Abstract
In this study, the Saccharomyces cerevisiae (S. cerevisiae) was modified by γ-ray. The RNA-seq results reflect that the high γ-ray energies could change some gene fragments, such as deletion, recombination, and mutation. The biosorption of strontium ions (Sr2+) to different types of S. cerevisiae (S. cerevisiae (K-0), modified S. cerevisiae (Y-7), and non-living S. cerevisiae (H-K)) from the simulated high-level liquid waste (S-HLLW) was assessed at different experimental conditions. The sorption experimental results show that, under an appropriate condition, γ-ray radiation can enhance its biosorption capacity slightly of Sr2+ to S. cerevisiae. The maximum metal uptake and efficiency of Y-7 under S-HLLW were 11.656mgg-1 and 37.91% at 32h (wet weight), respectively. They decreased to 9.46mgg-1 and 30.76% under radiation conditions. SEM-EDX and TEM analysis indicates that Sr2+ was adsorbed both on the cellular surface and the inner parts of the cells. Our experimental results fit well to the Langmuir and Freundlich model isotherms (r2 > 0.94), and the maximum biosorption capacity values reached qmax > 24.74mgg-1 at 32°C. Negative values ofΔG0 and positive values ofΔH0 were observed, indicating the spontaneous and endothermic nature of Sr2+ biosorption on modified S. cerevisiae. The biosorption kinetics follow a pseudo-second-order equation at 32°C (r2 > 0.94). The desorption efficiency of Sr2+ adsorbed onto Y-7 was 7.65 ± 0.52%, 76.51 ± 2.13%, and 65.62 ± 2.42% by deionized water, 1M HCl, and 0.1M EDTA-Na, respectively. However, they were lower than H-K (18.82, 83.32, and 73.32%). Our findings demonstrate that living S. cerevisiae (Y-7) is a promising sorbent material for the treatment of radioactive process streams.
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