Kavitha Jayachandran

Single-walled carbon nanotube (SWCNT) modified gold (Au) electrode for simultaneous determination of plutonium and uranium

A single-walled carbon nanotube-modified–Au electrode (SWCNT–Au) was employed for the simultaneous determination of Plutonium (Pu) and Uranium (U). The SWCNT–Au displayed excellent electrochemical catalytic activities towards Pu and U reduction compared to bare Au. In the differential pulse voltammetry technique (DPV), both Pu and U gave sensitive reduction peaks at 564 mV and −128 mV, respectively, versus a saturated Ag/AgCl electrode. Under the optimized experimental conditions, Pu and U gave linear responses over ranges of 10 to 100 μM (R2 = 0.990) and 3 to 10 μM (R2 = 0.987), respectively. The detection limits were found to be 8.2 μM for Pu and 2.4 μM for U.

A novel biamperometric methodology for thorium determination by EDTA complexometric titration

Abstract A biamperometric methodology is described for the determination of thorium by EDTA complexometric titration, based on the observed electrochemical behaviour of EDTA when the applied potential was ≥200 mV between the twin Pt electrodes. Studies carried out showed that a pH range of 2.4–2.7 was optimum for the determination. Accuracy and precision of the method were evaluated using different amounts of thorium ranging from 50 μg to 5 mg. Studies on the interference of uranium were carried out with different amounts of uranium ranging from 20 to 80% using the presently developed approach of biamperometry as well as the conventional indicator method. The method was employed for the determination of Th in (Th,U)O2 samples containing different amounts of Th and U.

Novel Electrochemical Synthesis of Polypyrrole/Ag Nanocomposite and Its Electrocatalytic Performance towards Hydrogen Peroxide Reduction

A simple electrochemical method of synthesis of polypyrrole/silver (PPy/Ag) nanocomposite is presented. The method is based on potentiodynamic polymerization of pyrrole followed by electrodeposition of silver employing a single potentiostatic pulse. The synthesized PPy film has embedded Ag nanocubes. The morphology and structure of the resulting nanocomposite were characterized by field emission scanning electron microscopy and X-ray diffraction. Electron paramagnetic resonance studies showed that silver nanoparticle deposition on polypyrrole leads to an increase in carrier density, indicative of enhanced conductivity of the resulting composite. Electrocatalytic performance of the prepared composite was examined for reduction of hydrogen peroxide and was compared with corresponding PPy film and bare glassy carbon electrode.

Extraction and electrochemical investigations of Pu(IV) employing green solvent system containing new bifunctional ligand and Bmim[NTf2] ionic liquid

Electrochemical investigations and extraction of Pu(IV) was investigated employing a new bifunctional ligand system (N,N-dialkyl carbamoyl methyl) (2-pyridyl-N-Oxide) sulfide C5H4NOSCH2CONR2, (where R = octyl) (NOSCO) dissolved in 1-butyl-3-methylimidazolium bis (trifluoromethanesulphonyl) imide ([Bmim][NTf2]). The extraction efficiency was found to be 84% in single contact. Cyclic voltammetry (CV) of Pu(IV) in aqueous and in ([Bmim][NTf2] + NOSCO) was carried out. Shifts of cathodic and anodic peak potentials of Pu(IV) in cyclic voltammograms were observed towards negative potentials in the extended electrochemical window for ionic liquid medium compared to aqueous medium. The diffusion coefficient and heterogeneous charge transfer coefficient were calculated for both aqueous and ionic liquid media. The redox reaction were found to be quasi reversible for both the media while the CV was broader in case of ionic liquid suggesting slow kinetics.

Poly(3,4-ethylenedioxythiophene)–Poly(styrenesulfonate)-Coated Glassy-Carbon Electrode for Simultaneous Voltammetric Determination of Uranium and Plutonium in Fast-Breeder-Test-Reactor Fuel

Uranium (U) and plutonium (Pu) contents in nuclear materials must be maintained to a definite level in order to get the desired performance of the fuel inside the reactor. Therefore, high accuracy and precision is an essential criterion for the determination of U and Pu. We already reported the voltammetric determination of Pu in the presence of U in fast-breeder-test-reactor (FBTR) fuel samples, but interfacial, coupled chemical reactions between U(IV) and Pu(IV) enhance the peak-current density of U(VI) reduction and thus make voltammetry unsuitable for the quantitative determination of U in the presence of Pu. Thus, developing a voltammetric method for the simultaneous determination of U and Pu is highly challenging. Herein, we report the simultaneous voltammetric determination of U and Pu in 1 M sulfuric acid (H2SO4) on a poly(3,4-ethylenedioxythiophene) (PEDOT)-poly(styrenesulfonate) (PSS)-modified glassy-carbon (GC) electrode (PEDOT-PSS/GC). The modified electrode shows enhanced performance compared with bare GC electrodes. The peak-current density for U(VI) reduction is enhanced in the presence of Pu(IV), but it attains saturation when [Pu]/[U] in solution is maintained ≥2. Hence, under these circumstances, the variation of Pu concentration no longer influences the U(VI)-reduction peak, and thus the quantitative determination of U in the presence of Pu is possible. No interference is observed from commonly encountered impurities present in FBTR fuel samples. This method shows accuracy and precision comparable to those of the biamperometry method. High robustness, fast analysis, simultaneous determination, reduced radiation exposure to the analyst, and ease of recovery of U and Pu from analytical waste makes it a suitable candidate to substitute the presently applied biamperometry method.

Performance evaluation of indigenous amperometers for the determination of uranium

The performance evaluation studies of three indigenously manufactured amperometers were carried out for uranium determination in U3O8 standard solution. Three analysts independently carried out ten determinations each of uranium by Biamperometric end point detection method with each of these amperometers. Two-way ANOVA test was performed on the data using MATLAB-7.0 software to test whether the variation in the observed data is statistically significant. No significant bias in the data produced by three analysts with three independent instruments was observed. The results obtained show that the indigenous amperometers are suitable for uranium determination in fuel materials and for nuclear material accounting, with high precision and accuracy.