Preparation of activated carbon from a renewable bio-plant of Euphorbia rigida by H2SO4 activation and its adsorption behavior in aqueous solutions

The use of activated carbon obtained from Euphorbia rigida for the removal of a basic textile dye, which is methylene blue, from aqueous solutions at various contact times, pHs and temperatures was investigated. The plant material was chemically modified with H2SO4. The surface area of chemically modified activated carbon was 741.2 m(2) g(-1). The surface characterization of both plant-and activated carbon was undertaken using FTIR spectroscopic technique. The adsorption process attains equilibrium within 60 min. The experimental data indicated that the adsorption isotherms are well described by the Langmuir equilibrium isotherm equation and the calculated adsorption capacity of activated carbon was 114.45 mg g(-1) at 40 degrees C. The adsorption kinetics of methylene blue obeys the pseudo- second-order kinetic model and also followed by the intraparticle diffusion model up to 60 min. The thermodynamic parameters such as Delta G degrees, Delta H degrees and Delta S degrees were calculated to estimate the nature of adsorption. The activation energy of the system was calculated as 55.5 1 kJ mol(-1). According to these results, prepared activated carbon could be used as a low-cost adsorbent to compare with the commercial activated carbon for the removal textile dyes from textile wastewater processes. (c) 2006 Elsevier B.V. All rights reserved.