Bioethanol for fuel is a renewable energy alternative to petroleum. However, because of the azeotropic point between ethanol and water, the separation and concentration of ethanol to yield a product with low water content by the usual method of distillation requires considerable energy. To develop an environmentally friendly method for purification of bioethanol, we examined the adsorption of ethanol on activated carbon prepared from lignin. The adsorption properties of ethanol on activated carbons at 303 K were compared with those of commercially available high-silica zeolites in batchwise fashion. The specific surface areas of activated carbons were found to be about 2000 m(2) g(-1) by the nitrogen gas adsorption method. The adsorption rate of ethanol on activated carbons in powder form reached equilibrium within 0.5 min, and the adsorption isotherm of ethanol on activated carbons from aqueous solution was of the Freundlich type. The adsorption results revealed that the adsorption capacities of activated carbons for ethanol were influenced by their hydrophobicity, micropore size and percentage of micropore volume. The highest adsorption capacity for 5 vol% ethanol was 280 mg g(-1) of the activated carbons prepared from lignin (at 900 degrees C and IR = 2). Thermogravimetric analysis (TGA) of activated carbons and high-silica zeolites with adsorbed ethanol was carried out to examine the adsorption mechanisms of ethanol. In both cases, ethanol was found to be selectively adsorbed in preference to water. Finally, activated carbons prepared from lignin maintained their activity even over 20 cycles of adsorption and desorption.