title: Selective recognition of uranyl ions from bulk of thorium(iv) and lanthanide(iii) ions by tetraalkyl urea: a combined experimental and quantum chemical study.
abstract: The selective separation of uranyl ions from an aqueous solution is one of the most important criteria for sustainable nuclear energy production. We report herein a known, but unexplored extractant, tetraalkyl urea, which shows supreme selectivity for uranium in the presence of interfering thorium and other lanthanide ions from a nitric acid medium. The structural characterization of the uranyl complex (UO2X2·2L, where X = NO3(-), Cl(-) and Br(-)) by IR, NMR and single crystal X-ray diffraction provides insight into the strong interaction between the uranyl ion and the ligand. The origin of this supreme selectivity for uranyl ions is further supported by electronic structure calculations. Uranyl binding with the extractant is thermodynamically more favourable when compared to thorium and the selectivity is achieved through a combination of electronic and steric effects.
authors.affiliation: Fuel Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India. skannan@barc.gov.in.
authors.forename: Bal Govind
authors.initials: BG
authors.lastname: Vats
authors.affiliation: Fuel Reprocessing Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India.
authors.forename: Debasish
authors.initials: D
authors.lastname: Das
authors.affiliation: Radiation Safety Systems Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India.
authors.forename: Biswajit
authors.initials: B
authors.lastname: Sadhu
authors.affiliation: Fuel Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India. skannan@barc.gov.in.
authors.forename: S
authors.initials: S
authors.lastname: Kannan
authors.affiliation: Fuel Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India. skannan@barc.gov.in.
authors.forename: I C
authors.initials: IC
authors.lastname: Pius
authors.affiliation: Fuel Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India. skannan@barc.gov.in.
authors.forename: D M
authors.initials: DM
authors.lastname: Noronha
authors.affiliation: Theoretical Chemistry Section, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India. smahesh@barc.gov.in.
authors.forename: Mahesh
authors.initials: M
authors.lastname: Sundararajan
authors.affiliation: Solid state physics division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India.
authors.forename: Mukesh
authors.initials: M
authors.lastname: Kumar