title: Selective preconcentration of uranyl ion by silica gel phases modified with chelating compounds as inorganic polymeric ion exchangers.
abstract: Four chemically modified chelating silica gel phases (I - IV) with ion exchange groups were tested for their potential capability to selectively bind, extract and preconcentrate uranyl ions (UO(2)(2+)) from different aqueous solutions as well as ore samples. Factors affecting such determination processes were studied and optimized. These included the pH of the contact solution, the mass of the silica gel phase extractant, the stirring time during the application of a static technique and the eluent concentration for desorption of the surface-bound uranyl ion and interfering anions and cations. All these factors were evaluated on the basis of determinations of the distribution coefficient value (K(d)) and the percent recovery (R%). Percent recovery values of 91% for silica phase (II) and 93% for silica phase (IV) were identified in the optimum conditions. The proposed preconcentration method was further applied to uranium ore samples as well as granite samples. The determined percentage and ppm values are in good agreement with the standard assigned ones. The structure of the synthesized silica gel phases (I - IV) and their uranyl bound complexes were identified and characterized by means of infrared analysis, thermal analysis (TGA) and potentiometric titration.
authors.affiliation: Division of Medical Chemistry, Faculty of Medicine, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia. memahmoud10@yahoo.com
authors.forename: Mohamed E
authors.initials: ME
authors.lastname: Mahmoud
authors.forename: Ibrahim M M
authors.initials: IM
authors.lastname: Kenawy
authors.forename: Ezzat M
authors.initials: EM
authors.lastname: Soliman
authors.forename: Medhat A
authors.initials: MA
authors.lastname: Hafez
authors.forename: Magda A A
authors.initials: MA
authors.lastname: Akl
authors.forename: Rabab R A
authors.initials: RR
authors.lastname: Lashein
mesh_terms: D000837:Anion Exchange Resins / Q000032:analysis*; D002411:Cation Exchange Resins / Q000032:analysis*; D002614:Chelating Agents / Q000737:chemistry*; D005782:Gels / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007477:Ions; D011199:Potentiometry / Q000379:methods; D012680:Sensitivity and Specificity; D058428:Silica Gel; D012822:Silicon Dioxide / Q000737:chemistry*; D013055:Spectrophotometry, Infrared / Q000379:methods; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D013818:Thermogravimetry / Q000379:methods; D013997:Time Factors; D014501:Uranium / Q000737:chemistry*
chemical_list: D000837:Anion Exchange Resins; D002411:Cation Exchange Resins; D002614:Chelating Agents; D005782:Gels; D007477:Ions; D014501:Uranium; D058428:Silica Gel; D012822:Silicon Dioxide