Adsorption of Acid Yellow 99 by polyacrylonitrile/activated carbon composite: Kinetics, thermodynamics and isotherm studies

Abstract

The adsorption of Acid Yellow 99 (AY99) onto polyacrylonitrile/activated carbon (PAN/AC) composite was investigated in aqueous solution in a batch system with respect to contact time, pH and temperature. Experimental data indicated that the adsorption capacity of (PAN/AC) composite for AY99 was higher in acidic rather than in basic solutions. Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms and the isotherm constants were determined. The activation energy of adsorption was also evaluated for the adsorption of AY99 onto (PAN/AC) composite. The pseudo-first-order and pseudo-second-order model equations were used to analyze the kinetics of the adsorption process. The dynamic data fitted the pseudo-second-order kinetic model well. The activation energy, change of free energy, enthalpy and entropy of adsorption were also evaluated for the adsorption of AY99 onto (PAN/AC) composite. The thermodynamics of the adsorption indicated spontaneous and exothermic nature of the process. The (PAN/AC) composite was characterized using Fourier transform infrared spectroscopy (FTIR) and its morphology was determined by scanning electron microscopy (SEM). The results indicate that (PAN/AC) composite could be employed as low-cost material for the removal of acid dyes from textile effluents. © 2014 Elsevier B.V.