Dye adsorption on mesoporous activated carbon fiber obtained from pitch containing yttrium complex

The adsorption of acid dyes (Acid Blue 9, Acid Blue 74, Acid Orange 10, and Acid Orange 51), direct dyes (Direct Black 19, Direct Yellow 11, and Direct Yellow 50), and basic dyes (Basic Brown 1 and Basic Violet 3) on a highly mesoporous activated carbon fiber (Y-ACF) obtained from pitch containing yttrium acetylacetonate was investigated in terms of size of dye molecules, and pore size and surface charge of the activated carbon fiber. The results were compared with that on a microporous activated carbon fiber (A-20). The high amounts of sterically small size of acid dyes and basic dyes were adsorbed on both Y-ACF and A-20. The amounts of direct dyes, which are large in one or two dimensions of molecular structures, adsorbed on a mesoporous Y-ACF were much higher than those on microporous A-20. The adsorbed amounts of direct dyes decreased with increasing pH in alkaline pH, in which the zeta potentials of Y-ACF show negative values. From these results, we can suggest that the adsorption of dyes on activated carbon fiber varies greatly by changing pore size and surface charge of activated carbon fiber. (C) 1999 Elsevier Science Ltd. All rights reserved.