In this article, activated carbon aerogels (ACAs) were prepared by CO2 activation. Their pore structures were investigated by N-2 adsorption-desorption analysis. ACAs have excellent microporosity (e.g. 0.36 cm 31 g) and mesoporosity (e.g. 1.72 cm(3)/ g). Adsorption characteristics of phenol, methylene blue, 12, and VB12 On ACAs in the liquid phase were studied by static adsorption experiments. Results showed that CO2 activation process is an effective way to introduce micropores in carbon aerogels, which is enhanced with the increase of activation time. As a result, the adsorption capacities of the four mentioned adsorbates on ACAs were improved gradually with the increase of activation time. However, mesopore volume is also a factor on improving adsorption properties for the relatively giant molecules methylene blue and VB12. (c) 2007 Wiley Periodicals, Inc.