Acidic Chloride Media Research Articles

Defatted microalgae Haematococcus pluvialis: A sustainable source for gold recovery

The defatted microalgae Haematococcus pluvialis (HP), obtained from various production lots, were subjected to two different treatments: drying without chemical treatment (DH1, DH2, and DH3) and treatment with concentrated sulfuric acid (TH1, TH2, and TH3). These treated materials were employed as efficient and eco-friendly adsorbents to investigate the adsorption behavior of Au(III) in acidic chloride media. The treated adsorbents demonstrated exceptional performance, achieving 100 % adsorption of Au(III) across a broad range of hydrochloric acid (HCl) concentrations from 0.01 to 5.00 M, whereas the dry adsorbents exhibited up to 90 % adsorption only at low HCl concentrations. Both dry and treated adsorbents exhibited superior selectivity for Au(III) in the presence of a mixture of precious metal ions. The adsorption isotherms of Au(III) followed the Langmuir type of adsorption mechanism, and the maximum adsorption capacities for Au(III) were estimated as 1.57, 0.88, and 1.52 mol kg–1 for DH1, DH2, and DH3, and 6.17, 4.80, and 5.37 mol kg–1 for TH1, TH2, and TH3, respectively. The adsorbed Au(III) ions were reduced to the elemental state, as confirmed by X-ray diffraction patterns, scanning electron microscopy/energy-dispersive X-ray analyses, and digital micrographs of the adsorbents after Au(III) adsorption. Successful desorption of the adsorbed Au(III) was achieved using acidic thiourea solution.

Obtention of Suitable Pregnant Leach Solution (PLS) for Copper Solvent Extraction Plants from Copper Concentrate Using Hydrogen Peroxide and Iodine in a Sulfuric Acid–Chloride Medium

Copper leaching presents an environmentally friendly alternative to traditional sulfide ore processing methods. This study investigates an efficient leaching process for copper concentrate, utilizing a solution of sulfuric acid (H2SO4) and potassium iodide (KI) in a chloride medium (NaCl), enhanced by hydrogen peroxide (H2O2) at room temperature. A significant aspect of this research was optimizing the KI concentration to minimize iodide sublimation into iodine gas (I2). Through the experimental design, the optimal dosages of reagents were determined, leading to maximized copper extraction of approximately 27% in 45 min of testing at room temperature. The results showed that it is possible to obtain a suitable pregnant leach solution (PLS) (i.e., in the range of 3 to 8 g/L of Cu) for treatment in available copper solvent extraction (SX) plants with a cost of less than 4.5 USD/t Cu, according to the economic analysis carried out. The results of this study determine the most effective operational conditions for leaching and ensure a suitable PLS for SX plants in a cost-effective and environmentally friendly manner. This approach could significantly contribute to more sustainable practices in the mining and processing of copper ores.

Towards continuous selective electrowinning of gold from waste printed circuit boards in acidic chloride medium: a parametric study

Towards continuous selective electrowinning of gold from waste printed circuit boards in acidic chloride medium: a parametric study

Separation and Characterization of Nickel Hydroxide from Waste Solution Using Ca(OH)2 Precipitation in Chloride Media

Nickel hydroxide (Ni(OH)2) is a valuable compound derived from nickel, widely utilized across various fields because of its versatile properties. This study aimed to characterize as-prepared β-Ni(OH)2 via chemical precipitation using various analytical techniques. X-ray diffraction (XRD) analysis confirmed the formation of a β-Ni(OH)2 hexagonal crystalline structure, validating the successful precipitation. Fourier-transform infrared spectroscopy (FTIR) spectra exhibited main characteristic peaks of (υOH) and υ(NiO), corresponding to the formation of nickel hydroxide (Ni(OH)2). Subsequently, X-ray photoelectron spectroscopy (XPS) revealed a prominent peak for Ni2+ oxidation, confirming the successful precipitation of nickel hydroxide at pH 6.5, which identifies the existence of impurities, such as chlorine and calcium, from the waste matrix. Scanning electron microscopy (SEM) micrographs demonstrated stratified granules with a nearly pure brucite crystalline phase, typical of β-Ni(OH)2. Furthermore, the surface morphology revealed a coarse texture and uneven clustering, suggesting possible elevated oxide levels on the Ni surface. Energy-dispersive X-ray spectroscopy (EDX) confirmed the presence of nickel (Ni) and oxygen (O), with Ca impurities attributed to the chemical precipitation process. Particle size distribution analysis estimated an average particle size of 2.0 µm. Additionally, the precipitation of nickel was investigated using inductively coupled plasma optical emission spectroscopy (ICP-OES). Ni was observed in decreasing order, 62.7 g/L, 0.8 g/L, and 0.501 g/L in the pregnant leach, precursor solution, and solid precipitate (cake), respectively. The separation of Ni(OH)2 through the precipitation process from the waste (acidic chloride media) enabled efficient recycling and re-use of nickel, which provides a cost-effective and environmentally friendly method for the highly efficient utilization of waste (acidic chloride media).

Separation of gallium(III) using 2-nonanone based on ion solvation in acidic chloride media

Gallium (Ga) is an indispensable electronic material for devices such as light-emitting diodes, and the demand for Ga is expected to increase. In this study, a comparative analysis was carried out on Ga(III) extraction by neutral ketones and ethers in the presence of highly concentrated hydrochloric acid (HCl). Generally, Ga(III) extractability was high using aliphatic and aromatic ketones. By comparison, Ga(III) extractability was lower using monoether compounds. High Ga(III) extractability was obtained using aromatic 1,2-diethers. Suitable solvents for Ga extraction were screened based on Hansen solubility parameters. 2-Nonanone (2-NON), an aliphatic ketone, was found to have a high extraction capacity (more than 95 mM) competitive with dibutyl carbitol. The physical properties of 2-NON a low water solubility (0.5 g dm−3), low viscosity (1.3 mPa·s), and a sufficiently high flash point (76 °C) are suitable for industrial processes. Ga(III) and Fe(III) were selectively extracted using 2-NON and other solvents. Ga(III) extracted using 2-NON was quantitatively stripped by contact with aqueous solutions with low HCl concentrations. 2-NON was used to separate Ga(III) from a mixed solution of metal ions to investigate recycling copper indium gallium diselenide solar cells. Ga(III) was selectively extracted from the mixture with over 90 % stripping. The concentrations of the metal ions in the stripping solutions were 1.0 mM for Cu(II), 9.9 mM for In(III), 56.7 mM for Ga(III), and 0.02 mM for Se(IV), suggesting that 2-NON can be used for Ga(III) separation.

Green and efficient coordination of Ti(IV) with bisamide solvent

Titanium(Ti) is known as a strategic metal due to its excellent physical and chemical properties. Ti based materials are widely used in many fields, such as aerospace, biomedical, and photovoltaic materials. Since the metal smelting industry is often accompanied by high pollution, deep eutectic solvent, as a new type of environmentally friendly solvent, is gradually being widely used in the field of metal separation and purification. Through the transformation from non-ionic organic deep eutectic solvents (DESs-5) to inorganic deep eutectic solvents (DESs-M), the efficient coordination of Ti(IV) in acidic chloride medium was achieved. Under the optimal condition, over 95% of Ti(IV) in aqueous solution can be coordinated into DESs in a single stage, which can be used for the separation and purification of Ti(IV). The formation mechanism of DESs-5 was revealed by the quantum chemistry method and the lowest energy mechanism in the conversion reaction process was revealed by frontier molecular orbital (FMO) theory. The thermodynamic and kinetic processes of the conversion reaction were analyzed, which provided important research data for the construction of DESs-based Ti(IV) separation and purification system.

Anticorrosion performance of nicotinic acid and nicotinic acid hydrazide blended with optimized potassium iodide against Q235 steel corrosion in acid-chloride medium

The most sorted corrosion-inhibiting additives are composed of compounds that are non-toxic, cheap, and soluble in an aqueous medium without requiring organic solvents or surfactants. Nicotinic acid (NTAD) and nicotinic acid hydrazide (NADH) are naturally derived compounds that are non-toxic, cheap, and very soluble in aqueous media. Hence, the present study investigates their anticorrosion performances in an equal mixture of 0.25 M H2SO4 and 0.5 M NaCl medium which mimics the acidic-chloride medium often encountered in typical industrial descaling and pickling processes. The study considered both the individual compounds and their blend with KI at different concentrations. The anticorrosion as well as the synergistic effects were evaluated with combined electrochemical and gravimetric methods. The low inhibition efficiency (%) approaching 50% and 70% were achieved with the individual NTAD and NADH, respectively, while enhanced inhibition efficiencies reaching 96% and 97% respectively, were achieved when blended respective inhibitors with an optimal KI concentration. The adsorption of the inhibitor molecules followed Langmuir isotherm with the Kads and ΔG0 increasing with the addition of KI. The positive synergistic index values confirmed synergism. The overall anticorrosion process as well as the synergistic effect of KI were validated with complementing intensive spectroscopy (FTIR and XPS analysis) and imaging (SEM and AFFM) methods. The experimental data collaborated with DFT computational and Monte Carlo molecular dynamics simulation studies in divulging the inhibition mechanisms of NTAD and NADH without and with KI blending.

Development of solvents for Au(III) extraction in hydrochloric acid media based on ion solvation with reference to the Hansen solubility parameters: Success of dicyclohexylketone

Ion solvation extraction using ethers and ketones is industrially applied for the extraction and separation of Au(III) from acidic chloride media. Although these have been in practical use since the 1970s, requirements for valid extractants (solvents) have not been systematically clarified. In this study, the relationship between Au(III) extractability using various organic solvents and their Hansen solubility parameters (HSPs) was investigated. The extractability of the solvents increases with the increase of the polar forces (δP) of the solvents, however, solvents with much higher δP values are water-miscible and unsuitable for solvent extraction. Hence a HSP sphere with center coordinates at δD = 17.73, δP = 7.82, δH = 2.48, where D, P and H represent dispersive, polar and hydrogen-bonding forces, was obtained from the results of extraction tests using 26 solvents, with the exclusion of HSPs for 25 water-miscible solvents. Twenty-four of the 26 solvents tested were properly classified as valid or invalid for the extraction of Au(III) using the Hansen sphere. The results suggest partial utility of the prediction of the extractability using HSPs. Dicyclohexylketone, which has HSPs within the sphere, was selected as a potential extractant: it showed sufficient extractability and selectivity for the extraction of Au(III).

Corrosion Studies of Mild Steel by using novel synthesized green inhibitor in Acid Chloride Medium.

Corrosion Studies of Mild Steel by using novel synthesized green inhibitor in Acid Chloride Medium.

Extraction of Au(III) Using Aromatic Ketones in Acidic Chloride Media

Recently, the extraction of Au(III) using the series of aliphatic ketones in hydrochloric acid media has been investigated in detail. The present study describes the extraction behaviors of Au(III) using a series of aromatic ketones, which has never been reported. Aromatic ketones with shorter alkyl side chains showed higher extractability. The rapid extraction and the extraction capacity using aromatic ketones were comparable to the industrial extractant dibutyl carbitol (DBC). Aromatic ketones, except acetophenone, are less soluble in water than DBC. The flash points of aromatic ketones are satisfactorily high for industrial operation, but their specific gravities comparable to that of water are unwelcome. Butyrophenone selectively extracted Au(III) from many other metals, except for high extraction of Fe(III) and Ga(III) at high concentrations. Au(III) extracted using butyrophenone recovered quantitatively as metallic gold by reduction using oxalic acid.

Palladium(II) extraction from acidic chloride media using an ionic liquid-based aqueous two-phase system (IL-ATPS) in the presence of dipotassium hydrogen phosphate salting-out agent and reductive stripping with hydrazine hydrate to recover palladium metal

Aqueous two-phase systems (ATPSs) based on ionic liquids (ILs) are efficient and green extraction systems. In this study, ATPSs consisted of three hydrophilic imidazolium-based ionic liquids ([C4mim]Br, [C6mim]Br, and [C8mim]Br) with phosphate, which were employed for Pd(II) extraction in acidic solutions. The obtained results showed that IL-ATPSs exhibited excellent Pd(II) extraction performance in acidic media, and Pd(II) was concentrated into ionic liquid rich upper phase. Palladium(II) extraction efficiencies of the three imidazolium-based ILs in acidic media were >98%, and the order of extraction efficiencies was: [C4mim]Br > [C6mim]Br > [C8mim]Br. Palladium(II) concentrated in IL-rich phase was recovered via direct reduction with hydrazine hydrate. Fourier transform infrared spectrometer (FT-IR) and mass spectrometry characterization indicated that Pd(II) migration into IL-rich phase followed an ion-exchange mechanism. Furthermore, transmission electron microscopy showed that “oil-in-water” micelles were formed during Pd(II) extraction.

Evaluating the Corrosion Inhibition Efficiency of Pyridinium-Based Cationic Surfactants for EN3B Mild Steel in Acidic-Chloride Media

Two new effective corrosion inhibitors, namely N-(n-octyl)-3-methylpyridinium bromide (Py8) and N-(n-dodecyl)-3-methylpyridinium bromide (Py12), have been presented. The cationic pyridinium-based surfactants were analyzed for the corrosion protection of general purpose steel (EN3B) against a strong corrosive media (3.5% NaCl, pH 1.5). The results of the electrochemical measurements, i.e., Tafel polarization, linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) revealed a mixed-type behavior of both inhibitors, and the maximum inhibition efficiency (IE) achieved with Py8 and Py12 was 85% and 82%, respectively. The process of adsorption of synthesized inhibitors followed the Langmuir adsorption isotherm, and a higher value of Kads highlighted the existence of strong interaction between inhibitors and the EN3B mild steel surface. Furthermore, the values of ΔG°ads were calculated to be −32 kJ mol−1 for Py8 and −33 kJ mol−1 for Py12, indicating the coexistence of both physisorbed and chemisorbed molecules. The surface morphology of EN3B mild steel samples was observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM), where the reduced surface roughness in the presence of Py8 and Py12 in chloride media further supported the evidence of an efficient inhibition process. Density functional theory (DFT) calculations reveal excellent correlation with the experimental results, with Py8 showing superior corrosion inhibition potential, signifying that the alkyl chain length and intramolecular charge transfer are crucial factors in deciding the inhibition performance of the synthesized cationic surfactants. Furthermore, this study proposes the mechanism for the adsorption of the surfactant-based inhibitors over the EN3B mild steel surface, which leads to the formation of an effective and protective anticorrosive film.

Comparative studies of three isatin-thiosemicarbazones against corrosion of AA6060 aluminum alloy exposed to acidic NaCl medium

Three isatin-thiosemicarbazone derivatives with different substituents (R) attached at C5 of the indolin-2-one ring, TSC-ISA-R (R = -H, -OCH3 and -OCF3), were synthesized and evaluated as medium-term corrosion inhibitors for AA6060 aluminum alloy exposed to acidic chloride medium. The inhibitory behavior and performance of TSC-ISA-R were investigated in relation to the molecular modification by field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), potentiodynamic polarization (PDP) analysis and weight loss measurement. Quantum chemical calculation and molecular dynamics (MD) simulation were further performed to study the inhibition behavior of the derivatives towards the corrosion of AA6060 alloy. Surface morphology analysis showed that TSC-ISA-OCH3 significantly mitigated the corrosion of the alloy while TSC-ISA-OCF3 had little inhibition effect. The inhibition efficiencies observed from weight loss measurements for TSC-ISA-H, TSC-ISA-OCH3 and TSC-ISA-OCF3 at 3 × 10–2 mM were 27.03%, 79.73% and 12.16%, respectively. PDP analysis indicated that both TSC-ISA-H and TSC-ISA-OCH3 were cathodic type inhibitors and TSC-ISA-OCF3 was a mixed-type one primarily hindering the cathodic reactions of AA6060 alloy. The results of EDS and XPS revealed that TSC-ISA-R molecules were adsorbed on the alloy surface, and the adsorption was closely correlated with the substituent modification. The theoretical results obtained from quantum chemical calculations and MD simulations for the protonated TSC-ISA-R correlated well with their ranking of the experimental inhibition efficiencies. The substituent effects of -R were proposed to significantly affect the electron densities on para-amino N1 and exocyclic imino-N2 atoms of TSC-ISA-R capturing H+ in the medium, and thereby probably underlay their differences in the inhibition behavior and performance.

Acidic Chloride Leaching of NMC Cathodes Combined with Solvent Extraction for the Production of Value Metals from Spent Lithium-Ion Battery

Lithium-ion battery is the technology of choice in the development of electric vehicles. This technology is now mature although there are still many challenges to increase their energy density while ensuring an irreproachable safety of use. For this goal, it is necessary to develop new cathodic materials that can be cycled at higher voltages and electrolytes compatible with these materials. But the challenge does not only concern the production of efficient batteries for the electrochemical storage of energy since lithium-ion battery technology relies on the use of critical and/or strategic value resources. It is therefore crucial to include Lithium-ion batteries development in a circular economy approach very early. In particular, optimized recycling and reuse of battery components must both minimize their impact on the environment and limit geopolitical issues related to tensions on the mineral resources necessary for lithium-ion battery production. Although recycling will never replace mining, it reduces resource dependence by ensuring the presence of exploitable resources in the territory, which is particularly important for countries like France where exploited or exploitable resources are limited.This conference addresses the development of a new hydrometallurgical process combining leaching of cathodic material from spent lithium-ion battery in acidic chloride media and solvent extraction process. Most of recycling processes reported in the literature rely on the sulphate route and a few studies investigate the potentialities of the chloride route despite many advantages and the possibility to develop new chemistry, which could get easier the metal separation. The leaching mechanisms and the solvent extraction equilibria will be presented in this conference. Based on the comprehension of the physicochemistry of leaching and solvent extraction, the present study will introduce a new hydrometallurgical process for the production of cobalt, nickel, manganese and lithium from spent cathodic materials.

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−.

Targeted synthesis of two iron(III) tetradentate dibasic chelating Schiff base complexes toward inhibition of acidic induced steel corrosion: Empirical and DFT insights

Two new azomethine chelates for Fe3+ ions were prepared from two dibasic tetradentate chelating imine ligands. The studied Schiff base ligands were 2,2′‐((1E,1′E)‐((4‐nitro‐1,2‐phenylene)bis(azanylylidene))bis(methanylylidene))bis(4‐bromophenol) (NABS) and 2,2′‐((1E,1′E)‐((4,5‐dimethyl‐1,2‐phenylene)bis(azanylylidene))bis(methanylylidene))bis(4‐bromophenol) (MABS). Alternative spectral and physicochemical tools such as Fourier transform infrared spectroscopy (FTIR), C13 NMR, 1H NMR, and CHN analyses, thermogravimetric analysis (TGA), molecular electronic spectra, and magnetic susceptibility measurements were applied to inspect the structural composition of the compounds under investigation. In addition, the DFT approach was used to optimize the geometry of all compounds in order to get ideal structures and important characteristics. The synthesized compounds examined as an anticorrosive films of C‐steel in acidic chloride medium utilizing theoretical and electrochemical studies such electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and potentiodynamic anodic polarization curve (PAP) approaches. The inhibition efficiency augmented with the increasing of the inhibitor dose. The prepared Schiff bases and their iron complexes exhibited protection capacity around 96.8% in the presence of 0.5 mmol L−1. PDP outcomes approve the additive molecules act as mixed inhibitors. The Langmuir model is followed by Schiff bases and their iron complexes as it is contains both chemical and physical adsorption on the metal interface. The surface morphology of the substrate (in blank and inhibited systems) was scanned using field‐emission scanning electron microscopy (FESEM). A good agreement among experimental techniques and corresponding density functional theory (DFT) results was found, which confirmed the purity of the studied compounds and suggested octahedral geometry around Fe(III) ions in both MABSFe and NABSFe complexes.

Synthesis of Iron Nanomaterials for Environmental Applications from Hydrometallurgical Liquors

Hydrometallurgical leaching solutions are often rich in iron, which was traditionally considered a major impurity. However, iron can be selectively separated and recovered by applying appropriate solvent extraction and stripping techniques, and the resulting solutions can be valorized for the synthesis of high-added-value products, such as magnetic iron oxide nanoparticles (mIONPs). The aim of this study was to synthesize high-quality mIONPs from solutions simulating the composition of two alternative stripping processes. The precursor solutions consisted of Fe(II) in an acidic sulfate environment and Fe(III) in an acidic chloride medium. The Fe(II)-SO4 solution was treated with a mixture of KNO3-KOH reagents, and the product (M(II)) was identified as pure magnetite with a high specific magnetization of 95 emu·g−1. The treatment of Fe(III)-Cl solution involved the partial reduction of Fe(III) using metallic iron and the co-precipitation of iron cations with base addition combined with microwave-assisted heating. The product (M(III)) was a powder, which consisted of two phases, e.g., maghemite (75%) and magnetite (25%), and also had a high magnetic saturation of 80 emu·g−1. The nanopowders were evaluated for their effectiveness in removing Cr(VI) from contaminated waters. The maximum adsorption capacity was found to be equal to 11.4 and 17.4 mg/g for M(II) and M(III), respectively. The magnetic nanopowders could be easily separated from treated waters, a property that makes them promising materials for the water treatment sector.

Localized Corrosion Susceptibility of 434 Ferritic Stainless Steel in Acid Chloride Media

The pitting corrosion resilience and passivation behaviour of 434 ferritic stainless steel was studied in 1 M H2SO4 solution at 0% to 2% NaCl concentration by potentiostatic technique and optical illustration characterization. Data showed 434 steel underwent metastable pitting activity at the lowest metastable pitting potential and current by reason of the effect of SO42- anions within the electrolyte. Addition and increase in Cl- anion concentration decreased the potential while simultaneously increasing the current value at which metastable pitting occurs till 1% NaCl concentration. The presence of chlorides decreased the passivation range of the steel with regards to Cl- anion concentration compared to the electrolyte without chlorides till 0.5% NaCl concentration. Beyond this concentration no further decrease in the steel’s passivation range was observed despite increase in chloride concentration. Beyond 1% NaCl concentration passivation of the steel completely collapsed signifying threshold chloride concentration for optimal steel utilization on astringent conditions. Potentiostatic data showed variation in chloride concentration from 0.25% to 1% had strong effect on the pitting resistance of 434 steel. Optical images of 434 steel morphology at 0%, 0.25% and 2% NaCl concentration in 1 M H2SO4 solution showed important details. At 0% and 0.25% NaCl concentration, corrosion pits were clearly visible though the dimension and depth of the pits from the electrolyte with 0.25% NaCl concentration were more defined and deeper. At 2% NaCl concentration, corrosion pits were larger and the surface morphology showed severe morphological deterioration by reason of the synergistic action of SO42- and excess Cl- anions.

Extraction of Platinum Hexachloride Anion Using Two Amido Hydrogen Atoms of Secondary Diamides with Different Spacer Length

Abstract Three secondary diamides having different space lengths were prepared and their extraction behavior toward Pt(IV) was investigated in acid chloride media. Given 1H NMR investigation, the carbonyl oxygen atoms were not protonated and only NH protons were applied to the solvation extraction of [PtCl6]2−. The effect of spacer length between two NH hydrogen atoms is discussed for s size-discriminating effect of a chlorometalate through the results of the extraction.

Stoichiometry of the Nickel Complex Formed with LIX 63 Hydroxyoxime under Acidic Chloride Conditions

ABSTRACT The extraction of nickel by LIX® 63 hydroxyoxime (‘hydroxyoxime’) under acidic (10–100 g/L hydrochloric acid) chloride conditions was investigated with the intent of determining the stoichiometry of the resulting complex in solution. Maximum loading and continuous variation tests indicate that nickel is extracted as a cationic salt with chloride counter-ions, the resulting complex exhibiting octahedral coordination with 1:3:2 nickel:hydroxyoxime:chloride stoichiometry. This species is also observed to readily form under mildly acidic (pH 1–4) chloride conditions, with the extent of formation being independent of pH. Nickel extraction kinetics were moderately fast, equilibrium being reached in 10 minutes. The behaviour of this system helps to provide clarity in relation to complex stoichiometry and the role of different ligands in synergistic systems utilising LIX 63 and an organic acid such as Versatic 10, opening up the possibility of nickel extraction from acidic chloride media using LIX 63.