Utilization of fluidized bed reactor for the production of adsorbents in removal of malachite green

Activated carbon was prepared from rubberwood (Hevea brasiliensis) sawdust by steam and chemical treatments. Steam activation was carried out in high temperature fluidized bed reactor (FBR) using steam as quenching medium. Chemical activation was carried out by using phosphoric acid. The adsorption capacity was determined by using iodine number and methylene blue number and surface area by ethylene glycol mono ethyl ether (EGME) method. Further the adsorption studies were carried out using malachite green dye. Langmuir, Freundlich and Temkin adsorption isotherms were analyzed and Langmuir isotherm shows satisfactory fit to experimental data. The adsorption capacity was found to decrease in the order; steam activated carbon > acid + steam activated carbon > commercial activated carbon > acid activated carbon. Temperature effects on adsorption were carried out and it was found that the adsorption reaction was endothermic. Thermodynamic analysis of the process confirms its endothermicity. The adsorption kinetics was found to follow pseudo-second-order kinetic model. (c) 2005 Elsevier B.V. All rights reserved.