Kinetics and Equilibrium Studies on Biosorption of Chromium (VI) By Mixed Biosorbents

Biosorption is a process, which represents a biotechnological innovation as well as a cost effective excellent tool for removing heavy metals from aqueous solutions. The kinetics and equilibrium of the biosorption of Chromium (VI) from aqueous solution were investigated using immobilized mixed biosorbents of Annona squamosa seeds and Aspergillus niger in a batch system. The biosorption characteristics of Chromium (VI) ions were studied with respect to well-established effective parameters including initial metal ion concentration, pH, temperature and biosorbent dosage. Biosorption equilibrium was established in about 24 h. The Chromium (VI) sorption data were analyzed using the Lagergren first and second order kinetic models. The Lagergren second-order rate equation was the most appropriate equation to predict the biosorption capacities of immobilized mixed biosorbents. The equilibrium data were analyzed using the Langmuir adsorption isotherm. The characteristic parameters of Langmuir sorption isotherm provided the best correlation for Chromium (VI) onto immobilized mixed biosorbents.