Abstract

The article presents results obtained during investigation of Eu(III) ion removal from aqueous solutions using triacetate cellulose films and styrene-divinylbenzene copolymer beads containing tetraoctyl diglycolamide (TODGA). A simple method for manufacturing films containing up to 50 % w/w TODGA is provided. Solution acidity effect on the removal rate of Eu(III) ions was studied. Maximum removal of Eu(III) ions was obtained in nitric acid solutions with concentrations of 1-6 mol/l. Additionally, increase in the europium removal rate is also observed at pH > 2 for beads and in the pH range of 2 to 4 for films. In the former case increase in the removal rate is explained by increase in the nitrate ion concentration in the solution and Eu(NO3)3(TODGA)3 complex formation, and in the latter case – by decrease in TODGA protonation rate with рН growth. Observed trends indicate a high similarity in surface sorption mechanisms between the materials studied. Sorption equilibrium of Eu(III) ions onto the styrene-divinylbenzene copolymer beads impregnated with TODGA is adequately fitted to Langmuir sorption isotherm. The maximum sorption capacity of this material for Eu(III) removal from solutions with nitric acid concentration of 1 mol/l is 7.4 mg/g. It has been found that the maximum removal rate of Eu(III) ions by the triacetate cellulose films is achieved for TODGA content in the films ≥ 40 % w/w. The possibility of selective europium sorption from natural water using both beads and films is shown. Although cations present in natural water do not bind to sorbents studied, there is still slight deterioration in sorption properties when moving from model solutions to natural water. Complete desorption of Eu(III) ions from the film surface is achieved by washing three times with an EDTA solution, рН = 6.8. Prepared films can be reused for Eu(III) ion removal.

Highlights

  • Processing and disposal of nuclear wastes as well as determination of trace amounts of radionuclides in the environment objects have become increasingly relevant due to nuclear industry development

  • Sorption properties of polymeric beads based on styrene-divinylbenzene impregnated with tetraoctyl diglycolamide (TODGA)

  • Lanthanides and actinides are usually extracted by TODGA or related ligands from concentrated solutions of nitric acid

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Summary

Introduction

Processing and disposal of nuclear wastes as well as determination of trace amounts of radionuclides in the environment objects have become increasingly relevant due to nuclear industry development. One of the most promising extractants for actinides removal is tetraoctyl diglycolamide (TODGA) (Fig. 1) [13,14,15,16,17,18,19,20]. This ligand has an especially great affinity for americium. The carrier should be inert, resistant to acidic media and radiation Good examples of such materials are different polymers in the powder, bead, and film forms. Film composition is typically adjusted individually in each separate case

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