HDEHP Research Articles

Stability of primary emulsion assisted with nanoparticle in emulsion liquid membrane process for zinc extraction

In the present work, primary water-in-oil (W/O) emulsion consisting blended surfactant and nanoparticle is used for the improvement of ELM stability for zinc extraction. The components used in ELM were di-(2-ethylhexyl)phosphoric acid (D2EHPA) and bis(2,4,4-trimethylpentyl)thiophosphinic acid (Cyanex 302) as a base and synergistic carrier,palm oil as a diluent, sorbitan monooleate (Span 80) and polyoxyethylene sorbitan monooleate (Tween 80) as a surfactant, iron (III) oxide (Fe2O3) as a nanoparticle stabilizer and acidic thiourea as a stripping agent. There are several operating parameters including hydrophilic-lipophilic (HLB) value, mixed surfactant concentration, homogenizer speed as well as nanoparticle concentration were investigated in primary W/O emulsion preparation. The results show that emulsion stability increases up to 88% while droplet diameter decreases by 70% at HLB 8, 5% (w/v) of blended mixture surfactant, 8000 rpm of homogenizer speed and 0.02% (w/v) of nanoparticle concentration at fixed 3 min of emulsification time within 60 min of phase separation. It is expected that the extraction of zinc during the formation of W/O/W emulsion increases as it may offer large surface area for solute pertraction and reduced destabilization phenomenon. Hence, the usage of blended mixture surfactant accompanied by nanoparticle (Fe2O3) in the emulsion making has high potential to enhance the emulsion stability in emulsion liquid membrane process of zinc extraction.

Indium Extraction from Sulfate Solutions with Di(2-Ethylhexyl)Phosphoric Acid in the Presence of Organic Proton-Donor Additives

Indium Extraction from Sulfate Solutions with Di(2-Ethylhexyl)Phosphoric Acid in the Presence of Organic Proton-Donor Additives

Indium Extraction from Sulfate Solutions with a Mixture of Di(2-Ethylhexyl)Phosphoric Acid and Octyl Alcohol

Indium Extraction from Sulfate Solutions with a Mixture of Di(2-Ethylhexyl)Phosphoric Acid and Octyl Alcohol

Periodic Expansion and Contraction Phenomena in a Pendant Droplet Associated with Marangoni Effect.

A spontaneous oscillation between the expansion and contraction of a nitrobenzene pendant droplet containing di-(2-ethylhexyl)phosphoric acid (DEHPA) was observed in an aqueous phase under alkaline conditions. We described this phenomenon as the spontaneous oscillation of the oil–water interfacial tension. The oscillation characteristics such as the induction period and the interfacial-tension oscillation frequency were investigated under different temperatures and aqueous phase polarities. The effects of the interfacial tension of the biphasic pendant-droplet, the surface excess of the surfactant molecules, and the amount of nitrobenzene elution from the droplet to the aqueous phase on the oscillation characteristics were investigated. Consequently, the periodic expansion–contraction oscillation mechanism was explained through the adsorption–desorption cycle of DEHPA with respect to the aggregate formation of the inverted micelle of DEHPA. This study was based on a simple vibration phenomenon of interfacial tension, and is extremely important for clarifying the predominant factors that cause fluctuations in the free interface energy, which has been ambiguous.

Development of micro polymer inclusion beads (µPIBs) for the extraction of lanthanum

Separation based on polymer inclusion membranes (PIMs) offers an attractive green alternative to conventional solvent extraction by reducing the amounts of extractants used and practically eliminating the use of diluents. Micro polymer inclusion beads (µPIBs) are similar or even identical in composition to PIMs but they are characterised by significantly higher specific surface area which leads to faster extraction and back-extraction.µPIBs composed of di-(2-ethylhexyl)phosphoric acid (D2EHPA) (30 – 80 wt%) as the extractant and poly(vinyl chloride) (PVC) or poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) (70 – 20 wt%) as the base polymer were fabricated via a novel phase inversion microfluidic method and applied to the extraction of La3+ for the first time. The highest D2EHPA concentration, which produced stable, homogeneous and spherical µPIBs, was found to be 60 wt% D2EHPA. La3+ could be efficiently extracted into these µPIBs from aqueous feed solutions at pH 2.5 and subsequently quantitatively back-extracted in a 0.3 M sulfuric acid receiving solution.µPIBs of a composition (45 wt% D2EHPA and 55 wt% PVC) identical to that of a PIM previously studied for the selective extraction of La3+ and having the same mass exhibited 6 times higher surface area and 4.4 times higher initial mass transfer rate in the extraction of La3+. These results clearly demonstrate the suitability of the newly developed µPIBs for the separation of La3+.

Indium Extraction from Sulfuric Acid Solutions in Systems with Poly(2-ethylhexyl)-phosphonitrile Acid

Indium (III) extraction with poly(2-ethylhexyl)phosphonitrile acid (P2EHPNA, HX), di-(2-ethylhexyl)phosphoric acid (D2EHPA), as well as their mixtures with trialkylbenzylammonium chloride (TABAC) from sulfuric acid and zinc sulfate solutions in kerosene was studied. It has been shown that in a wide range of acidity (0.5–2.5 M H2SO4), the extraction capacity of P2EHPNA is much higher than that of D2EHPA. A significant increase in the extraction ability is explained by the absence of cyclic dimerization, characteristic of D2EHPA. Indium extraction decreases with an increase in the acidity of the aqueous solution. It was assumed that indium is extracted into the organic phase by a cation exchange mechanism with the formation of complexes InX3(HX)3n–3 and InX3(HX)2n–3, where HX is the monomer group of the extractant, and n = 2÷4. The introduction of TABAC into the organic phase containing P2EHPNA and D2EHPA leads to a strong decrease in the extraction ability of the reagents. The isotherm with 0.3 mol/dm3 of P2EHFNA in kerosene has a steep character. This makes it possible to extract almost completely (> 99%) in 1–2 steps with indium content of 0.5 g/dm3 in the initial solution. Since the stripping of In with mineral acids from P2EHPNA is impossible, its stripping was carried out with alkaline solutions of a complexing agent (polyhydric alcohol – sorbitol). It was shown that the degree of stripping with sorbitol solutions (2.0 M NaOH + 2.0 M sorbitol) is about 100% already in 3 minutes of phase contact. It has also been shown that when P2EHPNA in kerosene is used, not only almost complete strippig of indium with sorbitol solutions takes place, but also its noticeable concentration in re-extracts in one step (~ 35 g/dm3). At the same time, the phase separation was fast and high quality. It is obvious that the extraction systems with P2EHPNA is of interest for indium extraction from various technological solutions. This work was conducted within the framework of the budget project 0287-2021-0014 for Institute of Chemistry and Chemical Technology SB RAS using the equipment of Krasnoyarsk Regional Research Equipment Centre of SB RAS.

Equilibrium studies on reactive extraction of glycine with di(2‐ethylhexyl)phosphoric acid dissolved in n‐octanol, butyl acetate and solvent oil

AbstractBACKGROUNDReactive extraction is an efficient and highly selective technique for the separation of polar organic compounds. In this work, we used three kinds of extractants, namely acidic di(2‐ethylhexyl)phosphoric acid (D2EHPA), neutral tributyl phosphate (TBP) and basic trioctyltertiaryamine (7301) dissolved in three diluents with different polarity (strong‐polar n‐octanol, weak‐polar butyl acetate and non‐polar solvent oil) for optimization of a reactive extraction system. Based on the result, the reactive extraction kinetics of glycine by D2EHPA and the factors that affect the distribution ratio (D) were discussed in detail. Finally, the reactive extraction mechanism was analyzed, and an extraction model was proposed.RESULTSD2EHPA + n‐octanol is the best system for the reactive extraction of glycine. The apparent equilibrium constant K was calculated to be 1.71 L mol−1 and the physical extraction distribution constant (m) was 0.10. The reactive extraction equilibrium of glycine by D2EHPA can be reached in 1 h and room temperature is suitable for the extraction. D2EHPA reacted with glycine to form a 1:1 type ion‐pair complex, and the structure of the complex is less affected by aqueous pH. Chemical extraction is dominant in the extraction process. The distribution ratio D increases with the increase of D2EHPA concentration. pH and polarity of the diluent also have an influence on extraction efficiency.CONCLUSIONThe results provide preliminary practical information and a theoretical basis for the separation of glycine, which would be beneficial for the purification of glycine and the treatment of wastewater containing glycine. © 2021 Society of Chemical Industry (SCI).

Extraction of Ga(III) by Di‐(2‐ethylhexyl)phosphoric acid (D2EHPA)‐Modified XAD‐4 Resins Prepared by Solvent‐Nonsolvent Modification

AbstractGallium (Ga) is one of the most important elements that are widely used in electronic devices. The development of Ga recovery technology is an important issue for resource recycling. In this study, di‐(2‐ethylhexyl)phosphoric acid (D2EHPA)‐modified XAD‐4 resin (DMR) is prepared by the solvent‐nonsolvent method. The evolution of pore characteristics demonstrates that the solvent‐nonsolvent treatment is advantageous for the immobilization of D2EHPA in XAD‐4 resin. The adsorption isotherm of Ga(III) can be described by the Langmuir isotherm model. The Ga(III) adsorption kinetics follows the pseudo‐second‐order model. The immobilized D2EHPA shows good stability. The reusability study indicates that DMR can maintain the performance after three cycles of adsorption and stripping. The results for the treatment of a practical leaching solution from GaN/Al2O3 wafer further demonstrate that DMR can be applied effectively for Ga(III) recovery.

A Polymer Inclusion Membrane for Sensing Metal Complexation in Natural Waters

Metal speciation studies are of great importance in assessing metal bioavailability in aquatic environments. Functionalized membranes are a simple tool to perform metal chemical speciation. In this study, we have prepared and tested a polymer inclusion membrane (PIM) made of the polymer cellulose triacetate (CTA), the extractant di-(2-ethylhexyl) phosphoric acid (D2EHPA), and the plasticizer 2-nitrophenyloctyl ether (NPOE) as a sensor for Zn and Cu complexation studies. This PIM, incorporated in a device with an 0.01 M HNO3 receiving solution, is shown to effectively transport free metal ions, and it is demonstrated that the presence of ligands that form stable complexes with divalent metallic ions, such as ethylenediaminetetraacetic acid (EDTA) and humic acid (HA), greatly influences the accumulation of the metals in the receiving phase due to the increasing metal fraction complexed in the feed phase. Moreover, the effect of major ions found in natural waters has been investigated, and it is found that the presence of calcium did not decrease the accumulation of either Zn or Cu. Finally, the PIM sensor has been used successfully to evaluate metal complexation in a river water affected by Zn pollution.

Statistical optimization of extraction column parameters for the zinc (ll) solvent extraction by D2EHPA in a continuous mode

The efficiency of zinc(II) extraction with di(2-ethylhexyl) phosphoric acid (D2EHPA) diluted in kerosene has been investigated in batch and continuous extraction columns, enabling a comparison between the performance of spray and packed column. The effect of pH of the aqueous phase, reaction time, and extractant volume ratio were considered as the operational variables in a lab-scale mixer-settler in batch mode. The optimum values for each variable were determined and used as the constant values in the pilot-scale continuous setup for optimization of the extraction process in the columns. A pilot-scale setup can provide more relatable results to industrial-scale production. The effect of dispersed phase flow rate, system temperature, nozzle diameter, and height of packing were investigated in continuous mode in spray and packed pilot-scale columns. To minimize the number of experiments, the response surface methodology (RSM) design of experiments (DOE) was adopted using five levels for each parameter. The effect of each variable and their binary and ternary interactions were analyzed by analysis of variance (ANOVA) with a confidence level of 95%. Maximum zinc extraction efficiency in the batch mode was 93.63%, which occurred at the pH of 2, a reaction time of 25 min, and an extractant volume ratio of 15% (V/V D2EHPA to kerosene). Maximum zinc extraction in the spray and packed columns were 76.13% and 84.06%, respectively. Despite the lower extraction efficiency in the continuous mode, a considerably lower required organic to aqueous ratio make these setups more favorable over traditional mixers.

SOLVENT EXTRACTION OF ZINC FROM ACIDIC LEACH SOLUTIONS

An initial test work was carried out to demonstrate that solution produced by autoclave acid leaching of Electric Arc Furnace Dust (EAFD) from the steel production could be processed through solvent extraction (SX) to recover zinc. Solvent extraction is a process for purification of the leach solution that extracts mainly zinc from other metallic impurities. To assess zinc extraction different counter-current extraction and strip configurations were tested. Extractant Di-2-ethylhexyl phosphoric acid (D2EHPA) and Shellsol D100 as a diluent were used in this investigation. The main operational parameters and the results obtained in the test work are presented in this paper. Well over 90% of the zinc was extracted from the pregnant leach solution using multi-stage SX circuit configuration and pH adjustment. Details of circuit configurations, phase disengagement times and crud generation are also shown.

Separation of cobalt, lithium and nickel from the “black mass” of waste Li-ion batteries by ionic liquids, DESs and organophosphorous-based acids extraction

New methods of metal extraction from the “black mass” (BM) from spent lithium-ion batteries have been presented with ionic liquids (ILs), Deep Eutectic Solvents (DESs) and organophosphorous-based acids. The low-temperature method of extraction of cobalt, nickel, lithium and other metals without pre-leaching of BM with acids have been proposed in comparison with many methods already described in the literature. Extraction has been studied in detail with ILs: methyltrioctylammonium chloride ([N8,8,8,1][Cl], Aliquat 336), trihexyltetradecylphosphonium chloride ([P6,6,6,14][Cl], Cyphos IL 101), trihexyltetradecylphosphonium thiocyanate ([P6,6,6,14][SCN]), benzethonium tricyanomethanide ([Benzet][TCM]), as well as with DESs mixtures and well known organophosphorous-based acids: bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex 272) and di-(2-ethylhexyl) phosphoric acid (D2EHPA). It was shown that fast and efficient extraction, with 90–100 wt% recovery of Co(II), may be obtained using DESs. Well known for the extraction of metal ions from the aqueous phase ILs, binary mixtures of ILs (synergistic effect) and Aqueous Biphasic System (ABS) method with NaCl, {[P4,4,4,14][Cl] + NaCl + Co(II)} have shown very low efficiency in the recovery of metals from BM. The extraction of cobalt (30–58 wt%) and the high extraction efficiency of lithium (41–92 wt%) and nickel (37–52 wt%) was obtained using Cyanex 272 in a mixture with diethyl phosphite. Process factors such as solvent content, extraction additivities, stripping and precipitation methods, temperature, holding time, pH and liquid/solid as well as organic/water ratios were studied. For all extractions, the selectivity and distribution ratios were described. A schematic flow chart for the selective recovery of cobalt(II), lithium(I) and nickel(II) from BM has been proposed. The presented extraction processes can compete with the costly hydrometallurgical methods for recovering metals from secondary waste.

Prediction of Flooding in a Pulsed Packed Column for Continuous Pertraction of Dysprosium by an Emulsion Liquid Membrane

For the first time, Dysprosium was extracted by the novel method of emulsion liquid membrane in a pulsed packed column in a continuous process. Emulsion liquid membrane (ELM) was comprised of D2EHPA (di-2-ethylhexylphosphoric acid) as carrier and Span 80 (Polysorbate 80) as the surfactant in kerosene as the diluent and nitric acid as internal phase. In this work, the packed column was characterized from a hydrodynamic point of view including flooding condition and holdup at flooding points. Operational parameters affecting the flooding points, such as pulsation intensity and flow rate of continuous and dispersed phases have been studied. It was found that increase in pulsation intensity up to 1.5 cm/s and phases flow ratio up to 1.5 cause the reduction of the maximum throughput of the column. Furthermore, two new empirical correlations are proposed for the prediction of holdup at flooding points and flooding velocities with a mean deviation of 2.92% and 1.37%, respectively. The results also demonstrate that about 99.7% of Dysprosium was extracted under specific conditions. Also, recovered membrane phase showed an extraction efficiency that was as high as the fresh membrane phase. These results confirmed the possibility of applying of an ELM for continuous extraction of Dysprosium.

Purification of recovered phosphoric acid by extracting aluminium with di-2-ethylhexyl phosphoric acid

The extraction of aluminium from dilute phosphoric acid with di-2-ethylhexyl phosphoric acid (DEHPA) was optimized using response surface methodology. The optimization was based on the experimental three-level central composite face-centred design (CCF) and was conducted on real-life samples. The three variables included were pH, extractant concentration and aqueous to organic phase ratio (AO). Under the optimized conditions (pH 2.5, 0.6 M DEHPA and AO ratio 1:2), extraction efficiency of 99% for aluminium in four extraction stages is achieved. The purified phosphoric acid solution can then be utilized by the fertilizing industry. Stripping tests for organic phase loaded with aluminium were conducted with sulphuric acid. Extremely high stripping efficiency was obtained with 0.9 M sulphuric acid resulting in the recovery rate of 88% in one stage. After stripping, the aluminium sulphate solution can be reused as a precipitation agent for phosphorus in the wastewater treatment process.

A STUDY OF CHROMIUM (VI) IONS FIXATION AND TRANSPORT USING POLYMER INCLUSION MEMBRANE CONTAINING D2EHPA AS COMPLEXING AGENT

In this paper, polymeric inclusion membranes (PIMs) containing cellulose triacetate (CTA) and polycaprolactone (PCL) as polymer matrix and di-(2-ethylhexyl) phosphoric acid (D2EHPA) as a specific carrier were prepared by solution casting followed by solvent evaporation. Different polymeric membranes were modified by the addition of polyelectrolytes: polyvinylpyrrolidone (PVP), polyanetholsulfonic acid (PATSA) and polyethylene imine (PEI). 2-Nitrophenyl octyl ether (NPOE) was added in the different membranes as plasticizer. All synthesized membranes were characterized by Fourier transform infrared (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). Transfer of chromium through selective membranes is accomplished by using a specific compound, called carrier. A study of the fixation and transport of Cr (VI) across a polymer inclusion membrane PIMs has shown a good removal from the treated solution. The Cr (VI) removal efficiency reached 42% after 8 hours of transport using the membrane containing (CTA + PCL + PATSA + D2EHPA) and 43% for only 2 hours using the membrane containing (CTA + PCL + PATSA+ NPOE).

Experimental verification on stability analysis of supported-liquid-membrane separation of metal ions by in-situ electrical impedance spectroscopy

BackgroundSupported liquid membrane (SLM) is a very promising method for the recovery and separation of valuable or toxic species from aqueous streams; however, stability is always a critical issue in practice. It is highly desired to develop a non-destructive technique to real-time monitor or detect the stability of an SLM process. MethodsThe stability of an SLM processes was real-time analyzed by electrical impedance spectroscopy (EIS). The separation of equimolar Zn(II) and Cu(II) from sulfate solution through an SLM containing di(2-ethylhexyl) phosphoric acid (D2EHPA) in kerosene was selected as the model system owing to the established knowledge of extraction chemistry. Experiments were performed with two types of membrane supports (polycarbonate and poly(vinylidene) fluoride), different D2EHPA concentrations in the organic phase (0.001–0.1 mol/L), pH values of the feed (3.0–5.0) and strip (1.0–3.0) phases, and stirring speeds (0–200 rpm). Correlations between the membrane impedances analyzed according to a proposed equivalent circuit diagram and the separation factors of Zn2+ over Cu2+ measured by SLMs were done to verify the progress of the loss of membrane liquid. Significant findingsUnder the conditions studied, the variations of membrane impedances and separation factors with time using both types of membrane support followed similar trends in most cases. A stability factor of a SLM process based on membrane impedance data was defined, which enables us to predict its relative stability. The present results also demonstrated that all parameters including membrane type, carrier concentration, aqueous pH values, and stirring speed influenced the transport and separation of Zn2+ over Cu2+ and SLM stability.

Silver extraction using emulsion liquid membrane system containing D2EHPA-TBP as synergistic carrier: optimization through response surface methodology

ABSTRACT The present investigation deals with silver extraction using an emulsion liquid membrane. The emulsion liquid membrane system consists of paraffin as organic phase, Span 80 as surfactant, Di-(2-ethylhexyl) phosphoric acid (D2EHPA) and Tributyl Phosphate (TBP) as carrier, and hydrochloric acid as stripping agent. Experiments were designed and modeled by response surface methodology using Design Expert 11 software, which determines the extraction rate as a function of Span 80 concentration, D2EHPA concentration, TBP concentration, HCl concentration, and treatment ratio. The ANOVA results indicate that the model is statistically significant because of the high R 2 (0.9828) and the low p-value of <0.0001. The results showed that the silver extraction increases by increasing all affecting parameters up to their optimal values and after that extraction rate decreases with increasing of them. The process was optimized to obtain maximum extraction rate, minimum D2EHPA concentration, and minimum treatment ratio. The optimal conditions were obtained at a surfactant concentration 3.26% (V/V), D2EHPA concentration 0.0045 mol/L, TBP concentration 5% (V/V), HCl concentration 0.56 mol/L, and treatment ratio 0.5. Under these conditions, the silver extraction rate was 99.87%.

Y-019. Immunomodulatory effect of vitamin D on the activators of transcription and transcription factors of CD4+ T cell subsets in pregnant women with preeclampsia

Supported liquid membrane (SLM) is a very promising method for the recovery and separation of valuable or toxic species from aqueous streams; however, stability is always a critical issue in practice. It is highly desired to develop a non-destructive technique to real-time monitor or detect the stability of an SLM process.The stability of an SLM processes was real-time analyzed by electrical impedance spectroscopy (EIS). The separation of equimolar Zn(II) and Cu(II) from sulfate solution through an SLM containing di(2-ethylhexyl) phosphoric acid (D2EHPA) in kerosene was selected as the model system owing to the established knowledge of extraction chemistry. Experiments were performed with two types of membrane supports (polycarbonate and poly(vinylidene) fluoride), different D2EHPA concentrations in the organic phase (0.001–0.1 mol/L), pH values of the feed (3.0–5.0) and strip (1.0–3.0) phases, and stirring speeds (0–200 rpm). Correlations between the membrane impedances analyzed according to a proposed equivalent circuit diagram and the separation factors of Zn2+ over Cu2+ measured by SLMs were done to verify the progress of the loss of membrane liquid.Under the conditions studied, the variations of membrane impedances and separation factors with time using both types of membrane support followed similar trends in most cases. A stability factor of a SLM process based on membrane impedance data was defined, which enables us to predict its relative stability. The present results also demonstrated that all parameters including membrane type, carrier concentration, aqueous pH values, and stirring speed influenced the transport and separation of Zn2+ over Cu2+ and SLM stability.

Application of saponified D2EHPA for the selective extraction of manganese from spend lithium-ion batteries

Solvent extraction is used for the selective extraction of manganese from an industrial leaching solution based on active material from spent lithium-ion batteries. As solvent 100 g L−1 di-(2-ethylhexyl) phosphoric acid (D2EHPA) diluted in Isopar L and an addition of 5 vol% tributyl phosphate is used. D2EHPA is well studied for the separation of manganese from cobalt and nickel but no data can be found on the influence of saponification. The influence of the saponification degree on the extraction yield and selectivity is investigated for two extraction stages. An overall extraction yield of 98.7% is achieved. 40% saponified D2EHPA for the first and 20% for the second stage at a phase ratio of 2.33 shows the best performance in terms of extraction yield and selectivity. The saponification influences the pH shift during the extraction from initial 2.8 to 3.4.

Selective Recovery of Iron by Solvent Extraction from Ni-Laterite Leach Solutions, as Precursor for the Synthesis of High Added-Value Nanomaterials

Iron is the major impurity in the pregnant leaching solutions (PLS) derived from heap and atmospheric acid leaching of low-grade laterite ores. The PLS can be considered as a secondary resource for the synthesis of high added-value iron nanomaterials, provided that the iron is selectively separated from the polymetallic PLS solution. In this study, the feasibility of selective iron separation was investigated by applying a solvent extraction technique based on the use of Di-2-ethylhexyl phosphoric acid (D2EHPA) and Tri-butyl phosphate (TBP) extractants. The effect of several parameters such as initial pH and PLS composition was studied to identify the conditions allowing the maximum possible separation of iron with the minimum co-extraction of other valuable metals. It was found that the best separation of Fe could be obtained when the initial pH of the aqueous phase was regulated close to 1.4. The recovery of iron from the loaded organic phase was studied using sulfuric acid as stripping reagent and elemental iron as solid reducing agent. It was found that 90% of Fe(III) could be stripped out by applying the metallic iron (galvanic) stripping.