Determination of the total concentration and speciation of Uranium in natural waters by the Resin Titration method

An Optical Fiber Sensor for Uranium Detection in Water

An optical sensor for uranyl has been prepared based on a gold-plated D-shaped plastic optical fiber (POF) combined with a receptor consisting of a bifunctional synthetic molecule, 11-mercaptoundecylphosphonic acid (MUPA), with a phosphonic group for complexing the considered ion, and a sulfide moiety through which the molecule is fixed at the gold resonant surface as a molecular layer in an easy and reproducible way. The sensor is characterized by evaluating the response in function of the uranyl concentration in aqueous solutions of different compositions and real-life samples, such as tap water and seawater. The mechanism of the uranyl/MUPA interaction was investigated. Two different kinds of interactions of uranyl with the MUPA layer on gold from water are observed: a strong one and a weak one. In the presence of competing metal ions as Ca²⁺ and Mg²⁺, only the strong interaction takes place, with a high affinity constant (around 10⁷ M⁻¹), while a somewhat lower constant (i.e., around 10⁶ M⁻¹) is obtained in the presence of Mg²⁺ which forms stronger complexes with MUPA than Ca²⁺. Due to the high affinity and the good selectivity of the recognition element MUPA, a detection limit of a few μg L⁻¹ is reached directly in natural water samples without any time-consuming sample pretreatment, making it possible for rapid, in situ controls of uranyl by the proposed sensor.

Uranium concentrations in sediment pore waters of Lake Neusiedl, Austria

The goal of the present investigation was to measure ²³⁴U/²³⁸U activity ratios in pore waters of Lake Neusiedl, Austria, in order to learn more about uranium in groundwaters of the Lake Neusiedl/Seewinkel region. Pore waters of waterlogged sediments (at 1m depth) in the littoral zone of Lake Neusiedl were analyzed. The pore water samples were collected in the National Park Lake Neusiedl/Seewinkel from pristine sites that were not influenced by neighboring fertilized fields or vineyards. Uranium isotopes were extracted from 1.5L of sediment pore water and measured by α-particle spectrometry. Uranium concentrations were found to be unexpectedly high (up to 853μgL^-1) especially in pore waters of salt-rich locations. ²³⁴U/²³⁸U activity ratios were between 0.91 and 1.09 for all pore water samples, irrespective of their origin from the east or west littoral zones of the lake. Uranium and mineral salts concentrations were strongly correlated. ²²²Rn concentrations were low (between 22 and 42BqL^-1). The results provide insight into the high degree of mobility of U(VI) in sedimentary environments, in the presence of migrating Na₂SO₄-type saline waters.

Deferoxamine–paper for iron(III) and vanadium(V) sensing

The development of a sensor based on the functionalization of common filter paper with deferoxamine (DFO) is proposed with the prospect to produce a solid phase for iron(III) and vanadium(V) sensing. The main features of this sensor are the simplicity of operation, good sensitivity and feasible applicability to real samples without the need of pre-treatment procedures. DFO was selected not only for it is easily anchored to the solid support, but also because it forms colored complexes with iron(III) and vanadium(V); hence, the developing of a simple colorimetric sensor can be considered. In particular, an innovative and economic way to perform colorimetric measurements using a desktop scanner is described. A complete characterization of the functionalized material is also reported.