Zero-valent Nano-iron Removal From Groundwater In Reo <sub> 4 </ Sub> <sup> - </ Sup>

Nuclear energy as an important and clean energy in the world, has been widely used. Nuclear energy has brought great economic benefits to the human society, but if the nuclear wastes produced are mismanaged, it will lead to nuclear pollution. Nuclear waste will pollute the ecological environment and threaten human health seriously.As a radioactive element, Tc has a high fission yield (6.13%) and complicated chemical behavior. Tc exists in the form of dissolved TcO4- in the soil, which is difficult to be adsorbed by soil particles. It is also difficult to be fixed by common approach. The ordinary laboratory experiments is not easy for radioactive element. Non radioactive Re and Tc are very similar in physical and chemical properties, so we select Re instead of Tc for text object. Re is reduced and fixed by nano-iron, whose results and reaction laws will be analyzed and argued in this thesis.First of all, this experiment will use spectrophotometry to determine ReO₄^- concentration, and make sure the best measuring method of ReO₄^-. Results show that, the effect is best when adding 3.0 mL ethyl violet whose mass fraction is 0.1%, and with benzene as the extractant.Secondly, producing the nano-iron particles by liquid phase reduction method, and using the produced nano-iron to reduce and fix ReO₄^- and study the reaction affected by the initial concentration of ReO₄^-, pH and temperature. Experimental results show that, the lower the concentration of ReO₄^-, the faster the reaction rate, but it has little effect on the removal rate; the removal rate of ReO₄^- is best when the pH is 7 or Slightly alkaline, and it can be up to 98%; with the temperature increasing, both the reaction rate and removal rate of ReO₄^- are increased, but it's not significant.Finally, we make the soil column experiment. With Br- as tracer, we study the migration regularity of ReO₄^- and removal rule of ReO₄^- by nano-iron particles and calculate strainaway rate of ReO₄^- by nano-iron particles.The results show that the faster the flow velocity, the faster the migration of ReO₄^-, but the lower the removal rate; the removal rate of ReO₄^- can be up to about 70% when the flow velocity is 0.1 mL/min, so it can effectively prevent the migration of ReO₄^- in the groundwater.According to these studies, we can get a conclusion. The homemade nano-iron particles in laboratory has the best function for the fixed effect of the ReO₄^- in soil, which provide a theoretical and practical basis for the further thorough understanding of the removal of Tc by nano-iron particles.