Abstract: Activated carbons were prepared using fir sawdust as raw material after pretreatment and the combination of phosphoric acid and sulfuric acid as activator. The methylene blue adsorption value is higher than 338 mg/g, the iodine value is higher than 1 287 mg/g with the yield is higher than 45%. The effect of concentrated sulfuric acid amount, pretreatment time, pretreatment temperature, impregnation ratio and activation temperature on the methylene blue and iodine adsorption properties of the activated carbons were studied.The results showed that adding a small amount of concentrated sulfuric acid solution could promote the penetration of phosphoric acid into lignocellulose, enhance the activation of phosphoric acid,and increase the adsorption capability of activated carbon. The pretreatment time and temperature were controlled for 1 h at 240 ℃. This condition can significantly improve the activated carbon adsorption capacity. The expansion effect of impregnation ratio on the microporous activated carbon was not significant. The activation temperature significantly affects the adsorption capacity of activated carbon, and the activation temperature should be controlled at 450 ℃.

Key words: activated carbon, phosphoric acid, adsorption performance