Search

Introduction: Temporomandibular joint plays an important role in maintaining a balance between structures of oral-facial complex. And morphology of Condyle is an essential part of temporomandibular joint that response to functional load, masticatory muscle activity constantly even after completion of the growth. Therefore, its morphology directs the adaptations to these functional forces. Aim: To evaluate the TMJ morphology characteristics in various growth patterns using CBCT. Materials and Methods: The present study was conducted to evaluate and compare morphology of TMJ in different vertical growth pattern individuals in North Indian population using CBCT. Pretreatment cone-beam computed tomography (CBCT) images of 10 Hypodivergent, 10 Normodivergent and 9 Hyperdivergent subjects were analyzed using SN- mandibular plane angle. Morphological parameters of TMJ such as anterior, superior, posterior joint space, condylar axial angle, mandibular fossa depth, intercondylar distance, medio-lateral and anterio-posterior width were measured and statistical analysis were done using One Way ANOVA and Post hoc Tukey test. Results: A statistically significant difference was noted in the superior joint space among Group I(4.04±0.10), Group II(3.73±0.36) and Group III(3.06±0.22)with p=0.00 and significantly correlated to facial morphology. Conclusion: TMJ morphology varies according to different growth patterns.

Feasibility was established for direct dissolution-extraction of uranium employing adduct of N,N-dihexyl octanamide (DHOA), thus eliminating discrete aqueous phase and free acid usage. Various aspects of dissolution of solid uranium dioxide and extraction of uranium into molecular diluent viz. n-hexane and neoteric solvents viz. room temperature ionic liquid (RTIL) and supercritical carbon dioxide (SC CO2) were studied. The organic adduct was found to have composition DHOA.(HNO3)0.78(H2O)0.4. Adduct miscibility and UO2 dissolution behavior was markedly different for RTIL and n-hexane. The dissolution process, studied by monitoring UV–Vis spectra, was found to be pseudo first order with a rate constant of of 0.074 min−1 and 0.036 min−1 for n-hexane and RTIL respectively. Irrespective of medium, dissolution-extraction efficiency of ≥90% was achievable. Using RTIL for dissolution-extraction medium and SC CO2 for stripping is promising in terms of overall efficiency as well as RTIL recovery by avoiding aqueous cross contamination.

The study demonstrates the accomplishment of single step, direct supercritical fluid carbon dioxide (SC CO2) dissolution and extraction of uranium from crude matrices viz. yellow cakes (>90%) and rock phosphate ores (70%) employing adducts of trialkyl phosphates and nitric acid, thus avoiding free acid usage and eliminating number of process steps. Rock phosphate ore was made amenable for supercritical fluid extraction (SFE) system by unique strategy of pyrohydrolytic removal of fluorine. Pressure and temperature conditions, which were found to influence uranium extraction efficiency, were optimized at 150 atm. and 323 K. Two milliliter of adduct amount was found to be adequate. Adducts of branched alkyl phosphate, tri-isoamyl phosphate and tri-ethyl hexyl phosphate (TEHP), yield better purity in comparision to straight chain tri-butyl phosphate (TBP).

Present study reports simultaneous batch and column extraction of Pu(IV) and Am(III) followed by selective stripping from actual analytical waste solution generated during quality control operations. N, N, N′, N′ tetra(2-ethylhexyl) diglycolamide (TEHDGA), di(2-ethylhexyl) phosphoric acid (DEHPA), individually and their combination, encapsulated in polyether sulphone resin beads have been investigated. TEHDGA + DEHPA encapsulated resin showed better performance with respect to kinetics (2 h) and extent of extraction (KD ~ 8000 at 5 M nitric acid) for both Am(III) and Pu(IV). Interesting presence of DEHPA, inefficient as extractant at high nitric acid molarity, improved polymer extraction characteristics. Extraction selectivity over assorted metal ions and reusability for three cycles of operations was established.

The public acceptance of clean energy production from nuclear reactors demands the development of innovative methods to minimize and recycle the actinide waste with little or no impact to the environment. Nuclear fuel before it could be qualified has to undergo stringent quality control (QC) measures at various stages of fabrication. Analysis of carbon content in nuclear fuel is one such QC checks which produces refractory alumina crucibles containing plutonium embedded in molten solidified Cu. Development of a method for recovery of plutonium (Pu) from these refractory materials, accumulated over the years, is crucial prior to their disposal. The conventional process of acid leaching, using HF + HNO3 mixture, is time consuming and generates large volume of radioactive acid waste. To eliminate these drawbacks, a simple pre-treatment method of fusion with NaOH was adopted prior to acid leaching for recovery of Pu from these alumina crucibles. A number of small scale experiments were conducted by varying process parameters and fusion temperature of 600 °C and 16 M HNO3 as leachant were found to be optimum for maximum recovery of Pu. The final recovery of 96.5% was arrived by biamperometric analysis of Pu in acid leachate. The efficiency of recovery of Pu was reconfirmed by its gamma spectrometric assay in the residual precipitate. Experiments were also carried out by treating alumina crucible with NaOH in a single step and heating uninterruptedly to check the feasibility of scaling-up the process. The fused product and precipitates obtained during leaching were characterised using X-ray diffraction analysis (XRD).

Pyridinium and methyl ammonium based macroporous bifunctional anion exchange resin was synthesized from commercially available resin, Reillex™ 402 and investigated for selective extraction of neptunium(IV) from nitric acid medium. Acid stability of the resin was found to be satisfactory. Due to the possibility of existence as multiple oxidation states of Np, UV–Vis spectrophotometry and electrochemical methods were used to probe the redox speciation and warrant ion exchange separation of Np(IV). Ferrous sulphamate was used for simultaneous reduction of Np(V), (VI) and Pu(IV) to (IV) and (III), respectively. Batch sorption studies revealed fast kinetics (1 h.) of uptake having KD,NP(IV) of 425 at 4 M and capacity of 42 mg g−1. Stripping with ascorbic acid yielded quantitative results. Simultaneous determination of Np and Pu was standardized by electrochemical method. Selective separation of Np(IV) by column operation was carried out successfully for a mixture of (Np + Pu) and also (Np + Pu + U) corresponding to waste stream.

Plutonium recovery is inevitable from plutonium bearing alumina crucibles generated over the years as part of carbon analysis during chemical quality control of nuclear fuels. This is a challenging task owing to the complex nature of matrix. The first stage of methodology development of plutonium recovery involved usage of CeO2 bearing crucibles. Cerium distribution in alumina crucible was investigated by examination of surface morphology. Various aqueous recovery routes were tested initially with CeO2 bearing crucibles and 4 M HF–8 M HNO3–NH4NO3 was found to be most promising (60% recovery). The same route yielded 90% plutonium recovery from alumina crucibles.

Bifunctional resins having pyridinium and methyl ammonium-based dicationic groups, separated by a five carbon spacer, have been prepared by chemical modification of Reillex™ 402 poly(4-vinyl pyridine). Batch sorption studies carried out for the three resins (I, II, III), which differ by degree of functionalization and physical form, revealed very fast kinetics, with III having highest K D value (650 at 7.5 M). The capacity of III was 4.5 meq/g. The resin was selective for Pu sorption from nitric acid medium having assorted metal ions and the Pu content of resultant raffinate was below the disposal limit. Column experiments with III show fast loading and elution of Pu(IV).

Halide anion free hydrophilic Deep Eutectic Solvent (DES) based on choline dihydrogen citrate and urea (1:2 mol ratio) was prepared and successfully employed for dissolution of uranium compounds. Dissolution study was carried out with oxides viz. UO2, UO3 and crude yellow cakes viz. magnesium diuranate, sodium diuranate. Novel route of in-situ, single step eutectic solvent preparation and U compound dissolution was found to be promising in terms of better dissolution efficiency and process simplification. The resultant systems were probed with electrochemistry and UV–Vis spectrophotometry to get an insight about the uranium species. In all the four systems prepared by in-situ mode, stabilization of uranium in U(VI) oxidation state in the form of oxo species was indicated. This halide anion free eutectic system was amenable to be used in SC CO2 extraction set-up. SC CO2 extraction of uranium dissolved in eutectic solvent was found to be influenced by various extraction conditions viz. pressure, temperature, static and dynamic time. Uranium extraction efficiency of upto 65% for oxide system was achievable by SC CO2 modified with TTA.

Supercritical Fluid Extraction (SFE) and purification of uranium, from crude sodium diuranate (SDU) containing uranium (53%), iron (22.2% of U) and rare earth impurities (4% of U), has been studied. Adduct of tri-butyl phosphate (TBP) and nitric acid (HNO3) has been used for uranium dissolution and extraction. Carbon dioxide has been used as supercritical fluid. For 200 mg of crude SDU, operating parameters such as temperature, pressure, quantity of TBP·HNO3 adduct, static and collection time have been optimized at 323 K temperature, 15.20 MPa pressure, 1 mL of TBP·HNO3 adduct, 20 min. static time and 20 min. collection time. Under these conditions, uranium extraction efficiency was 95 ± 5%. Addition of free nitric acid leads to improvement in purity of uranium. Uranium was stripped from SFE extract and precipitated as ammonium diuranate (ADU), which was then subjected to second cycle of SFE. After two cycles of SFE, purification factor of uranium was found to be 4970, 90, 110 and 60 with respect to iron, yttrium, ytterbium and erbium respectively.

N,N-dialkyl aliphatic amides with varying alkyl groups viz. N,N-dibutyl-2-ethyl hexanamide (DBEHA), N,N-dibutyl-3,3-dimethyl butanamide (DBDMBA), N,N-dihexyl octanamide (DHOA), N,N-di-sec-butyl pentanamide (DBPA), N,N-dibutyl octanamide (DBOA), have been evaluated for solvent extraction of thorium from nitric acid medium into the hydrophobic ionic liquid phase, 1-butyl-3-methyl imidazolium hexafluorophosphate. Distribution ratio values were markedly higher for room temperature ionic liquids (RTIL) as compared to molecular diluent, n-hexane. DBOA yielded the highest extraction. The extraction behaviour of Th(IV) into RTIL was found to be different from n-hexane with respect to extraction kinetics, effect of molarity of nitric acid and stoichiometry of Th(IV)-amide complex. Thermodynamic studies revealed that the extraction was enthalpy driven. Mechanism of the extraction was found to be dependent on the nitric acid molarity of the aqueous phase. High stripping efficiency was obtained with supercritical carbon dioxide which also provided insight into the mechanism of extraction into RTIL phase. Extraction of Th(IV) from aqueous phase (having low acid molarity, 0.2 M) into RTIL employing DBOA followed by stripping with supercritical carbon dioxide modified with DBOA·HNO3 adduct yielded the highest overall efficiency.

In the present study, we explored the extraction of Cd2+ by supercritical fluid carbon dioxide using calixarenes as complexing agents in acidic medium. The optimum conditions for the extraction of cadmium were found to be 30 min of static extraction followed by 30 min of dynamic extraction, a temperature of 323 K, a pressure of 20.27 MPa, a CO2 flow rate of 2 mL min–1, and a nitric acid concentration of 0.1 M. Among the studied calixarenes, hexaacetylcalix[6]arene gave the maximum extraction efficiency of (90 ± 2)% in acidic medium. The presence of fluorinated pentadecafluoro-n-octanoic acid led to the enhancement of the extraction efficiency. The formation of a cadmium–calixarene complex was supported by energy-dispersive X-ray spectrocopy and UV–visible absorbance spectrocopy. Calixarene and its complex with cadmium were found to have distinctly different features in their scanning electron microscopy images. A solvent extraction study was carried out to study the thermodynamic aspects of complex format...

Imino diacetamide styrene divinyl benzene (IDAA SDVB) resin was synthesized and evaluated for separation of molybdenum (Mo) from simulated dissolver solution of irradiated uranium–aluminium alloy. Detailed studies were carried out to understand the influence of various parameters on sorption of Mo. The kinetics of Mo sorption is found to be fast and the kinetics data fit well to the pseudo-second order kinetic equation. Sorption of Mo is found to decrease with the increase of feed acidity. The loading capacity of resin is determined to be 30 mg g−1, the sorption isotherm data fit well to the Langmuir model. Batch sorption experiments with simulated dissolver solution showed quantitative uptake of Mo along with some co-extraction of iodine (I). Column runs have demonstrated that co-extracted ‘I’ could be scrubbed easily with solutions of feed acidity. Finally, sorbed Mo could be eluted with 3.0 M HNO3. XAFS and FT-IR studies of Mo sorbed on to IDAA SDVB resin have shown that Mo is sorbed in the +6 oxidation state (in the form of MoO42−), wherein the complex attains octahedral geometry with contribution from four oxygen atoms of the molybdate anion and two oxygen atoms of the amidic moiety of the imino-diacetamide ligand.

N,N-dialkyl aliphatic amides with varying alkyl groups viz. N,N-dibutyl-2-ethyl hexanamide (DBEHA), N,N-dibutyl-3,3-dimethyl butanamide (DBDMBA), N,N-dihexyl octanamide (DHOA), N,N-di-sec-butyl pentanamide (DBPA), N,N-dibutyl octanamide (DBOA), have been evaluated for supercritical fluid extraction (SFE) of uranium and thorium from nitric acid medium as well as from tissue paper matrix. The trend in extraction efficiency could be correlated to the structure of the amides and the amide complex of uranium/thorium. Straight chain amide DBOA was found suitable for SFE of both uranium and thorium. Under optimised conditions (200 atm. pressure, 323 K temperature, 30 min static time followed by 30 min dynamic time, 0.5 M amide in methanol), (94 ± 3)% uranium and (85 ± 4)% thorium could be extracted from 4 M nitric acid medium. For tissue paper matrix, under optimised conditions (200 atm pressure, 323 K temperature, 45 min static time followed by 30 min dynamic time, 0.2 M amide in methanol) (87 ± 7)% uranium and (88 ± 7)% thorium were extractable. For the amide having branching at Cα, DBEHA, extraction efficiency of thorium was as low as 7% for 2 M HNO3 medium while extraction efficiency of uranium was still 95%. For tissue paper matrix, extraction efficiency for uranium with 0.2 M DBEHA (in methanol) was 86% while only 11% thorium was extractable under same conditions. This fact could be exploited for separation of thorium and uranium.

The present study describes the extraction of lead(II) from acidic medium with supercritical carbon dioxide using various calixarenes. It involves the investigation of the effect of temperature, acid molarity, and the metal to complexing agent molar ratio on supercritical fluid extraction efficiency. Efficient extraction of Pb(II) was observed for p-t-butylcalix(4)arene with (92 ± 3)% extraction at 323 K, 20.27 MPa, 30 minute static time followed by 30 minute dynamic time and a metal to complexing agent molar ratio of 1:5. The complexing ability of Pb(II) with calixarene was established by absorption and energy dispersive spectroscopy. The scanning electron micrograph of calixarene and the lead–calixarene complex was studied. The structure of the Pb(II)–calixarene complex has been proposed based on solvent extraction in hexane and IR spectroscopic analysis of the extract. Thermodynamic aspects of extraction were also studied and the extraction reaction was found to be entropy driven. Interference from other metal ions, on Pb(II) extraction behaviour, has been investigated. The developed method has been utilized for extraction of Pb(II) from real samples viz. paints, batteries, tobacco and wastewater.

Various calixarenes were evaluated for the supercritical fluid extraction of uranium from nitric acid medium. The extraction efficiency was found to be affected by various parameters, namely pressure, temperature, CO2 flowrate, extraction time, and molarity of nitric acid. The addition of HPFOA (pentadecafluoro-n-octanoic acid) for the production of CO2-phillic fluorinated counter ion enhanced the extraction efficiency. Under optimized conditions (pressure of 200 atm, temperature of 323 K, 30 minutes of static time followed by 30 minutes of dynamic time, CO2 flowrate of 2 mL min−1, nitric acid molarity of 0.1 M) for uranium: calixarene: HPFOA mole ratio of 1:5:10, highest extraction efficiency could be obtained with p-tert.-butyl calix[6]arene (79.9%). Solvent extraction study with hexane as the organic phase indicated the formation of [UO2 (calixarene)]2+. In order to assess the suitability of the developed method to extract uranium in the presence of a host of other ions, extraction efficiency for other...

Supercritical carbon dioxide (SC CO2) extraction of uranium from nitric acid medium employing various crown ethers was studied. CO2-phillic C–F bonds in pentadecafluoro-n-octanic acid (HPFOA) counter ion enhanced the extraction efficiency. Pressure (100−300 atm) and temperature (323−353 K) were found to influence extraction efficiency by affecting SC CO2 density as well as due to large size cluster formation of supercritical fluid near critical point thereby resulting in reduced interaction with solute. Pressure of 200 atm and temperature of 323 K were found to be optimum. The trend in efficiency for benzo substituted crown ethers was due to the combined effect of cavity size and number of ether oxygen atoms. The extraction efficiency among 18-crown-6 series is influenced by the extent of basicity of ether oxygen, which in turn is dictated by the substituent group. Efficiency also decreased beyond 2 M nitric acid due to co-extraction of crown-nitric acid complex. Uranium: crown: HPFOA mole ratio influenced extraction efficiency, having optimum value at 1:10:100. Under optimized conditions with ditertiarybutyldicyclohexano-18-crown-6 the efficiency was found to be (86±5) %.

SAR (Synthetic Aperture Radar) images in the northwest Bay of Bengal indicate the existence of internal waves and their occurrence and intensity is topography dependent as indicated by in-situ data and satellite information. To complement and comprehend the observations, a three-dimensional Princeton Ocean Model is applied to study the generation and propagation of internal waves. The model domain is configured with a variable curvilinear grid and the input fields comprise bathymetry, initial temperature and salinity, wind stress, air-sea heat flux and tidal information. The numerical investigation indicated a predominant activity of internal waves in the north, and the rationale is three-fold. The first one could be the stable stratification due to fresh water discharge from head-bay major river system, secondly, the significant magnitude/range of the tides and finally, the bathymetry in the coastal waters off Paradip is about 12% shallower compared to that of Visakhapatnam and further south. The cumulative effect of these causes the predominance of internal waves in the north. The core of the energy is essentially in the low-frequency range and the model is able to simulate semi-diurnal and diurnal components reasonably well up to 6 h frequency (0.162 cph).

Uranium from different uranium oxide matrices was extracted with tri-n-butyl phosphate–nitric acid (TBP–HNO3) adduct using supercritical carbon dioxide (SC CO2). While 30 min dissolution time at 323 K was sufficient for U3O8 and UO2 powder, UO2 granule (at 333 K) and crushed green pellet (at 353 K) required 40 min. Crushed sintered pellet required 60 min at 353 K for complete dissolution. Influence of various experimental parameters such as temperature, pressure, volume of TBP–HNO3 adduct, acidity of nitric acid used for preparing TBP–HNO3 adduct and extraction time on uranium extraction efficiency was also investigated. For UO2 powder, temperature of 323 K, pressure of 15.2 MPa, 1 mL TBP–HNO3 adduct, 10 M nitric acid and 30 min extraction time was found to be optimum. ~70% uranium extraction efficiency was obtained on extraction with SC CO2 alone which increased to 90% with the addition of 2.5% TBP in SC CO2 stream. Extraction efficiency was found to vary linearly with TBP percentage and nearly complete uranium extraction (~99%) was observed with 20% TBP. Nearly complete extraction was also achieved with addition of 2.5% thenoyltrifluoroacetylacetone (TTA) in methanol. The optimized procedure was extended to remove uranium from simulated tissue paper waste matrix smeared with uranium oxide solids.

In the supercritical fluid extraction of uranium from acidic medium employing TBP as co-solvent, effects of various parameters on extraction efficiency were studied. Variation in pressure (80–300 atm), temperature (308–353 K), CO2 flow rate (0.5–3 mL/min), co-solvent percentage (1–10%), molarity of nitric acid (0.5–10 M) were found to influence uranium extraction efficiency. The uranium extraction efficiency depends on distribution ratio and kinetics of transport of U-TBP complex into supercritical CO2. In the 150–300 atm pressure range, variation in extraction efficiency was similar to that of uranium distribution ratio under equilibrium conditions. Whereas below 150 atm, it closely followed supercritical CO2 density variation which could be attributed to non-equilibrium behavior that eventually attained equilibrium. In the non-equilibrium region, increased supercritical CO2 density with pressure favored enhancement in solubility as well as extraction kinetics of the U-TBP complex. Increase in temperature generally resulted in enhanced volatility of U-TBP complex and a decrease in supercritical CO2 density which in turn affected the extraction efficiency. Up to 333 K temperature, extraction efficiency gradually increased due to enhancement in volatility of U-TBP complex which more than compensates for decrease in the supercritical CO2 density. Beyond this temperature, the steep fall in the extraction efficiency is attributed to combined effect of saturation in volatility of the U-TBP complex and significant decrease in the density of supercritical CO2 approaching the critical value at which supercritical CO2 tends to form large clusters thereby resulting in steep decrease in its solvating power. Extraction efficiency was found to increase with nitric acid molarity up to 7 M and afterwards showed small decrease possibly due to competitive co-extraction of HNO3. Up to CO2 flow rate of 1 mL/min increase in extraction efficiency was observed which attained saturation afterwards. Linear increase in extraction efficiency was observed with the amount of TBP. Extraction efficiency was found to increase linearly with logarithm of extraction time. Under optimised conditions (150 atm, 333 K, 1 mL/min CO2 flowrate, 10% co-solvent, 7 M nitric acid and 30 min dynamic extraction time) extraction efficiency was found to be (98±2) was observed. 30 min dynamic extraction mode was found equivalent to 40 min static mode. Online complexation mode was more efficient than in situ mode.

Cucurbit[n]urils (CBn) are a new class of macrocyclic cage compounds capable of binding organic and inorganic species, owing to their unique pumpkin like structure comprising of both a hydrophobic cavity and a hydrophilic portal. The thermodynamics of the complexation of Eu(III) with CBn of a different cavity size viz. cucurbit[5]uril (CB5) and cucurbit[7]uril (CB7) has been studied by UV-Vis spectroscopy and calorimetry at 25 °C whereas the structure of the complexes was investigated using time resolved fluorescence spectroscopy (TRFS) and extended X-ray absorption fine structure spectroscopy (EXAFS) in a formic acid–water mixture (50 wt%). This is the first report on the structural investigation of Eu–CBn complexes in solution. The thermodynamic data (ΔG, ΔH and ΔS) for Eu(III) complexation with CBn reveal the formation of a 1 : 1 complex with CB5, while both 1 : 1 and 1 : 2 complexes are observed with CB7. The signatures of these species are observed in ESI-MS measurements, which corroborates with the species postulated in thermodynamic studies. The complexation reactions are found to be driven by ΔS as ΔH is either small negative or positive indicating the formation of inner sphere complexes, which is in line with TRFS and EXAFS results. These studies show that Eu(III) caps one of the CB5 portals by binding with all the carbonyl groups in the 1 : 1 Eu–CB5 complex, whereas in the 1 : 1 Eu–CB7 complex, Eu(III) interacts with only a few of the carbonyl groups of CB7. The computational studies (DFT calculations) on Eu–CB5 and Eu–CB7 complexes further support the experimental data.

Tsunami waves are considered the most dangerous natural hazard affecting the population of the world living near the coastal belts. With the increasing intensity of economic exploitation of coasts ...

There has been extensive loss of life and damage associated with severe tropical cyclones in the South Asian region. The Bay of Bengal and the Arabian Sea are the two marginal seas of the North Indian Ocean and have given rise to storm surges during the pre-monsoon (April-May) and the post- monsoon period (October-December). Table 1 lists the events where the loss of lives were 1000 or more.

A new method has been developed for separation and purification of fission 99 Mo from neutron activated uranium–aluminum alloy. Alkali dissolution of the irradiated target (100 mg) results in aluminum along with 99 Mo and a few fission products passing into solution, while most of the fission products, activation products and uranium remain undissolved. Subsequent purification steps involve precipitation of aluminum as Al(OH) 3 , iodine as AgI/AgIO 3 and molybdenum as Mo-α-benzoin oxime. Ruthenium is separated by volatilization as RuO 4 and final purification of 99 Mo was carried out using anion exchange method. The radiochemical yield of fission 99 Mo was found to be >80% and the purity of the product was in conformity with the international pharmacopoeia standards.

Various β-diketones viz. acetylacetone (AA), trifluoroacetylacetone (TFA), hexafluoroacetylacetone (HFA), thenoyltrifluoroacetylacetone (TTA) and heptafluorobutanoyl-pivaroylmethane (FOD) were evaluated as chelating agents for the supercritical fluid extraction of thorium from tissue paper matrix. In-situ chelation mode was found to be more effective than online chelation mode. A combination of tributyl phosphate (TBP) and β-diketones further enhanced the extraction efficiency. The extraction efficiency trend observed in all the cases was: TTA > FOD > HFA > TFA > AA. A correlation was observed between extraction efficiency and degree of fluorination in the side arms of β-diketones. This could be attributed to the fact that in supercritical CO 2 , higher fluorination results in higher percentage of enol content, greater dissociation into enolate ion and higher solubility and stability of /?-diketones as well as of Th-β-diketone chelates. Highest extraction efficiency with TTA was probably due to the presence of aromatic thenoyl group. The spectra of the extracted Th-chelates displayed peaks in the visible region, which shifted towards UV region with increasing fluorination. In the Th-TTA chelate spectrum, red shift was observed.