▎ 摘　　要

NOVELTY - Preparing graphene by crude black lignin involves crushing to 80 meshes with crude lignin of papermaking black liquor extracted by acid deposition or electrolysis, washing by deionized water until the washing liquid is neutral, centrifuging, filtering, and drying at 50-70 degrees C. The dried lignin powder is weighed and ratio of lignin and potassium hydroxide and sodium hydroxide is 20:1-5. The deionized water is added to dissolve lignin, stirred in the magnetic stirrer for 0.5-1 hours, and filtered. USE - Method for preparing graphene by crude black lignin (claimed). ADVANTAGE - The method enables to prepare graphene by crude black lignin that is good for purifying, separating and forming thinner carbon layer, reduces the graphitization temperature and requirement of the production device, and does not need high pressure for sintering. DETAILED DESCRIPTION - Preparing graphene by crude black lignin involves crushing to 80 meshes with crude lignin of papermaking black liquor extracted by acid deposition or electrolysis, washing by deionized water until the washing liquid is neutral, centrifuging, filtering, and drying at 50-70 degrees C. The dried lignin powder is weighed and ratio of lignin and potassium hydroxide and sodium hydroxide is 20:1-5. The deionized water is added to dissolve lignin, stirred in the magnetic stirrer for 0.5-1 hours, and filtered. The filtrate is evaporated at 50-70 degrees C, and dried to obtain alkali lignin loaded with potassium ion and sodium ion. The ratio of calcium salts, borate salt, nickel salt and swelling agent is 6-3:6-3:1-2:1-3. The ratio of composite expansion catalyst and alkali lignin is 100:10-25. The composite expansion catalyst is crushed to 80 meshes to obtain solution containing calcium ion, barium ion and doped alkali lignin powder with nickel ion and deuterium. The alkali lignin powder is placed in corundum crucible with vacuum for sintering with (-)0.08 megapascal pressure. The nitrogen or argon is injected to normal pressure, and process is repeated for 3 times. The temperature is raised to 800-1400 degrees C for 0.5-4 hours. The sintered material is cooled to room temperature to obtain sample. The obtained sample is treated with 1 mole of hydrochloric acid for 24 hours, washed by deionized water to neutral, filtered, and dried to obtain black liquor lignin-based graphene.