TBP Concentrations Research Articles

Pharmacokinetics of Oral Tebipenem Pivoxil Hydrobromide in Subjects with Various Degrees of Renal Impairment.

ABSTRACTTebipenem pivoxil hydrobromide (TBP-PI-HBr) is an oral carbapenem prodrug antimicrobial agent with broad-spectrum activity that includes multidrug-resistant (MDR) Enterobacterales. This study evaluated the safety, tolerability, and pharmacokinetics of TBP-PI-HBr in healthy subjects with normal renal function (cohort 1) and subjects with various degrees of renal impairment (RI [cohorts 2 to 4]) or end-stage renal disease (ESRD) receiving hemodialysis (HD) (cohort 5). Subjects in cohorts 1 to 4 received a single oral dose of TBP-PI-HBr (600 mg). Subjects in cohort 5 received single-dose administration (600 mg) in 2 separate periods: pre-HD (period 2) and post-HD (period 1). Pharmacokinetic (PK) parameters for TBP, the active moiety, were determined using noncompartmental analysis. Compared with cohort 1, the TBP plasma area under the curve (AUC) increased 1.4- to 4.5-fold among cohorts 2 to 4, the maximum concentration of drug in plasma (Cmax) increased up to 1.3-fold and renal clearance (CLR) decreased from 13.4 L/h to 2.4 L/h as the severity of RI increased. Plasma TBP concentrations decreased over 8 to 12 h in cohorts 1 to 4, and apparent total body clearance (CL/F) correlated (R2 = 0.585) with creatinine clearance (CLCR). TBP urinary excretion ranged from 38% to 64% of the administered dose for cohorts 1 to 4. Subjects in cohort 5 had an approximately 7-fold increase in TBP AUC and elimination half-life (t1/2) versus cohort 1. After 4 h of HD, mean TBP plasma exposure decreased by approximately 40%. Overall, TBP plasma exposure increased with increasing RI, highlighting the renal route importance in TBP elimination. A dose reduction of TBP-PI-HBr may be needed in patients with RI (CLCR of ≤50 mL/min) and those with ESRD on HD. TBP-PI-HBr was well tolerated across all cohorts. (This study has been registered at ClinicalTrials.gov under registration no. NCT04178577.).

1121. Bioequivalence of Two Formulations of Oral Tebipenem-Pivoxil Hydrobromide in Healthy Subjects

Abstract Background Tebipenem-pivoxil-hydrobromide (TBP-PI-HBr) is a novel oral carbapenem being developed to treat serious bacterial infections including complicated urinary tract infection. The objectives of this study were to assess the bioequivalence (BE) of two tablet formulations of TBP-PI-HBr in healthy adult subjects under fasted conditions and to evaluate the food-drug interactions of the registration drug product. Methods This was an open-label, randomized, single-dose, semi-replicate, 3-sequence, 4-period crossover, BE, and food effect study. Subjects were randomized to one of three sequences where they received a single 600 mg oral dose of TBP-PI-HBr, as either the reference clinical study drug product (Treatment A) or the registration drug product (Treatment B) under fasted conditions. Subsequently, all subjects received a single 600 mg oral dose of TBP-PI-HBr as the registration drug product under fed conditions. There was by a 7-day washout between each period. Whole blood sampling to determine TBP pharmacokinetics (PK) was conducted predose and up to 24 hours post dose in each period. Safety and tolerability were monitored throughout the study. Results Thirty-six healthy, adult male and female subjects were enrolled and completed the study. The TBP-PI-HBr registration product was bioequivalent to the clinical study product (Figure 1). For TBP, 90% confidence intervals (CIs) for AUC0-t, AUC0-inf, and Cmax were within the 80% to 125% BE limits when administered under fasted conditions. A standard high-fat/high-calorie meal had no meaningful effect on the total plasma exposure of TBP after administration of the registration product, thus, overall exposure based on AUC0-t and AUC0-inf was comparable under fed and fasted conditions (Figure 2). Five (14%) subjects reported adverse events of mild severity. No deaths, serious AEs or discontinuations due to AEs were reported, and no clinically relevant ECGs, vital signs or safety laboratory findings were observed. Figure 1. Arithmetic mean plasma TBP concentrations following a 600 mg dose of clinical study drug product (A1 and A2) and registrational drug product (B) – PK population. Figure 2. Arithmetic mean plasma TBP concentrations following a 600 mg dose of registrational drug product (B) under fasted and fed conditions – PK population. Conclusion The TBP-PI-HBr registration product was bioequivalent to the clinical study product under fasted conditions, and no meaningful effect of a high fat meal on TBP PK was observed. Disclosures Vipul K. Gupta, Ph.D., Spero Therapeutics (Employee, Shareholder) Gina Patel, PhD, Spero Therapeutics, Inc. (Consultant) Leanne Gasink, MD, Spero Therapeutics, Inc. (Consultant) Floni Bajraktari, MSc, Spero Therapeutics, Inc. (Employee) Yang Lei, PhD, Spero Therapeutics, Inc. (Employee) Akash Jain, PhD, Spero Therapeutics, Inc. (Employee) Praveen Srivastava, MS, BS, Spero Therapeutics, Inc. (Employee) Angela Talley, MD, Spero Therapeutics, Inc. (Employee)

Halogenated compound secreted by marine bacteria halts larval urchin development

Marine bacteria are ubiquitous, and yet their ecological functions have not been fully characterized. The globally distributed, biofilm-forming Pseudoalteromonas genus produces a variety of potentially bioactive halogenated organic products. One such secreted compound, 2,3,4,5-tetrabromopyrrole (TBP), has been found to be biocidal for several taxa of phytoplankton while stimulating the settlement and metamorphosis of coral at nanomolar doses. Here, we tested whether the presence of TBP affects early development in sea urchins that are not in direct contact with a benthic microbial film. Lytechinus variegatus embryos were exposed to varying TBP concentrations for different time durations over the first 48 h post-fertilization. Concentrations as low as 500 nM markedly reduced larval survivorship and retarded development. These deleterious effects became more pronounced as the concentration and duration of exposure to TBP were increased. Impairments in development when exposed to TBP appeared to be reversible, provided low exposure concentrations (< 500 nM – 1000 nM) for limited exposure durations (< 1–4 h). Preliminary immunofluorescence staining showed spindle defects in dividing embryos when exposed to TBP at high concentrations, which may have contributed to mortality and impaired growth. While TBP and other bacterial compounds like it may serve as settlement cues for corals, their cytotoxicity to single-cell algae and larval urchins could hint at the dangers of the benthos to some developing invertebrate embryos. If true, such compounds, along with the bacterial taxa that produce them, likely play underappreciated roles in the ecology, and potentially the evolution, of planktonic development in macroinvertebrates.

Bioconcentration of 2,4,6-tribromophenol (TBP) and thyroid endocrine disruption in zebrafish larvae

2,4,6-tribromophenol (TBP) is generally used as a brominated flame retardant but is produced in the degradation of tetrabromobisphenol-A. Although TBP is frequently detected in the environment and in various biota, including fish species, we still know little about its toxicity and environmental health risk. Here we investigated the bioconcentration and effects of TBP on the thyroid endocrine system by using zebrafish as a model. Zebrafish embryos (2 h post-fertilization, hpf) were exposed to five concentrations of TBP (0, 0.3, 1, 10, and 100 μg/L) until 144 hpf. According to our chemical analysis, TBP underwent bioconcentration in zebrafish larvae. However, acute exposure to TBP did not affect the hatching of embryos or their risk of malformation, nor the growth and survival of larvae, indicating low developmental toxicity of TBP. The whole-body thyroxine (T4) contents were significantly increased in zebrafish larvae after exposure to TBP, indicating thyroid endocrine disruption occurred. Gene transcription levels in the hypothalamic-pituitary-thyroid (HPT) axis were also examined in larvae; these results revealed that the transcription of corticotrophin-releasing hormone (crh), thyrotropin-releasing hormone (trh), and thyroid-stimulating hormone (tshβ) were all significantly downregulated by exposure to TBP. Likewise, genes encoding thyronine deiodinases (dio1, dio2, and dio3a/b) and thyroid hormone receptors (trα and trβ) also had their transcription downregulated in zebrafish. Further, the gene transcription and protein expression of binding and transport protein transthyretin (TTR) were significantly increased after TBP exposure. Taken together, our results suggest the bioavailability of and potential thyroid endocrine disruption by TBP in fish.

Effect of tertiary butylpyridine in stability of methylammonium lead iodide perovskite thin films

Perovskite material is a great visible light absorber in perovskite solar cells (PSCs). PSC has reported power conversion efficiency (PCE) of 22.1%. However, performance instability of the solar device base on this material hampers its commercialization. One of the factors responsible for performance instability in the cell is temperature. In this work, we carried out stability study of perovskite film treated with tertiary butylpyridine (tBP) as a surface modifier. Concentrations of tBP added in perovskite material film were varied and the samples were subjected to temperature degradation test in a temperature-controlled chamber for 120 h. Ultraviolet–visible (UV–Vis) spectrophotometers, Fourier-transform infrared (FT-IR) spectrometers and X-ray diffractometers (XRD) were used to characterize the properties of the temperature-stability-tested samples. The results show that the sample treated with 100 $$\upmu $$ l of tBP has the best resistance to temperature degradation after the duration of the test. The surface-modified perovskite films, with 100 $$\upmu $$ l of tBP, may reduce the degradation of PSCs.

Extraction of Uranium from Synthetic Nuclear Conversion Plant Waste

ABSTRACTThe nuclear conversion plant operated at Necsa in the past resulted in the formation of a large amount of waste material containing ~ 50% U, which has reuse potential if the recovery thereof can be achieved. The waste material contains various impurities of which F, Ca, and Fe have been identified as the main contributing impurities after dissolution. These impurities are present in the waste material in varying concentrations and could interfere with the U recovery. During this investigation, the possibility of varying impurities being present during purification was addressed by simulating the waste material using synthetic solutions to investigate the effect of different concentrations of the main impurities, as well as nitric acid and TBP concentrations on the extraction of U. The results from this simulated approach will serve as motivation for obtaining more of the real waste samples for further investigation and confirmation of results. This was done using a statistical design of experiments approach, giving a predictive model which can be used to predict U recovery for a given waste sample composition. It was found that nitric acid had the most significant influence on U extraction, where an optimum amount (97%) was achieved in 5 M nitric acid at, or above 30% TBP. At low nitric acid concentrations, it was found that the U extraction increased with increasing TBP and decreasing F concentrations. An unexpected interaction between F and Fe was observed, which led to an increase in U extraction as the Fe concentrations were increased due to complex formation with F, which limits the amount of F available which would have decreased U extraction due to competition. Furthermore, a mathematical model was derived which describes the U extraction as a function of varying impurity, nitric acid and TBP concentrations. Optimum extraction conditions were confirmed using a feed solution containing additional impurities (Al, Na, K and Si) which are present in the waste material in concentrations above 0.5 wt %. While confirming the optimum extraction conditions, the validity of the statistical model was also confirmed from these experiments, indicating its suitability for U extraction predictions as a function of impurity concentrations.

Legacy PBDEs and NBFRs in sediments of the tidal River Thames using liquid chromatography coupled to a high resolution accurate mass Orbitrap mass spectrometer

Surface sediment samples (n = 45) were collected along a 110 km transect of the river Thames in October 2011, starting from Teddington Lock out through the industrial area of London to the southern North Sea. Several legacy and novel brominated flame retardants (NBFRs) were analysed, including 13 polybrominated diphenyl ethers (PBDEs) (congeners 17, 28, 47, 99, 100, 153, 154, 183, 196, 197, 206, 207 and 209), hexabromocyclododecane (HBCDDs), tetrabromobisphenol A (TBBPA), hexabromobenzene (HBB), 2,4,6-tribromophenol (TBP), 2-ethylhexyl 2,3,4,5-tetrabromobenzoate (EH-TBB or TBB), bis(2-ethylhexyl) tetrabromophthalate (BEH-TEBP or TBPH), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), decabromodiphenyl ethane (DBDPE), pentabromoethylbenzene (PBEB), anti/syn-dechlorane plus (a/s-DP), 2,2′,4,4′,5,5′-hexabromobiphenyl (BB153) and α-,β-1,2-dibromo-4-(1,2-dibromoethyl) cyclohexane (α-,β-DBE-DBCH or TBECH). A novel analysis method based on liquid chromatographic separation, followed by high resolution accurate mass detection using the Orbitrap platform was used for quantification. Results revealed that BDE-209 had the highest concentrations (<0.1 to 540 μg kg−1 dw) and detection frequency, accounting for 95% of all PBDE congeners measured. Indicative evidence of debromination of the PentaBDE technical mixture was observed through elevated relative abundance of BDE-28 in sediment compared to the Penta-BDE formulation. NBFRs were detected at comparable levels to PBDEs (excluding BDE-209), which indicates increasing use of the former. Spatial trend analysis showed that samples from industrial areas had significantly higher concentrations of Σ12PBDEs, ΣHBCDDs, TBBPA, BEH-TEBP, BTBPE and TBP. Three locations showed high concentrations of HBCDDs with diastereomer patterns comparable to the technical mixture, which indicate recent input sources to the sediment.

Fast and simple determination and exposure assessment of bisphenol A, phenol, p-tert-butylphenol, and diphenylcarbonate transferred from polycarbonate food-contact materials to food simulants

Polycarbonate (PC) plastics find extensive use in baby bottles, food storage containers, and various kitchen items. Possibly hazardous chemicals, bisphenol A (BPA), phenol, p-tert-butylphenol (TBP), and diphenylcarbonate (DPC), are source materials or by-products from PC production. Therefore, a fast and simple analytical method was developed to determine and assess the exposure of BPA, phenol, TBP, and DPC transferred from PC food-contact materials to four different food simulants (water, 4% acetic acid, 50% ethanol, and n-heptane) at different temperatures. The method was validated in terms of limit of detection (LOD) and quantification (LOQ), recovery, and precision for the detection of BPA, phenol, and TBP using HPLC-FLD and of DPC using HPLC-UV. BPA, phenol, TBP, and DPC concentrations transferred from 200 PC samples to food simulants were determined. The highest migration levels of BPA (54.3 μg L−1) and phenol (43.8 μg L−1) were found in 50% ethanol at 70 °C. TBP did not migrate to any simulant. DPC did not show any migration from PC samples into water and only migrated from a cup to 4% acetic acid at 70 °C and 100 °C, whereas migration occurred from several cups, ladles, spoons, and tongs to 50% ethanol and to n-heptane at 25 °C. Food simulants and temperature were the crucial factors for the migration of BPA and phenol from PC samples. Estimated daily intakes (EDIs), based on food consumption and food-type distribution factors, for BPA, phenol, and DPC were calculated to be 0.007, 0.001, and 2.5 × 10−4 μg kg−1 bw day−1, respectively.

Tribromophenol affects the metabolism, proliferation, migration and multidrug resistance transporters activity of murine melanoma cells B16F1

Murine melanoma cells B16F1 were exposed to the flame retardant and wood preservative chemical 2,4,6-tribromophenol (TBP) during 24 and 48 h, at the concentrations found in human diet. TBP-exposed cells had increased MTT and Alamar blue® metabolism and ABCB5 mRNA levels (qPCR), but the cells had decreased proliferation (crystal violet assay), migration (scratch assay), and drug-effux transporters activity (rhodamine B efflux assay). Exposure to TBP did not affect the cell viability (neutral red and annexin V-PI assays), colony formation (colony number, clonogenic assay), and the levels of reactive oxygen species (DCF probe) or P53 mRNA (qPCR). The tested TBP concentrations had low toxicity to melanoma cells B16F1. However, dual effect on metastatic profile and chemoresistance suggests that the increase of ABCB5 positively modulates the cell chemoresistance, but decreases cell migration and proliferation. These findings may be explored in cancer therapy.

Organic and Third Phase in HNO3/TBP/n-Dodecane System: No Reverse Micelles

ABSTRACTThe composition and speciation of the organic and third phases in the system HNO3/TBP (tri-n-butyl phosphate)/n-dodecane have been examined by a combination of gravimetric, Karl Fischer analysis, chemical analysis, FTIR, and 31P NMR spectroscopy, with particular emphasis on the transition from the two-phase to the three-phase region. Phase densities indicate that third-phase formation takes place for initial aqueous HNO3 concentrations above 15 M, while the results from the stoichiometric analysis imply that the organic and third phases are characterized by two distinct species, namely the mono-solvate TBP⋅HNO3 and the hemi-solvate TBP⋅2HNO3, respectively. Furthermore, the 31P NMR spectra of organic and third phase show no significant chemical differences at the phosphorus centers, suggesting that the second HNO3 molecule in the third phase is bound to HNO3 rather than TBP. The third-phase FTIR spectra reveal stronger vibrational absorption bands at 1028, 1310, 1653, and 3200–3500 cm−1, reflecting higher concentrations of H2O, HNO3, and TBP. The molecular dynamics simulation data predict structures in accord with the spectroscopically identified speciation, indicating inequivalent HNO3 molecules in the third phase. The predicted structures of the organic and third phases are more akin to microemulsion networks rather than the distinct, reverse micelles assumed in previous studies. H2O appears to be present as a disordered hydrogen-bonded solvate stabilizing the polar TBP/HNO3 aggregates in the organic matrix, and not as a strongly bound hydrate species in aggregates with defined stoichiometry.

Development of Mathematical Model of H2O-HNO3-UO2(NO3)2-TBP-diluent System

The mathematical model of H2O-HNO3-UO2(NO3)2-TBP-dodecane system has been elaborated. Mole fractions and volume ones and rational activity coefficients have been used in order to create the system of equations on the base of mass action law. Method for calculating activity coefficients was provided. The formation constants of uranyl nitrate di-solvate and mono-solvate and di-solvate of acid have been determined. Interaction between uranyl nitrate di-solvate and dodecane and between TBP and dodecane was taken into account. Activity coefficients of nitric acid and uranyl nitrate in mixed solutions were considered. Errors of adequacy have been determined for the systems containing 30% and 12% TBP concentrations.

住宅における空気・ハウスダスト中SVOC濃度測定

In recent years, indoor air pollution due to phthalate esters has gained increasing attention. In particular, phthalate esters present in house dust have been reported to have a considerable impact on infant health. This study was investigated the concentration of phthalate esters in indoor air and house dusts in residential houses (n=21). Collected indoor air and house dust were analyzed for 11 substances. As a result, phthalate esters concentrations in indoor air were 0.7～29.3μg/m3 for 2E1H, 0.1～2.0μg/m3 for D6, 0.1～0.9μg/m3 for DBP and 0.1～1.2μg/m3 for DEHP. The concentrations of DEP, TBP, D6, BHT and DBA in house dust were less than detection limit. But, these were detected for TCEP (20～40μg/g), DOA (2～70μg/g), DBP (15～200), DEHP (50P:810(μg/g), 95P:4660(μg/g)). Assuming that an infant intakes 10.3 mg/kg/day of house dust in 95 percentile, infants would intake 47.9μg/kg/day DEHP which exceeds the guidelines for tolerable daily intake (TDI) and reference dose (RfD).

Electrochemical Behavior of Cerium (IV) Species in n-TriButylPhosphate

This work investigates the electrochemical behavior of Ce(IV) complexes extracted in n-tributylphosphate (TBP) from nitric aqueous solutions as an entry to the direct electrochemical characterization of plutonium in organic extractants related to nuclear fuel reprocessing. Ce(IV) complexes displayed a reversible electrochemical reduction wave in TBP, which could be observed only at glassy carbon electrodes. At slow scan rates, that reduction wave showed a Nernstian dependence on the logarithm of both nitric acid and TBP concentrations in the organic phase, featuring the exchange of nitrates and TBP upon reduction to Ce(III). The presence of increasing amounts of a common degradation product of TBP, such as hydrodibutyl phosphate (HDBP) resulted in a shift of the Ce(IV) reduction wave towards more negative potential values, a behavior consistent with the formation of HDBP-Ce (IV) complexes.

Study on uranium recovery from tungsten residue: separation of U from Fe, Mn, Zr, Ti, Th, and Sc with mixture of N235 and TBP

Mixture of N235 and TBP was applied for the separation of UFe/MnZrTiThSc by extracting U and Fe from hydrochloric acid medium. Then, acetic acid was utilized to scrub impurities from the loaded organic phase. The extraction was investigated at different concentrations of TBP, N235, hydrochloric acid, metal ions and extraction times. And the scrubbing of metal impurities was studied at different concentrations of acetic acid and scrubbing times. Finally, a process for uranium recovery from tungsten residue has been developed, generating with a final product U3O8 of 99.7 % purity and an overall uranium recovery of 91.8 %.

Pollution profiles and risk assessment of PBDEs and phenolic brominated flame retardants in water environments within a typical electronic waste dismantling region.

The aim of this study was to assess the pollution profiles of various typical brominated flame retardants in water and surface sediment near a typical electronic waste dismantling region in southern China. We found that polybrominated diphenyl ethers (PBDEs), 2,4,6-tribromophenol (TBP), pentabromophenol (PeBP), tetrabromobisphenol A (TBBPA), and bisphenol A (BPA) were ubiquitous in the water and sediment samples collected in the study region. In water, Σ19PBDEs (sum of all 20 PBDE congeners studied except BDE-209, which was below the detection limit) levels ranged from 0.31 to 8.9×10(2)ngL(-1). TBP, PeBP, TBBPA, and BPA concentrations in the water samples ranged from not being detectable (nd-under the detection limit) to 3.2×10(2) (TBP), from nd to 37 (PeBP), from nd to 9.2×10(2) (TBBPA) and from nd-8.6×10(2) ng L(-1) (BPA). In sediment, Σ19PBDEs ranged from nd to 5.6×10(3) ngg(-1), while BDE-209 was the predominant congener, with a range of nd to 3.5×10(3) ngg(-1). Tri- to hepta-BDE concentrations were significantly (p<0.01) correlated with each other, except for BDE-71 and BDE-183, and octa- to nona-BDEs concentrations were significantly (p<0.05) correlated with each other, except for BDE-208. BDE-209 was not significantly correlated with tri- to nona-BDEs. Risk assessments indicated that the water and sediment across the sampling sites posed no estrogenic risk. However, different eco-toxicity risk degrees at three trophic levels did exist at most sampling sites.

Real-Time Interaction between TVR and the TATA Box of the Human Triosephosphate Isomerase Gene Promoter in the Norm and Pathology

The TATA-binding protein (TBP) is a key part of the transcription complex of RNA polymerase II. Alone or as a part of the basal transcription factor TFIID, TBP binds the TATA box located in the core region of the TATA-containing promoters of class II genes. Previously, we studied the effects of single nucleotide polymorphisms (SNPs) on TBP/TATA-box interactions using gel retardation assay. It was demonstrated that most SNPs in the TATA boxes of some human gene promoters cause a 2- to 4-fold decrease in TBP/TATA affinity, which is associated with an increased risk of hereditary diseases, such as β thalassemias of diverse severity, hemophilia B Leyden, myocardial infarction, thrombophlebitis, lung cancer, etc. In this work, the process of TBP/TATA complex formation has been studied in real time by a stopped-flow technique using recombinant human TBP and duplexes, which were identical to the TATA box of the wild-type and a SNP-containing triosephosphate isomerase gene promoter and were fluorescently labeled by the Cy3/Cy5 FRET pair. It has been demonstrated for the first time that real-time binding of TBP to the TATA box of the TPI gene promoter is complete within 10 s and is described by a single-stage kinetic model. The complex formation of TBP with the wild-type TATA box occurs 5.5 times faster and the complex dissociation occurs 31 times slower compared with the SNPcontaining TATA box. Within the first seconds of the interaction, TBP binds to and simultaneously bends the TATA box. Importantly, the TATA box of the wild-type TPI gene promoter requires lower TBP concentrations compared to the TATA box containing the -24T → G SNP, which is associated with neurological and muscular disorders, cardiomyopathy, and other diseases.

Extraction of Ruthenium using Both Tertiary and Quaternary Amine from Chloride Media

Ruthenium extraction from a solution bearing 0.1 g/l Ru and 0.0358 M HCl was independently carried out with Alamine 336 and Aliquat 336 in kerosene with tri-n-butyl phosphate as the phase modifier. The effect of various parameters such as concentrations of extractant, hydrochloric acid, sodium chloride and TBP on extraction of ruthenium(III) was investigated. Ruthenium extraction increased with increasing extractant concentration up to 25% beyond which it decreased. With Alamine 336, the percentage extraction increased with increasing HCl concentration up to 6 M and then it decreased, but that with Aliquat 336 increased up to 4 M, and decreased beyond that. Ruthenium extraction from 4.5 M NaCl solution using 25% Aliquat 336 and 20% TBP in kerosene was maximum and that from a 2 M NaCl solution using Alamine 336 was maximum. The extracted species for Alamine 336 and Aliquat 336 were R 3 NH + RuCl . and R 3 NCH RuCl , respectively. The effect of various diluents such as kerosene, benzene, toluene, xylene, hexane, and cyclohexane on extraction of ruthenium was studied. The extraction isotherm with 25% Aliquat 336 indicated quantitative extraction in two stages both at O:A ratio of 1:1 and 2:1. The thermodynamic parameters such as ΔH, ΔG, and ΔS were also determined.

Extraction and Stripping Behavior of Iron (III) from Phosphoric Acid Medium by D2EHPA Alone and Its Mixtures with TBP/TOPO

In the present study an attempt has been made to understand the extraction and stripping behavior of iron (III) with D2EHPA alone and its mixture with TBP or TOPO in phosphoric acid medium. Effect of variables such as concentrations of iron (III), phosphoric acid, and phosphate in the aqueous phase, D2EHPA, TBP, and TOPO concentrations in the organic phase and temperature on the extraction process has been studied. The extraction of iron (III) decreased with increase in phosphoric acid concentration. The increase in D2EHPA concentration increased the extraction of iron (III). The presence of TOPO or TBP with D2EHPA showed antagonism. The increase in temperature decreased the extraction of iron (III) with D2EHPA alone and its mixture with either TOPO or TBP showing the exothermic nature of the extraction reaction. The stripping of iron (III) by various reagents followed the order: oxalic acid > phosphoric acid > hydrochloric acid > sulphuric acid > mixture of sulphuric and hydrofluoric acids > ascorbic acid > citric acid irrespective of extraction systems. Higher temperature favors the stripping. The effect of diluents on iron (III) extraction has also been studied. The mechanism of extraction has been explained in the light of the results obtained.

Developing a Thermodynamical Method for Prediction of Activity Coefficient of TBP Dissolved in Kerosene

Results of the experimental measurements on the partial molar volume of kerosene used as a medium for dissolving TBP are utilized to determine the activity of TBP in the binary kerosene-TBP solution through the application of Gibbs-Duhem equation. The treatment is based on combination of the experimental data with the thermodynamic values available on the compressibility factor of pure kerosene at room temperature. It is shown that the activity of TBP in kerosene has a positive deviation from ideality with an activity coefficient derived as follows:1) at X TBP ≤ 0.01: γ TBP = 42.530, 2) at the 0.01 X TBP 0.2: 3) at the higher TBP concentrations 0.2 X TBP 0.97: and 4) at TBP Raoultian concentrations 0.97 ≤ X TBP:γ TBP = 1. These quantities can be utilized at temperature closed to 298 K.

Chemical equilibrium constants of rare earth nitrates and tri- n-butyl phosphate complex formation

Mixed rare earth nitrates (RE i (NO 3) 3) in the aqueous solution was mixed with tri- n-butyl phosphate (TBP, ( n-C 4H 9O) 3PO) dissolved in kerosene for the formation of their corresponding complexes (RE i (NO 3) 3· n i ( n-C 4H 9O) 3PO) at 303 K. The effects of initial concentrations of both TBP and mixed rare earth nitrates on the equilibrium constants of their complex formations were investigated. The complexes were formed almost immediately after mixing. The simultaneous formations reached their chemical equilibria within a few minutes by shaking the mixture at 200 r/min. The chemical equilibrium constants of the complex formations were independent of the initial TBP concentrations. However, they were decreased by reducing the concentration of RE i (NO 3) 3. All equilibrium constants of the simultaneous complex formations were less than 0.7, while the average molar ratio of TBP to RE i (NO 3) 3 of the complexes varied between 1.0 and 1.6. The chemical equilibrium constant for the formation of La(NO 3) 3·( n-C 4H 9O) 3PO was 0.09, while that of Dy(NO 3) 3·( n-C 4H 9O) 3PO was 0.68. The ascending sequence of chemical equilibrium constants for the simultaneous formations was La, Ce, Pr, Nd, Eu, Y, Sm, Gd, and Dy.