Adsorption kinetics of aqueous binary mixtures containing phenol, RED31 and/ or black5 on activated carbon prepared from waste tires

Abstract

Activated carbon produced from waste tires (AC-Tires) and commercial activated carbon (AC-COM) which are highly mesoporous and microporous; respectively, were used to investigate their adsorption equilibrium and kinetics towards phenol and Red31 (Black 5). Experimental competitive adsorption kinetics for phenol/Red31 (Black 5) systems consisted of single-solute and binary mixtures, namely, simultaneous adsorption kinetics, phenol adsorption kinetics followed by Red31 and Red31 adsorption kinetics followed by phenol. Adsorption equilibriums of phenol and Red31 (Black 5) adsorbed onto AC-Tires and AC-COM were found to be described well by Freundlich and Langmuir isotherms, respectively. The actual transport mechanism inside the activated carbon particles is shown to be Knudsen diffusion and the adsorption rate controlling step is described well by the intraparticle diffusion model. The porous structure and pore size distribution of the activated carbons has significant effect on the adsorption capacity and kinetics towards phenol and Red31 (Black 5).