▎ 摘　　要

NOVELTY - Preparing graphene oxide and magnetic sludge biochar composite material comprises (i) washing and drying the sludge to constant weight, grinding, then transferring to pyrolysis in nitrogen atmosphere, grinding and sieving to obtain sludge biochar SBC, (ii) adding cobaltous nitrate hexahydrate and ferric chloride hexahydrate into ultrapure water to dissolve, adding SBC into the above solution, adjusting the pH to alkaline using sodium hydroxide, keep stirring continuously during the above process, then drying, transferring to pyrolysis under nitrogen protection, grinding and sieving to obtain magnetic sludge biochar (CoFe2O4-SBC), (iii) adding graphene oxide into ultrapure water for ultrasonic homogenization to obtain graphene oxide suspension, and (iv) adding CoFe2O4- sludge biochar obtained in step (ii) into graphene oxide suspension obtained in step (iii), ultrasonically homogenizing, drying and pyrolysis in high-temperature tube furnace, grinding and sieving to obtain final product. USE - The graphene oxide and magnetic sludge biochar composite material is useful in removal of low-concentration imidacloprid in water (claimed). ADVANTAGE - The material: has strong magnetic properties and separated from water after adsorption, and has high removal rate for low concentration of imidacloprid in water and maximum adsorption capacity of 9.79x 103 mu g/g at 35 degrees C. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (1) graphene oxide and magnetic sludge biochar composite material obtained by above method; and (2) use of graphene oxide and magnetic sludge biochar composite material in removal of low-concentration imidacloprid in water, comprising adding sludge biochar, magnetic sludge biochar CoFe2O4-SBC and graphene oxide and magnetic sludge biochar composite material GO/CoFe2O4-SBC as adsorbents into solution of low concentration imidacloprid, after adsorption equilibrium, filtering the membrane to obtain solution after imidacloprid removal.