Ammonium diuranate

About: Ammonium diuranate is a research topic. Over the lifetime, 193 publications have been published within this topic receiving 1460 citations. The topic is also known as: ammonium uranate(VI).

Sorption of uranium on magnetite nanoparticles

Abstract: Magnetite (Fe3O4) nanoparticle was synthesized using a solid state mechanochemical method and used for studying the sorption of uranium(VI) from aqueous solution onto the nanomaterial. The synthesized product is characterized using SEM, XRD and XPS. The particles were found to be largely agglomerated. XPS analysis showed that Fe(II)/Fe(III) ratio of the product is 0.58. Sorption of uranium on the synthesized nanomaterials was studied as a function of various operational parameters such as pH, initial metal ion concentration, ionic strength and contact time. pH studies showed that uranium sorption on magnetite is maximum in neutral solution. Uranium sorption onto magnetite showed two step kinetics, an initial fast sorption completing in 4–6 h followed by a slow uptake extending to several days. XPS analysis of the nanoparticle after sorption of uranium showed presence of the reduced species U(IV) on the nanoparticle surface. Fe(II)/Fe(III) ratio of the nanoparticle after uranium sorption was found to be 0.48, lower than the initial value indicating that some of the ferrous ion might be oxidized in the presence of uranium(VI). Uranium sorption studies were also conducted with effluent from ammonium diuranate precipitation process having a uranium concentration of about 4 ppm. 42% removal was observed during 6 h of equilibration.

The effect of solubility on inhaled uranium compound clearance: a review.

Abstract: Research on inhaled industrial uranium compounds has shown that solubility influences the target organ, the toxic response, and the mode of uranium excretion. Consideration of physical chemical properties indicates that the dissolution of industrial uranium oxides is expected to be strongly dependent on process history, and that dissolved uranium exists in vivo in the hexavalent state regardless of the oxidation state of the inhaled compound. The overall clearance rate of uranium compounds from the lung reflects both mechanical and dissolution processes. Mechanical clearance rates are highly variable among individual workers studied, but dissolution rates of inhaled compounds are similar among the mammalian species studied. Results from experiments in vivo and accidental worker exposures indicate that the uptake of dissolved uranium from the lung is more rapid than the dissolution rate of most industrial uranium compounds. These results indicate that the absorption rate of inhaled uranium can be approximated by the dissolution rate of most industrial compounds. Dissolution rates of UF6 and UO2(NO3)2 are more rapid than the mechanical clearance rates and dominate the overall lung clearance rate. UF4, UO3, and ammonium diuranate have intermediate dissolution rates that are similar to mechanical clearance rates and exhibit high variability among uranium specimens. U3O8 and UO2 have slow dissolution rates such that pulmonary clearance rates are dominated by mechanical processes. Industrial uranium ores, oxides, and fluorides are often variable mixtures of relatively soluble and insoluble fractions. Dissolution rates measured in vitro can be used with biokinetics models to reduce the uncertainties in dosimetry associated with inhalation exposures to mixtures.

Study on Sorption Characteristics of Uranium onto Biochar Derived from Eucalyptus Wood

Abstract: In this study, the sorption characteristics of U(VI) onto eucalyptus biochar as a function of various operating parameters such as solution pH, initial metal ion concentration, contact time and ionic strength of the medium are reported. Biochar was characterised using various techniques such as CHNS element analysis, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). SEM analysis showed the presence of micro- and macropores in the sorbent, and FTIR spectra confirmed the presence of functional groups like carboxylic (−COOH), hydroxyls(−OH), carbonyls(–C=O), etc. Maximum sorption of about 95% is found to occur in the pH range of 5 to 6. U(VI) sorption onto biochar reached equilibrium within 20 min at pH 5.5. The kinetic data were analysed using both pseudo-first-order and pseudo-second-order kinetic models, and the latter is found to be more appropriate to explain the observed kinetics. The equilibrium data were correlated with Langmuir and Freundlich models, and the maximum monolayer adsorption capacity obtained from the Langmuir model was 27.2 mg/g at 293 K. From EDS, FTIR and XPS measurements, it is found that the sorption process involves chemical interaction between the U(VI) and the surface functional groups on the adsorbent. Efficient removal of low level of uranium from ammonium diuranate supernatant demonstrates its utility as sorbent for waste water treatment.