Adsorption thermodynamics and kinetics of ranitidine hydrochloride onto superheated steam activated carbon derived from mung bean husk

Pharmaceutical compound possessing eco-toxicological effects in the aqueous system have been a growing concern over the few decades. The present work investigates the use of low cost mung bean husk (MBH), an agriculturalwaste, for the preparation of superheated steam activated carbon towards removal of ranitidine hydrochloride (RH) from synthetic wastewater. The adsorbent was examined as a function of dosage (0.010-1 g), pH (2-12), agitation (40-120 rpm) and temperature (303-318 K) for the optimization of operational parameters. The experimental equilibrium data were evaluated by non linear Langmuir, Freundlich, Sips and Redlich-Peterson models. The Sips model was found to express high level of agreement with experimental data. The maximum sorption of 100 ppm RH onto MBH derived steam activated carbon (MBH-SAC) was estimated to be 99.16% at 298 K. The kinetic study conducted at four temperatures indicates that the adsorption process follows the fractionary order kinetics. A negative value (-11.307 kJ mol (1)) of enthalpy change (Delta H degrees) suggests that the adsorption process was exothermic. Gibbs free energy (Delta G degrees) confirms that the reaction of the adsorption process was spontaneous and feasible in nature. The results suggest that MBH-AC can be used as an efficient and low cost adsorbent for the removal of RH from aqueous solution. (C) 2014 Elsevier Ltd. All rights reserved.