Elucidation of Sorption Mechanism of R. arrhizus for Reactive Blue 222 using Equilibrium and Kinetic Studies

Abstract

The equilibrium and kinetics of the biosorption of Reactive Blue 222 from aqueous solution were investigated using dead biomass of Rhizopus arrhizus in a batch system. Biosorption equilibrium was established in about 180 min. The sorption data obtained at pH 1.5 conformed well to the Langmuir isotherm model. The Reactive Blue 222 biosorption data were analyzed using the pseudo-first, the pseudo-second order, Elovich kinetics models as well as intra-particular rate diffusion and liquid film diffusion. The second-order equation was the most appropriate equation to predict the biosorption capacities of the biosorbent. The reusability of the biosorbent was tested in five consecutive adsorption–desorption cycles and the regeneration efficiency was above 97%. The XRD, SEM, FITR analyses helped to elucidate the mechanism of biosorption. From the practical viewpoint, the abundant and inexpensive dead fungal biomass could be used as an effective, low cost and environmentally friendly biosorbent for the removal of Reactive Blue 222 from the aqueous solution.