Formation Of Neutral Complexes Research Articles

Advanced Uranium Removal with Pure, Nonfluorinated Ionic Liquids: Fine-Tuning Hydrophilic and Hydrophobic Properties for Enhanced Selectivity.

Ionic liquids (ILs) have significant potential for eco-friendly extraction of uranium from aqueous solutions, which is critical for nuclear technology, fuel cycle management, and environmental protection. This study examines the impact of the adjustable hydrophobic/hydrophilic properties of ILs on the removal of uranium(VI) (UO22+) from aqueous solutions utilizing both a novel hydrophilic IL (1-butoxyethyl-1-methylmorpholinium butoxyethylphosphite - Mor1-2O4-BOEP) and 1-heptyl-1-methylmorpholinium heptylphosphite (Mor1-7-HP) as an example of a hydrophobic IL with a similar structure. The transfer mechanism of uranyl ions from water to organic or solid phases closely depends on the physicochemical properties of ILs, especially their hydrophobicity. The hydrophobic Mor1-7-HP extracts uranyl via neutral complex formation as UO2(NO3)2-(Mor1-7-HP)2. Conversely, hydrophilic Mor1-2O4-BOEP induced selective precipitation as UO2(NO3)-(BOEP), transferring uranyl to the solid phase. Optimization of the working parameters, in terms of acidity of the aqueous solution and amount of ILs used, allowed the extraction of over 98% of U(VI). The stoichiometry of the organic complex and the precipitate was determined using physicochemical techniques. These tunable H-phosphonate-based ILs have advantages over traditional solvent extraction and conventional ILs, allowing easier handling, improved selectivity, and lower environmental impact. This work advances uranium separation techniques with applications in hydrometallurgy, particularly in the treatment of wastewater and radioactive waste for sustainable uranium recovery.

ВПЛИВ ЛАЗЕРНОГО ВИПРОМІНЮВАННЯ НА ОПТИЧНІ ВЛАСТИВОСТІ ТОНКИХ ПРИПОВЕРХНЕВИХ ШАРІВ НАПІВПРОВІДНИКІВ

Optical studies of the reflection spectra of n-Si(100) single crystals with a resistivity of ρ = 5 Ω∙cm; n-GaAs with a resistivity of ρ = 10 Ω∙cm; CdTe (111) with a resistivity of ρ = (2÷5)∙109 Ω∙cm; Cd1-хZnxTe (x=0.1) solid solutions with resistivity ρ = (5÷30)∙109 Ω∙cm in the spectral range (0.2-1.7)-10-6 m before and after laser irradiation in the energy range 66 mJ/cm2-108 mJ/cm2 for n-Si (100) and n-GaAs (100), in the energy range of 66 mJ/cm2 - 164 mJ/cm2 for CdTe(111), in the energy range of 46.6 mJ/cm2 - 163.5 mJ/cm2 for Cd1-хZnxTe (x=0.1) solid solutions. An increase in the reflectivity of single crystals of n-Si (100), n-GaAs (100), p-CdTe (111) and solid solutions of Cd1-хZnxTe (x=0.1) under this laser treatment was experimentally observed. This integral effect is explained by the differences in the optical characteristics of the near-surface layer and the material volume (the complex refractive index of the near-surface layer differs from the complex refractive index of the material volume). The obtained spectra of optical reflection of the samples show that laser-stimulated interaction of impurities and defects occurs during irradiation, which leads to the formation of neutral complexes and a decrease in the intensity of impurity scattering processes. Experimental studies have shown that the main mechanism of pulsed laser irradiation influence on the optical properties of thin surface layers of the studied crystals is structural heterogeneity, i.e. absorption due to the presence of semiconductor sites with defective structure and the ability to actively absorb point defects and bind impurities. In silicon, the role of a heter is played by the surface layers of SiOx, SiO2, Si3N4, SiO2-xP, SiC and others; in gallium arsenide, by Ga2O3, As2O5 and others; in p-CdTe (111) single crystals and Cd1-хZnхTe (x = 0.1) solid solutions, the role of a getter is played by cadmium, tellurium, zinc oxides and their complexes.

Identification and quantification of the adsorption mechanisms of the cationic surfactant the cetylpyridinium chloride on Moroccan Na-montmorillonite

The modification of the clays (montmorillonite) by surfactants finds several applications in various fields, such as cosmetics, drugs, nanomaterials, etc. The experimental and the simulation of the adsorption of the cetylpyridinium surfactant on a Moroccan Na-Montmorillonite-type clay surface have been investigated. The adsorption rate of cetylpyridinium reached 2 CEC (Cation Exchange Capacity) and the maximum amount of adsorption increases for co-ion Br - more than Cl - . These results have been proven and we can conclude that the amount of adsorption varies according to the surfactant critical micelle concentration (CMC). The simulation shows the arrangement of the cationic surfactant’s ions adsorbed on the basal surface. Where the cetylpyridinium are organized in two layers in a bimolecular and paraffinic manner. The binding coefficients for the formation of neutral complexes of either cationic surfactant’s ions and the clay are calculated by a theoretical model and the binding force of the cationic surfactant ion on the surface of the clay depends on the co-ion. The FT-IR and XRD analyses showed that the surfactant is in strong interaction with montmorillonite for a surfactant adsorption rate lower than the CEC, and that the orientation of the surfactant molecules on the surface of the clay changes with the amount adsorbed to CP-Cl, especially for an adsorbed amount greater than the CEC.

Antitumor activity of Pd(II) complexes with N,S or O,S coordination modes of acylthiourea ligands

Seven new complexes (1–7) of Pd(II) with N-alkyl- and N,N-dialkyl-N′-acylthioureas were prepared and characterized by elemental analysis and spectroscopic techniques. The crystal structures of the coordination compounds [PdCl(PPh3)(5-cloropiridyl-N′-benzoylthioureato-k2N,S)] (2), cis-[Pd(PPh3)2(N-morpholyn-N′-benzoylthioureato-k2O,S)]PF6 (4) and cis-[Pd(PPh3)2(N,N-diphenyl-N′-thiophenylthioureato-k2O,S)]PF6 (7) were determined by X-ray crystallography. The present study reports on an interesting contribution on the chemistry of Pd(II)/acylthiourea complexes, where the use of monosubstituted acylthiourea conducts to formation of neutral complexes with general formula [Pd(Cl)(PPh3)(acylthiourea)], with a N,S-coordination mode. On the other hand, cationic complexes with formula [Pd(PPh3)2(acylthiourea)]+, with O,S bidentately coordinated to the metal, are obtained by using a disubstituted acylthiourea derivative. The antitumor activity of the N-alkyl- and N,N-dialkyl-N′-acylthiourea ligands and their palladium (II) complexes with synthesized triphenylphosphine were evaluated against the growth of the DU-145 tumor cells (prostate cancer cells), (MDA-MB-231 (breast cancer cells), L929 (healthy mouse cells). The ligands are not cytotoxic, but the complexes showed good cytotoxicity against the tumor cells tested in this work, and were even better, when compared to the IC50 reported for the cisplatin. The complexes showed better activity results in MDA-MB-231 tumor cells, than for the DU-145 tumor cells. Complexes 1 and 6 showed high cytotoxic activity at low micromolar concentrations (IC50 = 1.93 ± 0.45, 0.62 ± 0.08 μM) against MDA-MB-231 (human breast cancer cells). This result indicated that the binding of the ligands to the metal center increases their antitumor activity.

Trinuclear M3S4 cluster complexes with hemilabile phosphino-thioether ligands: Some experimental and theoretical aspects

Reactions of [W3S4(tu)8(H2O)]Cl4⋅2H2O (tu = thiourea) with (PhCH2CH2)2PCH2CH2SR (R = Ph (PS1) or n-pentyl (PS2), followed by chromatography on silica gel with a solution of KPF6 in acetone as eluent, result in [W3S4Cl3(PS1)3]PF6 ([1]PF6) and [W3S4Cl3(PS2)3]PF6 ([2]PF6) in moderate yields. Crystal structures of [1]PF6 and [2]PF6 were determined by X-ray single crystal analysis. All three phosphine-thioether molecules are bidentately coordinated to tungsten atoms in such a way that the phosphorus atoms are in the trans position to the capping µ3-S atom. The compounds were characterized by 1H, 31P{1H} NMR, and UV–vis spectroscopies and electrospray-ionization mass spectrometry. Unlike similar molybdenum complexes, interaction of [1]PF6 or [2]PF6 with Bu4NCl does not lead to the formation of neutral complexes [W3S4Cl4(PS)2(PS*)] with the monodentate coordination of one of the PS ligands. This indicates weaker hemilabile properties of phosphino-thioether ligands in the tungsten complexes. Consequently, both [1]PF6 and [2]PF6 exhibit significantly lower catalytic activity than the molybdenum analogues in the benchmark reaction of nitrobenzene reduction into aniline with Ph2SiH2. The DFT calculations were performed to determine the relative stability of possible isomers with the chelate, bridging and monodentate manner of coordination of the PS ligands to {M3S4} (M = Mo, W) clusters, taking (CH3)2PCH2CH2SCH3 as a model.

The Reactivity of Phosphanylphosphinidene Complexes of Transition Metals Toward Terminal Dihaloalkanes.

The reactivities of phosphanylphosphinidene complexes [(DippN)2W(Cl)(η2-P–PtBu2)]− (1), [(pTol3P)2Pt(η2-P=PtBu2)] (2), and [(dppe)Pt(η2-P=PtBu2)] (3) toward dihaloalkanes and methyl iodide were investigated. The reactions of the anionic tungsten complex (1) with stochiometric Br(CH2)nBr (n = 3, 4, 6) led to the formation of neutral complexes with a tBu2PP(CH2)3Br ligand or neutral dinuclear complexes with unusual tetradentate tBu2PP(CH2)nPPtBu2 ligands (n = 4, 6). The methylation of platinum complexes 2 and 3 with MeI yielded neutral or cationic complexes bearing side-on coordinated tBu2P–P-Me moieties. The reaction of 2 with I(CH2)2I gave a platinum complex with a tBu2P—P—I ligand. When the same dihaloalkane was reacted with 3, the P—P bond in the phosphanylphosphinidene ligand was cleaved to yield tBu2PI, phosphorus polymers, [(dppe)PtI2] and C2H4. Furthermore, the reaction of 3 with Br(CH2)2Br yielded dinuclear complex bearing a tetraphosphorus tBu2PPPPtBu2 ligand in the coordination sphere of the platinum. The molecular structures of the isolated products were established in the solid state and in solution by single-crystal X-ray diffraction and NMR spectroscopy. DFT studies indicated that the polyphosphorus ligands in the obtained complexes possess structures similar to free phosphenium cations tBu2P+=P−R (R = Me, I) or (tBu2P+=P)2.

1,2-Benzenedithiol and Toluene-3,4-dithiol Arsenic(III) Complexes-Synthesis, Structure, Spectroscopic Characterization and Toxicological Studies.

A new group of arsenic(III) complexes with bidentate S,S-donor ligands, 1,2-benzenedithiol (Ph(SH)2) and toluene-3,4-dithiol (MePh(SH)2), were synthesized. The use of arsenic(III) iodide and bromide promoted the formation of neutral complexes (1–4) with the general formula AsX(LS2) (X = I or Br, L = MePh or Ph). The crystal structures of these compounds were determined using single-crystal X-ray diffraction (scXRD). Unlike other arsenic(III) complexes, AsBr(PhS2) complex (2) was found to crystallize with a rare 13 molecules in the asymmetric unit. The compounds were also characterized by conventional physico-chemical techniques (Fourier transform infrared (FT-IR) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, nuclear magnetic resonance (NMR), high-performance liquid chromatography (HPLC), elemental analysis (EA) and electrospray ionization-mass spectrometry (ESI-MS)). The results from structural and spectroscopic studies were supported by DFT calculations using the B3LYP/LANL2DZ and (or) 6-31+G(d,p) approaches. The cytotoxicity of these complexes was estimated for human acute promyelocytic leukemia cell line (NB4). They exhibited remarkable cytotoxicities after 48 h of treatment with IC50 equal to about 10 µM and 40 µM for complexes with 1,2-benzenedithiolato and toluene-3,4-dithiolato ligand, respectively. Their toxicity was lower than that of commonly used chemotherapeutic As2O3 (IC50 = 1.4 µM).

Coordination of pyrazole-benzothiazole hybrids to the [ReO]3+ and fac-[Re(CO)3]+ cores

The reaction of the pyrazole-benzothiazole hybrids 2-(3,5-dimethylpyrazol-1-yl)benzothiazole (dmp) and 2-(2-benzothiazolyl)-4,5,6,7-tetrahydro-2H-indazol-3-ol (Hbth) with [Re(CO)5Cl] resulted in the formation of neutral complexes with the general formula [ReCl(CO)3(HL)] (HL = dmp (1), Hbth (2)). 1-(Benzo[d]thiazol-2-yl)-4-methyl-1H-pyrrol-2-ol (Hbtm) gave the trimeric species [Re(btm)(CO)3]3 (3) by reaction with [Re(CO)5Cl]. Reaction with [ReVOCl3(PPh3)2] led to the isolation of the oxo-bridged dimeric compound (µ-O)[ReOCl2(dmp)]2 (4) and [ReOCl(bth)(bth1)] (5) [bth1 = 2-(benzo[d]thiazol-2-yl)-1,2,4,5,6,7-hexahydro-3H-indazol-3-one] by reaction with dmp and Hbth, respectively. The reactivity of Hbtm with trans-[ReOCl3(PPh3)2] in ethanol gave [ReOCl(btm)(btm1)] (6) [btm1 = 2-(benzo[d]thiazol-2-yl)-5-methyl-1,2-dihydro-3H-pyrazol-3-one], whereas [ReOCl(btm1)(btz)] (7) [btz = 1-(benzo[d]thiazol-2-yl)-4-(1-iminoethyl)-3-methyl-1H-pyrazol-5ol] formed in acetonitrile using the same reactants. The rhenium(V) complexes [ReO(OMe)(btm)(btm1)] (8) and [ReO(OEt)0.96(I)0.04(btm)(btm1)] (9) were isolated upon reacting Hbtm with cis-[ReO2I(PPh3)2] in methanol and ethanol, respectively. The structures of complexes 1–9 were determined by X-ray diffraction methods and confirmed spectroscopically.

Synthesis of new triazolyl-oxazoline chiral ligands and study of their coordination to Pd(II) metal centers

We report an improved protocol for the synthesis of TryOx, a family of N,N chiral ligands in which a 1,2,3-triazol-4-yl moiety bears a chiral 2-oxazoline as the substituent in 4 position. TryOxs were successfully employed for the preparation of cationic Pd(II)-allyl complexes of formulation [Pd(allyl)(TryOx)]+ in which they behave as bidentate N,N chelating ligands. On the other hand, reaction of TryOxs with an equimolecular amount of [PdCl2(CH3CN)2] leads to the formation of neutral complexes which according to NMR, ESI-MS and molar mass determination (VPO) appear to be dimeric species of formulation [PdCl(µCl)(TryOx)]2 in which monodentate TryOxs link to palladium with the N atom of the oxazoline ring. X-rays diffraction studies show that upon crystallization these dimers transform into monomeric compounds of formulation [PdCl2(TryOx)], where the ligands behave as N,N chelating.Treatment of the [PdCl(µCl)(TryOx)]2 dimers with an equivalent of TryOx affords mononuclear neutral dichloro species of formulation [PdCl2(TryOx)2]. X-ray diffraction studies show that the two TryOx units are equivalent behaving as monodentate ligands coordinated to the metal through the oxazoline N atom.

Defects responsible for charge carrier removal and correlation with deep level introduction in irradiated β-Ga2O3

Carrier removal rates and electron and hole trap densities in β-Ga2O3 films grown by hydride vapor phase epitaxy (HVPE) and irradiated with 18 MeV α-particles and 20 MeV protons were measured and compared to the results of modeling. The electron removal rates for proton and α-radiation were found to be close to the theoretical production rates of vacancies, whereas the concentrations of major electron and hole traps were much lower, suggesting that the main process responsible for carrier removal is the formation of neutral complexes between vacancies and shallow donors. There is a concurrent decrease in the diffusion length of nonequilibrium charge carriers after irradiation, which correlates with the increase in density of the main electron traps E2* at Ec − (0.75–0.78) eV, E3 at Ec − (0.95–1.05) eV, and E4 at Ec − 1.2 eV. The introduction rates of these traps are similar for the 18 MeV α-particles and 20 MeV protons and are much lower than the carrier removal rates.

Synthesis and characterization of copper, nickel, cobalt, zinc complexes with 4-nitro-3-pyrazolecarboxylic acid ligand

In the continuation of our systematic research of pyrazole coordination compounds, complexes of Cu(II), Ni(II), Co(II) and Zn(II) with 4-nitro-3-pyrazolecarboxylic acid ligand (L) were synthesized in the reaction of warm ethanolic solutions of the ligand and CuCl2·2H2O, Ni(CH3COO)2, CoCl2·6H2O and Zn(CH3COO)2, mixed in the metal-to-ligand ratio of 1:2. As the compounds could not be obtained in the form suitable for single-crystal structure analysis, their bis(ligand) structures, ML2 (M = CuII, NiII, CoII and ZnII) were proposed on the basis of elemental analysis, IR spectrometry, conductometric and TG–MS measurements. The low conductivity of the compounds additionally supports the deprotonation of the ligand and the formation of neutral complexes. The solvent content was calculated using the thermogravimetric (TG) data. According to TG data, the copper(II) compound crystallizes with 8 while nickel(II) complex with 4 water molecules, CuL2·8H2O, NiL2·4H2O. Complexes of Co(II) and Zn(II) contain 1 and 1.5 water molecules. Despite the differences in solvation properties, the high similarity in the course of the decomposition refers to the similar coordination mode of the organic ligand. The crystal and molecular structures of HL·H2O and NH4[LHL] were determined by single-crystal X-ray structure analysis. Biological research based on determining the inhibition effect of commercial fungicide Cabrio top, ligand, and all newly synthesized complexes on Ph. viticola has been carried out using the phytosanitary method.

Potential Fluctuations and Localization Effects in CZTS Single Crystals, as Revealed by Optical Spectroscopy

Reports on Cu $$_2$$ ZnSn(S $$_x$$ Se $$_{1-x}$$ ) $$_4$$ (CZTSSe) solar cell devices all show an open-circuit voltage lower than expected, especially when compared to CuIn $$_x$$ Ga $$_{1-x}$$ (S,Se) $$_2$$ devices, which reduces their power efficiency and delays their development. A high concentration of intrinsic defects in CZTSSe, and their stabilization through neutral complex formation, which induces some local fluctuations, are at the origin of local energy shifts in the conduction and valence band edges. The implied band tail in Cu $$_2$$ ZnSnS $$_4$$ is studied in this work by combining three types of optical spectroscopy data: emission spectra compared to photoluminescence excitation spectroscopy, emission spectra as a function of excitation power, and time-resolved photoluminescence spectra. All these data converge to show that both the bandgap and the band tail of localized states just below are dependent on the degree of order/disorder in the Cu/Zn cation sublattice of the quaternary structure: in the more ordered structures, the bandgap increases by about 50 meV, and the energy range of the band tail is decreased from about 110 to 70 meV.

Comparative study on the extraction of trivalent americium and europium by CMPO in imidazolium-based ionic liquids and dodecane

ABSTRACTThe extraction of Am3+ and Eu3+ by octyl(phenyl)-N,N-diisobutyl carbamoylmethylphosphine oxide (CMPO) in eight imidazolium-based ionic liquids and in n-dodecane was studied and compared. Slope analysis indicates that the ligand/metal ratio in the extracted complexes in ionic liquids is much larger than that in n-dodecane. Nitric acid has different impacts on the extraction, depending greatly on the nature of the ionic liquids. A mixed-extraction mechanism, namely cation exchange plus the formation of neutral complexes (solvation), was proposed for the extraction in the ionic liquid systems. In addition, temperature was found to have a remarkable influence on the extraction. Highly exothermic enthalpy changes were obtained for the extraction in ionic liquid systems. This work provides further insight into the particular role played by the unique properties of ionic liquids in the extraction of metal ions from nitric acid media.

Synthesis and structural studies of half-sandwich Cp* rhodium and Cp* iridium complexes featuring mono, bi and tetradentate nitrogen and oxygen donor ligands

A series of Cp*Rh and Cp*Ir complexes of various nitrogen and oxygen donor ligands were synthesized and characterized. Mono, bi and tetradentate ligands were used to synthesize mononuclear and dinuclear complexes. Schiff base derivatives of picolinic hydrazine and 5-aminoquinoline were used in the synthesis of complexes 1–8. Among the ligands used for complexation, L1 and L2 act as bidentate, L3 as monodentate and L4 as tetradentate in forming the corresponding complexes. All the complexes were characterized by spectroscopic techniques and the structures of complexes 2, 3, 5 and 7 were unambiguously characterized by single crystal X-ray crystallography. Complexes 2 and 7 were found to have $${\uppi }$$ - $${\uppi }$$ stacking interactions and solvent to complex interactions, respectively. Metal-mediated deprotonation of N-H and monodentate binding of nitrogen are attributed to the formation of neutral complexes whereas ionic complexes are formed by (N,O) bonding. SYNOPSIS Half-sandwich Cp* rhodium and Cp* iridium complexes of Schiff base derivatives of picolinic hydrazine and 5-aminoquinoline were synthesized, characterized and their structures studied by single crystal X-ray analysis. Various binding modes of the complexes were unambiguously confirmed.

Ruthenium(III) Complexes of Heterocyclic Tridentate (ONN) Schiff Base: Synthesis, Characterization and its Biological Properties as an Antiradical and Antiproliferative Agent.

The current work reports the synthesis, spectroscopic studies, antiradical and antiproliferative properties of four ruthenium(III) complexes of heterocyclic tridentate Schiff base bearing a simple 2′,4′-dihydroxyacetophenone functionality and ethylenediamine as the bridging ligand with RCHO moiety. The reaction of the tridentate ligands with RuCl3·3H2O lead to the formation of neutral complexes of the type [Ru(L)Cl2(H2O)] (where L = tridentate NNO ligands). The compounds were characterized by elemental analysis, UV-vis, conductivity measurements, FTIR spectroscopy and confirmed the proposed octahedral geometry around the Ru ion. The Ru(III) compounds showed antiradical potentials against 2,2-Diphenyl-1-Picrylhydrazyl (DPPH) and 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radicals, with DPPH scavenging capability in the order: [(PAEBOD)RuCl2] > [(BZEBOD)RuCl2] > [(MOABOD)RuCl2] > [Vit. C] > [rutin] > [(METBOD)RuCl2], and ABTS radical in the order: [(PAEBOD)RuCl2] < [(MOABOD)RuCl2] < [(BZEBOD)RuCl2] < [(METBOD)RuCl2]. Furthermore, in vitro anti-proliferative activity was investigated against three human cancer cell lines: renal cancer cell (TK-10), melanoma cancer cell (UACC-62) and breast cancer cell (MCF-7) by SRB assay.

Ruthenium (II) complexes containing 2-mercaptothiazolinates as ligands and evaluation of their antimicrobial activity

In this work, two novel ruthenium-based compounds containing mercaptothiazolinate ligands were synthesized. A methanol (MeOH) solution containing [RuCl2(PPh3)3], 2-mercaptothiazoline (Hmctz) or 2-mercaptobenzothiazoline (Hmcbtz) (ligand/Ru=2) and triethylamine (NEt3) was refluxed leading to the formation of neutral complexes with the general formula cis-[Ru(N–S)2(PPh3)2] (N–S=mctz− – complex 1; N–S=mcbtz− – complex 2). We used NMR (1H and 31P{1H}), vibrational spectroscopy (FTIR), and elemental analysis to analyze these two complexes. Cyclic voltammetry revealed that complexes 1 and 2 underwent a reversible one-electron process due to the Ru(III)/Ru(II) pair. Reactivity of the complexes 1 and 2 with dmso leading to the substitution of one PPh3 by dmso was observed (complexes 3 and 4). Complex 1 showed higher antimicrobial activity against Gram (+) and Gram (−) bacteria (Bacillus subtilis and Escherichia coli, respectively). The formation of complex [Ru(mctz)2(dmso)(PPh3)] (3) was faster than complex [Ru(mcbtz)2(dmso)(PPh3)] (4) and this may account for the higher antibacterial activity of complex 1. Single-crystal X-ray diffraction furnished the molecular structures of complex 1 and of the product of its reaction with dmso, [Ru(mctz)2(dmso)(PPh3)] (3).

Effect of room temperature ionic liquid on the extraction behavior of Plutonium (IV) using a novel reagent, bis-(2-ethylhexyl) carbamoyl methoxy phenoxy-bis-(2-ethylhexyl) acetamide [Benzodioxodiamide, BenzoDODA

A novel Plutonium (Pu) (IV) selective ligand, bis-(2-ethylhexyl) carbamoyl methoxy phenoxy-bis-(2-ethylhexyl) acetamide (BenzoDODA) was studied for its Pu(IV) extraction behavior in presence of 1-alkyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] imide {[Cnmim][Tf2N]}ionic liquids. BenzoDODA was observed to behave differently in RTIL compared to n-dodecane toward Pu(IV) extraction. The presence of C4mimTf2N tends to bring about significant enhancement in the extraction of Pu in both the acidic media (HCl and HNO3) as compared to that of using n-dodecane as diluent. The investigation of the extraction mechanism revealed that while using in RTIL (as diluent), the cation-exchange prevails up to 3M acidity, in contrast to anion exchange mechanism ruling above 3M acidic strength. However, in n-dodecane (as diluent) the metal extraction takes place via formation of anion-assisted neutral complex formation only at all acidities. Studies on the nature of species formed by Pu(IV) and BenzoDODA in both HNO3 and HCl medium showed formation of a di-solvate species for RTIL in contrast to mono-solvate formed in n-dodecane. Selectivity of BenzoDODA-RTIL system appears to be lost at lower acidities due to significant extent of extraction of other matrix elements along with target metal ion. However at higher nitric acid concentration (7M) BenzoDODA was found to be selectively extracting Pu(IV).

Model for conductivity compensation of moderately doped n- and p-4H-SiC by high-energy electron bombardment

The model of conductivity compensation in SiC under irradiation with high-energy electrons is presented. The following processes are considered to cause a decrease in the free carrier concentration: (i) formation of deep traps by intrinsic point defects, Frenkel pairs produced by irradiation; (ii) "deactivation" of the dopant via formation of neutral complexes including a dopant atom and a radiation-induced point defect; and (iii) formation of deep compensating traps via generation of charged complexes constituted by a dopant atom and a radiation-induced point defect. To determine the compensation mechanism, dose dependences of the deep compensation of moderately doped SiC (CVD) under electron irradiation have been experimentally studied. It is demonstrated that, in contrast to n-FZ-Si, moderately doped SiC (CVD) exhibits linear dependences (with a strongly nonlinear dependence observed for Si). Therefore, the conductivity compensation in silicon carbide under electron irradiation occurs due to deep traps formed by primary radiation defects (vacancies and interstitial atoms) in the silicon and carbon sublattices. It is known that the compensation in silicon is due to the formation of secondary radiation defects that include a dopant atom. It is shown that, in contrast to n-SiC (CVD), primary defects in only the carbon sublattice of moderately doped p-SiC (CVD) cannot account for the compensation process. In p-SiC, either primary defects in the silicon sublattice or defects in both sublattices are responsible for the conductivity compensation.

Solvent extraction of tellurium from chloride solutions using tri-n-butyl phosphate: conditions and thermodynamic data.

The extractive separation of tellurium (IV) from hydrochloric acid media with tri-n-butyl phosphate (TBP) in kerosene was investigated. The dependence on the extraction of tellurium species, concentrations of tellurium and TBP, extraction time and stage, organic/aqueous ratio, and interferences from coexist metallic ions were examined and are discussed. Besides, the stripping agent and stripping time were also studied. It was found that the extraction reaction corresponds to the neutral complex formation mechanism and the extracted species is TeCl4 ·3TBP and that the extraction process is exothermic. The thermodynamic parameters of enthalpy (ΔH), entropy (ΔS), and free energy (ΔG) of the extraction process were evaluated at −26.2 kJ·mol−1, −65.6 J·mol−1 ·K−1, and −7.0 kJ·mol−1, respectively at 293 K.

Water Chemistry in a Supercritical Water-Cooled Pressure Tube Reactor

The long-term viability of a supercritical water-cooled reactor (SCWR) will depend on the ability of designers and operators to control and maintain water chemistry conditions that will minimize corrosion and the transport of both corrosion products and radionuclides, at a pressure of 25 MPa and temperatures from 300°C to 625°C. To achieve this goal, the behavior of low concentrations of impurities such as transition metal corrosion products, chemistry control agents, impurities in the feedwater, and radionuclides (fission and activation products) in subcritical and supercritical water must be understood. A second key aspect of SCWR water chemistry control will be mitigation of the effects of water radiolysis. Preliminary studies suggest markedly different behavior than that predicted by extrapolating conventional water-cooled reactor behavior. The principal challenge in predicting corrosion and fission product transport is the lack of thermochemical and kinetic data above 300°C. Calculations with extrapolated data show that the formation of neutral complexes increases with temperature and can become important under near-critical and supercritical conditions. The most important region is from 300°C to 450°C, where the properties of water change dramatically and solvent compressibility effects exert a huge influence on solvation. The potential for increased transport and deposition of corrosion products (radioactive and inactive), leading to increased deposition on fuel cladding surfaces and increased out-of-core radiation fields and worker dose, must be assessed. The commonly used strategy of adding excess hydrogen at concentrations sufficient to suppress the net radiolytic production of primary oxidizing species may not be effective in an SCWR. Because direct measurement of the chemistry under such extreme conditions of temperature, pressure, and radiation fields is difficult, the most promising approach involves a combination of theoretical calculations, chemical models, and experimental work.