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Poly(amidoamine) dendrimer functionalized carbon nanotube was demonstrated as highly efficient sorbent of the Pu4+ from radioactive waste solution. The second generation dendrimer was found to have more efficiency as compared to the 1st generation might be due to the availability of more functionality for coordinating to the Pu4+ ion. Analysis of different isotherm models revealed that, Langmuir isotherm was predominantly operating through chemi-sorption (with the sorption energy 10.07 and 16.95 kJ mol−1 for 1st and 2nd generation dendrimer) with the sorption capacity 89.22 mg g−1 and 92.48 mg g−1 for 1st and 2nd generation dendrimer, respectively. Analysis of different sorption kinetics model revealed that the sorption proceeded via pseudo 2nd order reaction. The 2nd generation dendrimer was found to be radiolytically more stable while oxalic acid was found to be suitable for quantitative back extraction of Pu4+.

Liquid–liquid extraction of neptunium from aqueous acidic solution using quaternary ammonium based task specific ionic liquid (TSIL) was investigated. The extraction of Np was predominated by the ‘cation exchange’ mechanism via [NpO2·Hpth]+ species for NpO2 2+, while NpO2 + was extracted in ionic liquid as [NpO2·H·Hpth]+. The extraction process was thermodynamically spontaneous while kinetically slower. Na2CO3 as strippant showed quantitative back extraction of neptunium ions from TSIL. TSIL showed excellent radiolytic stability upto 500 kGy gamma exposure. Finally, the TSIL was employed for the processing of simulated high level waste solutions revealing high selectivity of TSIL towards neptunium.

Wild type Rhizopus arrhizus biomass was demonstrated as highly efficient bio-sorbent for trivalent f-elements. Both Am3+ and Eu3+ were found to follow the Fruendlich isotherm through chemi-sorption. The sorption for Am3+ was found be faster compared to Eu3+ 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.

Extraction behaviour of trivalent americium and europium was investigated with 1-phenyl-3-methyl-4-acetyl-5-pyrazolone (HPMAP) and tri-n-octylphosphine oxide (TOPO) in a room-temperature ionic liquid, 1-methyl-3-octyl-imidazolium bis(trifluoromethylsulphonyl) imide (C8mim·Tf2N). In select cases, comparison was made using xylene, a molecular diluent. For binary extraction studies involving only PMAP, Eu3+ was marginally better extracted than Am3+ and the species extracted into C8mim·Tf2N conformed to species of the type M(PMAP)3 (where M = Am or Eu). On the other hand, cationic species were extracted for the ternary extraction systems involving HPMAP and TOPO. Luminescence spectroscopic studies suggested no inner-sphere water molecules in the extracted species. The luminescence decay lifetime showed mono-exponentials, suggesting the extraction of single species.

A combined experimental and theoretical study has been put forward to investigate the complexation behaviour of tetravalent Pu 4+ and hexavalent UO 2 2+ ions with the N,N-dihexyloctanamide (DHOA) ligand in different diluents. Solvent extraction experiments were conducted with Pu 4+ and UO 2 2+ ions using DHOA in different diluents, namely dodecane, toluene, chloroform, octanol, nitrophenyl-octyl ether (NPOE) and nitrobenzene (NB). The experimentally measured distribution coefficients (D) of both the Pu 4+ and UO 2 2+ ions followed the order: nitrobenzene > NPOE > octanol > chloroform > toluene > dodecane. In order to complement the experimental distribution data, the structure, energetic and thermodynamic parameters of the Pu 4+ and UO 2 2+ complexes with DHOA have been calculated using density functional theory. The free energy of extraction, Δ G ext , for the Pu 4+ and UO 2 2+ ions with DHOA was calculated using the Born–Haber thermodynamic cycle in the different experimentally studied diluents. The value of Δ G ext for the Pu 4+ ion in dodecane was found to be higher than that of the UO 2 2+ ion, as measured in the experiments. The value of Δ G ext was shown to increase with the increase in the dielectric constant of the diluent for both Pu 4+ and UO 2 2+ ions, similar to the experimental studies. Thus, the combined experimental and theoretical studies help to understand the underlying complexation mechanism of the UO 2 2+ and Pu 4+ ions with DHOA, which explains its selectivity towards the Pu 4+ ion.

A systematic photoluminescence based investigation was carried out to understand the complexation of Eu 3 + with different ligands (TBP: tri-n-butyl phosphate, DHOA: di-n-hexyl octanamide, Cyanex 923: tri-n-alkyl phosphine oxide and Cyanex 272: Bis (2,4,4 trimethyl) pentyl phosphinic acid) used for preferential separation of lanthanides and actinides in various stages of nuclear fuel cycle. In case of TBP and DHOA complexes, 3 ligand molecules coordinated in monodentate fashion and 3 nitrate ion in bidentate fashion to Eu 3 + to satisfy the 9 coordination of Eu. In case of Cyanex 923 and Cyanex 272 complexes, 3 ligand molecules, 3 nitrate ion and 3 water molecules coordinated to Eu 3 + in monodentate fashion. The Eu complexes of TBP and DHOA were found to have D 3h local symmetry while that for Cyanex 923 and Cyanex 272 were C 3h . Judd–Ofelt analysis of these systems revealed that the covalency of Eu O bond followed the trend DHOA > TBP > Cyanex 272 > Cyanex 923. Different photophysical properties like radiative and non-radiative life time, branching ratio for different transitions, magnetic and electric dipole moment transition probabilities and quantum efficiency were also evaluated and compared for these systems. The magnetic dipole transition probability was found to be almost independent of ligand field perturbation while electric dipole transition probability for 5 D 0 - 7 F 2 transition was found to be hypersensitive with ligand field with a trend DHOA > TBP > Cyanex 272 > Cyanex 923.

Poly(amidoamine) dendrimer functionalized carbon nano tubes were synthesized, characterized and used for the sorption of americium from aqueous acidic waste solution. The sorption of Am3+ has been found to take place through pseudo second order kinetics with the rate constants of 8.61E-05 and 5.38E-05 mg g−1 min−1for 1st and 2nd generation, respectively, followingLangmuir isotherm. The MWCNT-PAMAMG1 and MWCNT-PAMAMG2 have high radiolytic stability. The stripping study revealed that EDTA can be effectively used for almost quantitative back extraction of metal ion from both generation of dendrimer. Luminescence investigation revealed the presence of single species with no inner sphere water molecule. The 1st generation dendrimer complex was found to be more asymmetric compared to the 2nd generation. The analysis of Judd Offelt parameters and evaluation of photo-physical properties were carried out to understand the complexation of Am3+ with these sorbents.

Sulphoxide ligands in piperidinium based ionic liquid were demonstrated as highly efficient, selective and environmentally benign systems for the extraction of plutonium from acidic aqueous solution. The extraction followed ‘cation-exchange mechanism’ via [Pu(NO3)·L]3+ and [PuO2(NO3)·L]+ species. The extraction efficiency followed the trend: APSO > BPSO > BMSO. The phenyl substituted sulphoxides showed higher affinity for plutonium due to a combination of steric as well as electronic factors. Extraction process was thermodynamically spontaneous for all three solvent systems. Oxalic acid and sodium carbonate were suitable for quantitative stripping of Pu4+ and PuO2 2+, respectively. APSO in ionic liquid showed good radiolytic stability.

Diglycolamic acid-functionalized carbon nanotubes were employed for the efficient and selective separation of Pu4+, PuO22+ and Am3+. The sorption occurred through monolayer coverage via chemisorption following the Langmuir isotherm. The sorption of Am3+, Pu4+ and PuO22+ on DGA-CNTs proceeded via a pseudo-second-order rate kinetics with a rate constant in the order Am3+ < Pu4+ < PuO22+. The radiolytic stability for DGA-CNTs and the stripping behaviour of DGA-CNTs were investigated. Luminescence investigations revealed the presence of single species without an inner-sphere water molecule. On complexation, the asymmetry around Eu3+ was found to be enhanced along with the covalency of the metal–ligand bond. Additionally, DFT calculations were performed to investigate the coordination and complexation interaction behaviour of CNT-DGA towards the metal ions. The present DFT study revealed a tridentate coordination mode of the DGA moiety towards Pu4+ and Am3+ and a bidentate coordination mode towards PuO22+. The calculated binding energy of sorption with DGA-CNTs towards Pu4+ was found to be higher than that of PuO22+, in both the gaseous and aqueous phase, whereas for Am3+, it was higher than that for PuO22+ but less than that for Pu4+. The free energy of sorption was also found to be highest for Pu4+ uptake and lowest for PuO22+, in both the gaseous and aqueous phase.

Structurally modified CMPO functionalized pillar[5]arenes in ionic liquid were found to be highly efficient, and radiolytically stable systems for the selective separation of thorium. The extraction was demonstrated to proceed via ‘cation exchange’ mechanism through [Th.L (NO3)]3 + species while the DFT calculation was used for understanding the optimized ligand structure and its complexation with Th4 + ion in ionic liquid. Oxalic acid was found to be successful for almost quantitative back extraction of thorium from CMPO functionalized pillar[5]arene complex in ionic liquid.

An attempt was made to understand the sorption behaviour of Pu4+ and PuO2 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 Pu4+ and PuO2 2+, respectively. This biomass was found to be radiolytically stable and finally was applied for processing of SHLW from RR and FBR origins.

Extraction behaviour of trivalent actinides and lanthanides was studied using solutions of 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (HPMBP), a beta-diketone, in a room temperature ionic liquid, 1-methyl-3-octyl-imidazolium bis(trifluoromethylsulphonyl) imide (C 8 mim·Tf 2 N). The complex extracted into C 8 mim·Tf 2 N differs in its composition than those observed in molecular diluents such as benzene. Whereas, neutral ML 3 complex is predominant in molecular diluents, a positively charged complex, [ML 2 ·HL] + (where M = La 3 + , Eu 3 + , Lu 3 + and Am 3 + ; L = PMBP − ; HL = HPMBP), was identified to be extracted into the ionic liquid medium. Luminescence spectroscopic studies suggested presence of four inner-sphere water molecules in the extracted species. This paper reports for the first time the stability constant of a lanthanide (Nd 3 + ) complex with HPMBP in C 8 mim·Tf 2 N which are significantly larger than those reported in molecular diluents. Thermodynamic parameters were also determined to throw light on the nature of complexation.

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(NO 3 )·3SO] 3 + 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 NTf 2 − ion in the extracted thorium complex. 0.05 M 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.

The extraction efficiency for thorium followed the trend: Cyanex-923 > Cyanex-272 > DHOA > TBP. In case of TBP and DHOA the extraction proceeded via ‘solvation mechanism’ through Th(NO3)4·2L, while for Cyanex-923 and Cyanex-272 it proceeded via ‘ion exchange’ mechanism through (Th(NO3)2·2L)2+. The extraction process followed slower kinetics while change in Gibb’s energy revealed the spontaneity of the process. These ionic liquid based systems were found to be radiolytically stable, highly efficient and selective for Th. Oxalic acid was found to be suitable for almost quantitative stripping of Th from extracted ionic liquid phase.

The effect of tri-n-butyl phosphate (TBP) and iso-decanol as phase modifiers on the complexation of Eu3+ with octyl-phenyl N,N-diisobutyl carbamoyl methyl phosphine oxide (CMPO) was studied. On an increase of iso-decanol the extraction efficiency of Eu3+ decreases. The metal–ligand stoichiometry was found to be 1:3. The Eu complex of CMPO–TBP was more symmetric compared to CMPO–iso-decanol. The Eu3+ complex exhibited D3h and C3h symmetry for 30% and 5% iso-decanol, while that for TBP was C6v. The radiative, non-radiative life time, electric and magnetic dipole transition probabilities, branching ratio, quantum efficiency etc. were evaluated. The covalency between Eu3+ and CMPO is as follows: CMPO–TBP < CMPO-5% iso-decanol < CMPO-30% iso-decanol.

The extraction/complexation of uranyl ion by structurally modified sulphoxides in ionic liquid was investigated. These systems were found to be highly efficient, selective and radiolytically stable for hexavalent f-block elements. The extraction proceeds via ‘cation exchange’ mechanism through the species, [U(NO3)·2L]+. Processes were found to be kinetically slow, thermodynamically spontaneous and proceeded via single species. The extended resonance and steric crowding favoured the complexation of phenyl sulphoxides. Na2CO3 was found to be suitable for the quantitative back extraction of uranyl ion from the ionic liquid phase. Finally, these systems were employed for the processing radioactive waste.

Bioinspired ZrO2-epoxy, two-phase composite materials were fabricated by the freeze casting fabrication technique followed by polymer infiltration. These materials were intrinsically controlled by adding varying concentrations of the monofunctional alcohols ethanol (EtOH), n-propanol (n-PrOH) and n-butanol (n-BuOH). The microstructures of freeze cast scaffolds created with these alcohol additives demonstrated maximum pore areas (peak Ap) at concentrations of 10, 5–7 and 3 vol% for EtOH, n-PrOH and n-BuOH respectively. Differential scanning calorimetry analyses of binary mixtures of these additives and water suggested only n-PrOH was capable of developing clathrate hydrates. Measurements of the adiabatic compressibility of complete freeze casting slurries showed that a similar room temperature phenomenon, hydrophobic hydration, was occurring in all cases with the maximum effect occurring at the same additive concentrations as the peak Ap values. This highlights that effects occurring within the slurry at room temperature and before freezing may have a significant effect on the freeze casting process. Analysis of the mechanical properties shows that infiltration of the scaffolds can provide resistance to Euler buckling, resulting in strengths of ∼3 orders of magnitude greater than uninfiltrated (and therefore unsupported) scaffolds. This suggests that layered structural design elements, found throughout nature, may be harnessing this Euler buckling resistance to increase strength.

Ionic liquid-based solvent systems containing diglycolamide-functionalized calix[4]arenes (C4DGAs) are efficient for actinide ion extraction from nitric acid feeds. Therefore, the radiolytic stability of three C4DGAs (wide-rim, narrow-rim and both side DGA-functionalized calix[4]arenes) and TODGA (N,N,N′,N′-tetraoctyldiglycolamide) (used for comparison purpose), was evaluated by exposing their solutions in an ionic liquid as well as a 95:5 mixture of n-dodecane + isodecanol to gamma radiation up to an absorbed dose of 1000 kGy. Liquid-liquid extraction studies were carried out using 241Am as a radiotracer. Apart from a decrease in the DAm values, ascribed to radiolytic degradation, FT-IR, EPR and GC-MS studies were carried out to characterize the degraded species. The different extractants are less sensitive to radiolytic degradation in the ionic liquid than in the molecular diluent.

Novel ligand functionality, 5-bromo-N1, N3-bis(4,6-dimethylpyridin-2-yl)isophthalamide, was explored for highly efficient and selective separation of UO22+ and Th4+ in pyridinium based ionic liquid. The comprehensive investigation revealed that, both in ionic liquid as well as in molecular diluents the extraction predominantly proceeded via ‘solvation’ mechanism. However, the species involved in extraction were UO2(NO3)2, L and Th(NO3)4, L in ionic liquid, while UO2(NO3)2, 2 L and Th(NO3)4, 3 L in molecular diluent. The highly viscous ionic liquid resulted the mass transfer slower during extraction. In ionic liquid based system, the extraction processes were endothermic, spontaneous and entropy driven. Ionic liquid based solvent systems exhibited high radiation stability, which was attributed to the formation of resonance-stabilized aromatic cation as well as the restricted movement of radicals in viscous ionic liquid. The aqueous solution of sodium carbonate was found to be effective for the stripping of UO22+, while oxalic acid solution was found to be effective for Th4+. The solvent systems were used for processing of simulated high level waste solutions of a Research Reactor (RR) and Fast Breeder Reactor (FBR) origin.

An attempt was made to investigate the structural modification of CnmimNTf2 ionic liquid in combination with a novel ligand, 5-bromo-N1,N3-bis(1-methyl-1H-pyrazol-3-yl)isophthalamide on the extraction properties of tetra and hexavalent actinides. In C4mimNTf2, C6mimNTf2, the extraction processes predominantly followed the ‘cation exchange’ mechanism involving the species: [UO2(NO3)L]+ and [Th(NO3)2L]2+, whereas, in C8mimNTf2, the ‘solvation’ mechanism was found to be predominant involving neutral species UO2(NO3)2L2 and Th(NO3)4L3. The speciation was further confirmed by investigating the participation of imidazolium cation in extraction. In ionic liquid, the extraction processes were slower compared to that in the molecular diluent. The time required to attain the equilibrium D values followed the trend: C4mimNTf2 C6mimNTf2 > C8mimNTf2, which was ascribed to the enhancement in organophilicity of the cation on increasing the length of the side chain and hence the effect on their dissolution in water. Three cycles of 1 mM aqueous sodium carbonate solution and four cycles of 1 mM oxalic acid solution were sufficient for almost quantitative back extraction of U and Th, respectively.C8mimNTf2 based systems were better radio-resistant compared to the lower homologue.

A comparative evaluation was carried out for the extraction of Sr2+ using novel calix crown ether in molecular diluent and in ionic liquid. Though the trend in extraction profiles was found to be similar for both the systems, still, almost 5 times higher distribution ratio (D) values were observed in ionic liquid. The speciation studies revealed that; neutral Sr (NO3)2. DHCC species was formed in dodecane and the extraction followed through ‘solvation’ mechanism. However, ionic liquid medium (IL), anionic species, [Sr(NO3)3. DHCC]− was found to be predominating indicating ‘anion exchange’ mechanism. The slower kinetics of extraction in IL was attributed to the high viscosity of IL. The extraction process was found to be spontaneous, endothermic and entropy driven.IL based system was found to be radiolytically more stable compared to the molecular diluent (Mol dil) based system. The electron paramagnetic resonance (EPR) spectroscopic investigation revealed the formation of oxygen centered radical with orthorhombic symmetry (gx = 2.00105, gy = 2.00475, gz = 2.00835) in irradiated ligand. The density functional theoretical (DFT) calculation was utilized to investigate the complexation and speciation in detail in microscopic level.

This paper presents the effects of a technology-based engagement platform, referred to as IMPRES (Interactive Mobile Platform for Retaining and Engaging Students). IMPRES is a mobile application, b...

Synthetic polymers mimicking antimicrobial peptides (AMPs) in combating “superbugs” have received considerable attention in the genre of antimicrobial polymeric materials. Herein, we report the antibacterial and hemolytic activities of two series of random acrylate-based ternary copolymers with pendant hexamethylene ammonium, poly(oligoethylene glycol), and ethyl or N-methylethyl ammonium side chains. We have demonstrated that highly selective activity towards Escherichia coli (E. coli >68 times) and Bacillus subtilis (B. subtilis 400 times) compared to red blood cells can be achieved by controlling the structural composition of these copolymers via optimization of feed composition involving lipophilic units, cationic side-chain units, and neutral hydrophilic units. Furthermore, we have demonstrated a loss of viability for E. coli and B. subtilis following exposure to the copolymers using Fluorescence Lifetime Imaging Microscopy (FLIM), reinforcing the antibacterial efficacy of the synthesized ternary copolymers.

Direct contact membrane distillation (DCMD) has been conducted to treat hydraulic fracturing-produced water using polyvinylidenedifluoride (PVDF) membranes. Tailoring the surface properties of the membrane is critical in order to reduce the rate of adsorption of dissolved organic species as well as mineral salts. The PVDF membranes have been modified by grafting zwitterion and polyionic liquid-based polymer chains. In addition, surface oxidation of the PVDF membrane has been conducted using KMnO4 and NaOH. Surface modification conditions were chosen in order to minimize the decrease in contact angle. Thus, the membranes remain hydrophobic, essential for suppression of wetting. DCMD was conducted using the base PVDF membrane as well as modified membranes. In addition, DCMD was conducted on the base membrane using produced water (PW) that was pretreated by electrocoagulation to remove dissolved organic compounds. After DCMD all membranes were analyzed by scanning electron microscopy imaging as well as Energy-Dispersive X-Ray spectroscopy. Surface modification led to a greater volume of PW being treated by the membrane prior to drastic flux decline. The results indicate that tailoring the surface properties of the membrane enhances fouling resistance and could reduce pretreatment requirements.

Isothermal-based air dehumidification results in energy problems, low water vapour permeability and poor selectivity. Graphene oxide framework (GOF) membranes exhibit remarkable advantages in effective air dehumidification. In this work, different crosslinking agents, including glyoxal (GLX), oxalic acid (OXA) and ethylenediamine (EDA), were employed to tune the properties of GOF membranes through the casting knife technique. The physicochemical properties of the as-prepared membranes were investigated by using various techniques. The 2D arrangement of GO-based membranes ensured the frictionless nano-channels with an efficient flow rate and storage of water along with chemical interaction while hydrophilic groups on the GO surface. However, crosslinking restricted the mobility between consecutive GO layers, and the free volume and pore size became tuneable in the crosslinking structure. Given its capacity for low energy-efficient air dehumidification, the GLX-cross-linked GO membrane exhibited an excellent selectivity value of 2.8 × 106, and the less energy-consuming stability performance lasted for 120 h. These results indicate that the GLX-cross-linked GO membrane is suitable for practical applications.

Polyethylenimine (PEI), a cationic, hydrophilic flexible polymer has been incorporated into the polyamide (PA) skin layer through an interfacial polymerization (IP) reaction. The modified thin-film composite (TFC) membranes display improved forward osmosis performance: enhancement in water permeability and antifouling characteristics. The incorporation of PEI into the skin layer has been evidenced by different characterization techniques; FTIR for modification of surface functionalities, zeta potential for surface charge, water contact angle for hydrophilicity of the surface, SEM and AFM for surface morphologies including surface roughness, XPS for surface attachment of heteroatoms and their relative composition. PEI was found to induce a positive zeta potential, high degree of hydrophilicity and high factional free volume into the active skin layer. The increase in the relative composition of PEI in the active skin layer was found to decrease the surface roughness and the skin layer thickness. An optimized PEI composition showed significantly enhanced water permeability, salt rejection and fouling resistance in FO and pressure-retarded osmosis (PRO) mode.

Membrane distillation is an emerging technology for treating hydraulic fracturing flowback and produced waters (PW). Suppression of membrane fouling by inorganic and polar and non-polar organic compounds is a challenge. Here, polyhydroxyethyl methacrylate, polyacrylic acid, polvinylallyl imidazolium bromide and polyvinylhexyl imidazolium bromide chains have been grafted from the surface of polypropylene membranes. Fouling happens initially due to adsorption of organic compounds followed by scale formation. When challenged with PW, membranes modified with polvinylallyl imidazolium bromide chains provided the greatest resistance to fouling. For electrocoagulation pretreated PW and synthetic PW that contained mainly inorganic species, the flux decline was much less.

Supported ionic liquid membranes have been tested for fractionation of organic compounds. Imidazolium based ionic liquids; 1-allyl-3-vinylimidazolium bromide, 1-hexyl-3-vinylimidazolium bromide and 1-octyl-3-vinylimidazolium bromide were trapped in the pores of a polypropylene membrane. Fractionation of a feed stream consisting of benzene, naphthalene and phenanthrene in tetradecane and cis- and trans-stilbene in hexane were investigated. The receiving phase was hexane. Differences in the π electron cloud density of the aromatic solutes influence their interactions with the imidazolium cation, which can affect the rates of transport. In the case of the three aromatic solutes, the degree of conjugation and molecular weight increase in order benzene, naphthalene and phenanthrene. These opposing effects result in similar mass transfer coefficients for the three solutes for the three ionic liquids tested. However, for cis-and trans-stilbene, the mass transfer coefficient was larger for all three ionic liquids. It is likely that enhanced aromatic stacking of the trans- isomer led to a higher mass transfer coefficient. In addition, 1-hexyl-3-vinylimidazolium bis(trifluoromethylsulfonyl)imide was used as the liquid membrane phase to fractionate two nucleobases: thymine and cytosine in water. The receiving phase was also water. The membrane mass transfer coefficient for thymine was 5.5 times greater than cytosine indicating the possibility of exploiting multimodal interactions with the imidazolium group to fractionate compounds.

Super-wetting MOFs@graphene hybrid has shown promising application for oil/water separation, due to high porosity, low density, and controllable wettability, however, achieving excellent stability and recyclability are found to be still challenging. In this study, sandwich-like UIO-66-F4@rGO hybrid was synthesized by immobilization of UIO-66-F4 nanoparticles on rGO matrix, which featured the unique micro/nano hierarchy with hydrophobic characteristics. In order to realize the oil/water separation, as-prepared sandwich-like UIO-66-F4@rGO hybrid was applied as a potential candidate for constructing robust super-hydrophobic/super-oleophilic interfaces by using filter paper (FP) and melamine sponge (MS) as substrates. Typically, the surface modification of substrates can be easily achieved by simple dip-coating method, and interfacial adhesion between substrates and UIO-66-F4@rGO was enhanced by cross-linking of hydroxyl-fluoropolysiloxane (FPSO). Consequently, the super-hydrophobic/oleophilic UIO-66-F4@rGO/FP exhibited high contact angle of 169.3 ± 0.6° and was capable of separating various water-in-oil emulsions effectively. The flux and separation efficiency were 990.45 ± 36.28 Lm-2 h-1 and 99.73 ± 0.19 % driven by gravity, respectively. The super-hydrophobic/super-oleophilic UIO-66-F4@rGO/MS possessed selective oil absorption with absorption capacity of 26∼61 g/g depending on the viscosity of oils and continuous cleaning of oil spill. Furthermore, the UIO-66-F4@rGO composite could tolerate high/low temperature, corrosive solutions, and physical damage, displaying robust and stable super-hydrophobic/super-oleophilic interfaces for treating oily wastewater in harsh environments.

Impurity investigations are important in pharmaceutical development to ensure drug purity and safety for the patient. The impurities typically found in drug products are degradants or reaction products of the active pharmaceutical ingredient (API) or leachable compounds from the container closure system. However, secondary reactions may also occur between API degradants, excipient impurities, residual solvents, and leachables to form adduct impurities. We hereby report an adduct-forming interaction of API (moxifloxacin) with a leachable compound (ethylene glycol monoformate) in moxifloxacin ophthalmic solution. The leachable compound originated from a low-density polyethylene bottle used in the packaging of drug products. The adduct impurity was tentatively identified as 1-cyclopropyl-6-fluoro-7-(1-(2-(formyloxy)ethyl) octahydro-6H-pyrrolo[3,4-b]pyridin-6-yl)-8-methoxy-4-oxo-1,4-dihydroquinoline-3-carboxylic acid (C24H28FN3O6, MW = 473.19621) using accurate mass LC-QTOF analysis. The mass accuracy error between the theoretical mass and the experimental mass of an impurity was found to be 0.2 ppm. An MS/MS analysis was utilized to provide mass spectrometry fragments to support verification of the proposed structure.

ICP-AES based methodology was developed for the determination of trace metallic constituents in thorium matrix after preferential extraction of thorium using TBP, TOPO and DHOA. The distribution ratio for thorium followed the trend TOPO > TBP > DHOA with the formation of 1:2 complex. Oxalic acid was found to strip Th effectively. La, Ce, Pr, Gd, Dy, Lu can be determined at 0.1 mg L−1 using all the ligands, while common analytes can be determined at 0.1, 0.5 and 1 mg L−1 concentrations by using DHOA, TBP and TOPO, respectively.

Selective separation of uranium using bis(2,4,4-trimethylpentyl)phosphinic acid in xylene and C8mimNTf2 was investigated. For ionic liquid based system, the extraction kinetics was found to be slower with the predominance of ion exchange mechanism through [UO2(NO3)·2L]+, while for xylene based system solvation mechanism. The nature of the extracted species was found to be different in both the media as observed in luminescence study. Ionic liquid based system was more radioresistant than that of molecular diluents. Na2CO3 was successfully used for stripping. The selectivity was investigated by processing simulated high level waste of pressurized heavy water reactor origin.

Selective phase separation of Pu4+ and PuO22+ 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 Pu4+ and PuO22+ 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 Pu4+ and PuO22+ 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 Pu4+ions over PuO22+ with AFMWCNTs.

Amido amine-functionalized multi-walled carbon nanotubes (MWCNT-AA) were used for efficient and selective solid phase separation of plutonium(IV) and plutonium(VI). Langmuir, Freundlich, Dubinin–Radushkevich (D–R), and Tempkin isotherms were employed for understanding the sorption mechanism and Lagergren first order kinetics, an intra-particle diffusion model, and pseudo second order kinetics were applied to understand the sorption kinetics. The sorption proceeded through monolayer coverage of MWCNT-AA with capacities of 91.2 mg g−1 and 89.4 mg g−1 for Pu4+ and PuO22+, respectively following a Langmuir isotherm while the sorption kinetics followed a pseudo second order reaction with rate constants of 3.86 × 10−5 and 3.19 × 10−5 g mg−1 min−1 for Pu4+ and PuO22+ respectively. This MWCNT-AA showed high radiolytic stability and a method was developed for almost quantitative back extraction of plutonium in both the oxidation states from MWCNT-AA. Finally, the sorbent MWCNT-AA was employed for processing synthetic high level waste solution obtained from a research reactor origin. Moreover, density functional theory calculation was performed to examine the coordination and interaction behaviour of Pu4+ and PuO22+ ions towards MWCNT-AA. The present DFT study reveals that Pu is deca-coordinated (two from each of four nitrates and one AA) in the case of Pu4+ and octa-coordinated (two from each of two nitrates and one AA, and one from each of two oxo groups) in PuO22+. The calculated free energy of complexation was found to be almost three times higher for Pu4+ than PuO22+ both in the gas and aqueous phase, which thus confirms the experimentally observed higher sorption of Pu4+ compared to PuO22+ by MWCNT-AA.

An amide functionalized multiwalled carbon nanotube (CNT-DHA) was used for efficient and selective solid phase separation of tetravalent (Th4+) and hexavalent (UO22+) actinides. Langmuir, Freundlich, Dubinin–Rodushkevich (D–R) and Tempkin isotherms were employed for understanding the sorption mechanism while various models (Lagergren first order kinetics, intra particle diffusion model and pseudo second order kinetics) were applied to understand the sorption kinetics. The sorption proceeded via monolayer coverage of CNT-DHA with capacities of 32 mg g−1 and 47 mg g−1 for UO22+ and Th4+, respectively following a Langmuir isotherm while the sorption kinetics followed a pseudo second order reaction with rate constants of 0.044 and 0.095 g mg−1 min−1 for UO22+ and Th4+, respectively. The CNT-DHA was found to have high radiolytic stability up to 1000 kGy gamma exposure. The stripping study revealed that oxalic acid can be used for almost quantitative back extraction of Th4+ and for UO22+ sodium carbonate can be effectively used. DFT calculations were performed to understand the complexation of Th4+ and UO22+ with CNT-DHA. The structural parameters of UO22+ and Th4+ ions with CNT-DHA, and the large ion–ligand interaction energy were correlated with the higher selectivity of Th4+ ions over UO22+ ions.

A trialkylphosphine oxide functionalized task specific ionic liquid (PO-TSIL) with a NTf2− counter anion was synthesized and evaluated for the extraction of actinide ions such as UO22+ and Pu4+ from acidic feed solutions using room temperature ionic liquids (RTIL) such as [BMIM][NTf2] and [OMIM][NTf2] as the diluents. The extraction data were compared with those obtained with tri-n-octylphosphine oxide (TOPO) in the same set of RTILs. The extracted species following a cation-exchange mechanism were analyzed by the conventional slope analysis method. The nature of the bonding in the extracted complexes was investigated by various spectroscopic techniques such as luminescence and UV-visible spectroscopy. Studies on the stripping and radiation stability were also carried out for possible nuclear fuel cycle applications.

An ICP-AES based methodology was developed for the determination of 22 trace metallic constituents (Ca, Co, Cr, Pb, Cu, Fe, Ga, In, Mg, Mn, Na, Ni, Sr, Zn, Eu, Sm, Gd, Dy, B, Be, Cd and Ag) in high purity neptunium matrix alongwith simultaneous determination of Np. Np 295.660 nm line was found to have the best analytical performance. The spectral interference of Np on other analytes have been investigated which includes identification of interference free line, evaluation of correction factor and tolerance level of neptunium. Presence of U, Th, Zr and Pu on the determination of Np has also been studied. The method was validated using synthetic samples.

Keeping reprocessing of 233U–Th based fuel in perspective, solvent extraction of Th(IV), U(VI) and some relevant metal ions has been carried out from nitric acid media and simulated high-level waste (HLW) typical of a fast-breeder reactor using dihexyloctanamide (DHOA) in commercially available alternate diluents, viz. Solvesso 100 and ShellSol D70. Acid uptake constant (KH) and distribution ratios (D) of metal ions as a function of nitric acid, thorium ion and extractant concentrations are determined. Slope-analysis results showed various types of species extracted into the organic phase. For comparison, a similar set of experiments were carried out with tri-n-butyl phosphate (TBP) in both diluents. A few clear and interesting trends were observed in the variation of D values of metal ions. Interference of other relevant metal ions likely to get co-extracted along with Th(IV) and U(VI) was also studied by ICP-AES using a simulated HLW.

With an aim to understand the nature of species, cyclic voltammetry (CV) of Pu(IV) in dilute HBr and in a room temperature ionic liquid (RTIL), 1-octyl-3-methylimidazolium bromide (C8mimBr) was carried out. Shifts of cathodic and anodic peak potentials of Pu(IV) cyclic voltammograms were observed towards negative potentials in the extended electrochemical window for ionic liquid medium compared to 2 M HBr. The diffusion coefficient of the most likely species of Pu(IV) in aqueous medium was found to be greater than that of the corresponding species in ionic liquid while the activation energy showed reverse trend. The Pu(IV)/Pu(III) redox reaction was found to be exothermic in aqueous medium while it was endothermic in C8mimBr. The redox reaction was found to be quasi reversible for both the media while the extent of irreversibility was more in ionic liquid. UV-Vis spectroscopy of Pu in these media showed significant differences in the peak positions and their relative intensities, indicating the possible differences in the interactions of Pu(IV) with the solvent molecules resulting in speciation differences. A new prominent peak was observed in RTIL which could be for a new species of Pu(IV). Computational studies were also carried out to understand the solvation of Pu and the possibility of thermodynamic conversion from Pu(IV) to Pu(III).

An attempt was made to understand the complexation of Eu3+ with structurally modified CMPO-functionalized pillararenes by luminescence spectroscopy. Formation of single species with different numbers of inner sphere water molecules was found to be present for all the complexes. On increasing spacer length between ligating moieties and supramolecular pillararenes, the stereo-chemical crowding around ligating oxygen decreased. Therefore, strong covalent metal–oxygen bond was formed which was reflected in the increasing trend of the computed Ω2 values (Judd–Offelt parameter): LI (4.66×10−20) LII (3.19 ms)>LIII (2.94 ms) while the branching ratio values for all three complexes followed the same trend as β2>β4>β1. The other photo-physical constants like asymmetric factor, quantum efficiency, magnetic and electric dipole transition probabilities were also computed.

(Th,Pu)O2 fuel pellets were synthesised by coated agglomerate pelletization route and characterized for the chemical quality control. (Th,Pu)O2 pellets were characterized for trace metals by spectrometric methods and non metals by ion chromatographic, spectrophotometric, conductometric and manometric methods. H, F, B and Cd contents were found to be less than 1 ppm while that for V and Cl were found to be less than 10 ppm. The pellets were found to contain Cr, Cu, Mo, Na, Ni and Pb in the range of 10–50 ppm whereas Zn, Al, Ca and C in the range of 50–100 ppm. More than 100 ppm Si, Fe and Mg were found to be present in the (Th,Pu)O2 pellets. The O/M content of the pellets were found to be ~2.00. A comparative study on (Infrared) I.R. and microwave (microwave) dissolution were also used to ascertain the Th and Pu content in the (Th,Pu)O2 pellets.

Supported liquid membranes containing a solution of four calix-crown-6 ligands viz., calix[4]arene-bis-crown-6 (CC), calix[4]arene-benzo-bis-crown-6 (CBC), calix[4]arene-naphtho-bis-crown-6 (CNC), and bis-(octyloxy)calix[4]arene-mono-crown-6 (CMC) in a fluorinated diluent, phenyltrifluoromethyl sulfone (PTMS) along with small fraction of Alamine 336, were employed for the pertraction of radio-cesium from nitric acid feed solutions. The transport efficiency of the membranes followed the trend: CNC⪢CBC>CC⪢CMC. While 4.0×10 −3 M solutions of CBC, CC and CMC were used for the transport studies and near quantitative Cs(I) transport was seen at tracer scale after 4 h using CBC, transport studies with CNC were carried out at 1.0×10 −3 M due to solubility limitations. The mass transport rates for Cs(I) reported here is the fastest in a calix-crown-6 based SLM and shown to be promising for applications in nuclear waste remediation. Acid co-transport was observed with all the calix-crown-6 ligands which increased sharply if the membranes were used for longer time. 137 Cs spiked simulated high level waste (SHLW) was used as the feed to result in >60% transport of the metal ion and P ) and diffusion coefficient ( D o ) were also determined. The SLM was found to have limited stability to suggest that fresh membranes need to be used for better performance.