Adsorption of dyes from aqueous solution - the effect of adsorbent pore size distribution and dye aggregation

The removal of acid dyes, Tectilon Blue 4R,-Tectilon Red 2B and Tectilon Orange 3G, from single component solution by adsorption on activated carbon and bone char has been investigated in isotherm experiments. Results from these experiments were successfully modelled using Langmuir and Freundlich isotherm analyses. Nitrogen adsorption analysis was also undertaken and indicated that the activated carbon had a much higher specific surface than the bone char. Calculations involving the pore size distribution data indicate that only 14% of the total specific surface of the activated carbon is available for adsorption due to the high molecular area and aggregation of the dye. The equilibrium data indicate that dye aggregation takes place in the solid phase of both adsorbents with higher solid phase aggregation numbers found using the bone char, which is indicative of multilayer adsorption. (C) 2001 Elsevier Science B.V. All rights reserved.