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Separation of Yttrium - 90 From Radioactive Liquid Wastes by Using Liquid – Membrane Methods

Farahmand Asl, Elmira | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 45618 (46)
  4. University: Sharif University of Technology
  5. Department: Energy Engineering
  6. Advisor(s): Samadfam, Mohammad; Davarkhah, Reza
  7. Abstract:
  8. In this research project, It has been investigated the ability of thenoyltrifluoroacetone (HTTA) as a carrier for selective separation of yttrium ions from aqueous media using bulk liquid membrane (BLM) system as a simple model for selective separation of 90Y from radioactive liquid wastes by the mentioned technique. Thus, a study has been made on carrier-mediated transport of yttrium(III) using a bulk liquid membrane prepared by dissolving thenoyltrifluoroacetone (HTTA) in dichloromethane. It has been observed that the use of n-propylamine (n-PA) in source phase as a synergistic reagent showed a marked enhancement of transport of yttrium ion. The source phase comprised of a solution of yttrium(III) or its binary mixture with other cations such as Ni2+ , Co2+ , Ag+ , Fe2+ , Al3+, Cu2+, Hg2+, Cs+ and Sr2+ in aqueous solutions of pH5.4 in the presence of n-PA, while 1M nitric acid was serving as a stripping agent in the receiving compartment. The interference from different transition metal ions could be minimized by using cyanide ion as masking agent in source phase (The interference of Al3+ was eliminated by 5-sulfosalicylic acid in the latter phase). Various factors influencing the transport process such as the pH of the source phase, the concentration of HTTA and the organic diluent used in the membrane, type and concentration of the acid used as the receiving phase, stirring rate, temperature and time has been investigated and discussed. Three replicate experiments showed that a uphill transport (89.7±1/6%) of yttrium(III) from the source phase (10-3 M Y3+ , 1% n-PA , pH=5.4 , 5 mL) could be accomplished into the receiving phase (HNO3 1M ,10 mL) through the bulk liquid membrane (HTTA 0.02 M in CH2Cl2 , 20 mL) after 8.5 h. To establish the ability of this method for separation of 90Y from radioactive liquid wastes, at the achieved optimized conditions and a discrete experiment, 90Y in secular equilibrium with 90Sr in the source phase, was transferred into receiving phase and separated completely from its long-lived parent isotope and β activity in the latter phase was measured with a liquid scintillation counter. The activity of the transported 90Y was found to decay with a half-life 64.17+0.05 h which is in agreement with the reported value in the literature
  9. Keywords:
  10. Yttrium Ions ; 2-Thenoyl Trifluoroacetone ; Liquid Membrane ; Cyanide Ions

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