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1
Rodarte, Alma Isabel Marín. "Predispersed solvent extraction." Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/45173.
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A new solvent extraction method has been developed for the extraction of metal and organic ions from very dilute aqueous solutions. The new method, which has been named Predispersed Solvent Extraction (POSE), is based on the principle that 1 there is no need to comminute both phases. All that is necessary is to comminute the solvent phase prior to contacting it with the feed. This is done by converting the solvent into aphrons, which are micron-sized globules encapsulated in a soapy film. Since the aphrons are so small, it takes a long time for the solvent to rise to the surface under the influence of gravity alone. Therefore, the separation is expedited by piggy-back flotation of the aphrons on specially prepared gas bubbles, which are somewhat larger than aphrons and are called colloidal gas aphrons (CGA).
Copper, uranium and chromium ions, and alizarin yellow were extracted from very dilute aqueous solutions using PDSE. Tests were performed in a vertical glass column in both batch and continuous modes, and in a continuous horizontal trough. The new solvent extraction procedure worked very efficiently and very quickly under laboratory conditions. Higher than 99% extraction was achieved in many of the tests performed.
Master of Science
2
Tarkan, Haci Mustafa. "Air-assisted solvent extraction." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=102735.
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Air-Assisted Solvent Extraction (AASX) is a novel concept that uses a solvent-coated bubble to contact the organic and aqueous phases. The advantages over conventional solvent extraction (SX) are high solvent to aqueous contact area with reduced solvent volume and ease of phase separation due to the buoyancy imparted by the air core. This opens the way to treat dilute solutions (<1 g/L), such as effluents.The novel contribution in this thesis is the production of solvent-coated bubbles by exploiting foaming properties of kerosene-based solvents.
The basic set-up is a chamber to generate foam which is injected through a capillary (orifice diameter 2.5 mm) to produce solvent-coated bubbles (ca. 4.4 mm) which release into the aqueous phase. This generates a solvent specific surface area of ca. 3000 cm-1, equivalent to solvent droplets of ca. 20 mum. Demonstrating the process on dilute Cu solutions (down to 25 mg/L), high aqueous/organic ratios (ca. 75:1) and extractions are achieved. The solvent readily disengages to accumulate at the surface of the aqueous solution.
The LIX family of extractants imparts some foaming to kerosene based solvents but D2EHPA does not. An extensive experimental program determined that 1.5 ppm silicone oil provided the necessary foaming action without affecting extraction or stripping efficiency, greatly expanding the range of solvents that can be used in AASX.
To complement the foam study, films on bubbles blown in solvent were examined by interferometry (film thickness) and infra-red spectroscopy (film composition). A "bound" solvent layer was identified with an initial thickness of ca. 2 - 4 mum, comparable to that determined indirectly (by counting bubbles in an AASX trial and measuring solvent consumption). The film composition appeared to be independent of film thickness as it decreased with time.
As a start to scaling up, the single bubble generation system was adapted by installing up to 8 horizontal capillaries. The bubbles generated were ca. 3.4 mm. Trials showed the multi-bubble set up was a simple replication of the individual bubble case. Preliminary analysis of kinetic data shows a fit to a first-order model.
3
TRUJILLO, REBOLLO ANDRES. "SOLVENT EXTRACTION OF MOLYBDENUM." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184009.
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The equilibrium and the kinetics of the reaction of Mo (VI) with 8-hydroxyquinoline; 8-hydroxyquinaldine; KELEX 100; LIX63; and LIX65N were studied by solvent extraction. From the equilibrium studies it was concluded that in weakly acidic solution (pH 5 to 6) the overall extraction reaction is (UNFORMATTED TABLE FOLLOWS) MoO₄²⁻ + 2H⁺ + 2HL(o) ↔ (K(ex)) MoO₂L ₂(o) + 2H₂O (TABLE ENDS) where HL is the monoprotic bidentate ligand, "(o)" refers to the organic phase, and K(,ex) is the extraction constant. It was concluded that the complexation reaction requires four protons to convert molybdate into molybdenyl. The extractions constants for LIX63 and 8-hydroxyquinaldine, corrected for the side reaction of the ligand and metal, are 10¹⁶·⁴³ and 10¹⁴·⁴⁰, respectively. In the case of LIX65N, the plot of log(D) vs pH has a maximum at pH 1.0, which was explained qualitatively in terms of protonation of the ligand and molybdic acid at low pH. The extraction constant for the reaction of molybdic acid and the neutral ligand was estimated to be 100,000. The kinetics of extraction Mo (VI) with LIX63, 8-hydroxyquinoline, 8-hydroxyquinaldine, and Kelex 100 were studied in this work. In all cases, except 8-hydroxyquinoline, the rate-determining step of the reaction involves the formation of a 1:1 complex between the neutral ligand and several Mo(VI) species differing in the degree of protonation. The rate-determining step for the reaction of Mo(VI) with 8-hydroxyquinoline involves the formation of a 1:2 complex. The rate constant for the reaction of HMoO₄ with 8-hydroxyquinaldine is four orders of magnitude smaller than the corresponding value reported in the literature for 8-hydroxyquinoline. The slower reaction with 8-hydroxyquinaldine was attributed to the presence of the methyl group next to the nitrogen atom of the ligand which hinders its binding with molybdenum in the rate determining step of the reaction.
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Bajpayee, Anurag. "Directional solvent extraction desalination." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78539.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012."September 2012." Cataloged from PDF version of thesis.
Includes bibliographical references (p. 131-137).
World water supply is struggling to meet demand. Production of fresh water from the oceans could supply this demand almost indefinitely. As global energy consumption continues to increase, water and energy resources are getting closely intertwined, especially with regards to the water consumption and contamination in the unconventional oil and gas industry. Development of effective, affordable desalination and water treatment technologies is thus vital to meeting future demand, maintaining economic development, enabling continued growth of energy resources, and preventing regional and international conflict. We have developed a new low temperature, membrane-free desalination technology using directional solvents capable of extracting pure water from a contaminated solution without themselves dissolving in the recovered water. This method dissolves the water into a directional solvent by increasing its temperature, rejects salts and other contaminants, then recovers pure water by cooling back to ambient temperature, and re-uses the solvent. The directional solvents used here include soybean oil, hexanoic acid, decanoic acid, and octanoic acid with the last two observed to be the most effective. These fatty acids exhibit the required characteristics by having a hydrophilic carboxylic acid end which bonds to water molecules but the hydrophobic chain prevents the dissolution of water soluble salts as well the dissolution of the solvent in water. Directional solvent extraction may be considered a molecular-level desalination approach. Directional Solvent Extraction circumvents the need for membranes, uses simple, inexpensive machinery, and by operating at low temperatures offers the potential for using waste heat. This technique also lends itself well to treatment of feed waters over a wide range of total dissolved solids (TDS) levels and is one of the very few known techniques to extract water from saturated brines. We demonstrate >95% salt rejection for seawater TDS concentrations (35,000 ppm) as well as for oilfield produced water TDS concentrations (>100,000 ppm) and saturated brines (300,000 ppm) through a benchtop batch process, and recovery ratios as high as 85% for feed TDS of 35,000 ppm through a multi-stage batch process. We have also designed, constructed, and demonstrated a semi-continuous process prototype. The energy and economic analysis suggests that this technique could become an effective, affordable method for seawater desalination and for treatment of produced water from unconventional oil and gas extraction.
by Anurag Bajpayee.
Ph.D.
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Tavakolikhaledi, Mohammadreza. "Vanadium : leaching and solvent extraction." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/46814.
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The fundamental understanding of vanadium hydrometallurgy was developed in three phases: vanadium (V) leaching, vanadium (III) oxidative leaching, and solvent extraction of vanadium (V&IV).
In the first section, V₂O₅ leaching was studied in three steps. First, vanadium leaching and solubility of VO₂⁺ at different pH’s and temperatures were investigated in sulfuric acid. Secondly, the kinetics of vanadium leaching in pH 5 and pH 8 solutions, and the reductive leaching of vanadium pentoxide using sodium sulfite were studied. It was shown that the kinetics of acid leaching is rapid but suffers from low solubility of VO₂⁺ in solution. Thirdly, the shrinking sphere model was employed to analyze the kinetics of reductive leaching.
In the second step, V₂O₃ oxidative leaching was studied from 30°C to 90°C in sulfuric acid. This study has also been done in three different sections. First, the kinetics of oxidative leaching using oxygen was investigated. It was shown that this oxidative leaching is chemical reaction rate controlled with an activation energy of 69 kJ/mol. In the next step, it was shown that the presence of ferric enhanced kinetics significantly. Finally, oxidative leaching using a constant ferric-ferrous ratio from 1 to 300 was studied. The addition of KMnO₄ solution to the leach reactor was found to be a suitable oxidant for controlling solution potential. The oxidation rate using the constant ferric-ferrous ratio was very sensitive to temperature, with a large activation energy (38 kJ/mol) and the rate was proportional to the Fe(III)/Fe(II) concentration to the power of 0.47.
In the third part, purification of synthetic vanadium-containing solutions using the solvent extraction technique was investigated. Various solvent extractants have been tested for vanadium recovery from acid leachates. One of the biggest problems for purification of the vanadium solution is iron separation. Therefore, this research assesses selectivity of vanadium over iron. The extraction of vanadium (V&IV), iron (III&II) with phosphinic acid (CYANEX 272), phosphonic acid (IONQUEST 801), phosphoric acid (D2EHPA) and phosphine oxide (CYANEX 923) extractants is reported. In addition, the extraction reactions for vanadium (V) and (IV) extraction using CYANEX 923 and D2EHPA were also studied.
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Duhayon, Christophe. "Copper solvent extraction by ultrasound-assisted emulsification." Doctoral thesis, Universite Libre de Bruxelles, 2010. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210155.
Full textAbstract:
The goal of this research is to improve an extractive metallurgy process basedon solvent extraction. This process should fit the exploitation of small local
copper-rich deposits. In these conditions, the plant has to be as compact as
possible in order to be easily transported from one location to a subsequent
one. Improved extraction kinetics could ensure a high throughput of the
plant despite its compactness. In addition, the extraction reagent should
not be damaging for the environnement. On this basis, we propose to use
ultrasound-assisted solvent extraction. The main idea is to increase the
extraction kinetics by forming an emulsion in place of a dispersion thanks to
the intense cavitation produced by ultrasound. The benefit of this method
is to improve the copper extraction kinetics by increasing the interfacial
surface area and decreasing the width of the diffusion layer. We studied the
implementation of an highly branched decanoic acid (known as Versatic-
10®acid) as a copper extraction reagent dispersed in kerosene.
Emulsification is monitored through the Sauter diameter of the organic
phase droplets in aqueous phase. This diameter is measured during pulsed
and continuous ultrasound irradiation via a static light scattering technique.
The phenomenon of emulsification of our system by ultrasound is effective,
and the emulsification process carried out in the pulsed ultrasound mode is
at least as efficient as the emulsification obtained under continuous mode.
No improvement of emulsification is observed beyond a threshold time of
the ultrasound impulse. This may be attributed to a competition between
disruption and coalescence. The use of mechanical stirring combined with
pulsed ultrasound allows to control the droplet size distribution.
In presence of ultrasound, the extraction kinetics of Versatic-10 acid is
multiplied by a factor ten, and therefore reached a value similar to the kinetics
observed without ultrasound with an industrial extractant such as
LIX-860I®(Cognis). Extraction kinetics measurements are carried out by
monitoring the copper ion concentration in the aqueous phase with an electrochemical
cell.
We conclude that ultrasound-assisted emulsification can be implemented
under certain conditions. Emulsification is a first step, and the following
destabilization step has to be studied. The device using ultrasound-assisted
emulsification should be followed by an efficient settling-coalescing device. A
possible solution would be to promote emulsion destabilization by increasing
the ionic strength with an addition of MgSO4, a salt that is not extracted
by the extraction reagent in the considered range of pH.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
7
Suriyachat, Duangkamol. "Zirconium solvent extraction using organophosphorus compounds." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60718.
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This study compares zirconium extraction from hydrochloric acid solutions using either Cyanex 923 or Cyanex 925 in kerosene. While both are mixtures of trialkyl phosphine oxides, the trialkyl groups in the former have straight chains, while those in the latter have branched chains.The major variables studied were hydrochloric acid, extractant and zirconium concentrations, and phase ratio. With both reagents, zirconium is extracted rapidly. Extraction increases with increasing hydrochloric acid concentration, and zirconium is loaded as its neutral tetrachloride complex by a solvation reaction. The loaded zirconium forms a di-solvate, except at high excess extractant concentrations, where solvation numbers greater than 2 are found. At a constant total chloride concentration, the zirconium extraction level is maintained if hydrochloric acid is partially replaced by lithium chloride, provided sufficient hydrochloric acid is retained to prevent zirconium hydrolysis. Distribution coefficients decease with increasing zirconium concentration, suggesting that polymerization occurs in the aqueous phase.
For given conditions, zirconium extraction into Cyanex 923 is higher than for Cyanex 925. However, loading selectivity for zirconium over other metals has not been studied. A few preliminary experiments have shown that aqueous solutions of ammonium carbonate are potential stripping agents.
8
Hanif, Mohammed. "Mass transfer studies in solvent extraction." Thesis, Teesside University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328022.
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Chimpalee, Dolrudee. "Applications of ion-pair solvent extraction." Thesis, Queen's University Belfast, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336039.
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Lukhezo, Muchinyarawo. "Reactive solvent extraction of amino acids." Thesis, London South Bank University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245090.
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Anthony, Renil J. "Solvent Extraction of Lipids from Microalgae." Ohio University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1280854965.
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Ellis, Ross Johannes. "Chlorometallate extraction (base metals)." Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/5938.
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The work outlined in this thesis was sponsored, in part, by Anglo American and concerns the development of new technologies to achieve the concentration and separation of base metal values in chloride hydrometallurgical circuits. New processes for the production of zinc, cobalt and nickel aim to use solvent extraction to achieve the separation of metal values in highly concentrated acid chloride feeds containing iron and this thesis involves new extractants for potential use in these circuits. Anion exchange solvent extraction was chosen as the most practical approach and so a range of new reagents are described which remove zinc(II), cobalt(II) and iron(III) chlorometallates from acid chloride solutions via the reaction: nL(org) + nH+ + MClx n- [(LH)nMClx](org) Chapter 1 reviews the literature which concerns base metal chloride hydrometallurgy, presents a range of commercial processes and discusses the chemistry which underpins them. This chapter also outlines the new Anglo American circuits and the general approach to the design of base metal chlorometallate extractants. In Chapter 2, the analytical methods are discussed. These methods include the solvent extraction experiments that were used to define the behaviour of the new ligands and the techniques that were employed to examine the interactions between an extractant and a chlorometallate anion. Chapter 3 presents a series of five new amido-functionalised pyridine reagents that were designed to investigate the affect of hydrogen bond donor functionality on the extraction of zinc, cobalt and iron chlorometallates. The pyridine nitrogen atom is sterically hindered in the new reagents to suppress formation of inner-sphere complexes. Solvent extraction performance was found to vary considerably with hydrogen bond donor functionality and ligand structure. The ligand 2-(4,6-di-tertbutylpyridin- 2-yl)-N,N’-dihexylmalonamide (L2) was the strongest and most efficient extractant in this series and this was attributed to a ‘proton chelate’ six-membered ring interaction between the malonamide oxygens and the protonated pyridine nitrogen that resulted in a pre-organised array of N-H and C-H donors that could interact favourably with the chlorometallate anion. Chapter 4 explores a series of six new tertiary amine-based ligands which contain varying amido-functionality, e.g. 3-(di-2-ethylhexylamino)-N-hexylpropanamide (MAA). Zinc, cobalt and iron chlorometallate extraction studies show the amide and malonamide-functionalised ligands are notably stronger than the tertiary alkylamine control, tris-2-ethylhexylamine (TEHA). Platinum(IV) extraction is also discussed, showing that some of the new reagents are more efficient than the tren-based ligands previously described,{Bell Katherine, 2008 #93} which were the most efficient known. The enhanced extraction performance of the new ‘MAA-type’ ligands was again attributed to the formation of a ‘proton chelate’ six-membered ring forming [(LH)2MCl4] assemblies in the organic phase. Conditions have been identified which would allow separation of Fe(III), Co(II) and Zn(II) in circuits which use the ‘MAAtype’ reagents. Chapter 5 explores a series of three new malonamide reagents which contain varying alkyl-chain functionality, e.g. N,N’-dimethylhexylpentadecylmalonamide (M1), which are thought to extract chlorometallate anions via protonation of the carbonyl oxygens. Zinc, cobalt and iron chlorometallate extraction studies demonstrate that the malonamide ligands show high efficiency and selectivity for iron over zinc and cobalt. Performance as chlorometallate extractants was found to vary considerably with ligand structure and hydrogen bond donor functionality in all three ligand series, with a number of ligands showing potential for commercial application. Analysis of anion-host interactions suggests that chlorometallate binding in the organic phase probably proceeds via an array of both N-H and C-H weak hydrogen bonding interactions between the extractant and the outer-sphere of the metallate complex.
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Farawila, Anne. "Supercritical fluid extraction : Spectroscopic study of interactions comparison to solvent extraction." Université Louis Pasteur (Strasbourg) (1971-2008), 2005. https://publication-theses.unistra.fr/public/theses_doctorat/2005/FARAWILA_Anne_2005.pdf.
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Le dioxyde de carbone supercritique (SF-CO2) a été choisi afin d'étudier l'extraction en milieu supercritique d'ions métalliques tels que le césium et l'uranium. Un intérêt particulier a été porté au rôle de l'eau lors de ces extractions ainsi qu'à son interaction avec des agents chélateurs (AC). En première partie, les éthers couronne ont été choisis comme AC du césium et leur interaction avec l'eau a été étudiée dans le SF-CO2 en utilisant la spectroscopie InfraRouge à Transformée de Fourier (IR-TF). La configuration sandwich entre deux éthers couronne et une molécule d'eau a été observée dans le SF-CO2. Pour les configurations simple et pontée, l'équilibre a été défini et l'enthalpie de formation de la liaison hydrogène a été calculée. Ces résultats ont ensuite été comparés à ceux obtenus dans des mélanges de CHCl3 et de CCl4 en utilisant la spectroscopie à Résonance Magnétique Nucléaire (RMN). Pour conclure cette première partie, le rôle de l'eau a été étudié lors de l'extraction du picrate de césium par le DCH18C6 et les constantes d'équilibre ont été calculées. Dans une deuxième partie, l'extraction de l'uranium a été étudiée dans le SF-CO2. Des complexes de Phosphate de TriButyle (TBP), d'eau et d'acide nitrique ont été utilisés comme AC et oxydants. L'IR-TF a été utilisée pour étudier l'interaction entre le TBP et l'eau dans le SF-CO2. Ces résultats ont été comparés à ceux trouvés dans le CHCl3 en utilisant la RMN. Cette même spectroscopie a été utilisée pour comprendre les interactions entre l'acide nitrique, le TBP et l'eau, seuls puis dissous dans du CHCl3. La formation de microgouttelettes d'acide et d'eau dues à l'effet anti-solvant a été observée et quantifiée. Pour conclure ce travail de thèse j'ai réussi à optimiser l'extraction et la récupération d'uranium enrichi provenant de cendres d'incinération de déchets de fabrication de combustible nucléaire. Un complexe de TBP, d'eau et d'acide nitrique dissous dans du SF-CO2 a été utilisé à cette finSupercritical fluid carbon dioxide (SF-CO2) was chosen to study Supercritical Fluid Extraction (SFE) of cesium and uranium. At first, crown ethers were considered as chelating agents for the SFE of cesium. The role of water and its interaction with crown ethers were especially studied using Fourier-Transform Infra-Red (FT-IR) spectroscopy in SF-CO2. A sandwich configuration between two crown ethers and a water molecule was observed in the SF-CO2 phase for the first time. The equilibrium between the single and the bridge configurations was defined. The enthalpy of the hydrogen bond formation was also calculated. These results were then compared to the one in different mixtures of chloroform and carbon tetra-chloride using Nuclear Magnetic Resonance (NMR). To conclude this first part and in order to understand the whole picture of the recovery of cesium, I studied the role of water in the equilibrium between the cesium and the dicyclohexano18-crown-6. In a second part, the supercritical fluid extraction of uranium was studied in SF-CO2. For this purpose, different complexes of TriButyl Phosphate (TBP), nitric acid and water were used as chelating and oxidizing agents. I first used FT-IR to study the TBP-water interaction in SF-CO2. These results were then compared to the one obtained with NMR in chloroform. NMR spectroscopy was also used to understand the TBP-nitric acid-water interaction first alone and then in chloroform. To conclude my research work, I succeeded to improve the efficiency of uranium extraction and stripping into water for a pilot-plant where enriched uranium is extracted from incinerated waste coming from nuclear fuel fabrication. TBP-nitric acid complexes were used in SF-CO2 for the extraction of uranium from ash
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Fowler, Sandra Dee. "COPPER SOLVENT EXTRACTION FROM CHLORIDE-SULFATE MEDIA." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275369.
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Pornsinlapatip, Pornpun. "Flow-injection solvent extraction of metal chelates." Thesis, Queen's University Belfast, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284394.
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Copcutt, Robert Charles. "Modeling of a counter-current adsorption process for removal and recovery of dissolved organics from aqueous effluents." Thesis, University of Cape Town, 1988. http://hdl.handle.net/11427/23191.
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Healy, Mary Rose. "Outer-sphere interactions in metal solvent extraction systems." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/28712.
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This work aims to define the modes of action of a series of metal extraction ligands with particular focus on how these depend on the formation of supramolecular assemblies. Though solvent extraction processes are well established industrially often the understanding, particularly of the metal coordination chemistry, is less so. A greater understanding of a variety of solvent extraction systems can lead to the development of stronger and more specific extractants. Chapter 2 examines the role of inter-ligand interactions in the extraction of copper by phenolic oximes and pyrazoles. Computational methods are used to understand the importance of inter-ligand outer-sphere interactions in square-planar copper complexes. It is shown that functionalisation at different positions on the phenol ring can either stabilise or destabilise the copper complex and it is possible to predict the strength of extractants from DFT calculations. Substitution ortho to the phenolic oxygen in the oximes and pyrazoles can have a major effect of enhancing the strength of extractants by “buttressing” the H-bonding between ligands. However, in the amino-methyl substituted oximes buttressing is so strong that is has an adverse effect on complex formation. Crystal structures are confirmed by both ENDOR EPR spectroscopy and DFT structures. A series of 6-X-4-methyl-2-(5-alkyl-1H-pyrazol-3-yl)- phenols (X = H, OMe, Br and NO2) was synthesised and characterised (X = H, OMe, Br and NO2) and the copper extractant found to be 6-nitro-4-methyl-2-(5-(1,3,5-tri-methyl-pentyl)- 1H-pyrazol-3-yl)-phenol extractants. Computational DFT studies in the gas phase were carried out to calculate the formation energies of analogous phenolic pyrazole copper complexes. The predicted order of these energies followed the same trend shown by experimental solvent extraction studies. Studies also showed that substitution can affect not only complex stability through inter-ligand interactions through hydrogen bonding in the outer-sphere but also the strength of metal-ligand bonds. Chapter 3 looks at synergistic solvent extraction systems: where more than one extractant works together to provide additional strength and selectivity. Combinations of neutral N and O donor ligands with carboxylic, phosphinic and sulfonic acids were studied by solvent extraction, crystallographic and computational methods. Crystal structures and DFT-optimised structures show that ligands and acid form pseudo-tridentate ligands where both the neutral ligand and the deprotonated acid are coordinated directly to the metal centre with inter-ligand hydrogen bonding allowing for a more flexible backbone than a classic tridentate system. Although synergistic extractions systems often utilise carboxylic acids many of the structures show the similarities with systems containing phosphinic acids and it was shown experimentally that some extraction systems show greater synergism with phosphinic than carboxylic acid in the recovery of nickel. Chapter 4 deals with the extraction of molybdenum with commercial phosphinic acid extractant Cyanex 600. The propensity for molybdenum to form oxo clusters in aqueous solutions and the influence pH in both the speciation of the Mo species and extraction conditions contributes to a complex extraction profile. The pH dependence of extraction shows that different mechanisms operate at low (pH < 0) and high (pH > 0) pH. The extraction curve shows a conventional S-curve between pH 0 and 1.5 and slope analysis within this pH range gives a value very close to two but identification of structures which match this profile is complex. Maximum pH extraction is see at ~ pH 1.5. ESMS studies identified very similar species in the organic phase despite the variation seen in the S-curve. A survey of the structures of metal complexes of phosphinate ligands suggests that molybdenum-phosphinate complexes can often form cubane-like structure and negative ion ESMS data supports the concept of cluster formation in the organic phase. A common feature of the spectra are tetra- tri- and bi-metal- oxo species and spectra show a large number of peaks. It is very probable that the extraction of molybdenum(VI) with phosphinic acids is a dynamic system as extraction is influenced by the molybdenum speciation in the aqueous phase which is in turn influenced by both the pH and the molybdenum concentration both of which change over the course of a conventional extraction.
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Ashrafizadeh, Seyed Nezameddin. "Solvent extraction and liquid membrane separation of rhodium." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=37698.
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The aim of this work was to develop a viable solvent-extraction based system for the separation of rhodium (Rh) from aqueous chloride solutions. Ultimately, two different systems were developed. Kelex 100, a commercially available derivative of 8-hydroxyquinoline, was used as the extractant reagent in both of these systems. One of the systems involved the supported liquid membrane (SLM) extraction of Rh. In this system a very thin microporous "Gore-Tex" polymer sheet, impregnated with an organic solution of Kelex 100, served as the SLM. The other system involved the conversion of the chlorocomplexes of Rh to bromocomplexes prior to their solvent extraction with Kelex 100.The results of the lab-scale experiments using a SLM of Kelex 100 having a surface area of 44 cm2 are reported. The optimum conditions for Rh permeation were found as a feed solution of 2.5 M HCl and a strip solution of 0.1 M HCl. The SLM was quite stable at the optimum conditions with no sign of organic loss or membrane deterioration after 72 hours of operation. It was determined that the HCl activity gradient across the membrane acts as the driving force that "pumps" the non-aquated Rh chlorocomplexes against their concentration gradient. The mechanism of Rh permeation was the ion-pair formation between the protonated Kelex 100 and RhCl6 3- complexes. The rate of Rh permeation was in the order of 10-6 mol.m-2.s-1. The mechanism of HCl and H2O permeation, which were co-extracted along with Rh chlorocomplexes, were found to be the hydration of protons at the low feed acid region and the formation of microemulsions at the high feed acid region. The permeated acid and water were separated from the SLM receiving phase by contacting the latter phase with an organic solution of trioctylamine (TOA). The chlorocomplexes of Rh(III) and acid are readily extracted to the TOA organic phase and subsequently subjected to differential stripping with a concentrated solution of Cl- and a mild NaOH solution, respectively. By interfacing the TOA solvent extraction with the SLM of Kelex 100 highly concentrated solutions of Rh (at least 10 times the initial concentration) and raffinates essentially free of rhodium were produced.
The UV-Visible investigations revealed that the bromocomplexes of Rh undergo aquation to a much lesser extent than that of the chlorocomplexes. The chlorocomplexes of Rh were converted to bromocomplexes by precipitating first the Na(NH4)2Rh(NO2)6 salt and subsequently dissolving that in an HBr solution. The newly formed bromocomplexes of Rh(III) responded very favorably to extraction with Kelex 100. Relatively high distribution coefficients, about 20, and very steep extraction isotherms were generated. The freshly loaded Kelex 100 organic was efficiently stripped upon contact with a strip solution of 6--8 M HCl and a contact time of 10--12 hours. The developed system shows high promise from a practical implementation point of view.
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Gordon, Ross John. "Improved mass transport efficiency in copper solvent extraction." Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/5673.
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This thesis considers methods which can be employed to increase the mass of copper transferred into and out of the organic phase during the load and strip stages of commercial solvent extraction processes. Conventional 5-alkylsalicylaldoxime reagents transfer 1 mol of divalent copper per 2 mol of ligand in a neutral complex of the type [Cu(L-H)2] via a pH-swing process. New triacidic ligands have been designed which triple the molar transport of copper to form [Cu3(L-3H)2]. Until recently copper recovery by solvent extraction has been confined to oxidic ores which are leached with sulfuric acid. New leaching technologies generate high tenor copper sulfate feed streams from sulfidic ores. The conventional 5- alkylsalicylaldoxime reagents do not work effectively in conjunction with these leach processes as they do not consume the acid which is generated on loading the oxime. To address this problem ditopic zwitterionic ligands have been designed which can transfer both metal cation and attendant anion. These new metal salt reagents are diacidic, therefore not only transfer metal salts but also increase the molar transport relative to the conventional reagents. Equilibrium-modifiers are often added to improve the mass transport efficiency of conventional solvent extraction processes. The nature of their interaction with the species in solution is poorly understood. This thesis investigates their interaction with the free ligands and copper complexes to gain an understanding of their mode of action in order to rationalise the design of future modifiers to optimise recovery efficiencies. Increased molar transport is addressed in Chapter 2. The diacidic ligand 5- methylsalicylaldehyde-pivaloylhydrazide (L2) and its dinuclear copper complex [Cu2(L2-2H)2] were synthesised and characterised to gain an understanding of their speciation in solution. X-ray structural analysis of [Cu2(L2-2H)2] confirmed that the phenolate oxygen atoms bridge the copper centres rather than the amidato oxygen atoms of the hydrazone. Variable temperature magnetic susceptibility data confirm that the copper centres are antiferromagnetically coupled as expected for the Cu-OCu angle (99.6(2)°). An understanding of the coordination geometry of the dinuclear systems lead to design of triacidic ligands. A series of 3-hydrazono- and 3- hydroxyanil- 5-alkylsalicylic acids were synthesised. The prototype ligand 5-methyl 3-octanoylhydrazonosalicylic acid (L6) was demonstrated to triple molar transport and increase mass transport by 2.5 fold. Solvent extraction results indicate that copper is sequentially loaded as pH is increased. The plateaux observed in loading curves suggest formation of stable mono-, di-, and tri-nuclear copper complexes within the pH-ranges 1.75 - 2.75, 3.25 - 4.0 and > 4.25 respectively. The triacidic ligands were also demonstrated to double the molar transport of the conventional salicylaldoximes when used in 1:1 blends by formation of a ternary complex. Chapter 3 describes the incorporation of two tertiary amine groups into diacidic salicylaldehydehydrazone ligands to form dinucleating metal salt extractants. Piperidinomethyl, piperazinomethyl and dihexylamino groups were incorporated into various positions of the ligand including 3- and/or 5- positions of the salicylaldehyde or incorporated into the hydrazone. Solvent extraction results obtained for 3,5- bis((dihexylamino)methyl)salicylaldehyde-octanoic hydrazone (L20) are consistent with transfer of 1 mol of copper sulfate per mol of ligand in the organic phase between pH 2.0 and 2.5. This result is indicative of the formation of [Cu2(L20)2(SO4)2]. Conventional salicylaldoximes are “strong” copper extractants which require concentrated acid electrolyte to efficiently strip the copper from the organic phase. However, as the use of concentrated acid affects the quality of the copper cathodes, oxygen-containing equilibrium modifiers are often added. These facilitate copper stripping without adversely affecting the loading. The affect of 2-ethylhexanol (2- EH) and trioctylphosphine oxide (TOPO) on the extractive ability of 5-toctylsalicylaldoxime (19) in n-heptane is reported. Both are found to decrease copper extraction more under stripping conditions than loading conditions. 2-EH shows little affect at pH greater than 2.5. TOPO does not significantly affect copper loading at pH greater than 3.0. Evidence for the formation of the adduct [Cu(19-H)2)(TOPO)] was obtained from UV/Vis, IR, EPR and sonic spray mass spectrometry.
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Pschirer, David M. "Electrochemical uranium valence control in centrifugal solvent extraction contractors." Thesis, Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/12995.
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Shoko, Lay. "The chemistry of the alkali-induced solubilisation of coal." Pretoria : [s.n.], 2005. http://upetd.up.ac.za/thesis/available/etd-02222007-173845.
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Rashid, Salman Ghanem. "Studies on copper extraction with hydroxyoxime extractants for the design of hollow fibre membrane based extraction processes." Thesis, University of South Wales, 1999. https://pure.southwales.ac.uk/en/studentthesis/studies-on-copper-extraction-with-hydroxyoxime-extractants-for-the-design-of-hollow-fibre-membrane-based-extraction-processes(7e631b77-71e2-4d6e-8c03-4636d42f9f69).html.
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This work has included a review of the most relevant aspects of measurement techniques and mathematical models proposed in the literature to assess the equilibrium and mass transfer data of metal extraction by the use of chelating agents. The limitations of these techniques and models have been highlighted. Three chelating extractants diluted in EscaidllO were used to study the extraction equilibrium of copper. The extractants are 5-nonylacetophenone oxime (LIX84®), 5- dodeylsalicylaldoxime (LIX860®) and 50/50 v/v mixture of both oximes (LIX984®). The copper concentration changes in the aqueous and the organic phases were monitored by using atomic absorption spectrophotometer. Two mathematical models (a chemical model and a semi-empirical model) have been developed in this study to predict the equilibrium data of copper sulfate/hydroxyoxime system. The chemical model was found to fit all the three equilibrium systems (CuSO4/LIX84®, LIX860®and LIX984®) equally. The semi-empirical model based on Freundlich's adsorption equation was also found to fit the three systems but with less accuracy. The mass transfer characteristics and properties of copper extraction and recovery from an aqueous solution using LIX984® were studied using dispersion-based (rising drops) and dispersion-free techniques. In the dispersion-based technique the organic phase was dispersed in form of drops at the tip of hypodermic needle while the aqueous solution was used as a continuous phase. The extraction process was carried out in four different height columns under wide range of conditions. The effects of the columns' height, the dispersed and the continuous phases concentrations on the metal rate of mass transfer were investigated. It has been found in that the metal's rate of mass transfer and system's overall mass transfer coefficient have remained constant in all four columns. A model utilising the two-film theory, some of the dimensionless groups and the experimental results has been proposed in this work to calculate the local mass transfer coefficients in the dispersed phase and the continuous phase. The overall mass transfer coefficient and the calculated local coefficients were used to account for the reaction rate constant at the interface from the sum of the individual resistances to mass transfer. A dispersion-free technique consisting of a microporous hollow fibre module was used in this study to examine the mass transfer properties of the extraction and stripping processes of copper across an immobilised interface system. The extraction and re-extraction (stripping) processes in this system were conducted under a wide range of operating conditions and produced satisfactory results. In general it has been found that counter current flow arrangement gave higher concentration driving forces which were reflected in form higher metal concentrations at the extract phase. A generalised mathematical model was developed in this study which utilised Wilson's method, the experimental data, some dimensionless groups and the two-film theory to account for local resistances and predict the system's overall mass transfer coefficient. A correlation was established first to calculate mass transfer coefficients using a form of Leveque's equation which relates the two phase's physical properties and the system's parameters. The membrane mass transfer coefficient was calculated from the structural properties of the membrane material. While the resistance at the reaction interface was calculated under set of experimental conditions. The individual coefficients were then used to predict the overall mass transfer coefficient under any set of conditions by using the aditivity approach of the individual resistances to mass transfer. However, further checks and investigations are necessary to validate this model over variety of extraction systems and membrane configurations.
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Choi, Kwansik. "Molecular interactions in polar solvents." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/17851.
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Johnson, Timothy Lee. "Surface mediated reduction of chlorinated solvents by zero-valent iron /." Full text open access at:, 1997. http://content.ohsu.edu/u?/etd,598.
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Haupt, Petronella. "Effective solvent extraction of coal and subsequent separation processes." Diss., Pretoria : [s.n.], 2006. http://upetd.up.ac.za/thesis/available/etd-08282007-113611.
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Thesis (M. Eng.)(Chemical Engineering)--University of Pretoria, 2006.Accompanied by a CD-ROM containing Matlab programs. Includes bibliographical references. Available on the Internet via the World Wide Web.
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Cattrall, R. W. "Studies in solvent extraction chemistry and ion-selective electrodes /." Title page and contents only, 1985. http://web4.library.adelaide.edu.au/theses/09SD/09sdc369.pdf.
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Rodarte, Alma Isabel Marín. "Predispersed solvent extraction of copper from dilute aqueous solution /." This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-07282008-134126/.
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Chamupathi, Virittamulla Gamage. "Role of the interface in metal solvent extraction kinetics." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184256.
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Interfacially active reagents are utilized in metal solvent extraction processes and it is therefore important to understand the role of the liquid-liquid interface in the study of the kinetics and equilibria of extraction. The diffusion problems encountered in the traditional apparatus were overcome by using a high speed stirring apparatus. The microporous teflon membrane phase separator permitted more accurate measurements of interfacial areas, characterization of extraction kinetics of metal chelates, and a greater understanding of the phase separation mechanism. In contrast to the neutral ligands, the anionic ligand of dithizones and substituted dithizones showed significant interfacial adsorption at the chloroform/water interface as monitored spectro-photometrically. Equilibrium studies on p-halodithizones indicated that the adsorption constant increased as the substituent was altered from chloro to bromo to iodo, and with the distribution ratio of the ligand. Kinetic studies on dithizone and p-iododithizone with Ni(II) and Zn(II) indicated that the extent of participation of the interface in solvent extraction kinetics of these metal ions is dictated by the interfacial activity of the extractant and the mechanisms of the rate limiting step in the bulk aqueous and interfacial regions.
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Haq, Fida-Ul. "Solvent extraction of copper and zinc from aqueous solution." Thesis, Teesside University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283231.
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Mahmood, Z. "Some studies of modelling in solvent extraction of metals." Thesis, Teesside University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379117.
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Rambocus, Subhas. "Reactive solvent extraction of dicarboxylic and carboxylic-sulfonic acids." Thesis, London South Bank University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245144.
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Fowler, Michael James. "Construction of prototype system for directional solvent extraction desalination." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/76130.
Full textAbstract:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 37-38).
Directional solvent extraction has been demonstrated as a low temperature, membrane free desalination process. This method dissolves the water into an inexpensive, benign directional solvent, rejects the contaminants, then recovers pure water, and re-uses the solvent. In order to bring this technology closer to real world application, a continuous process prototype for a directional solvent extraction system was developed and tested. Octanoic acid was used as the solvent of choice, and a system capable of producing up to 7 gallons per day of fresh water was constructed. The system was tested to effectively desalinate the feed water, and the total system power was less than 7 kW. The system was constructed and first tested to run fresh water and solvent through it. Fresh water was dissolved in and separated, as expected, from the solvent at a rate of about 2 gpd. Saline water containing 3.5% sodium chloride was then used as feedwater and the desalinated water was recovered at a rate of about 1 gpd with an average salinity of 0.175%. Effective continuous operation of the directional solvent extraction prototype was demonstrated. Certain design improvements to increase efficiency, optimize component sizes, and decrease energy consumption are suggested. The demonstrated system has a wide range of applications, including production of fresh water from the sea, as well as, treatment of produced and flowback water from shale gas and oil extraction.
by Michael James Fowler.
S.B.
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Rodarte, Alma Isabel MarÃn. "Predispersed solvent extraction of copper from dilute aqueous solution." Diss., Virginia Tech, 1991. http://hdl.handle.net/10919/38846.
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Predispersed Solvent Extraction (POSE) was used to extract copper ions from dilute acidic aqueous solution. POSE is based on the principle that there is no need to comminute both phases. All that is necessary is to comminute the solvent phase prior to contacting it with the feed. This is done by converting the solvent into aphrons. which are micron-sized globules encapsulated in a soapy film. Since the aphrons are so small, it takes a long time for the solvent to rise to the surface under the influence of gravity alone. Therefore, the separation is expedited by piggy-back flotation of the aphrons on especially prepared gas bubbles, which are somewhat larger than aphrons and are called colloidal gas aphrons (CGA).
Polyaphrons of various types were studied extensively. The apparatus used to generate the polyaphrons was upgraded. The residence time distribution of a liquid in the polyaphron generator was determined. The particle size distribution of polyaphrons was determined using photo-microscopy and sedimentation among other methods.
Batch tests were done using both conventional and POSE. Results showed that POSE approaches equilibrium much faster than conventional extraction. Equilibrium isotherms were drawn and empirical equilibrium relationships were developed. The dynamics of the kinetics of the extraction was modeled using film theory.
Equipment for the POSE process was built. Experiments were carried out in continuous mode and the process was optimized. An empirical statistical equation was developed for the extraction process in continuous mode. Depending on the aqueous to solvent ration, more than 99% copper can be extracted.Ph. D.
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Sundell, Oscar. "Solvent extraction of antimony and tin from speiss leachate." Thesis, Luleå tekniska universitet, Kemiteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-65822.
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This work is a cooperation with Boliden Minerals AB, who recently has been interested in recovering more valuable elements from their byproducts. For this case, solvent extraction was chosen as a potential method of recovering these valuables, as it is a method considered to be ideal for separation of trace elements from large amounts of other substances. The goal for this work was to execute manual extraction experiments as a preparation for a bigger project at LTU. The objectives of this thesis included the investigation of the selectivity for extraction of tin and antimony, using different concentrations of hydrochloric acid in the feed solution, analysis of the equilibrium isotherms for Sn and Sb at 8M of HCl as well as the evaluation of the number of steps needed for future extraction experiments, using the McCabe- Thiele method. By executing manual experiments with a speiss precipitate dissolved in hydrochloric acid, the results obtained indicated that the selectivity increased with a higher content of HCl in the feed solution. Using different ratios between the aqueous and organic phase, the equilibrium curves denoted a pushback effect, causing antimony to migrate back into the aqueous phase at the saturation level of tin. By constructing a McCable-Thiele diagram according to the equilibrium curves, the number of steps could be evaluated to three.
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Dakubo, Francis. "Sustainable Mining - Solving the Problem of Chalcopyrite Treatment/Processing - Leaching, Solvent Extraction & Flotation." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/604862.
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Chalcopyrite ore forms the significant fraction of copper deposits in the earth crust. However, it is also the most difficult to treat using conventional ferric leaching methods. Smelting and electro-refining are currently the methods used in treating chalcopyrite concentrate obtained from froth flotation. Due to the ever increasing environmental requirements on smelters by the Environmental Protection Agency, new smelters are scarce in the United States. The scarcity of smelters has led to the urgent need to find a novel leaching method for the abundant chalcopyrite deposits in the USA and the rest of the world. This chapter(one) of the dissertation, therefore, investigated the leaching of chalcopyrite ore at pH 2 using a newly discovered oxidant (peroxodisulfate). Our results show that chalcopyrite leaching using peroxodisulfate follows a surface reaction shrinking core model. The activation energy of chalcopyrite leaching using peroxodisulfate ion was calculated as 41.1 kJ mol⁻¹. We also report that the leaching of chalcopyrite ore is affected by particle size and that stirring hurts leaching of chalcopyrite. Additionally, we found that peroxodisulfate can produce from sulfuric ions electrochemically. Hydrogen peroxide, permanganate, peroxodisulfate and ferric ions are all strong oxidants that have been researched in production pregnant leach solution (PLS) from chalcopyrite ore leaching. Because, solvent extraction is the next step in the recovery of copper from pregnant leach solutions (PLS). The questions, therefore, arises as to the fate of the organic extractant used in solvent extraction coming in contact with strong oxidant residual in the PLS. In chapter two of the dissertation, we studied the effect of strong oxidant residual in PLS on the degradation of organic extractants during solvent extraction of copper. Exposed organic extractants were analyzed using interfacial tension(IFT), Fourier Transform Infrared (FTIR) spectroscopy and CG LS. The results obtained from IFT and FTIR analysis, show no effect on the organic extractants exposed to sunlight and PLS containing the residual strong oxidant. Finally in chapter 3, the dissertation exams alternative water source for the flotation of chalcopyrite. Mineral flotation is a water-intensive process in mining. In order to sustain mining operations such flotation, which rely heavily on water, chapter 3 of the dissertation looks at using alternative water sources (in this case reclaimed wastewater) in the flotation of chalcopyrite ores; this effort is to limit the mining industries dependence on fresh ground water particularly in the Southwest of United States where water is a scarce commodity. The research studied the effect of reclaimed waste water on chalcopyrite flotation via contact angle and surface energy measurements. Furthermore, atomic force microscopy (AFM) and flotation tests were used to supplement the findings from contact angle and surface studies. We conclude here that the contact angle of a pure chalcopyrite surface was determined to be 75.6 degrees. We also found that pure chalcopyrite mineral surface is slightly polar with surface energies γCuFeS2^(LW) = 41.4 mJ/m² (apolar), γCuFeS2^(AB) = 2.9 mJ/m² (polar). The high value of the surface energy indicates pure chalcopyrite surface is slightly hydrophobic.
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Ola, Pius Dore. "Solvent extraction and liquid membrane containing ionic liquids and deep eutectic solvents for metal separation." Thesis, https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB13097323/?lang=0, 2018. https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB13097323/?lang=0.
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Navarro, Maria del Carmen. "Hydrogen stripping of copper from loaded LIX 65N." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66059.
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Tawfik, Wahid Yosry. "Design of optimal fuel grade ethanol recovery system using solvent extraction." Diss., Georgia Institute of Technology, 1986. http://hdl.handle.net/1853/11152.
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Wilson, Andrew Matthew. "Ditopic reagents for the solvent extraction of platinum group metals." Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/16864.
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This work aims to develop solvent extractants to recover platinum and palladium from highly acidic chloride solutions bearing other platinum group metals (PGMs). In general, metal values can be recovered by solvent extraction through three different mechanisms: metal cation extraction (1); metalate anion extraction (2); or metal salt extraction (3). Mn- + n(LH)(org) ⇌ [M(L)n](org) + nH+ (1) MClx n- + nL(org) + nH+ ⇌ [MClx(LH)n](org) (2) MClx + nL(org) ⇌ [MClxLn](org) (3) The main objective of this thesis is to establish whether ditopic extractants can be developed which have chemical functionalities that allow both mechanisms (2) and (3) to operate, co-extracting Pt(IV) and Pd(II) as their chloridometalates in an outer sphere binding site (2) and allowing their separation by raising pH to transfer the more kinetically labile Pd(II) to an inner sphere binding site (3) and releasing H2PtCl6 to the aqueous strip solution. A review of the literature is presented in Chapter 1, noting current commercially available extractants and the processes in which they are, or have been, applied. Particular attention is paid to the mode of action of the reported extractants and whether they extract metal cations, anions or metal salts. This chapter also outlines the proposed solvent extraction circuit in which new reagents developed in this thesis would be incorporated and the methods applied during the screening of candidate extractants. Chapter 2 deals exclusively with the use of reagents with inner-sphere binding sites for the selective extraction of palladium over platinum. Work on a series of oxime reagents synthesised for palladium extraction as part of preliminary MSci research (Andrew M. Wilson, MSci Thesis, University of Edinburgh, 2011) is reviewed. Studies of the hydrolytic stability of oximes indicate that they are unsuitable for incorporation into ditopic reagents for use in a circuit with a highly acidic feed solution. Thioethers were studied as alternatives as they show high kinetic selectivity for palladium over platinum and are more stable under acidic conditions. The synthesis and extraction properties of model reagents (largely arylalkyl thioethers) are reported and compared with those of the commercially available di-n-hexylsulfide. Incorporation of a polar group such as an amide provides phase transfer catalysis, accelerating the rate of transport of Pd(II) into the organic phase, but reducing selectivity over Pt(IV). The identification of functionalities that operate as receptors for chloridometalates by forming outer-sphere assemblies is explored in Chapter 3. The synthesis of amine, amide and amino-amide extractants from acid chloride streams and the effects of variations of functional groups on the extraction of PtCl6 2− are described. Secondary amides were found to be stronger extractants than tertiary amides, and aliphatic amides also show better metalate extraction than aromatic amides. The interactions between protonated aminoamide reagents and PtCl6 2− werre analysed by X-ray crystallography, noting that C-H∙∙∙Cl interactions with the “soft” chloridometalate anion are more common than with the “hard” chloride ion which shows a preference for more conventional N-H∙∙∙Cl interactions. Chapter 4 combines the reagent types explored in Chapters 2 and 3, in ditopic extractants that have both inner- and outer sphere binding sites. The synthesis and characterisation of a series of thioether amide reagents are reported and the selective extraction of platinum and palladium over other PGMs are discussed. In-house screenings of aryl- and alkylthioetheramide extractants showed selective co-extraction of Pd(II) and Pt(IV), rejecting Ir(III). Pt(IV) can be selectively water-stripped followed by ammonia-stripping of Pd(II). Industrial screenings at Johnson Matthey Technology Centre further exemplified the selectivity of these extractants over Ru(III) and Rh(III), although third phases were formed when the reagents were used for recovery from highly concentrated metal-feed solutions. The mode of action of the ditopic extractants is discussed, based on DFT calculations, crystal structure determinations and NMR studies, which support the formation of outersphere metalate assemblies and inner-sphere palladium complexes. Chapter 5 describes new difunctional (inner + outer sphere complexation) extraction by a single chemical entity, in this case an unsaturated N-heterocycle (an azole). The synthesis and characterisation of a series of hydrophobic azoles are described. These have basicities which allow protonation when contacted with strongly acidic solutions (2), but can be deprotonated in contact with water to allow their neutral forms to form inner-sphere complexes with Pd(II). Triazole-based reagents show the selective co-extraction of Pt(IV) and Pd(II) and, as with the ditopic thioetheramide reagents reported in Chapter 4, allow the selective water stripping of Pt(IV) and subsequent ammonia stripping of Pd(II).
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Young, Matthew J. "Utilization of predispersed solvent extraction for removal and enzymatic degradation of chlorinated solvents in ground water." Thesis, This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-08222008-063547/.
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Xie, Feng. "Solvent extraction of copper and cyanide from waste cyanide solution." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/25746.
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The potential use of two commercial extractants, LIX 7950, a guanidine derivative, and LIX 7820, a solvent mixture of quaternary amine and nonylphenol, for recovery of copper and cyanide from waste cyanide solution has been investigated. Low equilibrium pH favors copper extraction while a high molar ratio of cyanide to copper depresses the copper loading. It is confirmed that Cu(CN)²⁻₃ is preferentially extracted over Cu(CN) ³⁻₄ and CN- by the extractants.
Solvent extraction of the mixture of metal cyano complexes shows a selectivity order as follows: Zn > Ni > Cu > Fe. The presence of SO²⁻₄ or S₂O²⁻₃ shows an insignificant effect on copper extraction while SCN- ions may potentially compete for the available extractant with copper cyanide species and thus depress copper extraction significantly. Both extractants exhibit an affinity sequence as SCN- > CNO- > CN-> S₂O²⁻₃. The selectivity order of different anions with the extractants can be explained by the interrelated factors including anion hydration, charge density, compatibility of the formed complex with the organic phase and the geometry effect.
The extraction of Cu(CN)²⁻₃ with LIX 7950 is exothermic with an enthalpy change (ΔH°) of -191 kJ/mol. The copper extraction with LIX 7820 has little change when the temperature is varied from 25 °C to 45 °C. For both extractants, the loaded copper and cyanide can be stripped efficiently by a moderately strong NaOH solution. Further increase in NaOH concentration results in the formation of a third phase. The presence of NaCN can facilitate stripping of the loaded copper and cyanide by favoring the formation of Cu(CN)³⁻₄ in the stripping solution.
The important findings suggest a possible solution to the separation of metal cyanide species and free cyanide in the cyanide effluent. Both extractants can be used in a SX circuit for pre-concentrating copper into a small volume of strip solution which can be further treated by
electrowinning, AVR, SART or similar processes to recover copper products and cyanide. The free cyanide will remain in the raffinate solution from solvent extraction circuit which allows for the potential recycling of the barren solution to the gold cyanidation process.
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Valentin, Melissa McShea. "Laboratory study of solvent extraction of polychlorinated biphenyls in soil." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=31553.
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Polychlorinated biphenyls (PCBs) are toxic, stable organic contaminants that are present in air, water, soil, plants and animals all around the world. The market for PCB treatment technologies is estimated to be $300 to $600 million (Canadian dollars) for the year 2000, and will expand in future years. Existing treatment technologies to remove PCBs from soil are underutilized because they are more expensive than landfilling and incineration. This thesis presents a laboratory study of an innovative PCB remediation process that will extract PCBs from soil in-situ for subsequent destruction above ground. This remedy will remove PCBs from surficial soil without the need for excavation. Two laboratory studies were conducted on field-contaminated soil. The first experiment evaluated the effectiveness of hexane, methyl isobutyl ketone, and ethyl acetate in removing PCBs from soil. Ethyl acetate and MIBK were equally effective, removing 99% and 98% of PCBs from dry soil in 4 days, respectively. In the second experiment, soil was exposed to ethyl acetate for varying amounts of time, and some of the samples were treated a second time with fresh solvent. PCB removal increased as treatment time was increased from 10 minutes to 50, 250, and 1250 minutes, but the rate of PCB removal decreased as treatment time increased. The second 10-minute extraction removed an additional 1--10% of the remaining PCBs.
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Pitt, Julian Llewellyn. "The behaviour of mineral particles in uranium solvent extraction systems." Thesis, Imperial College London, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339619.
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Ungerer, Maria Johanna. "Separation of tantalum and niobium by solvent extraction / M.J. Ungerer." Thesis, North-West University, 2012. http://hdl.handle.net/10394/9850.
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Niobium (Nb) and tantalum (Ta) are found in the same group (VB) of the periodic table of elements and therefore have similar chemical properties, which is the reason why they are difficult to separate. They are usually found together in various minerals of which the most important are columbite ((Fe, Mn, Mg)(Nb, Ta)2O6) and tantalite ((Fe, Mn)(Nb, Ta)2O6).
Several methods have been used to separate Nb and Ta. Most methods use very high concentrations of hydrofluoric acid (HF) and sulphuric acid (H2SO4) as the aqueous phase, tributyl phosphate (TBP) as the extractant and methyl isobutyl ketone (MIBK) as the organic phase. High extraction can be achieved, but the reagents used are hazardous. With the increasing demand of both pure Ta and Nb, as well as stricter environmental requirements, a need exists to develop a more efficient and safer technique to separate Ta and Nb.
In this project the focus was on the solvent extraction (SX) of Ta and Nb with the possible application in a membrane-based solvent extraction (MBSX) process. For this purpose, eight different extractants were investigated, namely the cation exchangers di-iso-octyl-phosphinic acid (PA) and di-(2-ethylhexyl)-phosphoric acid (D2EHPA), the neutral solvating extractant 2-thenoyl-trifluoro- acetone (TTA), and the anion exchangers Alamine 336, Aliquat 336, 1-octanol, 2-octanol and 3-octanol. The extractant to metal ratio was varied from 0.1:1 to 10:1, while cyclohexane was used as diluent and 3% v/v 1-octanol was used as modifier for the organic phase. In addition, four different acids, hydrochloric acid (HCl), nitric acid (HNO3), sulphuric (H2SO4) and perchloric acid (HClO4), were used at different concentrations to determine the best combination for extraction.
First, fluoride salts of Ta and Nb (Ta(Nb)F5) were tested and the optimum results showed that the highest extraction was obtained with PA and D2EHPA, irrespective of the type of acid used. Similarly, irrespective of the acid used, extraction with PA and D2EHPA increased with increasing acid concentration, followed by Alamine 336, Aliquat 336 and then TTA and the octanols. Extraction values of 97% Ta at 15 mol/dm3 and 85% Nb between 12 and 15 mol/dm3 were obtained. Although extraction of both Ta and Nb was achieved with all the acids tested, only H2SO4 showed sufficient separation (log D = 3) of the two metals in the 0 to 2 mol/dm3 acid range and 15 mol/dm3 for PA and D2EHPA, respectively. Precipitation, probably due to hydrolysis of the metals, occurred in the absence of acid when using Alamine 336, Aliquat 336 and TTA. The octanols showed the least amount of extraction of Ta and Nb, irrespective of the acid investigated. The optimum extraction was achieved with an E/M ratio of 3:1 of PA and D2EHPA as the extractant and 10 mol/dm3 H2SO4 in the aqueous phase.
The NH4Ta(Nb)F6 salt solution was investigated using the optimum conditions for maximum extraction obtained from the Ta(Nb)F5 experiments, i.e. 4 mol/dm3 H2SO4 with an E/M ratio above 3:1 for the extractant PA and 4 mol/dm3 H2SO4 with an E/M ratio of 20:1 for the extractant D2EHPA. Kinetic equilibrium for PA was reached after 10 minutes and for D2EHPA after 20 minutes. The highest extraction of Ta (100%) above 3 mol/dm3 H2SO4 and Nb (54%) at 8 mol/dm3 with the highest separation factor of 4.7 with PA was achieved, followed by the 100% extraction of Ta above 5 mol/dm3 and 40% Nb at 10 mol/dm3 with the highest separation factor of 4.9 in D2EHPA. Although the aim of this study was the extraction and separation of Ta and Nb, the recovery or back extraction of the metals from the organic phase, as well as the membrane-based solvent extraction (MBSX) was briefly investigated. From the preliminary results obtained it became apparent that further research into the different aspects, including the type of stripping agent used, stripping agent concentration, effect of Ta to Nb ratio and different sources of Ta and Nb is needed to obtain the optimum conditions for the MBSX process and the subsequent recovery of Ta and Nb.Thesis (MSc (Chemistry))--North-West University, Potchefstroom Campus, 2013.
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Arnott, Iain. "Solvent extraction of fermentation products using electrostatic and centrifugal fields." Thesis, Heriot-Watt University, 1993. http://hdl.handle.net/10399/1465.
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McGillivary, Angela. "Reactive solvent extraction of #beta#-lactam antibiotics and other anions." Thesis, London South Bank University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326763.
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Fryer-Kanssen, Izaak. "Advancing solvent extraction technology for improved management of contaminated liquors." Thesis, Lancaster University, 2017. http://eprints.lancs.ac.uk/124321/.
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The separation of minor actinides (An) such as americium and curium (Am, Cm) from lanthanides (Ln) in spent nuclear fuel can reduce the radiotoxicity of the eventual waste product as well as the required size and environmental impact of any subsequent geological disposal. In addition, separation of these actinides from the lanthanides is essential for a strategy which aims to put the minor actinides back into the fuel cycle through transmutation by neutron bombardment, which would increase fuel efficiency. This work uses Density Functional Theory (DFT) and the Quantum Theory of Atoms in Molecules (QTAIM) to investigate the structure, stabilities and covalency of complexes of the lanthanides and minor actinides with several nitrogen donor ligands which have been developed for the difficult task of AnIII/LnIII separation. A systematic QTAIM study of Ln bond characterisation across the series is reported for one such ligand, bis-triazinyl-pyridine (BTP), confirming the general assumption that bonding in these complexes is ionic in character and largely similar. A small yet significant increase of the charge accumulation in the bonds of the An complexes of BTP was observed, and DFT studies of the An and Ln complexes found a slight energetic preference of the ligand for An complexation, together implying a small electronic contribution to the experimentally observed selectivity of the BTP ligand. A second nitrogen donor ligand, bis-triazinyl-phenanthroline (BTPhen) was studied, finding slightly higher measures of covalency in the metal-ligand bonds and a greatly improved energetic preference for An complexation. The effects of the addition of electron-directing groups to this ligand were investigated, finding little difference in the measures of covalency for these modified ligands. Several other nitrogen donor and mixed nitrogen/oxygen donor ligands were studied, including a novel sandwich complex, ultimately demonstrating a tentative correlation between enhanced covalency and stability.
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Doidge, Euan Douglas. "Designing reagents for the solvent extraction of critical metal resources." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31070.
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The work in this thesis aims to develop new systems for the more efficient recovery of metals from aqueous solution using solvent extraction. Understanding the underlying coordination chemistry to improve hydrometallurgical methods is crucial in order to meet the demand for critical metals for use in modern technologies, reduce the environment impact of recovery from primary mining deposits, and recycle valuable metals from secondary sources (e.g. mobile phones, WEEE). Chapter 2 examines the use of a simple primary amide that can load gold and other chloridometalates into a toluene phase through an outer-sphere mechanism. The loading of a variety of metals/metalloids from varying [HCl] is reported, highlighting the selectivity for gold over other metalates and chloride due to a combination of speciation of those metals and the relative ease of extraction of lower charged species (the Hofmeister bias). The advantages in loading/stripping, toxicity and mass balances compared to commercial alternatives are also outlined, in particular the efficacy of separating gold from a mixed-metal solution representative of those found in WEEE. The mode of action of the primary amide (and secondary/tertiary analogues) is determined using slope analysis, Karl-Fischer water determinations, NMR and MS measurements, EXAFS and computational models. The extraction occurs by the dynamic assembly of multiple amide ligands and gold metalates to generate supramolecular clusters held together through hydrogen-bonding and electrostatic interactions. The secondary and tertiary amides are found to be able to extract monoanionic metalates in a similar manner as the primary amide, although clustering occurs to a lesser extent. Whilst the secondary and tertiary amides are stronger gold extractants than the primary amide, they are not observed to be as successful when extracting from a mixed-metal solution. Instead, a 3rd phase is seen to form from these amides and some metals at higher metal concentrations, which removes the ligands from solution and prevents successful extraction of gold. Chapter 3 builds on an observation in Chapter 2 that a synergistic combination of a simple primary amide and an amine can extract chloridometalates that are typically difficult to solvent extract, such as iridium(III) and rhodium(III). These metalates, complexes with increased anionic charge and varying speciation in aqueous solution, are typically recovered last in a metal production flowsheet. The combination of a primary amide and primary amine was found to be the most effective at extracting the chloridometalates; the strength and strippability of the system is of particular interest in the context of rhodium(III) recovery as this metal currently is not extracted in commercial circuits. The mode of action of the system is investigated using similar techniques to Chapter 2, and reveals that the amine is the more important component of the synergistic mixture compared to the amide, with an improvement in extraction observed when both components are present. Rh(III) is extracted as a mixture of RhCl6 3– and RhCl5(OH2)2– complexes, dependent on the initial [HCl] concentration and the age of the initial aqueous solution. Chapter 4 investigates the feasibility of the recovery of lanthanides as anionic metalates from chloride-, nitrate- or sulfate-rich feeds. Reagents that have been found to be strong chloridometalate extractants, fragmented versions of these, and ‘classic’ commercial outer-sphere reagents are studied. The variations of ligand, anion type and concentration, proton concentration and solvent for the extraction of lanthanides is investigated. However, despite these permutations, no extraction of lanthanides is observed due to the difficulty in extracting more highly hydrated species and the lack of stability of the metalates in aqueous solution.
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Emeleus, Lucy C. "Novel ligands for the recovery of copper via solvent extraction." Thesis, University of Edinburgh, 1999. http://hdl.handle.net/1842/14790.
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Alvarenga, Carlos Leon Guimarães de. "Estudo da extração líquido-líquido de urânio com alamine 336 a partir de meio sulfúrico na ausência e na presença de íons cloreto." CNEN - Centro de Desenvolvimento da Tecnologia Nuclear, Belo Horizonte, 2010. http://www.bdtd.cdtn.br//tde_busca/arquivo.php?codArquivo=264.
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O urânio é geralmente recuperado de seus minérios através da lixiviação com ácido sulfúrico seguido de extração líquido-líquido (ELL) para produzir o concentrado de urânio (yellow cake). Essa rota é usada pelas Indústrias Nucleares do Brasil S/A - INB, em Caetité/BA, Brasil, que utiliza a amina terciária Alamine 336 para extrair urânio do licor sulfúrico e como reextratante utiliza o cloreto de sódio (NaCl). Devido à escassez de água na região em que se situa essa unidade, toda água utilizada no processo é recirculada após tratamento com cal. Como nesse tratamento o íon Cl- não é removido, sua concentração aumenta a cada ciclo de reutilização da água, diminuindo a eficiência de extração do urânio, causando queda na produção de concentrado de urânio e perdas financeiras. Eventualmente a INB é obrigada a adicionar água nova no processo para reduzir o teor de Cl-.
Este trabalho apresenta uma avaliação comparativa entre os seguintes sistemas de extração de urânio: U-H2SO4-Alamine 336 e U-H2SO4-Cl-Alamine 336. No primeiro sistema, a concentração de urânio variou entre 0,4 e 2,1 g/L. No segundo sistema, a concentração de urânio foi fixada em 2,0 g/L e a concentração de íons cloreto variou de 1,0 a 7,0 g/L. A concentração de Alamine 336 variou de 0,05 a 0,20 mol/L e a de sulfato (SO42-) de 0,24 a 1,05 mol/L nos dois sistemas. Exxsol D100 e tridecanol 5% v/v foram usados como diluente e modificador, respectivamente. Comparando os resultados obtidos, observa-se que a presença de cloreto na solução de alimentação tem impacto negativo sobre a extração de urânio com Alamine 336. Na ausência de cloreto atinge-se 90% de extração quando a concentração do extratante é de 0,10 mol/L ou maior, para todas as concentrações de sulfato e urânio utilizadas. Na presença de cloreto, o mesmo percentual é atingido apenas com concentrações de 0,20 mol/L do extratante e em concentração de cloreto abaixo de 3,0 g/L. Ou seja, a porcentagem de extração de urânio é reduzida drasticamente na presença de cloreto em altas concentrações, enquanto em baixas concentrações tal efeito negativo pode ser inibido aumentando a concentração de Alamine 336 ou diminuindo a concentração de sulfato. Para explicar o efeito negativo da presença do cloreto, dois prováveis mecanismos de extração para esses sistemas são apresentados: a competição entre o cloreto e o sulfato durante a protonação da amina e a extração do cloreto pelo complexo sulfato-amina, competindo com o trissulfatouranilato VI. Esses mecanismos podem ocorrer simultaneamente.Uranium is usually recovered from ores by sulphuric acid leaching followed by solvent extraction in order to produce a uranium ore concentrate. Such route is used by Indústrias Nucleares do Brasil S/A - INB, at Caetité/BA, Brazil, which uses the tertiary amine Alamine336 to extract uranium from the sulphuric liquor and a sodium chloride solution as stripping agent. Due to water scarcity in this region, all water used in the process is recirculated after treatment with lime. At this treatment the chloride ion (Cl-) is not removed, causing the increase in Cl- concentration with each recirculation of water, reducing the efficiency of extraction of uranium, causing a drop in production of uranium concentrate and financial losses. Eventually the INB Company is required to add new water in the process to reduce the content of Cl-. In this work, a comparative evaluation between the following uranium extraction systems is carried out: U-H2SO4-Alamine 336 and U-H2SO4-Cl-Alamine 336. In the first system, the uranium concentration ranged from 0.4 to 2.1 g/L. In the second system, the uranium concentration was set at 2.0 g/L and chloride ion concentration ranged from 1 to 7 g/L. In both systems the concentration of Alamine 336 ranged from 0.05 to 0.20 mol/L and the sulphate (SO42-) concentration from 0.24 to 1.05 mol/L. Exxsol D100 and tridecanol 5% v/v were used as diluent and modifier, respectively. The comparison of the results showed that chloride ions have a negative impact on the uranium extraction with Alamine 336. In the absence of chloride ions, 90% of extraction is achieved for extractant content of 0.10 mol/L or higher, for all sulphate and uranium concentrations studied. In the presence of chloride ions, the same extraction efficiency is reached solely for extractant content of 0.20 mol/L and for chloride ions content lower than 3.0 g/L. The percentage on the uranium extraction is drastically reduced at high chloride concentrations, whereas at low chloride concentrations such negative effect may be inhibited by increasing the Alamine336 concentration or decreasing sulphate concentration. In order to explain the negative impact of chloride ions on uranium extraction, two probable mechanisms of extraction for both reaction systems are shown: competition between chloride and sulphate in amine protonation and the chloride extraction by amine-sulphate complex, competing with uranium (VI) oxide sulphate. These mechanisms may occur simultaneously.