Recycling of acid from aqueous waste streams is highly important not only from the environmental point of view but also for developing the sustainable technology. One of the effective ways to recover ...acid from aqueous waste streams is the anion-exchange membrane based diffusion-dialysis. The work presents the synthesis and characterization of anion-exchange pore-filled membranes for the objective of recovery of high concentration of acid by diffusion dialysis. The membranes were prepared by anchoring the guest organic-inorganic anionic gel in the pores of the host poly(propylene) membrane by in situ UV-initiator induced polymerization of the appropriate monomers along with cross-linker. The removal of nitric acid in the presence of different representative monovalent, divalent and trivalent nitrates and the leakage of these ions through anion exchange membrane have been studied by DD technique for optimizing the chemical composition of the membrane. The nitric acid permeation rate of the membrane with the optimized composition has been found to be considerably faster than the commercial Selemion membrane without sacrificing salt leakage. The performance of the optimized pore-filled anion exchange membranes has been found to be independent of the acid concentration, nature of the anion and substrate and has been observed to be solely dependent on the guest inorganic-organic hybrid anionic gel component. The membranes have been found to be stable and reusable for the acid recovery. Removal of nitric acid as high as 90% from the simulated high level nuclear waste with the optimized grafted pore-filled membrane has been achieved with negligible salt transport.
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•Recycling nitric acid from aqueous waste important from environmental perspective.•For this, pore-filled AEM with hybrid organic-inorganic gel framework developed.•AEM characteristics found ideal for Diffusion Dialysis studies for acid recovery.•Removal of nitric acid by DD studied in presence of different valence cations.•Nitric acid removal as high as 90% from SHLW achieved with negligible salt leakage.
Four different structurally modified sulphoxides in ionic liquid were chosen for the development of efficient method for the extraction of thorium from aqueous acidic waste solutions. Novel ...piperidinium ionic liquid based solvent systems were found to be more efficient than the conventional imidazolium based systems. The extraction of thorium was predominated by ‘cation exchange’ mechanism via Th(NO3)·3SO3+ species. The trend in extraction efficiency followed APSO>BMSO>DHSO>DISO. The phenyl substituted sulphoxides showed higher affinity for thorium due to a combination of steric as well as electronic factors. All the extraction processes were thermodynamically spontaneous without participation of NTf2− ion in the extracted thorium complex. 0.05M oxalic acid was found to be suitable for almost quantitative stripping of thorium from loaded organic phase. APSO in ionic liquid was found to be radiolytically stable among the other four sulphoxides in ionic liquid.
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•Sulphoxides in piperidinium based ionic liquid: highly efficient system for the extraction of thorium•Cation exchange via Th(NO3). 3SO3+ species•Phenyl substituted sulphoxides have more extraction efficiency: Steric and Resonance factors•APSO highly radio resistant and thorium selective•Oxalic acid effective strippant
Designs for future gravitational wave detection facilities feature silicon test masses at cryogenic temperatures to reduce thermal noise and thermally induced aberrations. Designers call for ...operation at 123 K or close to 18 K to exploit the vanishing thermal expansion of crystalline silicon. The amount of absorbed heat that can be radiatively removed from the test masses is limited at these temperatures, forcing complex cooling scenarios to be considered, including conduction through suspension wires. This is particularly relevant for the kilohertz class of detectors that aim for extremely high circulating power, i.e., roughly a factor 20 more than the world record at the time of writing, to reduce quantum noise. We explore the impact of raising the test mass temperature and show that a dedicated kilohertz-band cryogenic instrument can do so without significant sensitivity penalty, thereby boosting the radiative cooling rate and allowing higher power operation with simpler suspensions. We also explore the implications of operating cryogenic broadband detectors at elevated temperatures. The work presented here was instrumental in the development of the Neutron Star Extreme Matter Observatory kilohertz-band gravitational wave detector design concept.
Solid-phase extraction of neptunium in pentavalent and hexavalent oxidation states from the acidic aqueous medium was investigated. The extraction of neptunium, carried out using
N
,
N
-dihexylamide ...functionalized multiwalled carbon nanotubes (MWCNT-DHA) showed high
K
d
values. The sorption was found to follow Freundlich isotherm via chemical interaction between the amide functionality and neptunium. The time-dependent sorption study showed that the kinetics followed pseudo second order rate constants. MWCNT-DHA was found radiolytically stable up to 1000 kGy. The selectivity of MWCNT-DHA for the sorption of Np ion was found to be satisfactory. Citric acid was evaluated as the best strippants.
Determination of trace metallic constituents in nuclear materials e.g. U, Pu, Am, Zr etc. by Atomic Emission Spectroscopy requires the separation of the major matrix without the loss of analytes at ...trace level. For DC Arc carrier distillation technique, carrier is used to separate the matrix physically according to the volatility of the analytes while appropriate extractant in suitable diluent is used for chemical separation in inductively coupled plasma atomic emission spectroscopy (ICP-AES). In the present study an attempt was made to develop a methodology for the determination of B, Cd, Mg, Zn, Al, Sr and Sc at trace level (up to 0.1 μg/mL) in uranium matrix without any chemical or physical separation. It involves identification of suitable analytical lines of uranium for its ICP-AES determination; study the spectral interference of uranium to choose interference free analytical lines, optimization of instrumental and experimental parameters etc. The method was validated using synthetic samples.
Selective phase separation of Pu 4+ and PuO 2 2+ was performed using N , N -dialkylamide functionalized multi-walled carbon nanotubes (AFMWCNTs). To understand the sorption kinetics, three widely ...accepted kinetic models (Lagergren first order kinetics, intra particle diffusion model and pseudo second order kinetics) were investigated. The sorption kinetics followed a pseudo second order kinetics with rate constants of 2.50 × 10 −5 g mg −1 min −1 and 4.30 × 10 −5 g mg −1 min −1 for Pu 4+ and PuO 2 2+ respectively. The analysis of the sorption mechanism through Langmuir, Freundlich, Dubinin–Rodushkevich (D–R) and Temkin isotherms revealed that the sorption proceeds via heterogeneous, non-ideal multi-layer adsorption following the Freundlich isotherm. The radiolytic stability of the AFMWCNTs and the stripping behavior of plutonium from the loaded AFMWCNTs were also investigated and finally AFMWCNTs were employed for the processing of simulated high level waste solutions originating from Research Reactors (RRs) and Fast Breeder Reactors (FBRs). Density functional theory calculation was used to understand the higher selectivity of tetra valent plutonium over hexa valent plutonium. The structural parameters of the AFMWCNT and its complexes of Pu 4+ and PuO 2 2+ were optimized along with the evaluation of their binding energy in the gas phase as well as solution phase. Orbital bonding analysis was carried out to rationalize the selectivity of Pu 4+ ions over PuO 2 2+ with AFMWCNTs.
Wild type
Rhizopus arrhizus
biomass was demonstrated as highly efficient bio-sorbent for trivalent f-elements. Both Am
3+
and Eu
3+
were found to follow the Fruendlich isotherm through ...chemi-sorption. The sorption for Am
3+
was found be faster compared to Eu
3+
while both proceeded via pseudo-second order reaction. EDTA was found to be effective strippant whereas up to 500 kGy, the bio-sorbent showed high radiolytic stability. Luminescence employed for probing the local environment of metal ion on sorption which revealed the presence of single adsorbed species with no inner sphere water molecules. The covalency of metal–ligand bond enhanced on complexation with the bio-sorbent.
An attempt was made to understand the sorption behaviour of Pu
4+
and PuO
2
2+
on
Rhizopus arrhizus
fungus. The sorption data were analyzed using Langmuir, Dubinin–Radushkevich, Freundlich isotherm ...and Tempkin isotherms, which revealed that the sorption proceeds via chemisorption through mono layer following Langmuir isotherm. the sorption kinetics were analyzed by different models revealing the predominance of pseudo 2nd order kinetics. Oxalic acid and sodium carbonate were used for effective stripping of Pu
4+
and PuO
2
2+
, respectively. This biomass was found to be radiolytically stable and finally was applied for processing of SHLW from RR and FBR origins.
•Synthesis of undoped and Eu and Tb-doped and Eu–Tb co-doped Strontium Molybdate (SMO) by co-precipitation method.•Characterization of the samples by XRD, SEM and DLS for particle size.•Observation ...of orange-red emission and blue-green emission from the Eu-doped and Tb-doped samples, respectively.•Optimization of the dopant ion concentration for white light emission from the co-doped sample.•Observation of cool day light white light emission with CCT 6863K from the co-doped system (Eu-0.5mol% and Tb-1mol%).
Nano ceramics of undoped and Eu and Tb-doped strontium molybdate (SMO) were synthesized via co-precipitation route and characterized by XRD, SEM and DLS techniques. It was observed that the average particle size for the samples was 90nm. A bluish emission attributed to the tetrahedral molybdate moiety was observed for the undoped system. The single-doped sample Eu3+:SMO gave orange-red emission, whereas the Tb3+:SMO sample showed blue-green emission. From the emission data, the site symmetry of the ions was estimated. Based on the emission data of single-doped samples, the co-dopant ions concentrations were tuned to extract white light emission from the system. It was observed that when doped with 0.5mol% Eu3+ and 1mol% Tb3+ and excited with 230nm, the system gave a ‘cool day light’ white light emission with a correlated color temperature (CCT) 6863K.
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