Tributyl Phosphate Research Articles

Solvent extraction of gold from a chloride-hypochlorite leached solution of waste printed circuit boards

ABSTRACT This study reveals the reclamation process of gold from a brine-leached solution of waste printed circuit boards (WPCBs) after the maximum leaching of base metals in a nitric acid medium. The brine leaching performed in the presence of hypochlorite yielded leach liquor of 152 ppm Au, 86 ppm, Cu, and 62 ppm Ni that underwent solvent extraction with tri-butyl phosphate (TBP) in Exxol D80. The gold extraction process was observed to be selective over base metal impurities, while the effect of TBP concentration, equilibrium pH, temperature, and organic-to-aqueous phase ratio was optimized. Experimental results showed the formation of complex into the extraction phase with the negative enthalpy change value of −98.7 kJ/mol. Thiosulphate mobilized stripping of gold from the loaded-TBP could give about 99% recovery efficiency of the solvent extraction process along with a good regeneration of the organic extractant to be re-used.

Increasing the recovery and selectivity of 238U, 235U, and 234U extraction with tri-n-butyl phosphate in mine tailing samples with a high copper content

Abandoned Cu mine tailings may be associated high concentrations of U. However, the presence of stable cations such as Cu, Fe, Al, Ca, or Mg, etc. in high concentrations can reduce the chemical efficiency of the liquid–liquid extraction method with tri-n-butyl phosphate (TBP); it can also inhibit the electrodeposition of U on the stainless steel planchet where the sample is measured. In this work we studied an initial stage of complexation with ethylenediaminetetraacetic acid (EDTA) and a back extraction with different solutions: H2O, Na2CO3, and (NH4)2CO3 at room temperature and at 80 °C. The sensitivity of the method was 4.9·10−4 Bq for 238U and 234U, and 2.3·10−5 Bq for 235U. The validation of the method achieved 95% of the results when using a |ζ-score| ≤ ± 2.0 and a relative bias (RB[%]) ≤ ± 20% as the acceptance criteria. The recoveries obtained with the proposed method were higher than those achieved with the extraction method without initial complexation and re-extraction with H2O for water samples. Finally, this method was applied in practice to study the tailing of an abandoned Cu mine and the activity concentrations of 238U and 235U were compared with those obtained by gamma spectrometry for 234Th and 235U. The means and variances of both methods showed no significant differences between these two isotopes.

Comparison of Cyclic Irradiation Behavior of Tri-Butyl Phosphate / Tri-Iso-Amyl Phosphate-Dodecane System in Nitric Acid Medium

ABSTRACT The degradation behavior of gamma irradiated solution of 1.1 M tri-butyl phosphate (TBP) in n-dodecane (n-DD) and 1.1 M tri-iso-amyl phosphate (TiAP) in n-DD loaded with nitric acid and uranium were compared up to 5 cycles upon recycling of the degraded solvent after 80 kGy in each cycle. The solvent was recycled by stripping the loaded metal with dilute nitric acid followed by alkali wash using sodium carbonate after each cycle. Subsequently, the physico-chemical properties and the metal extraction – retention properties of the recycled solvent were measured. The recycled solvent was analyzed using gas chromatographic and FT-IR spectroscopic analysis. Among the physico-chemical properties the interfacial tension of the recycled solvent decreased drastically after three cycles of irradiation, but the variation in the measured phase separation time was not significant. But, the concentration of the extractant (TBP/TiAP) decreased significantly upon recycling. Though the formation of nitro compounds was obvious from FT-IR analysis, the metal retention by recycled organic phases were comparable after each cycle of irradiation.

Chemiluminescence amplification via enhanced generation of bisulfite radicals for determination of tributyl phosphate flame retardant

Tributyl phosphate (TNBP) with remarkable biological neurotoxicity and genotoxicity is a typical organophosphate flame retardant (OPFR) emerging contaminant, which has been found frequently in water, atmosphere, and solid, etc. It is important to explore efficient sensing strategies for TNBP. Herein, a direct Ce4+/SO32- chemiluminescence (CL) system for efficiently and sensitively detecting TNBP flame retardant has been developed. The CL mechanism was uncovered by exploring reactive oxygen species (ROS), the emitting species, and reaction products. The results demonstrate that TNBP molecules induce the enhanced generation of HSO3•- radicals in Ce4+/SO32- system, and a large amount of SO2* are subsequently generated, which account for the amplified CL emission. In view of this, a novel CL sensor for TNBP is established, which shows the advantages of fast determination, great selectivity, wide linear range (50–10000 ng mL−1), low limit of detection (13.61 ng mL−1), and good precision (RSD < 4.67%, n = 13). This work further provides an interesting perspective for direct CL behavior of OPFRs, and paves the way for the real-time monitoring of emerging pollutants.

An improved microfluidic device to enhance the enrichment factors in liquid phase microextraction: application to the simultaneous extraction of polar and non-polar acids in biological samples

A new microfluidic device to enhance the enrichment factor in miniaturized systems is proposed. The microfluidic system was design for liquid phase microextractions, and it was applied to the simultaneous extraction of acidic compounds of a wide range of polarity (0.5 < log P < 3). The device operated under stagnant acceptor phase conditions and all the operational parameters involved were optimized. Tributyl phosphate was found to be a new highly efficient supported liquid membrane to simultaneously extract analytes of very different polarities. The optimal donor and acceptor phase were pH 2 and pH 13, respectively. The donor flow rate and the extraction time were investigated simultaneously, offering great versatility with high enrichment factors (EFs). Limits of quantitation were within 0.02 and 0.09 µg mL−1 for all compounds at 10 µL min−1 as donor flow rate and 20-min extractions, offering EFs between 11 and 18 with only 200-µL sample volume consumption. The method was successfully applied to human urine samples, observing recoveries between 47 and 90% for all compounds. This new proposed microfluidic system increases the wide range of applications, especially when the analytes are present in lower concentrations in the sample.Graphical

A new procedure for separating thallium from geological materials prior to stable isotope ratio determination by MC–ICP–MS

In this paper, a simple and efficient method is presented for the separation of Tl from various complex geological samples and subsequent accurate and precise Tl isotope measurements by multi-collector inductively coupled plasma–mass spectrometry (MC–ICP–MS). Chemical separation involves a two-stage tandem column method with tributyl phosphate (TBP) extraction resin and AG50W-X12 cation ion-exchange resin, which efficiently separate Tl from the matrix, interfering elements, and sulfate ions. External normalization to NIST SRM 981 Pb and standard–sample bracketing using NIST SRM 997 Tl were utilized for the instrumental mass bias correction. The ε205TlNIST 997 data are reported as the per 104 deviation of 205Tl/203Tl from NIST SRM997 (Rehkämper and Halliday, 1999; Vaněk et al., 2016). The overall external precision for the ε205TlSRM 997 values is estimated to be ±0.6 (2SD; n > 1000) and ± 0.8 (2SD; n = 5) based on repeated analyses of NIST SRM 997 and the geological reference material NOD-A-1, respectively. The Tl isotopic compositions of nine well-documented geological reference materials are in good agreement with the values reported in previous studies, confirming the validity of our new analytical procedure for the accurate determination of Tl stable isotopic compositions of geological samples.

Dynamic and mass-exchange parameters of scandium recovery by TVEX-TBP in column mode from the solution after salt chlorinator cake leaching

The paper deals with scandium extraction with Levextrel-type resin named TVEX contained tributyl phosphate (TVEX-TBP) in the column mode from the clarified solution formed after leaching salt chlorinator cake formed at Zaporozhye Titanium & Magnesium Combine Ltd. It was found that TVEX-TBP featured high extraction parameters. Total dynamic exchange capacity was defined. Mass-exchange parameters were calculated for scandium extraction in the column mode taking into account the impact of external diffusion kinetics: time to form the equation concentration front, front parallel transfer time, concentration and kinetic recovery factors, kinetic factor of external diffusion, linear speeds of the solution in the column and the equilibrium concentration front motion. The calculated mass-exchange parameters may be used to design the column cascade for scandium extraction from the clarified leaching solution of the salt chlorination cake in column mode. There are the following advantages of scandium extraction with TVEX-TBF in the column mode in comparison with its recovery in a reactor cascade: simpler hardware design and process control, the possibility to better wash TVEX from impurities, getting a strippant higher Sc concentration, reduced TVEX abrasion.

Separation of molybdenum from peroxotungstic acid solution by solvent extraction with TBP and TRPO

An increasing problem facing the tungsten industry is developing an effective separation of molybdenum from peroxotungstic acid solutions due to the similarities of these two metals. This study herein separates molybdenum from peroxotungstic acid solution for the selective production of tungsten from scheelite acid decomposition residue using hydrogen peroxide. Solvent extraction was the main method employed, and the feed was peroxotungstic acid solution containing peroxomolybdic acid. The concentration of tungsten and molybdenum in the feed and the raffinate were measured by Inductively Coupled Plasma (ICP) to characterize the separation efficiency. The results showed that in the peroxide solution, an organic phase of tributyl phosphate (80 %), trialkyl phosphine oxide (2 %), and sulfonated kerosene (18 %) was used effectively to separate molybdenum from tungsten in acid leach solutions. A maximum single-stage separation coefficient of 400 was reached under the following extraction conditions: temperature, 25 °C; contact time 4–6 min; separation time 4 min; and organic to aqueous ratio, 1.2. Using ammonium bicarbonate as the stripping agent, the stripping ratio of molybdenum and tungsten were 83 % and 33 %, respectively, and the corresponding separation coefficient was 10.

Экстракционное извлечение рутения из растворов аффинажного производства с использованием трибутилфосфата

The extraction of ruthenium from the nitrite solution at different concentrations of tributyl phosphate (TBP) was investigated. It has been established that undiluted TBP is an effective extractant for extracting the element from solution. The possibility of deep purification of the ruthenium extract from impurity platinum metals by washing the saturated organic phase with a solution of sodium nitrite was showed. It was revealed that a high degree of ruthenium stripping is achieved using an alkali solution.

Irradiation of plutonium Tributyl Phosphate complexes by ionizing alpha particles: a computational study

Irradiation of plutonium Tributyl Phosphate complexes by ionizing alpha particles: a computational study

Development of a three-stage, cross-current air sparged mixer-settler for the purification of degraded PUREX solvent

ABSTRACT Tri-butyl phosphate (TBP) diluted with in n-dodecane (n-DD) is used as the solvent in PUREX process. Solvent degradation due to radiolysis and hydrolysis during the process is one of the major problems prevailing in reprocessing plants. This paper presents an overview of the design, fabrication, and performance evaluation of a three-stage, continuous, cross-current air sparged mixer-settler developed for purifying the degraded PUREX solvent using hydrazine carbonate. The developmental program consisted of various stages, starting with small-scale batch experiments to investigate the solvent treatment kinetics and phase separation characteristics, followed by design fabrication and performance evaluation of three-stage air sparged mixer-settler. The study on solvent treatment kinetics in a 1.6 L batch air sparged mixer using 1.5 M hydrazine carbonate showed that the concentration of di-butyl phosphate (DBP) in the simulated degraded solvent could be reduced from 8,000 mg L−1 to less than 40 mg L−1 within 180 seconds. Performance evaluation of the three-stage air sparged mixer settler had shown that the DBP concentration in the simulated degraded organic phase could be brought down from 8,000 mg L−1 to less than 15 mg L−1, and the equipment could process up to 60 L h−1 throughput with negligible phase entrainment.

Stepwise Separation for Calcium Recovery from an Ammonium Sulfate Leaching System

Calcium recovery from high calcium solid waste is driven by the latter’s growing environmental impact, emphasizing the need to develop a high value-added utilization approach. Inspired by our previous study, we develop a stepwise separation strategy for calcium recovery from an ammonium sulfate leaching system to efficiently remove iron and unburned carbon residue. In this study, tributyl phosphate (TBP) used as the carbon residue adsorbent for calcium recovery exhibits high selectivity and good recycling stability. Adsorption measurements show that TBP yields a superior carbon residue adsorption ability with a maximum adsorption ratio greater than 95%. Moreover, the adsorption percentage is also kept more than 90% after 10 cycles, which substantiates the good potential of TBP for reuse. Besides, the low concentration (1 mol/L) of H2SO4 provides an acidic environment, which makes TBP more feasible to be applied in carbon residue adsorption and effective iron(III) stripping. Furthermore, it is inferred from the Fourier transform infrared spectroscopy/X-ray photoelectron spectrometer and density functional theory analyses that the enhanced carbon separation performance may be ascribed to the carboxyl in carbon residue coordinated to the donor oxygen atom of TBP at the position of P–O. This work provides the foothold for further research on the recovery of calcium from industrial by-products.

Occurrence Distribution and Risk Assessment of Organophosphate Esters in A Typical Area of the Estuary in the Yellow River Basin

As a type of emerging pollutant, organophosphate esters (OPEs) have the characteristics of toxicity, persistence, and bioaccumulation. Due to their wide use in production and life, OPEs pose potential risks to ecosystems when they enter the environment. In this study, the concentrations of 14 species of OPEs in surface water were determined using UPLC-MS/MS, and the spatial distribution of the OPEs in the surface water of the estuary of the Yellow River basin was further analyzed. The pollution sources were analyzed using correlation analysis and principal component analysis, and the ecological risk was evaluated. The results indicated that the concentration of Σ14OPEs in surface water ranged from 183.81 to 1674.52 ng·L-1, with an average concentration of 638.25 ng·L-1. Tris(2-chloroethyl) phosphate (TCEP) and tris(1-chloro-2-propanyl) phosphate (TCPP) were the main OPEs. The Xiaoqing River flowing through the urban area differed from the main stream of the Yellow River and other branches in terms of OPEs composition characteristics, which showed a greater impact from human activities. The distribution of Σ14OPEs showed an obvious regional pattern, with a trend of increasing and then decreasing along the direction of the Yellow River inlet. The results of source analysis revealed that human activities such as industrial wastewater discharge from different industries, transportation, and atmospheric deposition were the sources of OPEs in surface water. The ecological risk assessment results indicated that TCEP posed a high risk to aquatic organisms in the main stream of the Yellow River, Xiaoqing River, and Zhimai River, and tri-n-butyl phosphate (TnBP) and triphenyl phosphate (TPhP) posed a low risk at some sites.

Liquid–liquid separation of copper and nickel ammine complexes using phenolic oxime mixture with tributyl phosphate

ABSTRACT In the present study, a complete separation of copper over nickel has been studied from an ammoniacal leach liquor of nickel laterite ore generated via the Caron process. For this purpose, a phenolic oxime (LIX 84-IC) used as the extractant molecule was mixed with tributyl phosphate (TBP) to inhibit the co-extraction of nickel with copper loading into the organic phase. The antagonistic effect of TBP was confirmed by the distribution coefficients to be D mix << D LIX 84-IC + D TBP and negative values of ∆D. The highest separation (β Cu/Ni) of >1329 was yielded using the molar ratio of organic mixture at LIX 84-IC:TBP = 0.4:0.6 at an organic-to-aqueous phase ratio of 1. The thermodynamic properties of copper extraction exhibited an endothermic nature with ΔH° value of 5.4 kJ∙mol−1, indicating the formation of inner-sphere coordination between metal ions and the organic mixture. Further, the stripping of copper from the loaded organic phase was quantitatively achieved by contacting with 1.0 mol∙L−1 H2SO4 solution at the unit phase ratio.

Selective Solvent Extraction of Vanadium Over Chromium from Alkaline Leaching Solution of Vanadium Slag by D2EHPA/TBP

ABSTRACT A selective extraction process for recovering vanadium (IV) over chromium was proposed with use of a mixed extractant consisting of di(2-ethylhexyl) phosphate (D2EHPA) and tri-n-butyl phosphate (TBP). The influence of various factors, which included the initial aqueous pH value, the concentration of leach solution and D2EHPA, phase ratio (O/A), extraction equilibrium time and extraction temperature in the extraction process on the separation of V and Cr was investigated. Under the condition of the optimum extraction, vanadium extraction was above 94.0%. Meanwhile, under the optimum stripping conditions, the vanadium stripping was above 93.0% utilizing 1.5 mol/L sulfuric acid as the effective stripping reagent. The regeneration and reusability of the loaded organic phases after stripping were discussed. In addition, continuous three-stage extraction and stripping strategy indicated that the aggregate loss of vanadium was 0.885% and that the purity of vanadium was more than 99.9%. Under the condition of the optimum precipitation, when the pH value of the stripping solution was adjusted to 7.0 with ammonia water, the precipitation efficiency reached 99.93%. The calcination conditions (above 680 °C in air) were finally determined by TG-DTA and TG-MS experiments, and the V2O5 obtained by calcination was characterized by XRD. Additionally, a method for detecting impurity elements in vanadium matrix without interference was established. The recovery technology has practical significance in enlarging production scale, reducing specific energy consumption and cost, and realizing automatic control in vanadium leaching process.

Molecular thermodynamic model for solvent extraction of mineral acids by tri-n-butyl phosphate (TBP)

Removal or recovery of acids by solvent extraction is highly relevant for recycling, process control, and wastewater decontamination, especially in the hydrometallurgical industry. The construction and optimization of such processes would benefit from a molecular thermodynamic model that can predict liquid–liquid equilibria. Past attempts resulted in models that were not very predictive. Therefore, a new approach was followed and demonstrated for the extraction of the mineral acids (inorganic acids) HNO3, HCl, H2SO4, H3PO4, and H3AsO4 by tri–n–butyl phosphate (TBP). The semi-empirical OLI Mixed-Solvent Electrolyte (MSE) framework was used to construct the thermodynamic model for calculating the liquid–liquid equilibria. Contrary to previous attempts, this framework allows the description of both the aqueous and organic phases in one model, and it can accurately deal with the non-ideal behavior of concentrated electrolyte solutions. The best agreement between calculated and experimental distribution data was achieved by assuming that the extraction of mineral acids occurs via protonation of TBP and coextraction of the anions. At very high acid concentrations, also neutral acid molecules are transferred to the organic phase. The high accuracy of the thermodynamic model for all mineral acid systems considered in this study is an indication that this approach for modeling liquid–liquid equilibria is a universal one. Furthermore, the extraction of mineral acids can be predicted in mixed-acid systems and acid-salt systems that were not used to construct the model.

Performance of hydrophobic physical solvents for pre-combustion CO2 capture at a pilot scale coal gasification facility

Here, we present the first pilot plant data for hydrophobic physical solvents for CO2 and H2S removal from coal-derived H2-rich syngas. Four physical solvents were tested under pre-combustion CO2 capture conditions at bench scale and pilot plant scale: one baseline hydrophilic solvent and three hydrophobic solvents. The solvents were: (1) polyethylene-glycol-dimethyl ether (PEGDME), a hydrophilic solvent analog for the commercial process Selexol, (2) tributyl- phosphate (TBP), a commercially available hydrophobic solvent, (3) polyethylene glycol-poly(dimethylsiloxane) (PEG-PDMS-3), and (4) diethyl sebacate (CASSH-1), a novel, computationally screened hydrophobic solvent developed by the National Energy Technology Laboratory (NETL). All solvents were studied under pure gas (CO2/N2/H2/CH4) equilibrium conditions at NETL followed by pilot plant testing with syngas at the University of North Dakota Energy & Environmental Research Center (UND EERC). Long term performance of CASSH-1 and PEDGME was then assessed with results compared to process simulation predictions. Within experimental uncertainties, all solvents showed comparable CO2 absorption performance at above room temperature operation while the hydrophobic solvents had limited water uptake and low vapor pressure, which alleviates concerns related to corrosion, water absorption, and solvent loss to evaporation. These results indicate low viscosity, low vapor pressure hydrophobic solvents are a promising option for lower cost CO2 capture from high pressure syngas applications.

An efficient technique for the purification of fulvic acid extracted from leonardite

Fulvic acids (FAs) are significant natural organic compounds produced during the decomposition of plants and animals. There is great demand for FAs in pharmaceutical, cosmetic, and industrial applications. However, their use is declining due to the tedious purification process. This study developed a method to purify FAs extracted directly from leonardite-rich humic substances. The method introduces a permeation cell integrated with a polymer inclusion membrane to separate target impurities related to FAs from extractants and humic raw material sources. Polymeric membranes were prepared using fixed proportions of cellulose triacetate, tri octyl methylammonium chloride, tributyl phosphate, and 2-nitrophenyl pentyl ether. The purified fulvic acids, feed phase, and stripping phase products were characterized using SEM, EDX, FTIR, and UV-Vis. Fluorescence spectroscopy analysis was also performed to compare the purity intensity of fluorescence spectra of the respective components of the feed and stripping phase. In terms of purification, the membrane obstructed the passage of foreign ions and unwanted particles and allowed only FAs molecules to pass through. This research affirms that the present method is more effective, cheaper, and more convenient than the classical method for FAs purification.

Bioaccumulation and Trophic Transfer of Organophosphate Flame Retardants and Their Metabolites in the Estuarine Food Web of the Pearl River, China.

The accumulation and trophodynamics of organophosphate flame retardants (OPFRs) and their metabolites were investigated in the estuarine food web of the Pearl River, China. The mean ∑OPFR concentration among the investigated species increased in the following order: fish [431 ± 346 ng/g lipid weight (lw)] < snail (1310 ± 621 ng/g lw) < shrimp (1581 ± 1134 ng/g lw) < crab (1744 ± 1397 ng/g lw). The di-alkyl phosphates (DAPs) of di-(n-butyl) phosphate (DNBP), bis(2-butoxyethyl) phosphate (BBOEP), and diphenyl phosphate (DPHP) were the most abundant metabolites, with concentrations same as or even higher than their corresponding parent compounds. The log bioaccumulation factors for most OPFRs were lower than 3.70, and significant biomagnification was only found for trisphenyl phosphate [TPHP, with the trophic magnification factors (TMFs) > 1]. The TMFs of OPFRs, except for TPHP and tributyl phosphate had a positive correlation with lipophilicity (log KOW, p ≤ 0.05) and a negative correlation with the biotransformation rate (log KM, p ≤ 0.05). The mean TMF > 1 was observed for all of the OPFR metabolites based on the bootstrap regression method. The "pseudo-biomagnification" of OPFR metabolites might be attributed to the biotransformation of OPFRs in organisms at high trophic levels.

Wiped film evaporator with a roller wiper and an internally mounted condenser for the recovery of TBP and n-DD from degraded PUREX solvent

Wiped Film Evaporator (WFE) is a promising choice for processing viscous and thermally labile compounds due to its short residence time, enhanced heat transfer rates, and a high fraction of distillate yield in a single pass. This article evaluates the viability of a WFE with a roller wiper and an internally mounted condenser to recover tri-butyl phosphate (TBP) and n-dodecane (n-DD) from degraded PUREX solvent by vacuum distillation. Degraded solvents derived from different sources were purified using a combination of primary cleanup by sodium carbonate scrubbing and secondary cleanup by vacuum distillation using the WFE. Primary cleanup could efficiently remove the acidic degradation products of TBP. However, the scrubbed solvents were not of acceptable quality due to their poor physical properties. Secondary cleanup by vacuum distillation notably improved the physical properties of the solvent. A detailed quality assessment of the recovered solvents in terms of density, viscosity, interfacial tension (IFT), and phase separation time (PST) ratio showed that all the solvents recovered were of acceptable quality. The highest PST ratio and lowest IFT of the recovered solvents were 1.36 and 8.6 mN m−1, respectively. The maximum solvent recovery, TBP recovery, and n-DD recovery obtained were 93.8%, 83.8%, and 99.8%, respectively.