Thorium Complexation with Aliphatic and Aromatic Hydroxycarboxylates: A Combined Experimental and Theoretical Study.

Hydroxycarboxylic acids, viz., α-hydroxyisobutyric acid (HIBA) and mandelic acid (MA), have been widely employed as eluents for inner transition metal separation studies. Both extractants have identical functional groups (OH and COOH) with different side-chains.

Selective Extraction of Thorium(IV) from Uranium and Rare Earth Elements Using Tetraphenylethane-1,2-diylbis(phosphoramidate).

Tetraphenylethane-1,2-diylbis(phosphoramidate) in conjugation with a room temperature ionic liquid in chloroform medium is reported for the first time in the liquid-liquid extraction of thorium (Th). The extracted Th(IV) is collected as a white solid in the organic medium, thereby facilitating its easy separation. A high distribution ratio (D) of (12.

Nitric acid concentration strongly influences low level uranium determination on PEDOT-PSS coated glassy carbon electrodes.

Understanding the parametric optimization and addition of modifications in existing techniques are the keys to successful research in the analytical sciences. The present study reports an electroanalytical technique by modifying an electrode with PEDOT-PSS and adjusting the analyte solution to lower acidity (0.05 M) levels.

Chemical and Redox Speciation of Uranyl with Three Environmentally Relevant Bifunctional Chelates: Multi-Technique Approach Combined with Theoretical Estimations.

Carbon and phosphorous are two primary elements common to the bio-geosphere and are omnipresent in both biotic and abiotic arenas. Phosphonate and carboxylate are considered as building blocks of glyphosate and humic substances and constituents of the cellular wall of bacteria and are the driving functionalities for most of the chemical interactions involving these two elements. Phosphonocarboxylates, a combination of both the functionalities in one moiety, are ideal models to dig deep into for understanding the chemical interactions of the two functional groups with metal ions.

Elucidation of the sorbent role in sorption thermodynamics of uranium(VI) on goethite.

The sorption process of radionuclides, often conducted at ambient temperature, shows significant sensitivity to the surrounding temperature. Prediction of fate and transport in the environment, therefore, requires accurate thermodynamic data of their species defining sorption-desorption onto solid surfaces. Herein, we examined the thermodynamics of uranium(VI), U(VI), sorption onto goethite with particular emphasis on directly calculating the enthalpy of U(VI) surface species formed under slightly acidic pH conditions.

Electrochemical recovery of plutonium from aqueous carbonate waste solutions.

Recovery of plutonium from aqueous carbonate waste solutions generated during the reprocessing of spent nuclear fuel is a key concern for sustainable nuclear energy programmes and the remediation of radioactive waste. Reported methods proceed through secondary waste generation caused by acidification of carbonate waste and make the recovery process cumbersome. Herein, we report a simple method for the recovery of Pu as solid PuO powder from carbonate waste solution in a two-step process.

The aqueous interaction of neodymium with two omni existent biomoieties - a mechanistic understanding by experimental and theoretical studies.

Neodymium (Nd), a technologically important metal ion, has emerged as a major contaminant in aquatic systems in recent years owing to its surge in electrical and electronic applications as a permanent magnet. The chelating molecules present in hydro- and biospheres could substantially enhance its absorption and lead to transportation and migration of Nd from the source. The mechanistic understanding of the Nd interaction with naturally relevant biomoieties present in flora and fauna is of primitive importance to estimate the toxicological effects of the metal ion.

Experimental and theoretical approach to probe the aquatic speciation of transuranic (neptunyl) ion in presence of two omnipresent organic moieties.

Pyrazines are omnipresent in nature and have their occurrence in plants, microbes, food supplies, marine arenas. The present studies aimed at aquatic speciation of the neptunyl ion (NpO) with two pyrazine compounds namely pyrazine monocarboxylic acid (PMC) and pyrazine dicarboxylic acid (PDC). Absorption spectrophotometry was used to probe the stability, speciation and spectral properties for the complexation process.

Characterization of Thorium-Pyrazinoic acid complexation and its decorporation efficacy in human cells and blood.

Thorium (Th) exposure to the human beings is a radiochemical hazard and the chelation therapy by suitable drugs is the major prevention approach to deal with. The present studies aimed at usage of pyrazinoic acid (PCA), which is a prodrug to treat tuberculosis, for its usage as decorporating agent for thorium from human body. The present studies provide a comprehensive knowledge on the chemical interaction and biological efficacy of pyrazinoic acid (PCA) for decorporation of Thorium from the human body.

Stabilization of uranyl(v) by dipicolinic acid in aqueous medium.

Preparation of a stable U(v) complex in an aqueous medium is a challenging task owing to its disproportionation nature (conversion into more stable U(vi) and U(iv) species) and sensitivity to atmospheric oxygen. The stable uranyl (UO)/dipicolinic acid (DPA) complex ([UO(DPA)(OH)(HO)]) was formed at pH 10.5-12.

Accountancy for intrinsic colloids on thorium solubility: The fractionation of soluble species and the characterization of solubility limiting phase.

The extensive hydrolysis of tetravalent actinides leads to polynuclear formations through oxygen bridging facilitating the formation of colloids as end products. The pH, ionic strength has phenomenal effects on Thorium colloids formation. The quantitative estimation of colloids facilitates the fraction of soluble fraction into ionic, polymeric and colloidal forms of thorium.

Aquatic interaction of uranium with two naturally ubiquitous pyrazine compounds: Speciation studies by experiment and theory.

The present studies interpret the speciation of uranyl (UO) with the most ubiquitous class of natural species named pyrazines in terms of stability, speciation and its identification, thermodynamics, spectral properties determined by a range of experimental techniques and further evidenced by theoretical insights. UO forms ML and ML kind of species with a qualitative detection of ML species, while the ESI-MS identified the formation of all the complexes including ML. Both the ligands act as bidentate chelators with a difference in ring size and coordinating atoms in the complex formed.

Reduction in Coordination Number of Eu(III) on Complexation with Pyrazine Mono- and Di-Carboxylates in Aqueous Medium.

The denticity, flexibility, and steric hindrance of the ligand are key factors in deciding the mode and number of coordination around a metal ion on complex formation. The thermodynamic aspects of lanthanide complexation with various multidentate ligands provides a significant insight into understand the coordination chemistry of lanthanides in framing the relevant metal organic networks for the applications in biological, biochemical and medical aspects. The pyrazine carboxylic acids are known to form many structurally important complexes and further can form chelates with coordination number of eight for europium in which more water molecules can be knocked out from the primary coordination sphere than demanded by denticity of the ligand.

Colorimetric and visual determination of ultratrace uranium concentrations based on the aggregation of amidoxime functionalized gold nanoparticles.

The authors describe the synthesis and characterization of 3-mercaptopropionylamidoxime functionalized gold nanoparticles (AuNPs) for visual detection of uranium (U) by cloud point extraction. The method is capable of quantifying U at the concentration limits set by the World Health Organization in drinking water i.e.

Complexation of thorium with pyridine monocarboxylate-N-oxides: Thermodynamic and computational studies.

The feed wastes and waste water treatment plants are the major sources for the entry of N-oxides into the soils then to aquatic life. The complexation of actinides with potentially stable anthropogenic ligands facilitate the transportation and migration of the actinides from the source confinement. The present study describes the determination of thermodynamic parameters for the complexation of Th(IV) with the three isomeric pyridine monocarboxylates (PCNO) namely picolinic acid-N-oxide (PANO), nicotinic acid-N-oxide (NANO) and isonicotinic acid-N-oxide (IANO).

Structural, luminescence, thermodynamic and theoretical studies on mononuclear complexes of Eu(III) with pyridine monocarboxylate-N-oxides in aqueous solution.

The mononuclear complexes formed by Eu(III) with three isomeric pyridine monocarboxylate-N-oxides namely picolinic acid-N-oxide (PANO), nicotinic acid-N-oxide (NANO) and isonicotinic acid-N-oxide (IANO) in aqueous solutions were studied by potentiometry, luminescence spectroscopy and isothermal titration calorimetry (ITC) to determine the speciation, coordination, luminescence properties and thermodynamic parameters of the complexes formed during the course of the reaction. More stable six membered chelate complexes with stoichiometry (ML, i=1-4) are formed by Eu(III) with PANO while non chelating ML and ML complexes are formed by NANO and IANO. The stability of Eu(III) complexes follow the order PANO>IANO>NANO.

Stability, speciation and spectral properties of NpO complexes with pyridine monocarboxylates in aqueous solution.

Neptunyl ion as NpO is the least reacting and most mobile radioactive species among all the actinides. The picolinic acid used for decontamination is co-disposed along with the radioactive waste. Thus, in long term storage of HLW, there is high possibility of interaction of actinides and long lived fission products with the picolinate and can cause migration.