Kinetic, isotherm and thermodynamic studies on biosorption of chromium (VI) by using activated carbon from leaves of Ficus nitida

Background: Kinetics, thermodynamics and equilibrium of the removal of chromium(VI) ions from aqueous solutions by using chemically activated leaves of Ficus nitida were investigated. Adsorption runs were performed as a function of pH, mass of biosorbent, contact time, initial concentration of chromium(VI) ions and temperature. Results: The optimum conditions for maximum removal of chromium(VI) ion from aqueous solutions (about 99 %) were found to be 0.80 g of chemically activated leaves of F. nitida, 25 min, 50.0 mg/L of initial concentration of chromium(VI). Values of thermodynamic activation parameters proved that the biosorption process is spontaneous and endothermic. Results were analyzed by using Langmuir, Freundlich and Temkin models. Conclusions: Results of the study showed that the chemically activated leaves of F. nitida can be used as low cost, ecofriendly and effective sorbent for the removal of chromium(VI) from aqueous solutions.