Trioctylphosphine Oxide Concentration Research Articles

Preparation of new alginate capsules enclosing diatomite and organic extractants to uptake lanthanum

The present study conducted syntheses of Ca-alginate composite beads, which involved trioctyl-amine (TOA), tributyl phosphate (TBP), trioctylphosphine oxide (TOPO) organic extractants, and diatomite for separation of La(III) ions from dilute aqueous solutions. The surface morphology of the capsules was examined under Scanning Electron Microscopy, while their chemical structure was characterized using Fourier Transform Infrared Spectroscopy. Alginate composites were prepared by adding concentrations of TBP (1%–10%), TOPO (0.005 M–0.09 M) and TOA (1%–10%) organic extractants to the Na-alginate-diatomite mixture.The effects of various parameters on adsorption such as solution pH, contact time, metal ion concentration, and temperature, were individually tested using standard solutions of La(III). The maximum uptake capacity of the alginate composite adsorbent, consisting of TOA, diatomite, and alginate for La(III) ions, was examined at 25 °C. Adsorption data were analyzed using Langmuir, Freundlich, Dubinin–Radushkevich (D-R), Temkin, Flory-Huggins and Brunauer, and Emmett and Teller (BET) isotherm models. The biosorption isotherm parameters were estimated by both linear and nonlinear regression analyses. The results indicate that the Langmuir model provides a better fit than the other models for the adsorption equilibrium data.Thermodynamic parameters such as variations of enthalpy, entropy, and Gibbs free energy were calculated. The maximum uptake capacity of the alginate composite adsorbent, including TOA, diatomite, and alginate for La(III) ions from aqueous solutions was found to be 146.4 mg/g. The adsorption efficiency in dilute solutions was determined to be 97.2%.

Quantum chemical calculation assisted efficient lithium extraction from unconventional oil and gas field brine by β-diketone synergic system

The lithium extraction from emerging unconventional oil and gas (UOG) field brine by β-diketone synergic system was established and systematically studied for the first time. A synergistic system consisting of dibenzoylmethane (DBM) and trioctylphosphine oxide (TOPO) was screened for lithium extraction through high-precise DFT calculation, and the synergistic effects were revealed by FT-IR analysis. A state-of-the-art Li+-Mg2+-Ca2+ co-extraction and Li+ selective stripping (CESS) process was proposed to achieve high lithium recovery efficiency. The effects of saponification, phase ratio, extractant composition and stripping acidity on extraction efficiency were systemically studied using real UOG field brine. After three-stage countercurrent extraction, the lithium extraction efficiency reached 98.1 % with the DBM concentration of 0.25 mol/L, TOPO concentration of 0.25 mol/L, and saponification of 70 %. After selective stripping and scrubbing with gradient HCl concentrations, Li+ was further separated from Na+, Mg2+ and Ca2+. The mass ratio of Mg2+/Li+ was reduced by 49.7 times, Na+/Li+ was reduced by 102.4 times. This work bridged the gap in the solvent extraction of lithium resources from UOG field brines and provided ideas for UOG field resource exploit and comprehensive utilization.

CsPbBr3 perovskite nanowires and their optical properties

Abstract Inorganic cesium lead halide perovskites CsPbX3 nanocrystals (NCs) have been widely used in optoelectronic applications due to their excellent optical properties. Furthermore, the final morphology and size of as-grown CsPbX3 NCs play crucial roles in determining their stability and luminescent properties. Here, CsPbBr3 NCs with various morphologies such as nanocubes, nanospheres, nanorods (NRs) and nanowires (NWs) have been fabricated by controlling the amount of solvent octadecene (ODE), the concentrations of trioctylphosphine oxide (TOPO)/tetradecylphosphonic acid (TDPA), the reaction temperatures and the final cooling rate. Finally, high-quality CsPbBr3 NWs exhibiting cubic phase have been successfully obtained by optimizing the reaction parameters. These well-controlled CsPbBr3 NWs with aspect ratio ~19 show great potential in helping nanodevice development. In summary, this study provides important insights for producing inorganic perovskite materials with tunable morphologies and properties for multi-applications.

Extraction and Separation Factor for Lanthanum(III) and Cerium(III) Complexes from Aqueous Medium Using Ionic Liquid and Kerosene

In this work, an experimental study was carried out to find the best-operating conditions for the study of the extraction percentage (%E) and the separation factor (SF) of La(III) and Ce(III) complexes. To carry out this study, a variation of β-diketone concentrations was used, keeping the concentration of tri-octyl phosphine oxide (TOPO) continuous at 0.05 M. The ratio of organic phase to the aqueous phase (O/A) was also studied. The %E and SF were analyzed and compared in the 1,1,1-trifluoro-2, 4-pentanedione (TFA) with TOPO, and 1,1,1,5,5,5-Hexafluoro-2,4-pentanedione (HFAc) with TOPO in Ionic Liquid (IL) and Kerosene. The one-stage extraction efficiency in IL of La(III) and Ce(III) complexes was 42.13% and 77.48% for the TFA-TOPO system and La(III) and Ce(III) complexes were 94.33% and 97.67% for the HFAc-TOPO system. While the SF between Ce(III) and La(III) complexes was 4.91 for TFA-TOPO and 2.64 for HFAc-TOPO. On the other hand, the one-stage extraction efficiency in Kerosene of La(III) and Ce(III) complexes was 27.57% and 63.70% in the TFA-TOPO system. The one-stage extraction efficiency of La(III) and Ce(III) complexes were 99.87% and 99.73% for the HFAc-TOPO system in Kerosene while the SF between Ce(III) and La(III) complexes was 4.62 for TFA-TOPO and 0.49 for HFAc-TOPO. The main conclusion was that using two extractants (β-diketone and TOPO) produced a synergistic effect improving the extraction capacity and SF of La(III) and Ce(III) complexes for both systems in IL and Kerosene.

DETERMINATION OF THE AGING TIME OF COGNACS USING A LUMINESCENT SENSOR BASED ON THE TERBIUM(ІІІ) COMPLEX

The possibility of identification of the maturation time (age) marker of cognac – gallic acid – in cognac using a terbium ion-based (III) luminescent sensor is shown. Gallic acid was isolated from cognac by thin layer chromatography on Sorbfil plates; the sample volume applied onto the plate was 1 µL. It was found that acidic systems, such as ethyl acetate : acetic acid in a ratio of 95: 5 and benzene : methanol : acetic acid (100: 5: 1) are best eluting; the latter was selected for the test. A solid-phase sensitized terbium ion luminescence (III) with gallic acid was used as an analytical response. It was established that surface active, as well as a number of donator active substances do not affect the intensity of the luminescence of the complex. An increased intensity of luminescence of the sorbate complex is recorded in the presence of a donor-active additive, trioctylphosphine oxide (TOPO). Analysis of the luminescence spectra and the excitation of the sorbates of the complex in the presence of TOPO allowed concluding that its molecule is not part of the internal sphere of the complex, but play a role of water repellent, protecting from water molecules which deactivate luminescence, which increases the intensity of luminescence. The maximum concentration of terbium ions (ІІІ) and TOPO in the developing solution is 10-3 mol/l. A 4% aqueous hexamine solution was used to achieve the optimal pH value (6.5-7.8) in a developing solution. The luminescence is excited at λ excit. = 365 nm, the intensity of luminescence of terbium ions (III) is recorded at λ em. = 545 nm. Gallic acid is identified according to the calibration curve. A simple and reliable technique has been developed for identification of the age marker of cognac – gallic acid – in different brands and various maturation periods of cognac. The correctness of the results obtained was verified by the spike test. The relative standard deviation is (Sr) 5.2–7.0%. The detection limit of gallic acid is 0.002 μg/ml.

Response surface methodology for optimization of solvent extraction to recovery of acetic acid from black liquor derived from Typha latifolia pulping process

Most modern commodity chemicals are synthesized from fossil resources. Organic acids are attractive targets in process development for the emerging renewable resources based biorefinery industry. Liquid-liquid extraction (LLE) is a common separation method for the recovery of a solute from a solution and can be applied to the recovery of acetic acid from the black liquor of Typha latifolia pulp prior to the bioethanol fermentation process. LLE of acetic acid was studied using alkanes containing 37% (w/w) concentrations of trioctylphosphine oxide. The extraction yield has also been evaluated with a four-level factorial design. Four independent variables, pH (1–3), temperature (25–65°C), residence time (24–48min), and concentrated hydrolyzates (1–10 times), were screened. The results showed that a lower pH and temperature gave the highest yield for the extraction of the organic acid. The yield also increased with less concentrated hydrolyzates. However, the residence time did not affect the yield. The maximum extraction yield of acetic acid achieved 71.7% at pH 1.02, 31.4°C, 46.8min, and 1.07 times. And the maximum extraction yield of formic acid and lactic acid was 75.1% (obtained at pH 1.46, 25.0°C, 44.5min, and 1.04 times) and 65.0% (obtained at pH 1.71, 35.9°C, 44.6min, and 1.11 times), respectively. It appears that the stabilities of the extracted acids are highly affected by the initial feed concentration of the organic acid.

Recovery of Mercury Using a Trioctylphosphine Oxide-Based Supported Liquid Membrane System

Abstract Transport of mercury ions (Hg (II)), through a polypropylene (Celgard 2400) supported liquid membrane (SLM), employing trioctylphosphine oxide (TOPO) as carrier and toluene as a solvent, has been investigated. The work was conducted under different operating conditions with respect to feed pH and concentration, carrier concentration, and stripping phase concentration to explore optimum conditions for maximum extraction of Hg (II) ions; 0.2 mol/L was the optimum concentration of TOPO for recovery of mercury. Experiments were conducted in the cotransport mode using hydrazine as the stripping reagent. It was observed that extraction of mercury increased with increase in concentration of hydrazine up to 0.05 mol/L when stirred at 1,500 rpm. Extraction of mercury was about 90%, under optimum conditions in 3 h. The present SLM was found to be stable for about 50 h of use.

Removal of Chromium(VI) from Industrial Effluents Through Supported Liquid Membrane Using Trioctylphosphine Oxide as a Carrier

The present study describes extraction of chromium(VI) through supported liquid membrane (SLM), Celgard 2400, which was impregnated with trioctylphosphine oxide (TOPO) dissolved in toluene. The stripping phase was comprised of diphenylcarbazide (DPC) in sulfuric acid (H2SO4) whereas the feed phase consists of potassium dichromate (K2Cr2O7) and hydrogen peroxide (H2O2). The effects of concentrations of chromium, TOPO, DPC, and H2SO4 have been studied in order to evaluate the transport efficiency of chromium(VI) ion. The optimum experimental conditions for the chromium(VI) extraction were established as follows: 19.2 × 10−4 mol L-1 chromium ion, 1.5 mol L-1 H2O2 concentration in the feed phase, 0.1 mol L-1 TOPO concentration in the membrane phase and 0.001 mol L-1 DPC and 1.5 mol L-1 H2SO4 as stripping phase. The measurements of percent recovery, distribution coefficient, flux and permeability were made at the given optimized conditions. The extraction time and membrane stability were also investigated. Extraction efficiency of 80% was recorded in 180 min and the SLM system was found stable up to 10 days. The optimized SLM system was then applied on the paint industry wastewater; about 80% of chromium(VI) was successfully removed from the wastewater.

Solvent extraction of U(VI) by trioctylphosphine oxide using a room-temperature ionic liquid

The unique physical and chemical properties of room-temperature ionic liquids (RTILs) have recently received increasing attention as solvent alternatives for possible application in the field of nuclear industry, particularly in liquid-liquid separations of radioactive nuclides. We investigated solvent extraction of U(VI) from aqueous solutions into a commonly used ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C(4)mim][NTf2]) using trioctylphosphine oxide (TOPO) as an extractant. The effects of contact time, TOPO concentration, acidity, and nitrate ions on the U(VI) extraction are discussed in detail. The extraction mechanism was proposed based on slope analysis and UV-Vis measurement. The results clearly show that TOPO/[C(4)mim][NTf2] provides a highly efficient extraction of U(VI) from aqueous solution under near-neutral conditions. When the TOPO concentration was 10 mmol/L, the extraction of 1 mmol/L U(VI) was almost complete (> 97%). Both the extraction efficiency and distribution coefficient were much larger than in conventional organic solvents such as dichloromethane. Slope analysis confirmed that three TOPO molecules in [C(4)mim][NTf2] bound with one U(VI) ion and one nitrate ion was also involved in the complexation and formed the final extracted species of [UO2(NO3)(TOPO)(3)](+). Such a complex suggests that extraction occurs by a cation-exchange mode, which was subsequently evidenced by the fact that the concentration of C(4)mim(+) in the aqueous phase increased linearly with the extraction percent of U(VI) recorded by UV-Vis measurement.

Optimization of rheological properties of photopolymerizable alumina suspensions for ceramic microstereolithography

Microstereolithography (MSL) is a rapid prototyping technique to fabricate complex three-dimensional (3D) structure in the microdomain involving different materials such as polymers and ceramics. The present effort is to fabricate microdimensional ceramics by the MSL system from a non-aqueous colloidal slurry of alumina. This slurry predominantly consists of two phases i.e. sub-micrometer solid alumina particles and non-aqueous reactive difunctional and trifunctional acrylates with inert diluent. The first part of the work involves the study of the stability and viscosity of the slurry using different concentrations of trioctyl phosphine oxide (TOPO) as a dispersant. Based on the optimization, the highest achievable solid loadings of alumina has been determined for this particular colloidal suspension. The second part of the study highlights the fabrication of several micro-dimensional alumina structures by the MSL system.

Trioctylphosphine oxide-impregnated hollow fiber membranes for removal of phenol from wastewater

Trioctylphosphine oxide (TOPO) was immobilized in polypropylene hollow fiber membranes for removal of phenol from wastewater. Scanning electron microscopy showed white deposits of TOPO dispersed non-uniformly within the resulting extractant-impregnated hollow fiber membranes (EIHFM). The EIHFMs manifested high adsorption capacity and mass transfer rates, with adsorption equilibrium attained within 10–30min of operation. Experimental equilibrium adsorption capacities with a feed of 1000mg/L phenol were 32, 42, 52 and 57mg/g at 50, 100, 200 and 400g/L TOPO, respectively. During repeated operation with 1000mg/L phenol, the adsorption capacities of the EIHFMs remained stable at 32.2±1.3 and 52.3±0.9mg/g for 10 subsequent runs at TOPO concentrations of 50 and 100g/L, respectively. The EIHFMs, when used as adsorbents in a two phase partitioning bioreactor, alleviated substrate inhibition on Pseudomonas putida by rapidly adsorbing phenol to sub-inhibitory levels. Biodegradation of 1000 and 2000mg/L phenol was completed within 26 and 36h, respectively. These results suggest that the EIHFM is a promising technology for solventless extraction of aromatic compounds in wastewater treatment.

Characterizing the Influence of TOPO on Exciton Recombination Dynamics in Colloidal CdSe Quantum Dots

Surface ligands play a significant role in the carrier recombination dynamics of colloidal quantum dots (QDs). Trioctylphosphine oxide (TOPO) is a ligand used during CdSe QD synthesis, which binds to surface cadmium atoms, but, despite its widespread use, its effect on exciton relaxation rates is poorly understood. In this work, we extract TOPO–CdSe binding equilibria from isothermal titration calorimetry experiments and use them to study the effect of TOPO concentration on CdSe time-resolved photoluminescence. We develop a quantitative kinetic model of CdSe QD exciton relaxation that is based upon an ensemble probability distribution of bound ligands and show that bound TOPO gives rise to band-edge states that participate in carrier recombination dynamics. Optoelectronic applications of QDs necessitate a good understanding of interfacial dynamics so that charge separation, carrier transport, and other phenomena can be optimized. This technique is a promising step toward that goal that is useful for any l...

Automotive spent catalysts treatment and platinum recovery

The recovery of Platinum from spent catalysts was examined. Platinum leaching was studied considering particle size, temperature, solid-liquid and HCl/ HNO3 ratio effects. Many elements together with Pt were taken from a mixed spent catalyst sample. The main components of the leach liquor were Pt (1.84 g/ kg cat) and Fe (0.94 g/kg cat). Platinum was separated from the leach aqueous solution by using Tri-Octyl Phosphine Oxide (TOPO) in kerosene. The extraction was studied considering equilibrium time, TOPO and HCl concentration, tin(II) chloride presence and stripping agents. Iron represents the main ion competitor for Pt extraction.

Separation by competitive transport of uranium(VI) and thorium(IV) nitrates across supported renewable liquid membrane containing trioctylphosphine oxide as metal carrier

Supported renewable liquid membrane (SRLM) technique is investigated for the selective separation of uranium from thorium solutions. Trioctylphosphine oxide (TOPO) dissolved in dodecane is used as the metal carrier in the liquid membrane (LM) phase. The renewable LM configuration used is highly stable for consistent long run operations. Systematic investigations were carried out to investigate the transport of U(VI) across the SRLM under different experimental conditions such as, concentration of TOPO in the LM phase, concentration of U(VI), Th(IV) and nitric acid in the feed, receiving phase composition and hydrodynamic conditions across the polymeric membrane support. By combining the process of in situ precipitation of thorium carbonate in the receiving phase, an excellent separation of uranium from thorium with decontamination factor of the order of 350 could be achieved. The solid precipitate of thorium carbonate generated in the receiving phase did not create any hindrance to the transport of U(VI) across the SRLM. The parameters defining the transport mechanism of U(VI) across the SRLM are experimentally evaluated as; maximum permeability coefficient, PU=9.66×10−5cm/min, diffusion coefficient for U(VI) in the aqueous feed solution, Da=2.35×10−4cm2/min with length of the concentration depletion layer from membrane interface, da=4.17×10−2cm and membrane diffusion coefficient for UO2(NO3)2·2TOPO in the LM phase, Do=5.36×10−6cm2/min. The numerical model obtained with these parameters gives satisfactory concordance with the experimental results under given constraint of the concentrations of nitric acid, TOPO and U(VI). Selectivity of this separation process is tested by determining permeability of different metal ions across the SRLM under optimized conditions.

Conditioning hardwood-derived pre-pulping extracts for use in fermentation through removal and recovery of acetic acid using trioctylphosphine oxide (TOPO)

Abstract Extraction characteristics are shown for trioctylphosphine oxide (TOPO) dissolved in alkane for recovery of acetic acid from dilute water solution and hardwood-derived hemicellulose extracts. The recovery of acetic acid with TOPO is significantly influenced by the pH in the aqueous phase and lightly affected by temperature. In a one-stage extraction, 76.0% of the acetic acid could be extracted below pH 3. The yield of fractional extractions increase with increasing TOPO concentration in alkane and with increasing acetic acid concentration in the aqueous phase. It was found that for dilute extractions carried out at 70°C and pH 1, the solvent extraction is effective at 37% TOPO in alkane (w/w) and that little improvement is realized by further increases in TOPO concentration. Partition coefficients for green liquor and hot water extracts ranged between 2.0 and 2.5 at the tested conditions. Fermentation of hemicellulose extracts that had been treated with TOPO for removal of acetic acid was tested to determine whether TOPO processing resulted in any positive or adverse affects on the microbial activity. Fermentation of TOPO-treated green liquor hemicellulose extract with Pichia stipitis resulted in improved ethanol production relative to untreated extract. Accordingly, placement of TOPO extraction after hydrolysis and prior to fermentation is optimal for acetic acid recovery and maintenance of fermentation rates.

Recovery of acids from anaerobic acidification broth by liquid–liquid extraction

In this study, anaerobic acidification of sugar beet processing wastes and subsequent liquid–liquid extraction of produced fermentation metabolites were investigated. The aim of extraction experiments was to asses the influence of pH and extractant (trioctylphosphine oxide (TOPO) in kerosene) concentrations on the recovery of volatile fatty acids (VFAs) from fermentation broth. The effect of TOPO in kerosene concentration was as crucial as the effect of pH on the recovery of VFAs via extraction. Consequently, pH 2.5 was determined as optimum. At this pH, percent recoveries of VFAs were changed from 43% to 98%, depending on the type of the acid extracted (acetic, butyric, propionic and valeric acids) and the concentration of TOPO in kerosene (5–20%). As the concentration of TOPO in kerosene was increased, efficiency of extraction was increased. As a result, highest VFA recoveries (61–98%) were observed at 20% TOPO in kerosene with distribution ratio values ranging between 1.54 and 40.79. At pH 2.5, the increase in TOPO concentration directly increased the chemical oxygen demand (COD) removal efficiencies, as it does for total VFA recovery. Up to 72% COD removals were achieved, at 20% TOPO in kerosene at pH 2.5, while the removal efficiencies remained between 19% and 22% at pH 5.5.

Partition data of acetic acid between aqueous NaCl solutions and trioctylphosphine oxide in cyclohexane diluent

Abstract Salting out of acetic acid from aqueous NaCl solutions into cyclohexane containing various concentrations of trioctylphosphine oxide, TOPO, as an extractant have been studied at 30 °C. Loading of extractant with up to two molecules of acetic acid was observed, and the extraction coefficient for the fully loaded extractant has been evaluated. Partition profiles have been constructed from the experimental data for salt dependence of partition coefficients at various [TOPO]/[acetic acid] aqueous ratios. At low ratio salt effect is insignificant due to the nearly complete loading of the extractant. The sensitivity towards salt increases with increasing the ratio as a result of the ability of available free TOPO to complex with more acetic acid molecules salted out from aqueous phase.

A multiphasic hollow fiber reactor for the whole-cell bioconversion of 2-methyl-1,3-propanediol to (r)-beta-hydroxyisobutyric acid.

This paper describes the bioconversion of 2-methyl-1,3-propanediol to (R)-beta-hydoxyisobutyric acid (HIBA) by Acetobacter ALEI in a hollow fiber membrane bioreaction system arrangement that allows the integration of three liquid phases: the aqueous bioconversion phase, the organic phase consisting of a solution of trioctyl phosphine oxide (TOPO) in isooctane, and the third phase consisting of a basic stripping solution that allows reextraction of HIBA from the organic phase. A comparison of HIBA mass transfer experiments was carried out in the membrane reactor with two and three phases for different pH and TOPO concentrations. The use of the three-phase arrangement allows the extraction of high quantities of HIBA from the aqueous medium (higher than 85%) independently of the pH, whereas in the two-phase system the percentage of HIBA extracted from the aqueous medium was lower, 42% in the best case, and strongly influenced by the pH. The percentage of the extractive agent TOPO in the organic phase influenced on the mass transfer rate in both bi- and triphasic arrangements. By simply integrating the re-extraction phase in the system it was possible to increase the extraction yield by 2-fold, reduce the amount of TOPO by 4-fold, and operate at the more favorable pH 4. A bioconversion experiment was done in these conditions (pH = 4, TOPO = 5%) to confirm the advantages of including the third stripping solution. Fed-batch operation of the triphasic membrane reactor was maintained for more than 20 h, reaching an HIBA concentration in the stripping solution of 29 g L(-)(1).

Solvent Extraction Equilibria and Kinetics of Gallium(III) with 2-Thenoyltrifluoroacetone in the Absence and Presence of Trioctylphosphine Oxide in Toluene

Abstract The rate and equilibrium of solvent extraction of gallium(III) from aqueous perchlorate solutions into toluene with 2-thenoyltrifluoroacetone (Htta) was measured in the absence and presence of trioctylphosphine oxide (TOPO). A synergistic enhancement of the extraction was found when TOPO was added. When a correction was made for the association of Htta and TOPO in the organic phase which decreased their concentrations available for the extraction, the extracted adducts was found to be in the form of Ga(tta)3(TOPO)2. The rate of extraction was not high and it was dependent on the second order with respect to Htta and the inverse second order with respect to H+ in both the absence and the presence of TOPO. The rate was accelerated by addition of TOPO; the enhancement of the rate was proportional to the TOPO concentration.

A Statistical Model of the Extraction-Process Parameters of Uranium–N-Phenylbenzohydroxylamine–Trioctylphosphine Oxide Complex in Chloroform Solution

Abstract The solvent extraction of uranium has been carried out with chloroform solutions of N-phenylbenzohydroxamic acid (BPHA) and Trioctylphosphine oxide (TOPO). The experiments were statistically planned to quantitatively assess the effect of the concentration of BPHA, the concentration of TOPO and the aqueous-phase pH of the solution on the percentage extraction of uranium. In addition, the interactional influence of the above-mentioned variables was also studied. A regression equation has been developed which successfully predicts the percentage extraction of uranium with the values of the variables lying between the selected range of experiments.