trivalent metal nitrate hydrate, alkaline compound, and graphene oxide. USE - For absorbing heavy metal ion (e.g. Cr(VI)) in water (claimed). ADVANTAGE - The composite material has Cr(VI) absorption rate of 170 mg/composite material; is cost-effective; is prepared by simple method. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for the preparation of composite material involving: mixing the divalent and trivalent metal nitrate hydrate and alkaline compound solution with graphene oxide suspension, followed by hydro-thermal treating, and calcining at 480-520 degrees C for 4-6 hours.