Analysis and modeling of fixed bed column operations on flumequine removal onto activated carbon: pH influence and desorption studies

Flumequine adsorption from aqueous solutions by activated carbon was carried out in fixed-bed columns. Initially, batch adsorption experiments were developed in order to determine the equilibrium time and the adsorption isotherm of the system. Pseudo-first order, Elovich equation and pseudo-second order models were applied to the experimental data to determine the adsorption kinetics. Thermodynamic parameters of the adsorption system were evaluated, suggesting that chemical interactions could be occurring. In dynamic adsorption, the influence of several operation conditions such as initial concentration, volumetric flow rate and mass of adsorbent was evaluated. Experimental data were fitted to the Thomas model. The adsorption capacity of flumequine-activated carbon at various pH values was investigated. Results showed that pH values lower or higher than 6.3 (natural pH) decreased the adsorption capacity. Desorption studies of flumequine from activated carbon were developed. Experimental adsorption capacity values were fitted to Bangham and intra-particle diffusion models in order to propose and adsorption mechanism. (C) 2013 Elsevier B.V. All rights reserved.