| The nuclear industry is a complex system, including the uranium miningand extraction, purification, transformation, isotope enrichment, spent fueltreatment and high level radioactive waste disposal. Mistakes in every stepshould not be any problems; otherwise the consequence would be disastrous.Technetium is one of the most radioactive nuclear wastes. Technetium isdifficult to immobilize and exists as TcO4-in the soil. The redox reactionthermodynamic properties were obtained by mathematical calculations. It is acompletely spontaneous reaction, which disposed rhenium and technetium byzero-valent iron (ZVI). The active digits of ZVI and the mechanism of themodel of reduction reaction could be obtained by calculation.All isotopes of technetium are radioactive. technetium was taken place byrhenium, which has similar physicochemical property with technetium. ReO4-was reduced by ZVI and the reaction was investigated in kinetics. Theexperimental result was consistent with pseudo first order reaction, and theReO4-has a high removal rate within the experiment concentration. The reactionrate would speed up little with the increase of temperature. The reaction processmeets Arrhenius formula with the apparent activation energy of5.13kJ/mol.The treatment of ReO-4with ZVI will be superior performance could be as highas90%under an approximately pH=7or slightly acidic or alkaline reactionmedium. The kinetic law of this redox reaction was obtained; which provide a theoretical and practical basis for the further thorough understanding of theremoval of technetium by ZVI.Finally, the reaction model and the computer simulation experiment. Thekinetics model that rhenium immobilized by ZVI was studied.Langmuir-Hinshelwood dynamic is the best among different models. Theexperimental data was fitted through Runge-Kutta method by MATLAB. Thereaction orders and the reaction rate constant were obtained and the independentreaction number was determined. All the results were consistent with theoreticalcalculation. |
PDF Full Text Request