▎ 摘　　要

NOVELTY - The preparation method of graphene-cobalt ferrite composite super-capacitor electrode material involves (1) pre-processing stainless steel rolling oil sludge to obtain stainless steel rolling oil sludge powder, (2) leaching stainless steel rolling oil sludge powder with sulfuric acid solution to obtain ferrous ion, (3) oxidizing ferrous iron with hydrogen peroxide solution, (4) mixing iron salt solution obtained in step (3), cobalt(II) sulfate heptahydrate and graphene to obtain precursor, and (5) hydro-thermally reacting. USE - Preparation method of graphene-cobalt ferrite composite super-capacitor electrode material (claimed). ADVANTAGE - The method enables preparation of graphene-cobalt ferrite composite super-capacitor electrode material with excellent electrochemical properties, and effective realization of the resource utilization of waste, by simple and environmentally-friendly process. DETAILED DESCRIPTION - The preparation method of graphene-cobalt ferrite composite super-capacitor electrode material involves (1) pre-processing stainless steel rolling oil sludge to obtain stainless steel rolling oil sludge powder, (2) leaching stainless steel rolling oil sludge powder with sulfuric acid solution to obtain ferrous ion, (3) oxidizing ferrous iron with hydrogen peroxide solution, (4) mixing iron salt solution obtained in step (3), cobalt(II) sulfate heptahydrate and graphene to obtain precursor, and (5) hydro-thermally reacting, where in step (1), the stainless steel rolling oil sludge powder is prepared by mixing 5-9 wt.% potassium hydroxide solution and stainless steel rolling oil sludge in mass ratio of 3:1-5:1, ultrasonically oscillating, filtering, collecting the filter residue, drying the filter residue to constant weight, ball-milling, and crushing.