Adsorption of Alizarin Red S onto Biosorbent of Lantana camara: Kinetic, Equilibrium Modeling and Thermodynamic Studies

Adsorption of an anthraquinone dye Alizarin Red S onto biosorbent of Lantana camara has been studied on aqueous solutions. The batch adsorption experiments were conducted using simulated aqueous solutions and the effects of initial dye concentration, pH of solution, contact time and temperature were investigated. The prepared biosorbent was characterized using FTIR, SEM, elemental analysis and through the determination of pH(zpc). The equilibrium data were modeled with Langmuir and Freundlich isotherms. Freundlich model fitted very well with the equilibrium adsorption data and this provided evidence of multilayer adsorption of the dye molecules onto the active sites on the biosorbent. The kinetic studies revealed that the process was quite rapid and more than 90 % of equilibrium capacity was achieved within 80 min. The rates of adsorption were found to confirm to the pseudo-second-order kinetics with good correlations (R (2) > 0.99). The thermodynamic studies showed that the Alizarin Red S-biosorbent system is spontaneous, exothermic and favourable in nature.