Pyridine sorption from aqueous solution by rice husk ash (RHA) and granular activated carbon (GAC): Parametric, kinetic, equilibrium and thermodynamic aspects

The present study deals with the adsorption of pyridine (Py) from synthetic aqueous solutions by rice husk ash (RHA) and commercial grade granular activated carbon (GAC) and reports on the kinetic, equilibrium and thermodynamic aspects of Py sorption. Batch sorption studies were carried out to evaluate the effect of various parameters, such as adsorbent dose (m), initial pH (pH(0)), contact time (t), initial concentration (CO) and temperature (T) on the removal of Py. The maximum removal of Py is found to be similar to 96% and similar to 97% at lower concentrations (<50 mg dm(-3)) and similar to 79.5% and similar to 84% at higher concentrations (600 mg dm(-3)) using 50 kg m(-3) and 30 kg m-3 of RHA and GAC dosage, respectively, at 30 +/- 1 degrees C. Adsorption of Py is found to be endothermic in nature and the equilibrium data can be adequately represented by Toth and Redlich-Peterson isotherm equations. Py can be recovered from the spent adsorbents by using acidic water and 0.1 N H2SO4. The overall adsorption of Py on RHA and GAC is found to be in the order of GAC > RHA. Comparative assessment of adsorbents used by various investigators available in literature showed the effectiveness of BFA and RHA over other adsorbents. Spent RHA can simply be filtered, dried and used in the boiler fumaces/incinerators. Thus, its heating value can be recovered. (C) 2007 Elsevier B.V. All rights reserved.