EFFECT OF DYE NATURE ON ITS ADSORPTION FROM AQUEOUS-SOLUTIONS ONTO ACTIVATED CARBON

Liquid-phase adsorption of two dyes on activated carbon was measured i n the 283-323 K temperature range. Higher capacity and faster kinetics of adsorption were obtained for a basic dye than for an acidic dye un der comparable conditions, probably due to the different ionic natures of the dyes. The equilibrium data for acidic dye could be well descri bed by the Freundlich equation, but the best-fit model for basic dye c hanged from the Langmuir to the Freundlich equations when the temperat ure was raised. In addition, the thermodynamic functions were determin ed. A plot of the fraction of adsorption against (time)(1/2) was adopt ed to describe the adsorption process. It was shown that for an acidic dye the amount of adsorbent used played an important role in the adso rption mechanism.