Liquid-phase adsorption of phenol onto activated carbons prepared with different activation levels

The influence of the pore size distribution of activated carbon on the adso rption of phenol from aqueous solutions was explored. Activated carbons wit h different porous structures were prepared by gasifying a bituminous coal char to different extents of burn-off. The results of adsorption experiment s show that the phenol capacity of these carbons does not proportionally in crease with their BET surface area This reflects the heterogeneity of the c arbon surface for adsorption. The pore size distributions of these carbons, determined according to the Dubinin-Stoeckli equation, were found to vary with the bun-off level. By incorporating the distribution with the Dubinin- Radushkevich equation using an inverse proportionality between the micropor e size and the adsorption energy, the isotherms for the adsorption of pheno l onto these carbons can be web predicted. The present study has demonstrat ed that the heterogeneity of carbon surface for the phenol adsorption can b e attributed to the different energies required for adsorption in different -size micropores. (C) 2000 Academic Press.