Stripping Reagent Research Articles

A green and innovative approach to separate hexafluorophosphate from wastewater

Effluent derived from spent lithium-ion batteries (LIBs) electrolyte or discarded ionic liquids (ILs) is a potentially resource of hexafluorophosphate (PF6−) which can be recovered through solvent extraction. In this study, an efficient extraction approach was proposed to recover the hexafluorophosphate from solutions. A basic investigation on the interactions between extractants and hexafluorophosphate was firstly carried out using density functional theory (DFT), which demonstrated the stability of the extracted complex structure. The effects of extractant (Alamine336) and modifier, common anions and metallic ions in waste-streams, initial pH, and temperature on the extraction efficiency were explored. The results showed that 96.16 % of hexafluorophosphate could be extracted and transferred into organic phase using Alamine336/modifier as extractant under optimal conditions (0.15 mol/L of Alamine336 and 0.25 mol/L of modifier). The organic phase exhibited an excellent extraction capability of >95 % under optimal condition. Moreover, it was found that the use of sodium hydroxide as stripping reagent presented a superb stripping and cycling properties. Thermodynamic analysis and spectral data indicated that PF6− was extracted into the organic phase in the form of R3NH⋅PF6, which is a spontaneous exothermic process. The novel extraction method provides a broad application perspective for the removal and recovery of valuable hexafluorophosphate from aqueous system.

Solvent Extraction of Silver(I) using N,N-Diethylacetamido Substituted p-t-Octylcalix[4]arene in Nitrate Media

Solvent extraction of silver ions using tetrakis(N,N-diethylaminocarbonylmethoxy)-p-t-octylcalix[4]arene (EATOC) in chloroform from nitrate medium is presented. The influences on the extraction conditions affecting the behaviour of extraction depending upon the factors such as concentrations of acids, extractants and silver ions as well as extraction time were investigated. Various stripping reagents for back extraction to recover the loaded silver ions by forward extraction process were applied. The extraction mechanism of silver ions using EATOC was established on the 1H NMR chemical shift of the extractant as well as the slope assessments of extraction conditions both before and after loading the silver ions.

Recovery of Vanadium from Carbonated Solution by Extraction with Transformed Aliquat 336 and Stripping-Precipitation

ABSTRACT The leaching solution from the direct reduction-sodium smelting process of ultra-poor vanadium-bearing titanomagnetite contained sodium, vanadium, and impurities. It was carbonated to ensure sodium recovery, and the recovery of vanadium proved challenging. This study proposed and optimized a novel process of extracting vanadium from this alkaline carbonated solution using the transformed organic phase of 20 vol% (0.44 mol/L) Aliquat 336, 8 vol% 2-octanol, and 72 vol% sulfonated kerosene. To achieve superior vanadium extraction, Aliquat 336 in the organic phase was transformed into carbonate type by successively washing with NaHCO3 and NaOH solutions. The single-stage extraction efficiency of vanadium exceeded 85% at a pH of 8.0‒9.0 and an organic-to-aqueous phase ratio of 1:1. The thermodynamics of the vanadium extraction process was examined, confirming that the extraction process is an exothermic reaction (ΔH 0 = −9.56 kJ/mol). Furthermore, using a solution of 4 mol/L NH4Cl and 1 mol/L NH4OH with a pH of 8.8 as the effective stripping reagent to realize one-step stripping and precipitation of vanadium, the single-stage stripping efficiency of vanadium was 99.8%, and the precipitation efficiency was about 95%. Through this stripping-precipitation process, solid ammonium metavanadate with a purity of 98.14% was obtained in one step. The mechanisms of transformation, extraction, and stripping were studied via infrared spectra of the organic phases.

Ionic liquid for selective extraction of lithium ions from Tibetan salt lake brine with high Na/Li ratio

β-Diketones are often used to separate brine with a high sodium-to‑lithium ratio but cannot be widely used because of their high toxicity and water solubility. In this work, a functionalized ionic liquid was synthesized from 4,4,4-trifluoro-1-phenyl-1,3-butanedione and 1-hexyl-3-methylimidazolium chloride, which was verified by FT-IR and 1H NMR spectroscopy. An organic phase system was formed with this ionic liquid as the extractant and 2-octanone as the diluent, which had the advantage of achieving good extraction and separation performances without co-extractant. In addition, the brine used in this work is the real Chaka salt lake brine in Tibet, which provides a reference value for industrial application of separation of metal ions. The experimental conditions were optimized and the single-stage extraction efficiency of Li+ reached up to 94 %. Using LiCl solution and HCl as the washing and stripping reagents, the washing efficiency of Na+ and stripping efficiency of Li+ were above 98 % and 99 %, respectively. The raffinate was used to regenerate the organic phase, which reduced the use of alkaline reagents. Over 10 cycles of the extraction process, the extraction efficiency of Li+ maintained at approximately 86 %. The extraction mechanism was identified as ionic association using slope analysis and ultraviolet and infrared measurements.

Fabrication of polyethyleneimine functionalized magnetite nanoparticles for recyclable recovery of fucoidan from aqueous solution

Fucoidan is a kind of natural water-soluble fucose-rich sulfated polysaccharide with promising applications in the food and pharmaceutical industry. However, the traditional methods for fucoidan recovery from aqueous solution are expensive, time-consuming, and environmentally unfriendly. In this work, polyethyleneimine functionalized magnetite nanoparticles (PEI-MNPs) with well-defined core-shell structures were prepared by a Layer-by-Layer (LbL) approach using sodium tripolyphosphate (STPP) as a cross-linker. The as-prepared PEI-MNPs showed improved adsorption capability towards fucoidan at pH 4–8 due to the high density of cationic groups on the surfaces and the absence of internal pores. It was found that the adsorption process of fucoidan onto PEI-MNPs can reach to equilibrium in 50 min at room temperature. The maximum qe derived from the Langmuir isotherm at room temperature was 169.1 mg per g at a pH of 7. A selective fucoidan capture over a model protein BSA can be realized by adjusting pH (6–8) and salt concentration (0.5–2.5 M). The PEI-MNPs loading with fucoidan can be isolated from the final products by a neodymium magnet and regenerated by 4 M NaCl solution as stripping reagent. Therefore, this novel kind of PEI-MNP could be a promising candidate for highly efficient and recyclable recovery of fucoidan from an aqueous solution.

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.

Functionalization of Mesoporous Silica with a G-A-Mismatched dsDNA Chain for Efficient Identification and Selective Capturing of the MutY Protein.

MUTYH adenine DNA glycosylase and its homologous protein (collectively MutY) are typical DNA glycosylases with a [4Fe4S] cluster and a helix-hairpin-helix (HhH) motif in its structure. In the present work, the binding behaviors of the MutY protein to dsDNA containing different base mismatches were investigated. The type and distribution of base mismatch in the dsDNA chain were found to influence the DNA-protein binding interaction greatly. The [4Fe4S] cluster of the MutY protein is able to identify a G-A mismatch in the dsDNA chain specifically by monitoring the anomalies of charge transport in the dsDNA chain, allowing the entrance of the identified dsDNA chain into the internal cavity of the MutY protein and the strong DNA-protein binding at the HhH motif of the protein through multiple H-bonds. The dsDNA chain with a centrally located G-A mismatch is thus functionalized on mesoporous silica (MSN) via amination reaction, and the obtained dsDNA(G-A)@MSN is used as a powerful sorbent for the selective capturing of the MutY protein from complex samples. By using 0.5% NH3·H2O (m/v) as a stripping reagent, efficient isolation of the MutY protein from different cell lines and bacteria is achieved and the recovered MutY protein is demonstrated to maintain favorable DNA adenine glycosylase activity.

Development of purification of no-carrier-added 47Sc of theranostic interest: selective separation study from the natTi(n,p) process

Abstract Scandium-47 is one of the most promising medical radioisotopes, and its production and trace separation make it an attractive candidate for theranostic application. In this study, the production of no-carrier-added (NCA) 47Sc through the natTi(n,p) reaction and subsequent purification using liquid–liquid extraction was done for the theranostic application. The comparative separation of NCA 47Sc after the dissolution of an activated Ti target using Di-2-Ethylhexyl Phosphoric Acid (HDEHP) in kerosene was evaluated. The extraction process was optimized in terms of the concentration of extractant, extraction time, pH, and reaction temperature to achieve the maximum possible separation. HDEHP is efficient and promising for rapid extraction and separation of NCA 47Sc from Ti ions at low acidity (pH 0.85) with high extraction percent (>99%), contaminated with 22.3% of Ti ions after 5 min of extraction time. Different stripping reagents were used to separate loaded 47Sc and Ti ions. Firstly, 5 M HCl was enough for stripping the loaded Ti ions. Then the loaded 47Sc was separated with a purity of 100% using 0.05 M NaOH. The obtained results find the HDEHP a promising extractant for efficient separation of 47Sc from irradiated Ti target for preparing the 47Sc radiopharmaceuticals for theranostics applications.

Endothermic solvent extraction of copper (II) with furfuryl thioalcohol from sulfate medium

A simple solvent extraction method was developed to extract copper (II) from sulfate solution. The extraction of copper (II) with furfuryl thioalcohol was investigated. The effect of variables such as aqueous phase pH, furfuryl thioalcohol concentration, temperature, stripping reagents, and diluents was investigated. The extraction data revealed that using 15% (v/v) furfuryl thioalcohol with aqueous solution containing 0.5 mol L-1 Na2SO4, equilibrium pH 5.5, and phase ratio organic phase: aqueous phase (O:A) of 1:1 resulted in 98.20 percent extraction of copper (II) without nickel coextraction (II). Extraction isotherm results show that the extraction procedure is endothermic, with ΔH = 28.542 kJ mol-1 and ΔS = 41.740 J K-1 mol-1. Using 2.0 M H2SO4, copper loaded in organic phase was stripped at a rate greater than 99 percent.

Effect of spacer length between two weak NH hydrogen atoms of secondary diamido reagents on anionic platinum extraction

We have prepared three secondary diamides with 2-ethylhexyl branches and different spacer lengths as extraction reagents to investigate the extraction behavior of Pt(IV) in acid chloride media. Protonation of the carbonyl oxygen atoms of three diamides was investigated by peak observation of NH hydrogen atoms in 1H NMR spectra at varying HCl concentrations. The pKa values of the three diamides were determined, and the extraction was carried out at a lower HCl concentration using only NH hydrogen atoms for Pt(IV) extraction, not protonated carbonyl oxygen atom. The short time to reach equilibrium of Pt(IV) extraction indicated that the extraction occurred via outer-sphere coordination. Various spectroscopic data supported the extraction by the NH hydrogen atoms, and the extracted species were [PtCl6]2−. Slope analysis helped elucidate the stoichiometry but not the extraction mechanism, because of the high affinity of diamides and coexisting anions. Extraction reactions with the three diamides were also proposed. For selective extraction of [PtCl6]2−, extraction behavior of various metal ions were also carried out. For practical purpose, kerosene/2-ethylhexanol (80 vol%/20 vol%) was used as diluent, and selective extraction of [PtCl6]2− was compared using commercially available reagents, TOA, TBP, 2-ethylhexylacetoamide, and three diamido reagents. Furthermore, stripping of [PtCl6]2− loaded on three diamido reagents was investigated with stripping reagents. The spacer length of the three diamides significantly affected the extraction efficiency of [PtCl6]2−.

Pertraction of Vanadium(V) from Dilute Acidic Media by an Emulsion Liquid Membrane Containing a Commercial Extractant

AbstractEmulsion liquid membrane (ELM) pertraction of VV ions from dilute acidic solution by using a mixture of di(2‐ethylhexyl)phosphoric acid (D2EHPA) and mono(2‐ethylhexyl)phosphoric acid (M2EHPA) was studied. First, solvent extraction of VV from an aqueous medium was performed, and the optimum feed pH and extractant concentration were obtained. Tributyl phosphate was used as modifier to increase membrane stability and decrease membrane swelling. The effects of diluent type, extractant concentration of the emulsifier concentration, stripping reagent concentration (sulfuric acid), organic phase/stripping phase volume ratio, emulsification time and speed, feed initial pH, agitation speed, temperature, and contact time on VV extraction efficiency and ELM stability were considered.

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.

Abstract 2780: Development of automated multiplex immunofluorescence protocols for tumor microenvironment evaluation

Abstract Introduction: In recent years, the ability to detect several proteins on a single slide in Multiplex Immunofluorescence (mIF) experiments has become common place. This is possible thanks to factors such as development of antibodies of high quality, improvements in fluorescent technology, and automation of IHC staining. One of the advantages of multiplexing protein detection is to gain maximal data per tissue section, which is critical when samples are limited. Understanding co-expression and spatial organization of multiple targets within preserved tissue architecture is also important, especially in tumor microenvironment (TME) analysis. mIF plays a key role in research fields like tumor immunology where it is needed to catalog subsets of immune and cancer cells within the TME. Ultimately, this will enable the development of personalized, combinatorial therapeutic interventions. Materials and Methods: Selected antibody panels: Tonsil Panel 1: p40, CD3, CD8, CD20 & CD68 Tonsil Panel 2: LAG3 [BC40], LAG3 [CAL26], CD57, CD19, FOXP3, T-bet, PD-L1, PD-1 & GATA-3 Colon Cancer Panel: Granzyme B, CD8, CDX2, CD3 & Pan Cytokeratin Plus Melanoma Panel: Melan A, CD3, SOX10, CD8 & Granzyme B Detection was performed with Biocare MACH 2 Universal HRP Polymer. Fluorochromes: Opal 480, Opal 520, Opal 570, Opal 620, Opal 650 VALENT (Biocare Medical) fully automated staining platform was utilized to stain slides. Image acquisition and analysis was performed on an Olympus BX61 microscope coupled with the ASI FISH imaging system. In the workflow, a proprietary room temperature (RT) stripping reagent was utilized instead of the heat stripping step commonly used between antibody detection incubations. Results and Discussion: The antibodies used have been previously optimized for standard IHC protocols on VALENT using DAB. However, the sensitivity of tyramide detection is very high and for most of the antibodies, the incubation times had to be drastically reduced to minimize non-specific staining and the potential bleed-through to other filters for neighboring fluors. Additionally, Opal fluorochromes were diluted between 1:200 and 1:300. The RT stripping reagent helps in the preservation of tissue integrity even after the sequential detection of 5 antibodies. Additionally, by using this reagent, a rigorous order of primary antibody application is no longer needed. Finally, this reagent dimmed some autofluorescence coming from red blood cells. Following some brief optimization steps, we obtained strong and specific staining patterns similar to ones obtained with individual IHC experiments visualized with DAB. Conclusion: We have demonstrated the use on an automated platform of a RT stripping solution. Additionally, this reagent can be used with different antibodies in order to effectively characterize the TME in many cancers. Citation Format: Julio S. Masabanda, Sherry Wang, Joseph Vargas, Jason Ramos. Development of automated multiplex immunofluorescence protocols for tumor microenvironment evaluation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2780.

New process consisting of oxidative stripping of vanadium from loaded D2EHPA organic solution with H2O2 and direct precipitation with sulfuric acid

The traditional process of extracting V(IV) with di(2-ethylhexyl) phosphoric acid (D2EHPA) uses H2SO4 for V stripping and ammonium salt for V precipitation, leading to excessive consumption of H2SO4 and NH3·H2O, which results in a large volume of ammonia‑nitrogen wastewater. To solve this issue, a novel stripping reagent, H2O2, with the multifunction of oxidation and stripping, and a new method of precipitating vanadium from a solution of vanadium peroxy compounds were introduced to replace the traditional stripping reagent and ammonium salt precipitation, which requires separate stripping, oxidation, neutralisation and precipitation steps. The oxidative stripping of V from the loaded organic system consisting of 10% D2EHPA and 5% tri-butyl phosphate (TBP) in sulfonated kerosene using H2O2 was systematically investigated. The results indicated that 98.7% of the vanadium was stripped by three-stage cross-flow stripping under mild optimal conditions. Moreover, it was found that VO(O2)2–in the strip solution decomposed into VO(O2)+under oscillating conditions and the cation was synergistically re-extracted by D2EHPA and TBP, which resulted in a significant decrease in the stripping of vanadium and poisoning of the organic phase. The use of D2EHPA alone as the extractant can effectively prevent the problems encountered when H2O2 is used as the stripping reagent. The strip liquor could be used for direct precipitation of vanadium. A precipitation efficiency of 87% was obtained by adding a small amount of H2SO4. This new process combines oxidation, stripping and direct precipitation and exhibits the advantages of a short process flowsheet, with reagent savings (~95% decrease in H2SO4 consumption and no NH3·H2O consumption compared with traditional processes), and wastewater that is free of ammonia /nitrogen.

Tetrasulfonate calix[4]arene modified large pore mesoporous silica microspheres: Synthesis, characterization, and application in protein separation

Effective protein adsorption by solid matrices from complex biological samples has attracted attention for broad application in biomedical field. Immobilization of calixarenes to solid supports is an essential process for their application in protein separation and purification. Silica is the most widely used support material in calixarene immobilization. With high concentration of polymer microspheres as templates, the large pore mesoporous silica microspheres with controllable, uniform size and structure were successfully synthesized and the resulting large pore mesoporous silica microspheres were modified with water-soluble tetrasulfonate calix[4]arene of unique hollow cavity-shaped structure. The tetrasulfonate calix[4]arene modified large pore mesoporous silica microspheres (SCLX4@LPMS) were characterized by diverse analytical techniques and their protein adsorption performance were also investigated. The obtained SCLX4@LPMS gave rise to an adsorption efficiency of >90% for cytochrome c and lysozyme within a wide pH range of 3.0–10.0 and possessed remarkably high adsorption capacity of cytochrome c (363.64 mg g−1) and lysozyme (166.11 mg g−1). The retained cytochrome c and lysozyme can be readily eluted by using phosphate buffer solution containing NaCl as a stripping reagent with the recoveries of 81% and 86% after 5 times enrichment, respectively. The SCLX4@LPMS microspheres have been applied for the selective adsorption of proteins in real samples and had the application potential in protein adsorption, drug delivery, biosensors, and other biomedical fields.

Separation of thorium and uranium from xenotime leach solutions by solvent extraction using primary and tertiary amines

This study addressed the development of a continuous countercurrent extraction-scrubbing-stripping technique using a mixture of primary and tertiary amines as an effective extractant for both thorium (Th) and uranium (U) to simultaneously separate them from the leach solutions of xenotime concentrate from the Yen Phu mine (Vietnam). Systematic studies determined the optimum parameters of the separation, including the optimum concentrations of the mixture of the primary amine (N1923) and tertiary amine (tri-n-octyl amine), the optimum acidity (pH) of the feed liquor (Yen Phu xenotime leachate), the optimum contact time between phases for extraction, scrubbing and stripping processes, and the most suitable stripping reagent mixture. Using the optimum parameters, the optimum stage number and phase volumetric ratio for extraction, scrubbing, and stripping processes were calculated using the calculus method based on the law of matter conservation. The flow rates of both phases for extraction, scrubbing, and stripping were determined from the results of these studies and calculations. To optimize the separation of uranium and thorium from the Yen Phu xenotime leachate, counter-current simulations of extraction, scrubbing and stripping were done in a series of mixer-settler units. The results indicated that the selective separation of Th and U with almost no loss of rare earths (REs) and a minimal contamination of iron were obtained. The continuous countercurrent extraction-scrubbing-stripping technique shows potential applications in the commercial separation of Th and U from RE leachate after tests using a sequence of mixer-settler units on a pilot scale.

Selective removal of iron(III) from highly salted chloride acidic solutions by solvent extraction using di(2-ethylhexyl) phosphate

Metal ions including Fe3+, Ca2+, Mg2+, Ni2+, Co2+ and Cu2+ are commonly found in the leaching solution of laterite-nickel ores, and the pre-removal of Fe3+ is extremely important for the recovery of nickel and cobalt. Di(2-ethylhexyl)phosphate acid (D2EHPA) showed high extraction rate and selectivity of Fe3+ over other metal ions. The acidity of the aqueous solution is crucial to the extraction of Fe3+, and the stoichiometry ratio between Fe3+ and the extractant is 0.86:1.54. The enthalpy for the extraction of Fe3+ using D2EHPA was 19.50 kJ/mol. The extraction of Fe3+ was ⩾ 99% under the optimized conditions after a three-stage solvent extraction process. The iron stripping effects of different reagents showed an order of H2C2O4 > NH4HCO3 > HCl > NaCl > NaHCO3 > Na2SO3. The stripping of Fe was ⩾ 99% under the optimized conditions using H2C2O4 as a stripping reagent.

Functionalized Dipicolinic Acid Derivatives as TALSPEAK-MME Stripping Agents

ABSTRACT This work describes the results of an assessment of two derivatives of dipicolinic acid (DPA) as the actinide-selective stripping reagents in the combined HEH[EHP]/Cyanex-923 system, TALSPEAK-MME (mixed monofunctional extractants). One purpose of this investigation is to demonstrate probable advantages derived in phase-transfer kinetics by deploying dipicolinates as preorganized aminopolycarboxylate complexants in TALSPEAK-derived separation systems. The investigation is focused on the behavior of the lanthanides, Am, and selected transition metals (Zr, Mo, Pd, Ru, and Rh) in the extraction, solvent conditioning, and stripping steps. Solvent conditioning with glycine buffer solutions is shown to be effective for the removal of entrained HNO3 while also managing Pd concentration prior to actinide stripping. The efficacy of the DPA derivative during the actinide-selective strip was assessed, focusing explicitly on the effects of pH and ligand concentration and evaluating the stripping kinetics. These ligands were shown to be highly selective for americium, producing in the TALSPEAK-MME platform separation factors comparable to commonly used actinide selective stripping agents for radiotracer Eu, Am, a trans-lanthanide series and selected transition metals. The stripping kinetics study revealed very rapid phase-transfer reactions, reaching equilibrium in less than 10 s on vigorous agitation. Further work will be required to address the possible contamination of the product by selected transition metals (such as Zr) during the stripping step.

Selective separation of tungsten from the model and industrial effluents through supported liquid membrane

In this study, a selective separation of tungsten W (VI) from a mixed salt solution was done through a liquid-membrane technology. The transport of W (VI) across the supported liquid membrane was also applied on real sample. Tertiary amine (Tri-n-dodecylamine) was used as an organic carrier and a supported liquid membrane of polypropylene separator (celgard 2400) was used in this experimental work. The selective separation of W (VI) was optimized by various parameters i.e., concentration of metal in feed, concentartion of stripping agent, type of stripping reagents, carrier concentration and pH effect. The extraction of W(VI) was maximized by the concentration of carrier up to 0.2 mol/dm3 diluted in n-hexane. The optimum concentration of sodium hydroxide was 0.2 mol/dm3 in the strip phase. The transport of tungsten increases by the increase of the pH of feed solution to basic from acidic up to the pH 8. At pH 8 in the feed phase, tri-n-dodecylamine efficiently extracted W (VI) from feed through anion exchange mechanism. The time duration for the transport of tungsten was 6 h at room temperature. The optimized reaction of W(VI) for the selective separation was applied on the scheelite ore with 93% recoved. The single membrane was used in all experiments, which confirmed the durability and stability of polypropylene membrane.

Recovery of vanadium from acid leaching solutions of spent oil hydrotreating catalyst using solvent extraction with D2EHPA (P204)

In this paper, a process of selective extraction and separation of vanadium (IV) from acid leaching solution of spent oil hydrotreating catalyst by a solvent extraction method with P204 as an extractant was proposed. Because the leaching solution contained a large amount of elements such as nickel, aluminium and iron, the effects of various conditions on the separation of vanadium from nickel, aluminium and iron were investigated and the optimum conditions were determined. At the same time, the thermodynamic discussion on the extraction process of vanadium in the system was carried out. Using kerosene as a diluent and 20% (v/v) P204 as an extractant, the single-stage maximum extraction ratio of 93.47% for vanadium was obtained under the optimum extraction conditions of O/A ratio of 2, oscillation time of 8 min, extraction temperature of 298 k(25 °C) and pH value of initial aqueous phase of 2. After three stages of countercurrent extraction experiments, the concentration of vanadium, iron, nickel and aluminium in the loaded organic phase were 0.377, 0.001, 0.005 and 0.02 g/L, respectively, and their extraction ratios were determined to be 99.21%, 1.02%, 2.857% and 1.942%, respectively, realizing the selective extraction and separation of vanadium. With 2 mol/L of sulfuric acid as a stripping reagent, the complete removal of vanadium from the loaded organic phase could be achieved at O/A ratio of 2 by three stages of countercurrent experiments of vanadium removal. The thermodynamic calculation showed that the enthalpy change of the vanadium extraction in the system was −20.37 kJ.mol−1. This demonstrated that the extraction of vanadium from acid leaching solution of spent oil hydrotreating catalyst with P204 as the extractant was an exothermic reaction.