▎ 摘　　要

NOVELTY - Preparing multifunctional graphene oxide-chitosan (GO-CS) composite sponge comprises e.g. (1) preparing graphene oxide nano sheets by Hummer method, (a) graphite oxide synthesis stage: firstly adding concentrated sulfuric acid and concentrated nitric acid in a round bottom flask, magnetically stirring, then slowly adding 4 g natural crystalline flake graphite, acutely stirring, (b) mechanical stripping stage; (c) flocculating and drying stage; and (2) mixing the graphene oxide solution to prepare chitosan solution with chitosan, dissolving chitosan powder in acetic acid aqueous solution. USE - The composite sponge is useful in oil-water separation (claimed). ADVANTAGE - The composite sponge is biological environment-friendly material, has biocompatibility and good degradability, is suitable for secondary recovery, and does not cause any pollution, has graphene oxide composite material with high specific surface area, the expected to realize low-toxic efficient oil-water separating material, expected solves the problem that many oil pollution and oil-water separation process of biological adhesion problem, sponge porous aperture is 20-300 mu m, adsorption capacity reaches 50-200 g/g, and the testing the separation efficiency can reach not less than than 99.5%. DETAILED DESCRIPTION - Preparing multifunctional graphene oxide-chitosan (GO-CS) composite sponge comprises (1) preparing graphene oxide nano sheets by Hummer method, (a) graphite oxide synthesis stage: firstly adding 30-200 ml concentrated sulfuric acid and 15-100 ml concentrated nitric acid in a round bottom flask, magnetically stirring for 10-30 minutes under ice bath, then slowly adding 4 g natural crystalline flake graphite, acutely stirring to avoid graphite agglomeration; dispersing uniformly, then slowly adding 44 g potassium chlorate (speed control in one hour), at last, removing ice bath, reacting at room temperature for 50-150 hours, because the reaction will generate a large amount of chlorine, using sodium hydroxide solution to absorb the reaction-generated chlorine; after 50-150 minutes, oxidizing the flake graphite to graphite oxide, (b) mechanical stripping stage: after finishing the reaction, pouring the solution into 1000-2000 ml beaker, then adding de-ionized water to dilute, agitating with glass rod evenly, then allowing to stand for 0.5-2 hours, layering the solution, filtering, collecting solid, and then using de-ionized water to dissolve in 1000-2000 ml beaker, adding 5-30 ml 1-10 wt.% hydrochloric acid, stirring uniformly, then allowing to stand for 2-10 hours, taking the solution after layering, filtering, collecting solid, repeating two times, the color of the solution changed from dark green to light green, then allowing to stand for a day, after the color of the solution is changed into the dark, then using de-ionized water to dilute it into bright yellow, then ultrasonically processing for 5-30 minutes, then centrifuging, filtering, collecting the filtrate to obtain uniformly dispersed graphene oxide solution; (c) flocculating and drying stage: adding 5-50 ml 1-10 mol/l sodium hydroxide solution in the graphene oxide solution, uniformly stirring with glass rod, allowing to stand for 10-60 minutes, after precipitating out the graphene oxide solids, then filtering, collecting the solid, then using ethanol to wash to neutral, to remove sodium hydroxide flocculate, finally drying the solid to constant weight in the vacuum drying box at 40 degrees C to obtain the graphene oxide solid, by calculation, can obtain 1-20 g oxidized graphene solid; and (2) mixing the graphene oxide solution to prepare chitosan solution with chitosan (0.1-10 wt.%), dissolving chitosan powder (0.1-10 g, Mw=100-1000) in 100 ml of acetic acid aqueous solution (0.5-5 wt %); adding the 0.01-3 g graphene oxide powder into the chitosan acetic acid solution, continuously stirring the mixed solution 0.5-10 hours; pouring the oxidized graphene and chitosan into a plastic mold, and using preservative film to seal, completely freezing at by -20 degrees C to -70 degrees C for 10-60 hours, taking out and placing into a freeze dryer, freezing and drying for 2-7 days, the dried chitosan dry environment at room temperature for 24-72 hours, then three-dimensional net-shaped GO-CS composite sponge is formed by freeze-thawing ice crystals as a template, taking out and drying. INDEPENDENT CLAIMS are also included for (1) multifunctional graphene oxide-chitosan (GO-CS) composite sponge is prepared by the above mentioned method; and (2) use of sponge in the oil-water separation comprising using the chitosan pre-soaked by oil-water mixture at a specific ratio in the composite structure after absorbing water, expanding, taking out and obtaining the pure oil phase, the adsorption capacity reaches 50-200 g/g, and testing the separation efficiency can reach not less than 99.5%.