Biosorption of chromium(VI) from water onto the heat-treated biomass of Saccharomyces cerevisiae

Biosorption characteristics of Cr(VI) from aqueous solution by heat-treated Saccharomyces cerevisiae were investigated in a batch system. The influence of solution pH, initial Cr(VI) concentration, biomass concentration, co-existing ions, contact time and temperature on biosorption was explored. The biosorption was highly pH-dependent, and the optimum pH for biosorption was found to be 2.0. Adsorption capacity of Cr(VI) onto biomass decreased with a rise in biosorbent dosage and increased with the increasing initial Cr(VI) concentration. It was indicated that an increase in temperature would be favorable to Cr(VI) adsorption onto Saccharomyces cerevisiae in the range of 20 degrees C-40 degrees C. The biosorption process better followed the pseudo-second-order kinetic model, and the correlation coefficients obtained from the pseudo-second-order model were all higher than 0.99. The Langmuir and Freundlich isotherm models were applied to experimental equilibrium data. The Langmuir model better described the adsorption equilibrium than the Freundlich model. According to the Arrhenius equation, the activation energy of adsorption of chromium(VI) ions was determined as 18.37 kJ/mol. The calculated thermodynamic parameters indicated that Cr(VI) biosorption onto Saccharomyces cerevisiae was spontaneous and endothermic under studied experimental conditions. The results suggest that the biomass of Saccharomyces cerevisiae is a promising biosorbent for removal of chromium(VI) ions from the wastewater.