Crystallization of nickel sulfate and its purification process: towards efficient production of nickel-rich cathode materials for lithium-ion batteries

NiSO4·6H2O is an important salt for the battery-making industry. The extraction of nickel sulfate relies on the hydrometallurgical processing of nickel ores as well as the recycling of nickel-containing products. The last step in hydrometallurgical processing is the crystallization of nickel sulfate. Because of the similar ionic radius and ionic charge between nickel and magnesium ions, magnesium undergoes isomorphous substitution and replaces nickel ions in the crystal lattice structure of NiSO4·6H2O. This poses a challenge as achieving the desired metal salt purity is difficult, resulting in an inferior cathode material for nickel-containing batteries. In this work, the removal of magnesium during the purification process of NiSO4·6H2O crystals via a repulping process was thoroughly investigated. Moreover, the impurity uptake mechanisms of magnesium into NiSO4·6H2O crystals were investigated. The results indicated that repulping NiSO4·6H2O crystals with a saturated NiSO4 solution results in 77% removal of magnesium. Using a second-stage repulping process is less effective with only 26% magnesium removal. The purification efficiency of the two repulping stages was quantified by the equilibrium distribution coefficient, which corroborates the trend of decreased removal of magnesium in the second stage of repulping compared with the first stage. The primary impurity uptake mechanisms of magnesium into NiSO4·6H2O crystals were identified to be surface adsorption and lattice substitution (isomorphous substitution).

Investigating Metal-Tributyl Phosphate Complexes during Supercritical Fluid Extraction of the NdFeB Magnet Using Density Functional Theory and X-ray Absorption Spectroscopy

Supercritical fluid extraction (SCFE) is gaining significant interest as a green technology for the recycling of end-of-life waste electrical and electronic equipment (WEEE). Neodymium iron boron (NdFeB) magnets, which contain large quantities of critical rare-earth elements such as neodymium, praseodymium, and dysprosium, are widely used in wind turbines and electric/hybrid vehicles. Hence, they are considered a promising secondary resource for these elements when they reach their end-of-life. Previously, the SCFE process was developed for recycling WEEE, including NdFeB; however, the process mechanism remains unexplored. Here, density functional theory, followed by extended X-ray absorption fine structure and X-ray absorption near-edge structure analyses, are utilized to determine the structural coordination and interatomic interactions of complexes formed during the SCFE of the NdFeB magnet. The results indicate that Fe(II), Fe(III), and Nd(III) form Fe(NO₃)₂(TBP)₂, Fe(NO₃)₃(TBP)₂, and Nd(NO₃)₃(TBP)₃ complexes, respectively. This theory-guided investigation elucidates the complexation chemistry and mechanism during the SCFE process by rigorously determining the structural models.

Electrorefining for direct decarburization of molten iron

Recycling iron and steel is critical for environmental sustainability and essential to close material loops in circular economics. A major challenge is to produce high-value products and to control impurities like carbon in the face of stringent consumer requirements and volatile markets. Here, we develop an electrorefining process that directly decarburizes molten iron by imposing an electromotive force between it and a slag electrolyte. Upon anodic polarization, oxide anions from the slag discharge directly on carbon dissolved in molten iron, evolving gaseous carbon monoxide. In a striking departure from conventional practice that highly relies on reaction with solubilized oxygen, here electrorefining achieves decarburization by direct interfacial reaction. We demonstrate that this technique produces ultra-low-carbon steels and recovers silicon as a by-product at the cathode, requiring a low energy input and no reagents. We expect this process to be scalable and integrable with secondary steel mills.

A Rechargeable Mg|O2 Battery

Rechargeable Mg|O₂ batteries (RMOBs) offer several advantages over alkali metal-based battery systems owing to Mg’s ease of transport/storage in ambient environment, low cost originating from its high abundance, as well as the high theoretical specific energy of RMOBs. However, research on RMOBs has been stagnant for the past decade, largely owing to unacceptably poor electrochemical performance. Here, we present a RMOB that employs Mg anode, Mg((CF₃SO₂)₂N)₂-MgCl₂ in diglyme (G2) electrolyte, and commercial Pt/C on carbon fiber paper (Pt/C@CFP) oxygen cathode. This battery demonstrates unparalleled improvement over existing RMOBs by rendering a discharge capacity over 1.6 mAh cm⁻², achieving cycle lives up to 35 cycles with a cumulative energy density of ∼3.2 mWh cm⁻² at room temperature. This RMOB system seeks to reignite the pursuit of novel electrochemical systems based on Mg-O₂ chemistries.

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A rechargeable Mg|O₂ battery with prolonged cycle life (∼35 cycles) is demonstrated

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Mg((CF₃SO₂)₂N)₂-MgCl₂ in G2 enables reversible battery cycling O₂ environment

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A multistep discharge product formation pathway is proposed

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MgO is identified as the main discharge product

Urban mining of terbium, europium, and yttrium from real fluorescent lamp waste using supercritical fluid extraction: Process development and mechanistic investigation

There is a significant global push towards recycling of waste electrical and electronic equipment (WEEE) to enable the circular economy. In this study an environmentally sustainable process using supercritical carbon dioxide as the solvent, along with a small volume of tributyl-phosphate-nitric acid (TBP-HNO₃) adduct as the chelating agent, is developed to extract rare earth elements (REEs) from fluorescent lamp waste. It is found that mechanical activation using oscillation milling improves extraction efficiency. To elucidate the process mechanism, an in-depth characterization of solids before and after the process using transmission electron microscopy(TEM) and X-ray photoelectron spectroscopy (XPS)is performed. Furthermore, UV visible spectroscopy is performed to determine the coordination chemistry of the rare earths of interest, i.e., yttrium, europium, and terbium during the complexation with TBP-HNO₃ adduct. It is found that Al³⁺ and Ca²⁺ cations from the aluminium oxide (Al₂O₃) and hydroxyapatite (Ca₅(PO₄)₃OH) present in the fluorescent lamp waste compete with REEs in reacting with TBP-HNO₃ adduct; hence, REE extractions from real fluorescent lamp waste is less than previously reported extractions from synthetic feeds. Not only can management of fluorescent lamp waste help conserve natural resources and protect ecosystems, but it can also facilitate efficient utilization of materials and promote the circular economy.

Quantification of nickel, cobalt, and manganese concentration using ultraviolet-visible spectroscopy

Ultraviolet-visible spectroscopy is one of the most effective, inexpensive, flexible, and simplest analytical techniques to measure species concentration in the liquid phase. It has a wide range of applications such as wastewater treatment, dye degradation, colloidal nanoparticle characterization. It is used in almost every spectroscopy laboratory for routine analysis or research. In the present study, a feasibility study was carried out to find the application of UV-Vis spectroscopy for onsite measurement of nickel, cobalt, manganese, and lithium as a replacement for the conventional method to measure the concentrations of these elements in battery and other applicable industries. Samples with different concentrations of individual elements and composites were prepared and analyzed using an ultraviolet-visible spectrometer. Based on the obtained results, mathematical relationships between concentration and absorbance were defined. The calculated concentration of different elements using the developed relationships was compared with the measured concentration using ICP-OES to find any deviation between the two. The effect of various parameters such as concentration, path length, number of elements in the solution, density, and pH was analyzed to verify the feasibility. The obtained results show that this technique can be effectively used to measure the concentration of nickel and cobalt with high accuracy.

Chemical composition of Zhumeria majdae essential oil and its effects on the expression of morphine withdrawal syndrome and tolerance to the anticonvulsant effect of morphine on pentylenetetrazole-induced seizures in mice

Regarding the proven anticonvulsant effect of Zhumeria majdae essential oil (ZMEO) in previous studies we were prompted to investigate the ZMEO effects on the tolerance to the anticonvulsant effects of morphine and the morphine withdrawal syndrome. Tolerance to the morphine anticonvulsant effect was induced in mice by subcutaneous injection of 2.5 mg/kg of morphine for 4 days. Subsequent doses of ZMEO (20 mg/kg) were used to study the expression and development of morphine tolerance. Clonidine was used as the standard drug to inhibit the morphine withdrawal syndrome symptoms. To study the ZMEO effect on withdrawal syndrome, mice received appropriate morphine values for 4 days and on the fifth day, 60 min before administration of naloxone. The effective dose of ZMEO was determined and the number of jumps, stands and changes in the dry stool weight, as symptoms of withdrawal syndrome were evaluated. The dose of 20 mg/kg of ZMEO decreased the tolerance in development and expression groups significantly. Counting the number of jumping, standing and defecation were assessed 30 min after morphine and 1 h after the vehicle and clonidine. The dose of 40 mg/kg ZMEO decreased all the signs of withdrawal syndrome significantly. ZMEO was analyzed by GC/MS and linalool (53.1%) and camphor (23.8%) were characterized as the main components. The results suggest that ZMEO possesses constituent(s) that have activity against tolerance to the anticonvulsant effects of morphine and the morphine withdrawal symptoms.

Scale-Phobic Surfaces Made of Rare Earth Oxide Ceramics

Scaling or precipitation fouling involves crystallization of hard and chalky solid salts from a solution. Scaling results in significant production and energy losses and is a major concern in many industries. Here we investigate the scale-phobicity of rare earth oxide (REO) ceramics (particularly CeO₂, Gd₂O₃, and Er₂O₃) in comparison with glass and stain-less steel. We quantify the surface energy and its polar and apolar components for these materials using the Van Oss-Chaudhury-Good approach and show a direct correlation between surface energy and scale deposition. We also show that the polar component of surface energy is the main contributor to scale deposition; hence, REOs with minimal polar component represent high barrier to scale deposition. Moreover, we study the weight gain due to calcium sulfate dihydrate (gypsum) scale accumulation on these materials and show 55% and 77% reduction on REOs in comparison with bare glass and stainless-steel, respectively. We also evaluate the adhesion forces between salt and test materials using atomic force microscopy with a gypsum microparticle adhered onto a tipless cantilever. We show adhesion force between salt particles and REO surfaces is about half that of bare glass and stainless-steel because of the lower surface energy and polar component. We expect REO ceramics would find widespread applicability as robust scale-phobic surfaces in various industries.

Recovery of scandium and neodymium from blast furnace slag using acid baking-water leaching

The current study puts the emphasis on developing a pyro-hydrometallurgical process, called acid baking-water leaching, to recover scandium and neodymium from blast furnace slag produced by the ironmaking industry. In this process, the feed is mixed with concentrated sulfuric acid, digested at 200-400 °C, and leached in water at ambient conditions. This process offers several advantages including less acidic waste generation and rapid kinetics. With fundamental investigations into the digestion mechanism, acid to slag mass ratio and baking temperature are determined to have the most significant positive and negative impacts, respectively. At low acid to slag ratio, the silicate bearing phases in the feed do not digest, resulting in low extraction. At 200 °C baking temperature, a hydrated aluminum sulfate ((Al(H2O)6)2(SO4)3(H2O)4.4) phase with weak hydrogen bonds is formed that leaches in water rapidly (<10 min); while at 400 °C, Al2(SO4)3 with strong ionic bonds is formed that leaches at slower kinetics (>4 h). Fundamental investigations into the water leaching process indicate that the diffusion of water through the firm solid product (ash layer) is the rate determining step. We expect the results of this study would help enable valorization of industrial byproducts, in particular ironmaking slag.

Recovery and separation of phosphorus as dicalcium phosphate dihydrate for fertilizer and livestock feed additive production from a low-grade phosphate ore

With the rapid increase in the world population, the global demand for food production has been increasing steeply. This increase has resulted in an increased demand for phosphorus crop fertilizers and livestock feed additives. Considering recent predictions that the global reserves of high-grade phosphorus resources would deplete within 15 years, new initiatives have begun to utilize low-grade resources to ensure sustainable supply of this essential nutrient. The main challenge with the use of low-grade resources is the difficulty with the efficient and economical separation of phosphorus from the other constituent elements, such as iron, aluminum, and magnesium. Most previous studies on the adoption of low-grade phosphate ores have focussed on ore beneficiation processes which are expensive, complex, and in some cases inefficient. In this study, we develop an integrated process for the direct recovery and separation of dicalcium phosphate dihydrate for fertilizer and livestock feed additive production from a low-grade (2.0 wt% P) iron-rich (19.7 wt% Fe) phosphate ore. The process combines leaching using dilute sulfuric acid (0.29 M) and selective precipitation using calcium oxide. During selective precipitation, ethylenediaminetetraacetic acid (EDTA) is used as a stabilizing agent to prevent iron and phosphorus co-precipitation. This process can be operated as a closed loop, allowing the recovery and recycling of both water and EDTA, while eliminating the production of liquid waste. The developed process achieves around 70% phosphorus recovery as an industrial-grade (19 wt% P) dicalcium phosphate dihydrate product with minimal iron, magnesium, and aluminum contamination, while also producing value-added calcium sulfate dihydrate (gypsum) and iron/magnesium byproducts. This process enables economical and sustainable recovery of phosphorus from low-grade ores, which can address the rising global demand for food production.

A closed loop process was developed to extract phosphorus as dicalcium phosphate dihydrate from a low-grade ore for fertilizers and livestock feed additive production.

Supercritical fluid extraction for purification of waxes derived from polyethylene and polypropylene plastics

Polyethylene (PE) and polypropylene (PP) feedstock contain various additives, such as fillers and colorants, which either degrade or carry through the depolymerization process; thereby causing intense dark colors and a pungent petroleum odor. The combination of color and odor imposes several challenges, limiting the potential markets of the wax products. This study put emphasis on the development of an innovative and environmentally sustainable process based on supercritical fluid extraction (SCFE) to remove organic and inorganic contaminants that cause color and odor in waxes derived from recycled polymers. In terms of organic impurity removal, for PE 81% and for PP 97% removal efficiency was achieved. The color of PE and PP in terms of lightness under CIELAB (lightness, green-red, blue-yellow) color space was improved by 13 and 40 units, respectively. The purified waxes could be utilized in a variety of market segments, including color masterbatch, roofing shingles, rubber, and coatings. Compared with traditional purification technologies based on solvent extraction and absorbent filters, SCFE process offers exceptional advantages, including fast reaction rates, little liquid waste, ease of separation of solutes, and fewer separation stages. This novel process enables producing high-value water white waxes from reclaimed polymeric feedstock with a focus on clean technologies and enhanced resource efficiency.

Recovery of scandium from Canadian bauxite residue utilizing acid baking followed by water leaching

The current study put the emphasis on developing a novel and environmentally friendly waste valorization process, called "acid-baking water-leaching", to recover scandium from bauxite residue produced by the aluminum industry. In this process, bauxite residue is mixed with concentrated sulfuric acid, baked in a furnace at 200-400 °C, and leached in water at ambient conditions. Compared with direct acid leaching processes, the developed process offers the advantages of less acid consumption, less wastewater generation, and fast kinetics. With fundamental investigation into the reaction mechanism, acid baking temperature was shown to be the controlling factor that dictates the final phases of the process. Baking at 200 °C results in the formation of (H₃O)Fe(SO₄)₂ that leaches in water rapidly (<5 min), but extraction efficiency is low (58% scandium). In contrast, baking at 400 °C results in the formation of Fe₂(SO₄)₃ that leaches at slower kinetics (>45 min), but results in higher extraction efficiency (80% scandium). The acid baking water leaching process proves to be a promising technique as the first step of a potential near-zero-waste integrated process for the sustainable valorization of bauxite residue to help build the circular economy.

ZSM-5 decrystallization and dealumination in hot liquid water

ZSM-5 zeolite degrades the crystal surface framework and internal acid sites, dependent on the unique thermophysical nature of water solvent.

Technospheric Mining of Rare Earth Elements from Bauxite Residue (Red Mud): Process Optimization, Kinetic Investigation, and Microwave Pretreatment

Some rare earth elements (REEs) are classified under critical materials, i.e., essential in use and subject to supply risk, due to their increasing demand, monopolistic supply, and environmentally unsustainable and expensive mining practices. To tackle the REE supply challenge, new initiatives have been started focusing on their extraction from alternative secondary resources. This study puts the emphasis on technospheric mining of REEs from bauxite residue (red mud) produced by the aluminum industry. Characterization results showed the bauxite residue sample contains about 0.03 wt% REEs. Systematic leaching experiments showed that concentrated HNO₃ is the most effective lixiviant. However, because of the process complexities, H₂SO₄ was selected as the lixiviant. To further enhance the leaching efficiency, a novel process based on microwave pretreatment was employed. Results indicated that microwave pretreatment creates cracks and pores in the particles, enabling the lixiviant to diffuse further into the particles, bringing more REEs into solution, yielding of 64.2% and 78.7% for Sc and Nd, respectively, which are higher than the maximum obtained when HNO₃ was used. This novel process of “H₂SO₄ leaching-coupled with-microwave pretreatment” proves to be a promising technique that can help realize the technological potential of REE recovery from secondary resources, particularly bauxite residue.

In situ neutron powder diffraction study of the reaction M2O3 ↔ M3O4 ↔ MO, M = (Fe0.2Mn0.8): implications for chemical looping with oxygen uncoupling

The structural properties of (Fe_0.2Mn_0.8)_xO_y as a function of temperature under differing oxidizing and reducing atmospheres have been investigated using thermal gravimetric analysis and neutron powder diffraction techniques.

Hydrophobicity of rare-earth oxide ceramics

Hydrophobic materials that are robust to harsh environments are needed in a broad range of applications. Although durable materials such as metals and ceramics, which are generally hydrophilic, can be rendered hydrophobic by polymeric modifiers, these deteriorate in harsh environments. Here we show that a class of ceramics comprising the entire lanthanide oxide series, ranging from ceria to lutecia, is intrinsically hydrophobic. We attribute their hydrophobicity to their unique electronic structure, which inhibits hydrogen bonding with interfacial water molecules. We also show with surface-energy measurements that polar interactions are minimized at these surfaces and with Fourier transform infrared/grazing-angle attenuated total reflection that interfacial water molecules are oriented in the hydrophobic hydration structure. Moreover, we demonstrate that these ceramic materials promote dropwise condensation, repel impinging water droplets, and sustain hydrophobicity even after exposure to harsh environments. Rare-earth oxide ceramics should find widespread applicability as robust hydrophobic surfaces.

Selective transport of silver ion through a supported liquid membrane using hexathia-18-crown-6 as carrier

A facile supported liquid membrane (SLM) system for the selective and efficient transport of silver ion is introduced. The SLM used is a thin porous polyvinyldifluoride membrane impregnated with hexathia-18-crown-6 (HT18C6) dissolved in nitrophenyloctyl ether. HT18C6 acts as a specific carrier for the uphill transport of Ag+ ion as its picrate ion paired complex through the SLM. In the presence of thiosulfate ion as a suitable stripping agent in the strip solution, transport of silver occurs almost quantitatively after 4 h. The selectivity and efficiency of silver transport from aqueous solutions containing other Mn+ cations such as Mg2+, Ca2+, Co2+, Ni2+, Cu2+, Zn2+, Pb2+, Cd2+, Hg2+, Fe3+ and Cr3+ ions were investigated.

Dopamine compared with dobutamine in experimental septic shock: relevance to fluid administration

The hemodynamic effects of dopamine and dobutamine (at doses of 6 micrograms X kg-1 X min-1) were compared during fluid resuscitation from septic shock induced by endotoxin (3 mg/kg) in the dog. In the first part of the study, when a standard amount of saline solution was infused (in 24 dogs), dopamine infusion resulted in higher cardiac filling pressures than did dobutamine infusion, whereas dobutamine infusion resulted in higher cardiac output. In the second part of the study, when fluid infusion was titrated to maintain pulmonary artery balloon-occluded pressure at constant level (in 24 dogs), the total amount of fluids was significantly greater with dobutamine than when dopamine was used (109 +/- 13 vs 71 +/- 10 ml/kg). The combination of dobutamine with fluids resulted in significantly greater stroke volume (39.6 +/- 3.8 vs 21.0 +/- 4.0 ml, P less than 0.05) and oxygen consumption (194 +/- 18 vs 144 +/- 8 ml/min, P less than 0.05). The different effects of dopamine and dobutamine on cardiac filling pressures can be due to differences in effects on myocardial contractility, ventricular afterload, and cardiac compliance. This experimental study indicates that when fluid therapy is combined with adrenergic agents in resuscitation from septic shock, dobutamine can be associated with higher cardiac output and oxygen transport and can result in higher tissue oxygen consumption than dopamine.

Ultimate survival from septic shock

Detailed hemodynamic course during prolonged (less than 12 h) septic shock was studied in 23 patients, of whom 12 ultimately died from sepsis. Hemodynamic presentation was similar in fatalities and in survivors, except for a higher heart rate and a markedly higher blood lactate in fatalities (8.4 +/- 1.4 vs. 3.7 +/- 0.4 mEq/l, P less than 0.01). During fluid resuscitation, the pulmonary artery occlusive pressure associated with the highest left ventricular stroke work was usually around 17 mmHg, but in some patients above 20 mmHg. During the course of septic shock, left ventricular function improved in both fatalities and survivors, so that an altered cardiac function had no ultimate pejorative implication. The higher blood lactate in the absence of a different hemodynamic pattern tends to indicate that peripheral distributive defect remains the essential anomaly in septic shock. Arterial lactate appears to represent the most reliable indicator of ultimate prognosis in septic shock.

Haemodynamic, gasometric and haematological effects of air infusion in dogs: leukotriene inhibition with U-60,257

Air embolization has been shown to produce a reversible permeability-type of pulmonary oedema. The present study investigated the haemodynamic, gasometric and haematological changes associated with air infusion in the spontaneously breathing dog (weight 31 +/- 5 kg). Air was infused at a rate of 10 ml X min-1 for 60 min (10 dogs) or 180 min (5 dogs). During the air infusion, a dramatic increase in pulmonary artery pressure was associated with only a moderate increase in right atrial pressure and limited decreases in arterial pressure and in cardiac output. A marked decrease in end-tidal PCO2 reflected the increase in dead space. These changes were stable during air infusion, but rapidly reversed after the end of infusion. However, hypoxaemia, defined by a decreased PaO2/PAO2 ratio, deteriorated with time and was only partially reversible. At histological examination, interstitial pulmonary oedema was present around the pulmonary arterioles. Air infusion was associated with rapid decreases in circulating leukocytes and platelets and complement activation. Since leukotriene release might be associated with leukocyte activation in this model, seven additional dogs were pretreated by inhalation of 10 mg of the leukotriene inhibitor U-60,257. The increase in pulmonary vascular resistance and in pulmonary shunt were moderately reduced and the drop in circulating leukocytes and platelets was strikingly abolished in the treated animals. Air infusion in the spontaneously breathing dog represents a model of very stable and reversible pulmonary hypertension. It can reproduce important pathophysiological features implicated in the development of pulmonary oedema.(ABSTRACT TRUNCATED AT 250 WORDS)