Application of immobilized waste brewery yeast cells for Cd2+ removal. Equilibrium and kinetics

Abstract

In this investigation, the removal of Cd2+ by a brewery waste biomass in immobilized (Ca alginate beads) form was studied. The removal process was conducted at room temperature under batch conditions (magnetic stirring) using different initial cadmium concentrations. The equilibrium of biosorption was reached in 150 min for all employed initial concentrations. The maximum biosorption capacity was calculated to be 5.96 mg Cd2+ g-1 yeast for an initial Cd2+ concentration of 169 mg L-1. Langmuir and Freundlich adsorption isotherms were used to correlate the equilibrium adsorption data. Based on the correlation coefficients, it was concluded that the Langmuir isotherm is more suitable for describing the equilibrium data of cadmium biosorption. In addition, first and pseudo-second order kinetic models were applied to describe the biosorption process. The kinetic parameters for the pseudo-second order kinetics were determined.