Synthetic Pyrite Reduction Fixed Soil And Groundwater Rhenium Preliminary Inquiry

As a new-type of clean and efficient energy--nuclear energy has attractedmuch attention, but it is also a "double-edged sword", which brings peoplebenefits and provides convenience; on the other side, once improper use orhandling, it will bring great challenges to the environment, and pose a threat tohuman health directly or indirectly, and then causes disasters. How to effectivelyand properly handle the radioactive nuclear waste has become an importantproblem to use the nuclear energy.Chemical element Technetium (Tc) is one of the main radioactive pollutants,which is also the only one that all its isotopes are radioactive elements. Tc hasextremely complex chemical behavior and dreadful harm. Usually Technetiumin the form of (TcO4) dissolves in aqueous solution or in the soil, but can not befixed by soil or sediments, so deoxidizing the highly-charged Tc(VII) toinsoluble Tc(IV) is needed. The method of element substitution experiments,using non radioactive element Rhenium who has similar physical, chemicalproperties to replace Technetium, are studied and discussed in this paper.Preliminary study focused on using laboratory synthetic Pyrite to restoreand fix theRe O4in the soil and groundwater, and simply analyzed thedynamics as well as the influence of different factors on the effect of reductiveimmobilization. The experimental results showed that, the reduction reaction ofsynthesized pyrite to rhenium conforms to the first-order reaction kinetics, andthe reaction rate constant is0.0068h-1; when the pH value was4.1and4.9,FeS2removal rate to Rhenium can reach more than99%, and in the pH of4.1,reduction reaction was faster; when the pH value was under the same conditions,adding concentration of TOC would not affect removal rate of rhenium, butwould affect the reaction rate: the more adding concentration, the lower thereaction rate; when without TOC, the reaction rate was the fastest.Finally, the dynamic simulation experiments of soil column was conducted,and two different medium—quartz sand and soil—were used to study the migration rules ofRe O4ion and the removal rules of synthesized pyrite toRe O4ions. Experiments showed that, under same conditions, in quartz sandcolumn, the synthesized pyrite processing peak will not be affected obviouslyand no hysteresis phenomenon appeared; but in soil column, after thesynthesized pyrite processed, the rhenium removal lagged behind obviously. Theconclusion indicated that only2cm of pyrite can immobilize the rheniumobviously during its migration.