The Research Of Chemically Similarity Of Re/Tc And The Sorption Behavior Of Re Onto Modified GMZ Na-bentonite

In the present work, the chemically similarity of Re and Tc, and the feasibility of Re as a tracer to determine the recovery of 99 Tc during its determination and as a replacement to study the migratory behavior of 99 Tc in the environment was investigated in details.Firstly, the factors which affect the spectrophotometric analysis of Re(VII), including the concentration of reductive agent(SnCl2), concentration of color agent(dimethylglyoxime), and the time of coloration were optimized. Results show that ReO4- can be reduced to 4 valences at strong acidic media by Sn2+, then forms the complex with dimethylglyoxime. The complex is in yellow and has a max absorption peak at 440 nm in spectrogram. The detection limit of this method for Re(VII) is 6×10-6 mol?L-1.The chemically similarity of Re and Tc, including the evaporation stability of ReO4- and TcO4- in HCl and HNO3 medium and their behavior in TEVA column, was also studied. The results show that the evaporation stability of ReO4- and TcO4- in HNO3 media are high and there is no obvious loss of ReO4- and TcO4-. However, the recovery of ReO4- and TcO4- in HCl media is relatively low, and the loss of TcO4-mainly occurs when the sample solution is evaporated to dryness. TEVA resin has high adsorption ability towards both ReO4- and TcO4-. The sorbed ReO4- and TcO4- on TEVA column can be effectively eluted by the high concentration of HNO3. During the column separation process, it can be found that ReO4- is eluted earlier than TcO4-, which indicates that TEVA resin has higher affinity to Tc O4-.Moreover, the sorption behavior of Re in HDTMA modified GMZ Na-bentonite was researched. Results show that HDTMA is connected on the surface of bentonite and even inserted into its interlayer leading to an interlayer spacing expansion. The modified Na-bentonite has a much higher adsorption capacity to ReO4-. This exothermic absorption processes is barely affected by pH and interfering ions. It can be inferred that the adsorption mechanism would be surface precipitation...