Nuclear Science and Techniques ›› 2019, Vol. 42 ›› Issue (2): 20301-020301.doi: 10.11889/j.0253-3219.2019.hjs.42.020301

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Adsorption mechanism of U(Ⅵ) by bentonite

Zuoyong DU1,Yanhui WANG1,Dongrui LI1,Xianguo TUO2()   

  1. 1. Laboratory of National Defense for Radioactive Waste and Environmental Security, Southwest University of Science and Technology, Mianyang 621010, China
    2. Sichuan University of Science & Engineering, Zigong 643000, China
  • Received:2018-10-30 Revised:2018-12-08 Online:2019-02-10 Published:2019-02-19
  • Contact: Xianguo TUO E-mail:tuoxg@cdut.edu.cn
  • About author:DU Zuoyong, male, born in 1994, graduated from Southwest University of Science and Technology in 2017, master student, focusing on nuclide|DU Zuoyong, male, born in 1994, graduated from Southwest University of Science and Technology in 2017, master student, focusing on nuclide|TUO Xianguo, E-mail:<email>tuoxg@cdut.edu.cn</email>
  • Supported by:
    Supported by National Nature Science Foundation of China (No.41630646), Youth Found of National Nature Science Foundation of China (No.41603124)

Abstract: Background

The research on the disposal of clay rock in high-level waste is still in the initial stage, and little attention has been paid to the migration mechanism of nuclide in clay rock treatment system in previous work.

Purpose

This study aims at the adsorption behavior of U(Ⅵ) in Gaomiaozi bentonite and provide reference for the safety evaluation system of high level waste disposal storehouse.

Methods

The sorption behavior of U(Ⅵ) on Gaomiaozi bentonite was studied as a function of adsorption time, solid-to-liquid ratio, initial concentration of U(Ⅵ), pH value, the type of ionic species and ionic concentration by the static experimental method. Both scanning elextron microscope (SEM) and infrared spectrometer were employed to experimental observation.The adsorption kinetics and thermodynamic of U(Ⅵ) in bentonite was discussed.

Results

Experimental results showed that the equilibrium time of U(Ⅵ) sorption on bentonite was about 24 h. The optimum adsorption ratio was 1:300. The optimum initial concentration was 40 mg·L-1. When the pH value was 5, the ability of absorption reaches the best, the acid or alkaloid would affect the adsorption of bentonite on U(VI). Ca2+ and CO3 2- in solution significantly reduce the adsorption of U(VI) by bentonite, and the degree of influence increaseds with the increase of ion concentration.

Conclusions

The sorption isotherm of U(Ⅵ) can be simulated very well using the Freundlich and follow the quasi-2nd order kinetic equation, indicating that the adsorption is a multi-layer adsorption model.

Key words: Bentonite, U(Ⅵ), Adsorption, Dynamics model, Thermodynamic model

CLC Number: 

  • TL941