Effect of γ-ray radiation on the biosorption of strontium ions to baker’s yeast

Abstract

Radionuclide remediation is becoming an increasingly serious environmental problem, posing threat to biotic life. Biosorption is a technology for the treatment of wastewater containing metal ions. In this work, the biosorption of strontium ions (Sr2+) to baker’s yeast and the effect of γ-ray radiation on the biosorption process were investigated at different experimental conditions. The experimental results fitted well to the Langmuir and Freundlich model isotherms before and after the γ-ray radiation (r2 > 0.985), and the maximum biosorption capacity values were qmax > 33.0 mg g−1 at 30 °C. Negative values of ΔG0 and positive values of ΔH0 were observed indicating, the spontaneous and endothermic nature of Sr2+ biosorption on baker’s yeast, respectively. The biosorption kinetics followed a pseudo-second-order equation at different experimental temperatures (r2 > 0.999), the calculate results of the strontium sorption capacity at equilibrium (qe,cal) increased about 0.4–1.0 mg g−1 after γ-ray irradiated. The activation energy of baker’s yeast biosorption to Sr2+ decreased 0.79 kJ mol−1 after γ-ray radiation. The γ-ray radiation affects the amide bands of proteins and leads to a decrease of the isoelectric point from pH of 2.55 to 2.25 and an increase in the electronegativity of the cells wall. In summary, an appropriate γ-ray radiation condition not only has no negative effects, but also can enhance its biosorption capacity slightly of Sr2+ to baker’s yeast.