Probing and understanding interaction of Eu(III) with γ- alumina in presenceof malonic acid.

Radionuclide migration in aquatic environment is influenced by its sorption onto colloids/mineral oxides and the presence of organic complexing anions. With a view to understand the sorption of trivalent actinides by mineral oxides in presence of organic acid, in the present study, Eu(III), malonic acid (MA) and γ-alumina are considered as representatives of trivalent actinides, low molecular weight natural occurring organic acid and aluminol sites, respectively. The influence of MA on sorption of Eu(III) by γ-alumina was elucidated by batch sorption, spectroscopic techniques and surface complexation modeling, for the first time.

Delineating the influence of picolinic acid on Eu(iii) sorption by γ-alumina.

The present study aims at understanding the sorption mechanism of Eu(iii) by γ-alumina in the presence of picolinic acid (PA), a decontaminating agent used in the nuclear industry, through batch sorption studies, spectroscopy and surface complexation modeling. PA is weakly sorbed by γ-alumina, with the sorption increasing with pH up to 4.5 and decreasing with further increase in pH.

Complexation of U(VI) with Cucurbit[5]uril: Thermodynamic and Structural investigation in aqueous medium.

The assessment of cucurbituril (CBn) for selective removal of actinides from nuclear waste streams requires comprehensive understanding of binding parameters and coordination of these complexes. The present work is the first experimental report on complexation of actinide ion with Cucurbit[5]uril (CB5) in solution. The thermodynamic parameters (ΔG, ΔH and ΔS) for complexation of CB5 with U(VI) in formic acid water medium were determined using microcalorimetry and UV-Vis spectroscopy.

Complexation of Eu(III) with cucurbit[n]uril, n = 5 and 7: a thermodynamic and structural study.

Cucurbit[n]urils (CBn) are a new class of macrocyclic cage compounds capable of binding organic and inorganic species, owing to their unique pumpkin like structure comprising of both a hydrophobic cavity and a hydrophilic portal. The thermodynamics of the complexation of Eu(III) with CBn of a different cavity size viz. cucurbit[5]uril (CB5) and cucurbit[7]uril (CB7) has been studied by UV-Vis spectroscopy and calorimetry at 25 °C whereas the structure of the complexes was investigated using time resolved fluorescence spectroscopy (TRFS) and extended X-ray absorption fine structure spectroscopy (EXAFS) in a formic acid-water mixture (50 wt%).

Sorption of curium by silica colloids: effect of humic acid.

Sorption of curium by silica colloids has been studied as a function of pH and ionic strength using (244)Cm as a tracer. The sorption was found to increase with increasing pH and reach a saturation value of ∼95% at pH beyond 5.3.