Adsorption of 2-picoline onto bagasse fly ash from aqueous solution

The adsorption of 2-picoline from aqueous solutions onto bagasse fly ash (BFA), a solid waste collected from the particulate collection equipment attached to the stacks of bagasse fired boilers, is presented in this paper. The influence of various parameters like initial pH (pH(0)), adsorbent dose (m), contact time (t), initial concentration (C-0) and temperature (7) on the adsorption of 2-picoline from the aqueous solutions were studied using batch adsorption experiments. Equilibrium adsorption and kinetic studies for 2-picoline adsorption onto BFA were also carried out. Various adsorption isotherm equations, viz. Langmuir, Freundlich, Redlich-Peterson and Temkin equilibrium equations were used to test their suitability in describing experimental isotherm data. The adsorption of 2-picoline on bagasse fly ash follows second order kinetics and the equilibrium adsorption increases with increasing initial concentration. The equilibrium sorption isotherm data could be well represented by the Langmuir and Redlich-Peterson isotherm equations. The maximum removal of 2-picoline is found to be 98% at lower concentrations (<50 mg dm(-3)) and 49% at higher concentrations (600 mg dm(-3)) using 5 kg m(-3) of BFA dosage at normal temperature and natural pH(0) (similar to 6.5). Thermodynamic studies revealed that the adsorption of 2-picoline on BFA is endothermic in nature and that the isosteric heat of adsorption decreases with the increase in the equilibrium uptake of 2-picoline on the BFA surface. Desorption of 2-picoline from the loaded BFA using water at different pH, and various other solvents showed that 2-picoline could be recovered by using acidic water and 0.1N H2SO4. Comparative assessment of BFA and activated carbon showed the superiority of BFA in terms of 2-picoline uptake, the rate of adsorption and the eventual cost of operation. (C) 2007 Elsevier B.V. All rights reserved.