| During the process of construction,operation,maintenance and decommissioning,a large number of radioactive waste water will be produced in nuclear power plants.These wastewater components are complex and contain a large number of radioactive decay products.If discharged directly without purification,they will pose serious health threats to the ecological environment and human beings.As a pollution-free and environmentally friendly wastewater treatment method,biosorption has attracted more and more attention.In this paper,the mechanism and influencing factors for the adsorption of strontium ion by irradiated Saccharomyces cerevisiae has been investigated.And then,the adsorption capacity for strontium in medium-low waste liquid by irradiated Saccharomyces cerevisiae has been explored.The experimental results and conclusions are as follows:(1)The influence of environmental factors such as pH,temperature and initial strontium ion concentration on the adsorption of strontium ion by irradiated Saccharomyces cerevisiae was studied by CCD center composite experiment.When the pH value is 6.9,the temperature is 31 degrees,and the initial strontium ion concentration is 359.4mg/L,the adsorption capacity and adsorption rate of strontium ion to irradiated Saccharomyces cerevisiae can reach the maximum value,which are 30.726mg/g and 88% respectively.The results of SEM and EDS show that strontium ions are deposited on the cell surface by forming cluster like crystals with cell walls.(2)The kinetics,isotherms and thermodynamic results for the adsorption of strontium ions by irradiated Saccharomyces cerevisiae were investigated.The kinetic results showed that the adsorption is a rapidly process.Thermodynamic results show that adsorption is a spontaneous endothermic process.The desorption experiment results showed that the order of elution rate was HNO3>EDTA>HCl>NaOH>H2O,which showed that the adsorption was mainly chemical reaction.(3)the adsorption selectivity of strontium ion in simulated medium-low level radioactive waste by irradiated Saccharomyces cerevisiae were poor.The order of inhibitory effect of coexisting ions on strontium adsorption is Ni>Cr>Cs>Na>K.The adsorption behavior of Sr and Cs ions in binary solutions indicated that antagonism occurs in the adsorption process. |
