Comparing adsorption properties of NH4Cl-modified activated carbon towards chlortetracycline antibiotic with those of commercial activated carbon

摘要

In this work, kinetics, equilibrium, thermodynamic and other adsorption properties of a novel activated carbon with regular-shaped pores (NH4Cl-modified activated carbon, NAC) for removal of chlortetracycline antibiotic from aqueous solutions was compared with those of a commercial standard activated carbon (SAC). Effects of temperature, on chlortetracycline adsorption by both adsorbents were carefully investigated and compared. Then optimum conditions were used for comparing the adsorption properties of adsorbents. Among the isotherm models studied, the equilibrium experimental data of both activated carbons were followed by Redlich-Peterson model, and the parameters calculated from the studied models showed more favourability of chlortetracycline adsorption onto NAC via the physical pi-pi electron-donor-acceptor interaction. The experimental data were fitted to several kinetic models and, based on calculated respective parameters such as rate constants, equilibrium adsorption capacities, correlation coefficients and statistical indices, both the Ritchie second order and pseudo second-order model showed the best in describing the adsorption process for both activated carbons, and the kinetic performance of NAC was significantly higher than that of SAC. The calculated thermodynamic parameters of the adsorption process revealed that, under the conditions used in this study, the adsorption of chlortetracycline onto NAC is more feasible, spontaneous and endothermic than its adsorption onto SAC. Overall, the results indicated that, compared to SAC, NAC is a more suitable choice for removal of chlortetracycline antibiotic from aqueous solutions. (C) 2017 Elsevier B.V. All rights reserved.