S. Chandramouleeswaran

Barium borosilicate glass as a matrix for the uptake of dyes

Barium borosilicate (BBS) and sodium borosilicate (SBS) glass samples, prepared by the conventional melt-quench method, were used for the uptake of Rhodamine 6G dye from aqueous solution. The experimental conditions were optimized to get maximum uptake and was found to be 0.4 mg of dye per gram of BBS glass sample. For the same network former to modifier ratio, barium borosilicate glasses are found to have improved extent of uptake for the dye molecules from aqueous solutions compared to sodium borosilicate glasses. Based on 29Si MAS NMR studies on these glasses, it is inferred that significantly higher number of non-bridging oxygen atoms present in barium borosilicate glasses compared to sodium borosilicate glasses is responsible for its improved uptake of Rhodamine 6G dye. 11B MAS NMR studies have confirmed the simultaneous existence of boron in BO3 and BO4 configurations in both barium borosilicate and sodium borosilicate glasses. The luminescence studies have established that the dye molecule is incorporated into the glass matrix through ion exchange mechanism by replacing the exchangeable ions like Na+/Ba2+ attached with the non-bridging oxygen atoms present in the glass.

Boroaluminosilicate glasses: novel sorbents for separation of Th and U.

Boroaluminosilicate glass having a specific composition could be successfully used for the selective uptake of thorium from a mixture containing uranium by controlling the solution pH only. Single ion uptake studies showed that the uptake of uranium and thorium was maximum at pH of 4.5 and 7.5, respectively. But uptake studies using mixtures with uranium and thorium showed that irrespective of the pH, the uptake of thorium was higher than that of uranium.

Kinetic modeling: dependence of structural and sorption properties of ZnO—crucial role of synthesis

Zinc oxide nanoparticles were synthesized by two different routes namely pyrolytic and gel combustion methods and characterized using different techniques like XRD, TGA/DSC, diffuse reflectance spectrophotometry, zeta potential, NMR and IR. The efficiency of the nanoparticles with respect to sorption of different toxic species like chromate and rhodamine 6G was evaluated. The studies showed that the synthesis route adopted affects the characteristics of the nanoparticles, thus leading to the difference in sorption efficiency. The mechanism of sorption proposed was based on the different characterization studies and it was found that the sorption was not only an electrostatic interaction but can occur due to the presence of pores or some binding groups. The highly pH-dependent sorption efficiency of the nanoparticles is evident from the results, whereas their kinetics was described by a pseudo-second-order kinetic model and further explained by using Weber–Morris and Boyd models. The overall rate process appeared to be influenced by both external mass transfer and intraparticle diffusion. Considering the simplicity of the synthetic procedure and the possibility of a cost effective catalyst, the developed nanomaterials have great potential for applications in water treatment technologies.

Characterisation of nuclear fuel by spectroscopic evaluation of alpha autoradiographs

New methods for estimation of concentration and distribution of plutonium in (Th,Pu)O2 MOX fuel samples have been attempted by spectroscopic analysis of SSNTD based alpha images using UV–Vis spectrophotometry and photoluminescence spectroscopy. (Th,Pu)O2 MOX fuel samples having a large range of PuO2 concentration, were subjected to this study and found beneficial when compared with the conventional analysis of alpha autoradiographs. UV–Vis absorbance and photoluminescence of the alpha autoradiograph showed linear decrease proportionally to PuO2% in the fuel sample. Optical band gap was found to proportionally increase with PuO2% in the fuel sample which was revealed in UV–Vis spectrophotometry.

Effect of Synthesis Protocol on the Surface Charge of Zinc Oxide Nanoparticles and its Consequence on Sorption Ability

The surface charge of nanosorbents is a very important factor which affects applications. In the present paper, the surface charge of ZnO NPs was tailored using by adopting different synthesis protocols. The synthesized nanoparticles were characterized and zeta potential measurements showed that the ZnO Nps synthesized by pyrolysis method (ZnO (PY)) and the gel-combustion method (ZnO (GC)) possess a positive charge while the co-precipitation method results in nanoparticles (ZnO (CP)) with negative surface charge.

Fe3O4@SiO2 core-shell nanoparticles: Synthesis, characterization and application in environmental remediation

In this study, Fe3O4@SiO2 core-shell structure was synthesized by a one pot co-precipitation method, and its applicability as Low-Cost Abundantly available adsorbent for removal of heavy metal ions from simulated industrial waste water was examined. The detailed characterization of morphology showed that the Fe3O4 nanoparticle was coated with amorphous silica of a shell thickness of 2–3 nm. The core-shell magnetic nanoparticles (MNPs) showed a great removal capability of four different heavy metal ions (Zn (II), Co (II), Ni (II), and Cu (II). These MNPs showed high magnetic saturation values, which ensure the convenience of recovering sorbent for reusability with the assistance of external magnetic field. Specifically, this present study shows the use of MNPs as an effective recyclable adsorbent for environmental remediation.

Investigative studies of alpha irradiated PADC films: application to plutonium sources

Analytical evaluation of the effect of alpha fluence and energy on the properties of the irradiated PADC polymers was carried out. The images obtained by alpha irradiation on the films were analyzed using image analysis technique while UV–Vis spectrophotometry was used to understand the changes of the optical properties of the polymer. The results of this study could be applied for estimation of fluence and identification of energy of plutonium bearing sources in nuclear industrial facilities without having to use a dedicated and glove box enclosed equipment.

Flow Injection Analysis of Iron in Presence of Uranium

Analytical chemistry involves the science of providing information about the target in order to facilitate diagnoses and the making of educated, effective decisions. Trace level determination of metallic impunity is one of the imperative steps of chemical quality control of nuclear fuels. The spectra of U are so complex that a direct determination of the metal ions in presence of U becomes very difficult to interpret. Therefore separation becomes essential and regardless of the substantial furtherance in sensitivity using new instrumentation, conventional separation techniques are recurrently used to surmount interferences from matrix elements as well as to improve detection limits [1,2]. However separation results in increase of time of analysis and also great care is needed as there is a greater chance of contamination during reaction process. ICP-AES based method for direct determination of trace metallic constituents without any separation has been reported [3]. Another technique which is very useful is the Flow Injection Analysis (FIA) which has several advantages like small sample size, high sample throughput due to shorter reaction times, reproducibility, reliability, and ease of automation [4]. The concept of FIA depends on a combination of three factors: reproducible sample injection volumes, controllable sample dispersion, and reproducible timing of the injected sample through the flow system. The common feature of all Flow Injection (FI) methods is that the characteristics of fluid flow in closed medium are exploited for one or more of the following operations on a controlled amount of sample (a) the transport of samples, (b) the chemical pretreatment of samples and (c) the presentation of samples to a chemical instrument. As all samples and standards have identical residence times, the kinetic limitations of conventional analytical methods, in which samples and standards arc handled in parallel, do not apply. Thus it is not necessary for any of the chemical or physical processes in the system to be at equilibrium and restrictions on the stability of both the product and the reagents can be relaxed. Single Line Manifold (SLM) in which a reagent carrier stream continuously flows and a fixed volume of sample is injected into the flowing reagent carrier results in dispersion due to the combination of laminar flow (in which a parabolic velocity profile develops between the center stream line and the wall) and diffusion. Flow injection analysis of iron in various matrices has been reported [5-12].

Insight of solvent extraction process: Reassessment of trace level determinations.

Solvent extraction is hoary yet modern technique with great scope of research due to the various intriguing phenomena in the system. Tri-n-butyl phosphate (TBP) is a well known extractant which has been extensively used for separation of uranium matrix prior to elemental profiling. In this paper, one of the impurities namely Fe is being considered as it posed a challenge to the separation due to its co-extraction with TBP along with uranium. In these studies, for the first time, the existence of cation-cation inner sphere complexes between the UO2(2+)and Fe(3+) ions in both aqueous and organic phases have been establisted in addition to the selective separation of iron from uranium sample matrix using only TBP. The data from both spectrophotometric and thermophysical studies corroborated one another confirming the presence of cation-cation interactions (CCIs). The developed solvent extraction with only TBP showed almost no interferences on the iron extraction from matrix uranium and other co-ions like aluminum and copper. This has been the first time application of pure TBP for selective removal of iron from uranium samples. The procedure possessed excellent reproducibility and robustness.

N-benzoyl-n-phenylhydroxylamine impregnated Amberlite XAD-4 beads for selective removal of thorium.

n-Benzoyl-n-phenylhydroxylamine impregnated Amberlite XAD-4 beads were used for the removal of Th(IV) from a mixture of ions. The impregnated XAD was characterized using different techniques like weight and colour change, IR spectra, surface area and pore size measurements to confirm the presence of n-BPHA within the macroreticular resin structure. The experimental conditions were optimized to make the separation fast and selective. It was seen that the maximum sorption was achieved in the pH range of 3-7.5 and uptake was nearly complete within half an hour. The results obtained in the present study were subjected to extensive modelling in order to get a complete understanding of the sorption process. It is seen that the maximum uptake was calculated to be 500 mg/g and has very fast kinetics it was seen that the process is chemisorption. It was further deduced from the modelling that the overall sorption process was controlled dominantly by external mass transfer. Considering the simplicity this procedure, the present study has a possible application for the removal of thorium from different mixtures.