[Biosorption of Radionuclide Uranium by Deinococcus radiodurans].

As a biological adsorbent, Living Deinococcus radiodurans was used for removing radionuclide uranium in the aqueous solution. The effect factors on biosorption of radionuclide uranium were researched in the present paper, including solution pH values and initial uranium concentration. Meanwhile, the biosorption mechanism was researched by the method of FTIR and SEM/EDS. The results show that the optimum conditions for biosorption are as follows: pH = 5, co = 100 mg · L(-1) and the maximum biosorption capacity is up to 240 mgU · g(-1). According to the SEM results and EDXS analysis, it is indicated that the cell surface is attached by lots of sheet uranium crystals, and the main biosorpiton way of uranium is the ion exchange or surface complexation. Comparing FTIR spectra and FTIR fitting spectra before and after biosorption, we can find that the whole spectra has a certain change, particularly active groups (such as amide groups of the protein, hydroxy, carboxyl and phosphate group) are involved in the biosorption process. Then, there is a new peak at 906 cm(-1) and it is a stretching vibration peak of UO2(2+). Obviously, it is possible that as an anti radiation microorganism, Deinococcus radiodurans could be used for removing radionuclide uranium in radiation environment.

[FTIR analysis of Sr2+ biosorption by Bacillus spp. strains isolated from soil treated with gamma-ray radiation].

One strain bacterium was isolated from purple soil of Sichuan basin. It was subject to Bacillus according to analysis results of 16S rDNA. The effect of its biosorption to Sr2+ under gamma-ray radiation was studied in this paper. As for the whole kinetic biosorption curves, the results show that bacterial growth rates of test groups have retardation phenomena compared to the control groups without radiation. Such as the appearance of biosorption equilibrium retarded 1.5 d while the max growth rate retarded 0.5 d after the radiation SEM analysis showed that the bacterial cells had abnormity distortion after radiation. This proved that gamma-ray radiation can bring obvious damage to experimental bacterial cells. FTIR analysis results indicated that bacteria cells were damaged by radiation and Sr2+ has cooperation damage effects with radiation in aqueous condition, and the bacterial cells of log phase are easier to be damaged by coming forth radiation than those of lag phase. This radiation damage under different radiation condition mainly leads to that the characteristic peaks of amylase, protein amide and lipids on bacterial cells are slightly shifted.

[Biosorption of lead ions on dried waste beer yeast and the analysis by FTIR].

The biosorption of lead ions on dried waste beer yeast was investigated with respect to the adsorption conditions and the biosorption mechanism was analyzed with the instruments of AAS, SEM/EDS and FTIR. The results show that the metal uptake value obtained was 47.6 mg x g(-1) and the adsorptive efficiency was above 90%. Under our experiment conditions, the biosorption of Pb2+ on dried waste beer yeast is a fast process. The biosroption quantity of Pb2+ on beer yeast cells was 47.6 mg x g(-1) and the adsorption efficiency obtained was 91.6% in fisrt 30 min, then the metal uptake value obtained was 48.8 mg x g(-1) and the adsorptive efficiency was above 94% at 90 min. The cells cracking and breaking off were seen after the biosorption of lead ions on beer yeast through SEM analysis, and the cytoplasts from yeast cell should be responsible for the last period biosorption of lead ions. EDS analysis also proved that lead ions were absorbed on the yeast cells. FTIR analysis showed that the infrared spectrograms are different at different pH and biosorption time, especially hydroxyl groups, carboxylate groups and amide groups have obviously changed. Amylase and amide of protein were considered as main components to participate the chemical absorption of lead ions on yeast cells. Consequently, dried waste beer yeast is an inexpensive, readily available adsorbent for metals and especially has a high adsorption capacity for lead ions.