Abstract
An inexpensive adsorption method was developed for the removal of a hazardous methyl orange dye from aqueous system. The chemical modification of Ficus carica fiber was done with acrylic acid using ceric ammonium nitrate as initiator to change the surface morphology of the natural fibers for the improvement of interfacial adhesion between matrix and fibers. The modification of natural fiber and adsorption onto modified fiber was confirmed by scanning electron microscopy and Fourier transformer infrared spectroscopy. The effects of various reaction parameters such as temperature, pH, initial concentration, contact time, electrolyte and surfactants on the adsorption of methyl orange dye onto acrylic acid grafted F. carica fiber using batch technique have been studied. The equilibrium data was analyzed using the Langmuir, Freundlich, Tempkin, Harkin's-Jura and Dubinin-Radushkevich isotherm models. Experimental data was best represented by the Langmuir isotherm model. The maximum adsorption capacity of dye onto adsorbent was found to be 51.55 mg g(-1). The pseudo second order kinetic model adequately described the kinetic data. The calculated values of the thermodynamic parameters such as enthalpy change (Delta H), entropy change (AS) and free energy change (Delta G) were 6.74 kJ mol(-1), 64.63 J mol(-1) K-1 and -12.85 kJ mol(-1), respectively. This indicated the endothermic and spontaneous nature of the adsorption process. Further, the presence of cationic surfactant increased the adsorption capacity from 29.56 mg g(-1) to 32.04 mg g(-1). The desorption studies confirmed that 39.24% of dye was recovered in first cycle. (C) 2012 Elsevier B.V. All rights reserved.