Study Of The Biosorption Mechanism Of Radioactive Nuclide Uranium By S. Cerevisiae

The radioactive contamination has existed from the early days of foundation. We always make our effort to study different methods for changing this situation, but until now, there isn’t a equilibrium state between the nuclear power production and radioactive elements creation. Study of the biosorption mechanism of radioactive nuclide by S. cerevisiae was set as a starting point for the purpose of biosorption technology promotion. Specially, the main content can be boiled down to four aspects.1. The measurement condition of WGJ-III trace uranium analyzer:pH is in range of3to11, the amount of fluorescence enhancement agent is500ul. And the uranium concentration which is measured should be corrected when environmental temperature changes.2. The effects of contact time, concentration of biomass, pH and ionic strength on biosorption of uranium by living and dead cells were studied respectively. And the optimal biosorption conditions of living and dead cells were determined. We found that the biosotption capability of dead cells is higher than that of living cells. This may be the the result of the improvement of membrane permeability in the process of high pressure sterilization. And the high concentration of NaNO3has an obvious inhibiting effect on biosorption of uranium.3. The investigations of biosorption kinetics and biosorption isotherms for living and dead cells show that the biosorption dynamics processes of living and dead cells are highly conform to pseudo-second-order kinetics model. But biosorption isotherm studies show that the Freunslich isotherm fit equilibrium data of living cells very well, while the Langmuir isotherm is much better than Freunslich isotherm in fitting equilibrium data of dead biomass. The above results represent that the biosorption sites of dead cells are homogeneous, while uranium uptake by living cells is a complicated interaction process.4. The living and dead cells are characterized through TEM, EDS and FTIR analysis before and after biosorption. The results of TEM and EDS show that the needle-like uranium-phosphate around cell walls for both living and dead cells is a complexation that contain uranium. The further FTIR analysis illustrates that functional groups, such as carboxyl, hydroxyl, phosphate and amino groups play an important role in uranium biosorption.