Biosorption potential of a novel powder, prepared from Ficus auriculata leaves, for sequestration of hexavalent chromium from aqueous solutions

A novel biosorbent, powdered Ficus auriculata leaves (FALP), has been used to remove hexavalent chromium from aqueous solutions by use of a batch technique. The biosorbent was characterized by surface area analysis, Fourier-transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and scanning electron microscopy. The effects on adsorption of pH, initial Cr(VI) ion concentration, amount of FALP, agitation speed, and temperature were investigated. Equilibrium data from the biosorption study were evaluated by use of two and three-variable isotherm models. The equilibrium data were better fitted by use of a three-variable isotherm model. The kinetics of biosorption were examined by use of pseudo-first-order and pseudo-second-order kinetic models and an intraparticle diffusion model. The biosorption data were best fit by the pseudo-second-order kinetic model. Thermodynamic investigation revealed that biosorption of hexavalent chromium ions by FALP is spontaneous in nature, endothermic, and results in increased randomness. The study suggests that FALP could be used as a potential biosorbent for removal of hexavalent chromium from wastewaters.