Method for preparing expandable graphite by using ozone

Abstract

The invention relates to a method for preparing expandable graphite by using ozone. Concentrated sulfuric acid, fuming nitric acid, perchloric acid or mixed acid is adopted to oxidize crystalline flake graphite, together with oxidant, the temperature of the oxidation reaction is 5-50 DEG C, the oxidation reaction lasts for 30 min-100 hours, and then the pH value is adjusted to be 6-7 through suction filtration and water scrubbing, the oxidized graphite is dried for 10-72 hours at the temperature of 40-60 DEG C, and the expandable graphite is obtained. The mixed acid at least contains concentrated sulfuric acid, fuming nitric acid or perchloric acid; and the oxidant is ozone or mixed oxidant containing ozone. The method provided by the invention has the following advantages: the oxidative products of ozone are oxygen and water, no other residual materials are produced, and the secondary pollution is not caused; the ozone is easy to prepare, and the equipment and technique are simple; and the source of ozone is easy to obtain and is not limited by transportation conditions. Ozone is adopted to oxidize the graphite, so that the environmental protection is reduced, and the instability and insecurity of peroxides are also avoided, and meanwhile, the recycling of intercalation solution is facilitated.

Description

technical field [0001] The invention relates to a method for preparing a graphite material, in particular to a method for preparing expandable graphite by using ozone. Background technique [0002] Expandable graphite is a new type of compound with interlayer intercalation formed by natural flake graphite through oxidative intercalation reaction to insert heterogeneous atoms, molecules or ions between graphite flakes. When the expandable graphite is subjected to high temperature, the interlayer intercalation material is rapidly vaporized by the high heat, and the formed gas generates a huge stretching tension on the graphite sheet, so that the expandable graphite expands, and the expansion multiple is as high as tens to hundreds of times. The generated charcoal layer has excellent oxidation resistance and high temperature resistance, which can protect the material under the charcoal layer and achieve the purpose of flame retardancy and fire prevention. Compared with traditi...

AI Technical Summary

Problems solved by technology

The chemical oxidation method is to oxidize graphite with a mixed solution of strong oxidizing acids such as concentrated sulfuric acid, concentrated nitric acid, perchloric acid and strong oxidants such as potassium dichromate, potassium perchlorate, potassium permanganate, peroxide, etc. The method is simple, But acid consumption is big, is unfavorable for the recycling of acid solution, and may cause the pollution of heavy metal ion in the production process, relevant Chinese patent application publication number has: CN1462724A, CN11884060A, CN1613757A, CN101327926A, CN101786618A, CN101100297A etc.

The electrochemical method is to use natural flake graphite and auxiliary anode together to form an anode chamber, intercalation agents such as sulfuric acid solution and ammonium nitrate solution as electrolyte, and direct current or pulse current to anodize graphite. Compared with chemical methods, this method has a The amount of oxidizing agent is greatly reduced, but the equipment is more complicated. The relevant Chinese patent application publication numbers are: CNl1117021A, CN1113215A, CNl102444A, CN1096827A, CN1029693C, CN1030535C, etc.