The influence of tributyl phosphate on molybdenum extraction with solutions of dibutyl phosphoric acid

Comparative investigations were carried out to study the influence of TBP on Mo extraction by HDBP solutions in xylene and TBP in xylene. The dependences of D_Mo on HNO₃ concentration for both HDBP and D2EHPA have minima at about 3 mol/L HNO₃. This shows similar extraction properties of HDBP and D2EHPA. The presence of TBP in the solvent results in the reduction of Mo extraction and in an increase in the formal slopes of the falling and rising parts of the logD_Mo — log[HNO₃] curve from −0.5 and +2 up to −2 and +4. Solvent loading curves with Mo show that in the absence of TBP a molybdenum solvate with two molecules of HDBP is formed at low acidity. Anomalous increase in the maximum solvent loading in the presence of TBP is caused by the ability of TBP to extract Mo from oversaturated low acidity solutions following the acidic mechanism. A molybdenum solvate with two HDBP molecules and one HNO₃ molecule is possibly formed at high acidity. A flowsheet for Mo recovery from HLW with HDBP-TBP solvent was tested in centrifugal contactors.     

The influence of dibutyl phosphoric acid on zirconium extraction with diluted tributyl phosphate and the role of uranyl nitrate

Distribution coefficients of zirconium (D_Zr) in the 30% TBP — aqueous HNO₃ solution extraction system rise 1000–2000 times with the increase of the dibutyl phosphoric acid (HDBP) concentration from 0 to 0.01–0.08 mol/L. A solvate with the molar ratio Zr: HDBP=1 was found by IR spectroscopy and analytic methods in the initial range of HDBP concentration. In the presence of U(VI) D_Zr decreases with the growing U concentration, however, the ratio of Zr distribution coefficient in the presence of HDBP (D_AZr) to D_Zr determined in its absence, R_Zr=D_AZr/D_Zr, is rather high. Function of enhancement (F) was introduced for the evaluation of simultaneous influence of U and HDBP on Zr extraction. An increase of the U concentration resulted first in the decrease in F_Zr, and then in its increase. The rising part of the F_Zr curve was more noticeable at a molar excess of Zr over HDBP. The mechanism of Zr extraction by 30% TBP solution in the presence of HDBP when Zr is in excess to HDBP indicates the formation of the solvate with the ratio Zr: HDBP=1; in the presence of U(VI) the complex with the same ratio is formed by the HDBP interaction with U in the system with a great excess of both HDBP and Zr.     

Выделение меченых соединений методом препаративной хроматографии

Mica Track Microfilters (MTM) are successful applied to separate two different and strongly mixed liquid phases (emulsion). The organic and the inorganic phase of the emulsion were 30% tributyl phosphate (TBP) in kerosene and 2 N HNO₃ (or H₂O), respectively. Mica filters with sharp edges (i.e. etched with H₂F₂) and having pore sizes k of 8 μm > k > 2 μm are used to get under some well defined conditions a rather complete extraction of the aqueous phase out of the emulsion. The system was calibrated with the pure phases (water as well as TBP in kerosene), and the liquid throughput is shown as a function of the pore size of the filter. The throughput depends mainly on the pore size and not that much on the kind of liquid, it is slightly larger for water as compared to that of TBP in kerosene.     

Mathematical model of ree separation using heat oscillating extraction

The influence of periodical oscillations of the temperature on extraction and stripping processes in the extraction systems is studied. Two extraction system were investigated, No.1: 6M NaNO₃ — Nd(NO₃)₃ — Pr(NO₃)₃ — TBP — kerosene and No. 2: [Nd(NO₃)₃·3TBP] — [Pr(NO₃)₃·3TBP] — kerosene — 0.1M HNO₃. Mathematical model of the non-stationary membrane extraction is presented including the dependence of extraction rate constants on temperature. The values of activation energy for direct and reverse reactions of extraction and stripping reactions of Pr and Nd were calculated from experimental time dependencies of metal concentrations and temperature by solving reverse kinetics problem using the proposed mathematical model. Series of experiments with the effect of periodical temperature oscillations on the extraction system for separation of rare earth elements using bulk liquid membrane between two extractors were made. The mathematical model describes experimental data adequately. On the basis of the extraction rate constants and activation energies the optimization of the extraction process of separation of rare earth elements by liquid membrane under the effect of periodical temperature oscillations has been carried out. The optimal conditions of separation by liquid membrane were found: frequency and amplitude of thermal oscillations, liquid membrane flow rate and optimal ratio between organic and aqueous phase in the extractors.     

Ultrasound-assisted extraction of rare-earth elements from carbonatite rocks

In view of the increasing demand for rare-earth elements (REE) in many areas of high technology, alternative methods for the extraction of these elements have been developed. In this work, a process based on the use of ultrasound for the extraction of REE from carbonatite (an igneous rock) is proposed to avoid the use of concentrated reagents, high temperature and excessive extraction time. In this pioneer work for REE extraction from carbonatite rocks in a preliminary investigation, ultrasonic baths, cup horn systems or ultrasound probes operating at different frequencies and power were evaluated. In addition, the power released to the extraction medium and the ultrasound amplitude were also investigated and the temperature and carbonatite mass/volume of extraction solution ratio were optimized to 70 °C and 20 mg/mL, respectively. Better extraction efficiencies (82%) were obtained employing an ultrasound probe operating at 20 kHz for 15 min, ultrasound amplitude of 40% (692 W dm⁻³) and using a diluted extraction solution (3% v/v HNO₃ + 2% v/v HCl). It is important to mention that high extraction efficiency was obtained even using a diluted acid mixture and relatively low temperature in comparison to conventional extraction methods for REE. A comparison of results with those obtained by mechanical stirring (500 rpm) using the same conditions (time, temperature and extraction solution) was carried out, showing that the use of ultrasound increased the extraction efficiency up to 35%. Therefore, the proposed ultrasound-assisted procedure can be considered as a suitable alternative for high efficiency extraction of REE from carbonatite rocks.     

Study on ultrasonically assisted emulsification and recovery of copper(II) from wastewater using an emulsion liquid membrane process

The aim of this work was to study the emulsification assisted by ultrasonic probe (22.5 kHz) and investigate the removal of copper(II) ions from aqueous solution using water-in-oil-in-water (W/O/W) emulsion liquid membrane process (ELM). The membrane was prepared by dissolving the extractant bis(2-ethylhexyl)phosphoric acid (D2EHPA) and the hydrophobic surfactant sorbitan monooleate (Span 80) in hexane (diluent). The internal phase consisted of an aqueous solution of sulfuric acid. Effects of operating parameters such as emulsification time, ultrasonic power, probe position, stirring speed, carrier (D2EHPA) and surfactant (Span 80) concentrations volume ratios of organic phase to internal striping phase and of external aqueous phase to membrane (W/O) phase, internal phase concentration and choice of diluent on the membrane stability were studied. With ultrasound, the W/O emulsion lifetime were much higher than those reported previously by mechanical agitation. The effect of carrier and Cu(II) initial concentration on the extraction kinetics was also investigated. Nearly all of the Cu(II) ions present in the continuous phase was extracted within a few minutes. Additionally, the influence of H₂SO₄ concentration on the stripping efficiency was examined.     

Extraction of Uranium(VI) by Triphenylarsine and Triphenylphosphine Oxides from Nitric Acid Medium

The extraction of UO²⁺ ₂ from nitric acid solutions by two neutral donors ligands (L), triphenylarsine oxide (Ph₃AsO) and triphenylphosphine oxide (Ph₃PO), in chloroform is investigated. At low HNO₃ acid concentrations (<2 M), UO₂ ²⁺ is highly extracted as simple cation by Ph₃AsO and slightly extracted by Ph₃PO. The extraction constant of UO₂ ²⁺ from low nitric acid medium is found to equal 1212 ± 120. At higher HNO₃ concentration (>2 M), UO₂ ²⁺ is extracted by ion association mechanism as UO₂ (NO₃)₂- 2L, and the distribution ratio of UO₂ ²⁺ using Ph₃PO is found to be higher than that of Ph₃AsO. This is interpreted by the extraction competition of HNO₃ for Ph₃AsO. Spectroscopic investigations in the visible and IR regions supported the results obtained.     

Solvent extraction of cadmium and zinc from sulphate solutions: Comparison of mechanical agitation and ultrasonic irradiation

This research was conducted to evaluate the potential of ultrasonic irradiation during the solvent extraction of metals, and comparing its efficiency with a mechanically stirred system (MSSX). The simultaneous extraction of zinc and cadmium from sulphate solutions was investigated by di-(2-ethylhexyl) phosphoric acid (D2EHPA) as an organic extractant which was diluted (20%) in kerosene at the organic: aqueous phase ratio of 1:1 and the temperature of 25 °C. The influence of some critical parameters, including contact time, solution pH, ultrasonic power, and zinc/cadmium ratio were investigated on the extraction of the metals. Results show that D2EHPA selectively extract zinc rather than cadmium in both mechanically and ultrasonically mixed systems. It was also found that increase of ultrasonic power from 10 to 120 W cause a small decrease in zinc extraction; while, at low and high levels of the induced power, cadmium extraction was significantly decreased. Results also show that maximum extraction amounts of zinc (88.7%) and cadmium (68.2%) by the MSSX system occurred at the pH of 3 and the contact times of 3 and 20 min, respectively. Although capability of extraction in the ultrasonically assisted solvent extraction (USAX) system for both metals was higher, the selectivity was lower than that of MSSX system under different conditions especially in high zinc/cadmium ratios. It can be concluded that physical effects (i.e. mixing) inducing at low ultrasonic powers (below 60 W) mainly results in increasing solvent extraction rate, while the chemical actions applied at the higher powers have a negative outcome on the extraction rate particularly for cadmium.     

D2EHPA萃取稀土的有机相红外光谱及添加DMHPA的影响

本文研究了部分皂化的二（２－乙基己基）磷酸（Ｄ２ＥＨＰＡ）－正庚烷体系萃取稀土离子Ｙ＾３＋，Ｐｒ＾３＋，Ｎｄ＾３＋，Ｅｕ＾３＋后有机的傅里叶变换红外光谱（ＦＴ－ＩＲ）。发现不同稀土离子与萃取剂的配位能力有差异，并且皂化度对萃取有机相中的Ｐ＝Ｏ谱带的频率和吸收强度皆有影响，在Ｄ２ＥＨＰＡ中加入二（１－甲基庚基）磷酸（ＤＭＨＰＡ）导致Ｐ＝Ｏ谱带形状和吸收强度发生变化。     

Ultrasound-assisted extraction of chromium from residual tanned leather: An innovative strategy for the reuse of waste in tanning industry

The tannery industry generates huge amount of waste with high Cr concentration, being classified as a dangerous waste. The development of alternative treatments for these residues aiming environmental friendly protocols are important topics of research. In this work, the use of ultrasound (US) energy for Cr removal from residual tanned leather was investigated. Ultrasound-assisted extraction (UAE) experiments were carried out in several systems as ultrasonic baths, cup horns, and probes, allowing to evaluate several frequencies (20–130 kHz) and power delivered to the extraction system. The following experimental conditions were evaluated: extraction solution (HCl, HNO₃, H₂SO₄, CH₂O₂ and C₂H₂O₄), temperature (10–90 °C), time (1–40 min), US amplitude (10–90%), feedstock amount (50–450 mg), and concentration of extraction solution (0.1–4 mol L⁻¹). A multivariate factorial design with 10 axial points and 3 central points was applied. After UAE optimization an efficiency of 92% was achieved for Cr removal using 150 mg of feedstock, 3 mol L⁻¹ HNO₃, at 30 °C, 90% of amplitude, and 30 min. The same efficiency was not observed using mechanical stirring (100–500 rpm), which was lower than 65%. To prove the applicability of the proposed process some experiments for scaling up were performed using several reactor loads (1–9 L). Moreover, using the proposed UAE process Cr was efficiently removed at lower reaction time and at room temperature only by using US and diluted acid solution, representing energy and reagents saving.     

Distribution and dimerization of some μ-imidodiphosphates

The distribution of chelate-forming reagents on a basis of arylimidodiphosphate between different organic solvents and 0.1 mol L⁻¹ HNO₃ has been studied by liquid-liquid extraction of ⁴⁶Sc. The values of dimerization constants K₂ in selected solvents, particularly on the chlorine and chlorine-fluorine hydrocarbon basis as well as distribution constants K_D(HA) have been determined.     

Analysis of electronic vibration spectra of tetrabenzoporphin molecules on the basis of calculations of their normal vibrations

Quasi-line fluorescence and fluorescence-excitation spectra of tetrabenzoporphin (H₂TBP) and its deuterated derivative (D₂TBP) in n-octane at 77 K were measured and analyzed. A calculation of normal vibrations of the H₂TBP and D₂TBP molecules has been performed. The normal vibrations of these molecules were calculated with the use of the valence force fields of porphin and phenanthrene (the direct spectral problem was solved). Good agreement between the calculated and measured frequencies of the investigated normal vibrations has been obtained without correction of the transfered force constants. A detailed interpretation of the fluorescence spectra obtained is presented. It is shown that on deuteration of H₂TBP, the behavior of the quasi-lines in the fluorescence-excitation spectra in the region of resonance with the S₂←S₀ transition becomes more complex. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 3, pp. 375–382, May–June, 1999.     

Ultrasound effects on restricted silica gelation during silica extraction from Pyro-Metallurgical copper slag under acidifying conditions

Pyro-metallurgical copper slag (CS) waste was used as the source material for ultrasound (US) silica extraction under acidification processes with 26 kHz with HCl, HNO₃, and H₂SO₄ at different concentrations at 100, 300, and 600 W. During acidifying extraction processes, US irradiation inhibited silica gel formation under acidic conditions, especially at lower acid concentrations of less than 6 M, whereas a lack of US irradiation led to enhanced gelation. When US stopped, gelation occurred to a considerable degree, suggesting that the gel particle size distribution was aggregated in the 3–400 µm size range. However, with US, the size was mainly in the 1–10 µm range. Results of elemental analysis indicated that US treatment decreased the co-precipitation of other metal ions such as Fe, Cu, and Al sourced from CS for lower acidic medium, whereas the higher concentration medium accelerated silica gelation and the co-precipitation of other metals. With acids of HCl and HNO₃, and H₂SO₄, the gelations were less likely to occur at 6 M and 3 M during US irradiation, but acidic extraction without US was efficient for silica gelation and co-precipitation of other metals in the purified silica. The silica extraction yield with H₂SO₄ concentration of 3 M was 80% with 0.04% of Fe, whereas the silica product from HCl 6 M had a 90% extraction yield with only 0.08% of Fe impurity. In contrast, even though the non-US system of HCl 6 M had a higher yield at 96%, the final product had 0.5% Fe impurity, which was much higher than the US system. Consequently, the US extraction process was quite noticeable for silica recovery from CS waste.     

Mutual Chern-Simons theory and its applications in condensed matter physics

In this paper, the mutual Chern-Simons (MCS) theory is introduced as a new kind of topological gauge theory in 2+1 dimensions. We use the MCS theory in gapped phase as an effective low energy theory to describe the Z ₂ topological order of the Kitaev-Wen model. Our results show that the MCS theory can catch the key properties for the Z ₂ topological order. On the other hand, we use the MCS theory as an effective model to deal with the doped Mott insulator. Based on the phase string theory, the t-J model reduces to a MCS theory for spinons and holons. The related physics in high T _c cuprates is discussed.      

盐湖卤水中微量钒的浓度测定

为了测定盐湖卤水中微量钒的浓度,开发了一个钒的分离纯化流程来降低大量的共存离子的基质效应。该分离纯化流程包括萃取和反萃两个步骤。详细地研究了影响钒纯化效率的各种因素,得到钒的最佳分离纯化条件为:以正己烷为稀释剂,有机相中D2EHPA和TBP的体积百分比分别为30%及20%,在pH为3.0时萃取30 min;然后用3 mol/L H₂SO₄反萃 10 min。基于此分离纯化流程,将两个实际盐湖卤水样品中的微量钒纯化后,再用电感耦合等离子体质谱仪(ICP-MS)测定其浓度,该ICP-MS对51V 的检测灵敏度和检测限别为53 171 cps/(μg/L) 和1.88 ng/L。所得实际盐湖卤水钒测定结果的加标回收率接近100%而相对标准偏差低于0.6%,表明该方法可用于实际复杂体系中微量钒的浓度测定,例如海水和盐湖卤水。     

The chloroform / TBP / aqueous nitric acid interfacial system: a molecular dynamics investigation

We report MD studies on a chloroform / nitric acid water interface, either neat, or saturated by TBP molecules. Two extreme models are compared, where the acid is either neutral HNO₃ or dissociated to NO₃⁻ and H₃O⁺. The latter species are found to be “repelled” by the neat interface, while the neutral HNO₃ molecules are surface active. When the neat interface is saturated by TBP molecules, the latter form highly disordered arrangements instead of a regular monolayer, and water is dragged to the organic phase as 1:1, 1:2 and 2:2 hydrates of TBP. Simulations with the neutral HNO₃ model lead to extraction of acid to the organic phase, hydrogen bonded to the phosphoryl oxygen of TBP, forming HNO₃:TBP adducts of 1:1 and 2:1 types. Simulations with the ionic model lead to H₃O⁺:TBP adducts of 1:1, 1:2 and 1:3 types in the organic phase and significant mixing of the chloroform, TBP and water liquids in the interfacial region.     

Electrochemical behaviors of the magnesium alloy substrates in various pretreatment solutions

Interface reactions and film features of AZ91D magnesium alloy in pickling, activation and zinc immersion solutions have been investigated. The surface morphologies of the specimens were observed with scanning electron microscope (SEM). Electrochemical behaviors of AZ91D magnesium alloy in the baths of pickling, activation and zinc immersion were analyzed based on the open circuit potential (OCP) - time curves in various solutions. The results show that the corrosive rate in HNO₃ + CrO₃ or HNO₃ + H₃PO₄ pickling solution was more rapid than in KMnO₄ pickling-activation solution. Both α phase and β phase of the substrates were uniformly corroded in HNO₃ + CrO₃ or HNO₃ + H₃PO₄ pickling solution, the coarse surface can augment the mechanical occlusive force between the subsequent coatings and the substrates, so coatings with good adhesion can be obtained. In HF activation solution, the chromic compound formed via HNO₃ + CrO₃ pickling was removed and a compact MgF₂ film was formed on the substrate surface. In K₄P₂O₇ activation solution, the corrosion products formed via HNO₃ + H₃PO₄ pickling were removed, a new thin film of oxides and hydroxides was formed on the substrate surface. In KMnO₄ pickling-activation solution, a film of manganic oxides and phosphates was adhered on the substrate surface. Zinc film was symmetrically produced via K₄P₂O₇ activation or KMnO₄ pickling-activation, so it was good interlayer for Ni or Cu electroplating. Asymmetrical zinc film was produced because the MgF₂ film obtained in the HF activation solution had strong adhesive attraction and it was not suitable for interlayer for electroplating. However, the substrate containing compact MgF₂ film without zinc immersion was fit for direct electroless Ni-P plating.     

Intensities and satellites of 4ƒ-photoelectrons in thorium and uranium dioxides

In a comparison between photoelectron-spectroscopic intensities and theoretical orbital ionization cross-sections, it is found that whereas the intensities and cross-sections agree for the ratio of Th(4?) to O(1s) in ThO₂, the ratio for U(4?) to O(1s) in UO₂ differs from the theoretical ratio by 36%. It is shown that the deviation is attributable to the loss of U(4?) photoelectrons through the degradation of their kinetic energies into the tail on the high binding energy side of the spectrum. The results for ThO₂ imply a linear dependence of the inelastic scattering mean free path on kinetic energy; the results for UO₂ imply extensive configuration interaction between the 4? core-hole and unoccupied states of the cation, and they demonstrate the use of theoretical cross-sections to determine the extent.     

Superconducting and magnetic properties of new ternary borides with the CeCo3B2-type structure

Four new ternary boride systems with the CeCo₃B₂-type structure are reported with the general formulae: MRu₃B₂ (M = La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, Th or U), MRh₃B₂ (M = La, Ce, Pr, Nd, Sm, Eu or Gd), MOs₃B₂ (M = Lu or U) and MIr₃B₂ (M = La, Th or U). Most members of these systems were found to become either superconducting or magnetically ordered. The structure and properties of these materials are discussed in relation to those of other ternary systems previously reported to exhibit superconductivity and/or magnetic order.     

Neutron bound beta-decay: BOB

Frozen solution samples were made from gold chloride and KAu(CN)₂ solvated with TBP/xylene. The ¹⁹⁷Au M?ssbauer parameters were similar to those same species as frozen solutions or adsorbed onto activated carbon. Solvated samples from EuO dissolved in HCl or H₂SO₄ and frozen gave characteristic Eu(III) spectra. All the spectra were consistent with bonding to the TBP being through hydronium ions or water molecules.