Preparation, characterization and application of microwave-assisted activated carbons from wood chips for removal of phenol from aqueous solution

摘要

In this paper, activated carbons were prepared from lignocellulosic residue using microwave-induced chemical activation process, for removal of phenol (PhOH) from aqueous solutions. Wood chips and inorganic components (20% lime + 80% ZnCl2 or 20% lime + 40% ZnCl2 + 40% FeCl3) were mixed to form pastes with inorganic:organic ratios of 1.0 and 1.5 (PZnCW-1.0; PZnCW-1.5; PFeZnCW-1.0; PFeZnCW-1.5). The mixtures were pyrolysed in a microwave in less than 11 min. Afterwards a 6 mol L-1 HCl was used to treat the carbonised materials, under re flux, to eliminate the inorganic components-producing the activated carbons (ZnCW-1.0; ZnCW-1.5; FeZnCW-1.0; FeZnCW-1.5). Elemental analysis, FTIR, SEM,N-2 adsorption/desorption curves, TGA, XRD and X-ray fluorescence were used to characterise both intermediary materials and activated carbons. The results indicated that activated carbons had an ordered mesoporous and microporous structure with a high S-BET ranging from 647 to 914 m(2) g(-1), V-tot of 0.34-0.52 cm(3) g(-1) and V-mes between 0.14 and 0.27 cm(3) g(-1). For the adsorption experiment, pseudo first-order, pseudo-second order and Avrami fractional-order kinetic models were used to probe the kinetic of adsorption. Equilibrium time was attained after 10.4 min only. The maximum amounts of phenol adsorbed onto activated carbons at 25 degrees C were 434.2, 667.9, 256.5 and 233.5 mg g(-1) for ZnCW-1.0, ZnCW-1.5, FeZnCW-1.0 and FeZnCW-1.5, respectively. ZnCW-1.0 and ZnCW-1.5 exhibited excellent performance in the treatment of simulated effluents contaminated with mixtures of phenols in a complex medium. (c) 2016 Elsevier B.V. All rights reserved.