BIOMASS OF MUCOR HEIMALIS FOR THE BIOSORPTION OF CADMIUM FROM AQUEOUS SOLUTIONS: EQUILIBRIUM AND KINETIC STUDIES

The present study deals with the utilization of a cellulosic material, i.e. fungal biomass of Mucor heimalis, for the removal of cadmium from aqueous solution in a batch system. Effects of various parameters such as pH, biomass dosage, contact time, and initial metal concentrations were investigated. The sorption of cadmium followed pseudo-second-order rate kinetics (R-2=0.998). Intraparticle diffusion was found not to be the sole rate-controlling step. Thermodynamic studies revealed that the sorption of cadmium was feasible, spontaneous, and exothermic. Various isotherm models viz. Langmuir, Freundlich, Redlich-Peterson, Dubinin-Radushkevich, and Temkin isotherms were applied. The Langmuir and Redlich-Peterson models were found to be in good agreement with experimental data with high R-2, low RMSE, and low chi(2) values. The Redlich-Peterson isotherm constant g was found to be unity, which implies a good fit to the Langmuir model. The maximum sorption capacity calculated from the Langmuir isotherm was 85.47 mg/g at optimum conditions of pH 6.0, contact time of 35 min, biomass dosage of 1g/L, and temperature of 25 degrees C.