Cobalt In Solution Research Articles

Removal of Fe and Mn from Co leach solutions by adsorption on activated carbon based on post-consumer polyethylene terephthalate (PET) - Mechanism insights through linear and nonlinear isotherm and kinetic models

ABSTRACT The removal of Fe2+ and Mn2+ from cobalt sulfate-saturated solutions is frequently problematic for Cu-Co hydrometallurgical process performance. Among the applied and developed methods for the removal of these metals, adsorption has drawn less attention. This study investigates on the removal of Fe2+ and Mn2+ in industrial cobalt solutions known as raffinates by adsorption on activated carbon prepared from post-consumer polyethylene terephthalate (PET). The adsorption operating conditions were studied in synthetic solutions and industrial solutions. The Langmuir, Freundlich, and Temkin isotherms were then used to fit the adsorption data, while the pseudo-first-order (PFO), pseudo-second-order (PSO), and Elovich models were used to describe the kinetics. Linear and nonlinear kinetic and isotherm models were studied and compared. Furthermore, intraparticle diffusion (IPD) models were used to study the transfer mass mechanism. The results show that Fe2+ and Mn2+ are removed from Co solutions with the efficiencies of 62.14 and 68.43, respectively. The Langmuir model fits the Fe2+ and Mn2+ adsorption data better, indicating that chemisorption is preferred over physisorption, whereas the Freundlich model fits the Co2+ adsorption data better, indicating that physisorption is preferred over chemisorption. The PFO model describes well the kinetic behavior of Fe2+ and Mn2+, whereas the Elovich model describes better the kinetic behavior of Co2+. According to the IPD model, the step that limits the adsorption of Fe2+, Mn2+, and Co2+ is essentially diffusion through the activated carbon pores. The reported experimental results will highlight the use of activated carbon in the removal of Fe2+ and Mn2+ in Cu and Co hydrometallurgy.

Synthesis and Application of Titanium Carbide (Ti3C2)-Cobalt Sulfide (Co3S4) Nanocomposites in Amino Acid Biosensing.

Background The fabrication of titanium carbide (Ti3C2)-cobalt sulfide (Co3S4)-based biosensors with high sensitivity and selectivity can change the biosensor manufacturing industry completely. Molecular and clinical diagnostics, disease progression monitoring, and drug discovery could utilize these sensors for early biomarker detection. MXene (Ti3C2) is a two-dimensional material with exceptional electrical conductivity, hydrophilicity, great thermal stability, large interlayer spacing, and a high surface area. Ti3C2'sremarkable characteristics make it well-suited for biomolecule immobilization and target analyte detection. Co3S4is a transition metal chalcogenide that has shown great potential in biosensors. Co3S4 nanoparticles (NPs) can potentially enhance Ti3C2 electrocatalytic activity, particularly in amino acid detection. L-arginine is a semi-essential amino acid, and the body frequently uses it to support healthy circulation and plays a crucial role in protein synthesis. We fabricated the Ti3C2-Co3S4 biosensor for L-arginine detection. Aim This study aims to synthesize and apply Ti3C2-Co3S4 nanocomposites in amino acid biosensing. Materials and methods The Ti3C2 nanosheets were synthesized by the selective removal of an aluminum (Al) layer from the precursor (Ti3AlC2) using hydrofluoric acid (HF). The resulting mixture serves as an etchant, especially targeting the Al layers on Ti3AlC2while protecting the desired MXene layers at room temperature. Cobalt nitrate hexahydrate was dissolved in deionized water. Sodium hydroxide was added to the cobalt solution and stirred. Thioacetamide was added to the above solution and stirred (Solution B). A mixture of Solution A and Solution B was stirred for 30 minutes. The mixture is transferred to a hydrothermal reactor and maintained at a temperature of 180°C for 12 hours. Once the reaction completes, we cool the resultant mixture to room temperature and then filter it using the washing technique. The sample underwent a 12-hour drying process at 80°C. Results This study investigated the use of a biosensor that employed Ti3C2-Co3S4 NPs to detect the concentration of L-arginine. The X-ray diffraction (XRD) shows clear and distinct peaks, which means that the synthesized Ti3C2-Co3S4 nanostructures have a crystalline structure.Scanning electron microscopy (SEM) analysis revealed that the sheetlike structure of synthesized Ti3C2-Co3S4 nanostructuresrevealedthe crystalline morphology. The results of this study show that the Ti3C2-Co3S4NP-based biosensor can be used to detect L-arginine in a sensitive and selective way. Conclusion This study investigated the synthesis of Ti3C2-Co3S4NPs and their ability to detect L-arginine levels and show a distinct correlation between the L-arginine concentration and the fluorescence intensity, demonstrating the biosensor's effectiveness in detecting L-arginine levels.

RETRACTION NOTICE: Recovery of iron compounds and cobalt solutions from mining tailings

Retraction note: Zamarreño-Bastías, R. & Mera, A. C. (2022). Recovery of iron compounds and cobalt solutions from mining tailings. TECHNO REVIEW. International Technology, Science and Society Review Revista Internacional De Tecnología, Ciencia Y Sociedad, 12(4), 1–12. https://doi.org/10.37467/revtechno.v11.4492 The Editorial Office of Eurasia Academic Publishing Group has retracted this article. An investigation carried out by our Research Integrity Department has found a group of articles, among which this one is found, that are not within the thematic scope of the journal. We believe that the editorial process was manipulated and, furthermore, acceptance decisions were made under possibly inappropriate peer review.

Plasma-solution synthesis of cobalt oxides

The production of nanosized oxide materials is an important practical problem. This is due to the fact that many of these substances are intensively used as catalysts, microelectronic devices, medical applications, etc. Among the various methods for their production, methods based on the use of gas-discharge plasma are the least studied. But these methods, compared to others, have a number of significant advantages. Among them, the main ones are high process rates and the absence of additional reagents. Therefore, in this work the regularities of the processes of formation of insoluble compounds under the action of a direct current discharge of atmospheric pressure in air on aqueous solutions of cobalt (II) nitrate have been studied. The solutions served as the cathode and anode of the discharge. The discharge was excited by applying a high voltage to two pointed titanium electrodes placed above the liquid anode and liquid cathode in the H-shaped cell. The range of discharge currents was (20–80) mA, and the range of concentrations was (20–60) mmol l−1. It was discovered that when a discharge acts on a liquid anode, a colloidal solution is formed in it, the destruction of which leads to the formation of precipitates. Based on measurements of the kinetics of consumption of Co2+ ions (spectrophotometric method) and the power inputted in the discharge, the rates of this process, effective rate constants, as well as the degree of conversion of Co2+ ions and energy yields of conversion were determined. These parameters depended on the discharge current and the initial concentration of the solution. The values of the constants were ∼(0.2–6) × 10−1 s−1, the energy yields were ∼(0.2–0.5) ions per 100 eV, and the degrees of conversion were ∼(0.1–0.5). The resulting powders were analyzed by differential scanning calorimetry (DSC), x-ray diffraction (XRD), and energy-dispersive x-ray spectroscopy (EDS). The sizes of the powder aggregates were estimated from the results of scanning electron microscopy (SEM), transmission electron microscope (TEM) and Scherrer’s relation. It turned out that the resulting precipitates were a mixture of amorphous Co2+ and Co3+ hydroxides. Their calcination in air led, depending on the temperature, to the formation of predominantly cubic either CoO or Co3O4. The size of the aggregates of the calcined samples was ∼500 nm. The specific surface area of the powders, determined by the Brunauer–Emmett–Teller (BET) method, was ∼53 m2 g−1. The average pore volume and their size was ∼17 cm3 g−1 and ∼240 Å. The advantages of the proposed method over other methods are high process rates (process time ∼10 min) and the absence of any additional reagents.

Development of a conceptual direct solvent extraction (DSX) route and a flowsheet to produce purified concentrated cobalt and nickel solutions representing sulfuric acid leach liquor of laterite

Direct solvent extraction (DSX) was applied to produce purified concentrated Ni and Co solutions from a synthetic sulfuric liquor containing Ca, Cu, Mg, Mn, and Zn as impurities, which simulates the solution obtained by the sulfation-roasting-leaching process after precipitation of Fe, Al, and Cr. The commercial extractants Versatic 10, Cyanex 272, D2EHPA, TBP were used in 3 solvent extraction circuits. In the first circuit, operated at 40 °C, Versatic 10 (0.5 M) fully extracted Cu, Zn, Ni, and Co in 3 stages at O/A = 2:1, and pH 6.5, leaving remaining Mn (54% was extracted) and most of the Ca and Mg in the raffinate. The co-extracted Ca and Mg were fully scrubbed off the loaded Versatic 10 in 2 stages at O/A = 5:1, and pH 6.5. The other metals were stripped out of the Versatic 10 extract using a synthetic Ni spent electrolyte (60 g/L Ni, 2 M H2SO4) in 2 stages at O/A = 9:1. This loaded strip liquor was subjected to a second circuit with Cyanex 272 (0.64 M) operated at 50 °C. Three stages were required to fully extract Co, Cu, Mn, and Zn (O/A = 2:1, pH 4), whereas the raffinate containing 82 g/L Ni was deemed suitable for electrowinning. The co-extracted Ni(II) was fully scrubbed off the loaded Cyanex 272 in only 1 stage at O/A = 5:1, and pH 4. All Co, Cu, Mn, and Zn were stripped out from the scrubbed loaded Cyanex 272 in 2 stages at O/A = 10:1 using a synthetic Co spent electrolyte (45 g/L Co, 1 M H2SO4). The raffinate containing 58.4 g/L Co was submitted to a third circuit using a D2EHPA (0.6 M) + TBP (0.73 M) synergistic system operated at 50 °C. Zinc(II) was fully extracted by the D2EHPA + TBP system in 2 stages at pH 2 and O/A = 1:3, while Mn(II) and Cu(II) were fully extracted from the Zn-depleted raffinate in 2 stages at pH 3.5 and O/A = 2:1. The raffinate containing 58.3 g/L Co was deemed suitable for electrowinning. Copper(II), Mn(II), and Zn(II) were stripped out from the loaded D2EHPA + TBP in 3 stages at O/A = 2.5:1 using 1 M H2SO4. The real number of moles of extractants involved in the extractions and apparent equilibrium constants were estimated for all circuits. A flowsheet of the purification conceptual route is presented.

Synthesis, structural characterization and antitumor activities of manganese and cobalt isothiocyanate complexes with 2,2’-bipyridine

[Mn(SCN)2(2,2′-bipy)2] (1) and [Co(SCN)2(2,2′-bipy)2] (2) were synthesized at ambient temperature by adding aqueous solutions of manganese(II) or cobalt(II) chloride hydrate to aqueous acetonitrile solutions of 2,2′-bipyridine (2,2′-bipy) and potassium thiocyanate. Elemental analyses, FT-IR and UV–vis spectra were used to characterize 1 and 2. Single crystal X-ray diffraction was used to analyze the crystal structures of 1 and 2, revealing that the two are structurally similar. The molecular structures of 1 and 2 consist of Mn or Co ion chelated by two molecules of 2,2′-bipy through four nitrogen atoms and two NCS anions, giving distorted octahedral geometries. The isothiocyanate group is not bridging, instead, two ligands coordinate in a cis arrangement to the manganese or cobalt center by their nitrogen atoms while the sulfur atoms are free. Through hydrogen bonding and π–π stacking interactions, the discrete units of 1 and 2 extend to 3D supramolecular networks with flower and fishbone-like structures. The luminescence behavior of 2,2′-bipy, 1 and 2 were investigated. On HepG2 (liver) and MCF-7 (breast) cancer cells, the anticancer effects of 1 and 2 were evaluated. The activity of 1 and 2 on MCF-7 is more significant than that of HepG2. The IC50 of 1 was lower in HepG2 and MCF-7 cells than for 2.

3D POROUS COMPOSITE SCAFFOLDS WITH HIGH CALCIUM PHOSPHATE CONTENT AND ADDITION OF INORGANIC IONS FOR BONE REGENERATION APPLICATIONS

Critical-sized bone defects remain challenging in the clinical setting. Autologous bone grafting remains preferred by clinicians. However, the use of autologous tissue is associated with donor-site morbidity and limited accessibility to the graft tissue. Advances in the development of synthetic bone substitutes focus on improving their osteoinductive properties. Whereas osteoinductivity has been demonstrated with ceramics, it is still a challenge in case of polymeric composites. One of the approaches to improve the regenerative properties of biomaterials, without changing their synthetic character, is the addition of inorganic ions with known osteogenic and angiogenic properties. We have previously reported that the use of a bioactive composite with high ceramic content composed of poly(ethyleneoxide terephthalate)/poly(butylene terephthalate) (1000PEOT70PBT30, PolyActive, PA) and 50% beta-tricalcium phosphate (β-TCP) with the addition of zinc in a form of a coating of the TCP particles can enhance the osteogenic differentiation of human mesenchymal stromal cells (hMSCs) (3). To further support the regenerative properties of these scaffolds, inorganic ions with known angiogenic properties, copper or cobalt, were added to the coating solution.β-TCP particles were immersed in a zinc and copper or zinc and cobalt solution with a concentration of 15 or 45 mM. 3D porous scaffolds composed of 1000PEOT70PBT30 and pure or coated β-TCP were additively manufactured by 3D fibre deposition. The osteogenic and angiogenic properties of the fabricated scaffolds were tested in vitro through culture with hMSCs and human umbilical vein endothelial cells, respectively. The materials were further evaluated through ectopic implantation in an in vivo mini-pig model. The early expression of relevant osteogenic gene markers (collagen-1, osteocalcin) of hMSCs was upregulated in the presence of lower concentration of inorganic ions. Further analysis will focus on the evaluation of ectopic bone formation and vascularisation of these scaffolds after implantation in a mini-pig ectopic intramuscular model.

A dual functional turn off florescence sensor using metal–organic framework for sensitive detection of aluminum(III) in aqueous solution

AbstractAluminum, classified as one of the toxic heavy metals, has a recommended daily consumption limit of 3–10 mg, as specified by the World Health Organization (WHO). Herein, the selective and sensitive aluminum(III) fluorescence sensor based on TMU‐16 metal–organic frameworks (MOFs) in aqueous medium, is reported. A sensing pathway was found via the cation exchange between aluminum(III) and zinc(II) ions, and caused selectivity and sensitivity detection of aluminum(III) with a 5–100 ppm linear range and 1.99 ppm limit of detection (LOD).This sensor offers the advantage of accurately determining the concentration range of aluminum(III) ions. At low concentrations, only fluorescence quenching was observed, while at higher concentrations, fluorescence emission not only undergoes quenching but also exhibits a blue shift in wavelength. Notably, the sensor demonstrates no interference from cation solutions of mercury(II), zinc(II), nickel(II), lead(II), cobalt(II), cadmium(II), silver(I), chromium(III), and iron(III).Another significant feature of this sensor is its selectivity toward copper(II) and aluminum(III) ions, due to quenching fluorescence in the presence of copper(II) ion. The results presented the sensor's selectivity toward copper(II) at low concentrations and aluminum(III) at high concentrations.

Thermodynamics of the ion association of potassium cobalt(III) bis(1,2-dicarbollide) in acetonitrile, methanol and dimethyl sulfoxide

The molar conductivities, Λ, of dilute solutions of potassium cobalt(III) bis(1,2-dicarbollide) (K[COSAN]) in methanol (MeOH), acetonitrile (MeCN) and dimethyl sulfoxide (DMSO) were determined at different temperature ranges. The data were analysed in the frame of Barthel’s low-concentration chemical model (lcCM) to obtain the limiting molar conductivities,Λ∞, and standard association constants, KAo, of K[COSAN]. To confirm the ion association of oppositely charged ions K+ and [COSAN]–, molecular dynamics (MD) simulations were performed, in which the values of KAo from the potential of the mean force between the pair of particles (ions) were determined. From temperature dependence of KAo, the thermodynamic parameters for ion association, namely standard free enthalpy ΔGAo, enthalpy ΔHAo, and entropy ΔSAo, were estimated. The dilution enthalpies of concentrated solutions of K[COSAN] in organic solvents were also determined by using isothermal titration calorimetry (ITC). Our experimental results show that K+ and [COSAN]– ions form ion pairs in all the investigated solvents. Ion association is most pronounced in MeOH and MeCN and the least expressed in DMSO, the process is endothermic and is accompanied by an increase in entropy. The agreement between the calculated values of KAo and the thermodynamic parameters obtained by conductivity and MD simulations follow the same trend.

Surfactant-free synthesis and magnetic property evaluation of air-stable cobalt oxide nanostructures

We report the synthesis of metastable cobalt oxide (CoO) nanostructures via the low-temperature microwave-assisted solvothermal (MAS) process. An alcoholic solution of cobalt (II) acetylacetonate in a sealed vessel was irradiated with microwaves at a temperature <150 °C and a pressure below 100 psi. As-synthesized powder material was characterized in terms of its structure and morphology. X-ray diffractometry (XRD) indicates the formation of well-crystallized CoO nanoparticles without the need for post-synthesis annealing. The mean crystallite size of the nanoparticles was estimated to be 41 nm. The morphology of the as-prepared powder sample was evaluated by field-emission scanning electron microscopy (FESEM), which revealed the formation of densely packed nanospheres of diameter <100 nm. The CoO nanospheres were obtained without the need for any surfactants or capping agents; they were found to be quite resistant to oxidation in ambient air over several months. We attribute the stability of CoO nanospheres to their dense packing, the driving force being the minimization of surface energy and surface area. Fourier-transform infrared (FT-IR) spectroscopy and Raman spectroscopy confirm the formation of phase-pure CoO nanostructures. The deconvolution of the active modes in Raman spectra obtained at room temperature reveals the Oh symmetry in rock-salt CoO produced by the MAS route. We have analyzed its effect on the magnetic characteristics of the CoO nanostructures. Isothermal field-dependent magnetization (MH) and inverse magnetic susceptibility measurements show a phase transition from antiferromagnetic to ferromagnetic interactions in the CoO nanostructures at around 10 K. The results indicate that the phenomenon of magnetic phase transition as a function of temperature is unique to CoO nanoparticles. This finding reveals the magnetic behavior of CoO nanostructures and presents opportunities for its possible application as an anisotropy source for magnetic recording.

From nano-hydroxyapatite to pakhomovskyite: A particular phase transformation

Hydroxyapatite nanocrystals (nano-HAp) were dispersed in a highly concentrated solution of cobalt(II) ions. After 5 days the particles were completely transformed into a new phase, consistent with the one for the cobalt phosphate known as pakhomovskyite (PAk). The transformation process began with an amorphization, thus completely changing the thermodynamics involved in the crystallization process. The initial metastable amorphous material has a defined stoichiometry, Co2.5Ca6.5(PO4)6·nH2O, and it is capable of evolving to the PAk phase solely by remaining suspended in water over an extended period. Apparently, a non-classical crystallization has occurred, where there could be a process based on nano-cluster coalescence. Towards the end of the process the crystals, already transformed to the PAk phase, showed an accelerated growth accompanied by further enrichment in cobalt(II) ions.

A New Approach to the Preparation of Stable Oxide-Composite Cobalt–Samarium Catalysts for the Production of Hydrogen by Dry Reforming of Methane

A new approach to preparing a series of Co/Sm2O3 catalysts for hydrogen production by the dry reforming of methane has been developed. The catalyst precursors were synthesized with a simple method, including the evaporation of aqueous solutions of cobalt and samarium nitrates, followed by a short-term calcination of the resulting material. The as-prepared and spent catalysts were characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, temperature-programmed reduction, and thermogravimetric analysis. The content of cobalt in the synthesized materials affects their phase composition and carbonization resistance in the dry reforming of the methane reaction. It has been shown that preheating in N2 atmosphere produces catalysts that provide a stable yield of hydrogen and CO of 94–98% for at least 50 h at 900 °C. These yields are among the highest currently available for the dry reforming of methane catalysts made from Co-Sm complex oxides. It has been established that the decrease in the amount of cobalt in the catalyst and its preheating to an operating temperature of 900 °C in a nitrogen flow help to prevent the carbonization of the catalyst and the sintering of metal particles.

Thermodynamic evaluation and optimization of the As–Co, As–Fe and As–Fe–S systems

A critical evaluation of all available phase diagram and thermodynamic data for the As–Co and As–Fe binary systems as well as the As–Fe–S ternary system has been performed and thermodynamic assessments over the whole composition ranges are presented using the CALPHAD method. To predict thermodynamic properties and phase equilibria for these systems, the Modified Quasichemical Model (MQM) for short range ordering was used for the liquid phases. The Compound Energy Formalism (CEF) was used for the solid solutions. Since Co and Fe are ferromagnetic, magnetic contributions were added to describe the Gibbs energy of cobalt and iron rich solid solutions. Important uncertainties remain for the liquidus of As-rich regions in the binary subsystems.

Structural and Electrical Properties of "Cadmium Sulfide- Cobalt" Compound and Using it as a Gas Sensor

Background: Both the cubic (zinc blend) and hexagonal (wurtzite) phases of cadmium sulphide are semiconductors due to the presence of a row of four equally spaced Cd atoms surrounded by one S atom. Both the cubic and hexagonal crystal forms of Cd-S have very similar nearest neighbor bond lengths. Material and Methods: The cadmium sulfide compound was prepared at a concentration of 1 M by dissolving the percentage by weight of each of cadmium(13.326g) and sulfur (3.806g) in 100 ml of distilled water. Cobalt was prepared at a concentration of 0.5M by dissolving a percentage by weight of Cobalt acetate (14.55g) in 100 ml of distilled water. Films CdS and CdS:Co were prepared using the chemical method, which is the thermal chemical spraying technique, which deposited a solution of cadmium sulfide mixture of cobalt solution with cadmium sulfide on a glass floor.&#x0D; Results: The thickness of the prepared films was 100 mm. The surfaces of the prepared films were studied by measuring transmission electron microscopy. The results showed that the prepared films are homogeneous and have crystalline granules of spherical shape, and the addition of cobalt to the cadmium sulfide compound led to an increase in the particle size values. The electrical properties represented by measuring the voltaic- current were studied, and the results showed that the relationship between the voltaic- current is linear, and this indicates that the prepared films behave as ohmic.&#x0D; Conclusion: The continuous electrical conductivity was also calculated, and the results showed that the addition of cobalt acetate to the cadmium sulfide compound led to an increase in the electrical conductivity values. The gas sensitivity of the prepared films towards hydrogen sulfide gas was studied, and the results showed that the prepared films had good sensitivity, and adding cobalt acetate to the cadmium sulfide compound led to a decrease in the sensitivity values.

Synthesis, structure characterization and antitumor activities of copper and cobalt thiocyanate complexes with 3-acetlpyridine ligand

Complexes of [Cu(SCN)2(3-Acpy)2], (1) and [Co(SCN)2(H2O)2(3-Acpy)2], (2) were synthesized at ambient temperature by adding an aqueous solution of copper(II) or cobalt(II) chloride to H2O/CH3CN solution of 3-acetlpyridine (3-Acpy) and potassium thiocyanate. Elemental analysis, FT-IR and UV–vis spectra were used to comprehensively characterize complexes 1 and 2. Single crystal X-ray diffraction was used to analyze the crystal structure of complexes 1 and 2. In complex 1, the copper is bonded to two 3-Acpy ligands and two thiocyanates groups in trans mode giving square planer geometry. While, in complex 2, the cobalt ion is coordinated to two water molecules, two 3-Acpy ligands and two thiocyanates ions in trans mode giving an octahedral structure. Through hydrogen bonding, the discrete units of complexes 1 and 2 extend to form a 3D supramolecular network. Additionally, the luminescence spectra of complexes 1 and 2 were investigated. Complexes 1 and 2 were evaluated to determine whether they were able to inhibit the growth of liver cancer (HepG2 cells) and breast cancer (MCF-7 cells). Complex 1 exhibits lower IC50 values than complex 2 against both of the two human cell lines. In HepG2 cells treated with complexes 1 and 2 at dosages roughly half of the IC50, apoptosis of complexes 1 and 2 is triggered by 18% and 22%, respectively. It was found that copper complex 1 has a greater cytotoxic effect on MCF-7 and influences on late apoptosis of HepG2.

Facile metal-ion infiltration into polyimide membranes with coordination crosslinking for efficient gas separation

We report a facile metal-ion infiltration method for engineering the properties of 6FDA-DAM:DABA (6FDA: 4,4′-(hexafluoroisopropylidene)diphthalic anhydride, DAM: 2,4,6-trimethyl-1,3-diaminobenzene, DABA: 3,5-diaminobenzoic acid; referred to as 6FDD) polyimide membranes. The 6FDD polyimide membrane samples were simply immersed in metal ion (copper, zinc, and cobalt) solutions of various concentrations (1 and 10 wt%) to obtain metal-ion-infiltrated 6FDD membranes. The metal ions and the carboxylate group of the 6FDD polyimide form a coordination bond, which can increase the d-spacing between the inter-polymer chain distances and reduce polymer chain mobility. The coordination between the metal ion and the carboxylated polymer chain enhances the mechanical properties of the polyimide membranes. The metal ion coordination provides not only increased stiffness but also high resistance to the breaking point under elongation. The metal ions were distributed uniformly across the entire 6FDD membrane without any noticeable defects, which indicated the effectiveness and simplicity of the proposed method, which can be applied to versatile membrane module types and conformations. The metal-ion infiltrated 6FDD membrane exhibited improved gas permeability compared to that of the pure 6FDD membrane because of the enhanced diffusivity coefficient resulting from the increased d-spacing. Particularly, the metal-ion-infiltrated 6FDD membranes exhibited significantly higher plasticization resistance because of a decrease in the normalized CO2 permeability at 750 psi compared to that of the pure 6FDD membrane. For example, the normalized CO2 permeability of the 10 wt% copper-ion-infiltrated 6FDD membrane increased by 120% but that of pure 6FDD membrane increased by 315%. This was because the metal–carboxylate group coordination strongly prevented relaxation of the polymer chain when it was exposed to plasticizing gases at high gas feed pressures.

Transport Properties of Carbohydrates: Towards the Minimization Toxicological Risks of Cobalt and Chromium Ions

The influence of oligosaccharides (α-cyclodextrin, β-cyclodextrin and γ-cyclodextrin), and a polysaccharide, sodium hyaluronate (NaHy), on the diffusion of aqueous solutions of cobalt and chromium chlorides has been investigated. Cobalt and chromium are constituents of metal alloys for biomedical use, including dental prostheses. Thus, the release of these ions in the human body can lead to harmful biological effects. The interaction of metal ions with saccharides might have information on the role of mouthwashes in preventing these effects. This interaction has been assessed by measuring multicomponent intermolecular diffusion coefficients at 298.15 K. It has been found that β-cyclodextrin has the highest interaction towards cobalt and chromium ions. This work will contribute to unveiling the mechanisms responsible for transport by diffusion in aqueous solutions, and, therefore, mitigating the potential toxicity inherent to those metal ions.

Alleviating the toxic effects of Cd and Co on the seed germination and seedling biochemistry of wheat (Triticum aestivum L.) using Azolla pinnata

One of the most significant environmental challenges in the twenty-first century is heavy metal pollution. The potential use of fresh Azolla pinnata to alleviate the toxic effects of Cd and Co on the germination measurements of wheat seeds (Triticum aestivum L.) and the biochemistry of seedlings was studied. Two concentrations (80 and 100 mg L−1 solutions) of CdNO3 and CoCl2 were used before and after treatment with A. pinnata. The highest removal efficiency (RE) by A. pinnata was obtained on the fifth day, with a Cd RE = 55.9 and 49.9% at 80 and 100 mg L−1, respectively. Cadmium and cobalt solutions reduced the germination percentage, and the measured variables of wheat seeds meanwhile increased the radicle phytotoxicity. In contrast, the presence of A. pinnata in the germination medium increased all the measured variables and decreased radicle phytotoxicity. At 80 and 100 mg L−1, Cd significantly reduced the fresh and dry biomass, and height of wheat seedlings after 21 days of cultivation compared to Co. Cadmium and high concentrations of cobalt increased the contents of H2O2, proline, MDA, phenolic, and flavonoid compounds. The application of treated Cd and Co solutions by A. pinnata showed a decrease in H2O2, proline, phenolic, and flavonoid compounds levels accompanied by a reduction in catalase and peroxidase activities compared to the control. This study showed the positive role of A. pinnata in alleviating the metal impacts, particularly Cd, on the seedling growth of wheat and its germination.

The ion flotation of copper, nickel, and cobalt using the biosurfactant surfactin

Heavy metal contaminated waters are a significant environmental hazard, which require novel treatment methodologies. Further, the metals which might be recovered from these streams have significant intrinsic value, if they can be collected and concentrated. This work demonstrates, for the first time, the use of surfactin, an environmentally benign biosurfactant, for the flotation of metal ions (Cu2+, Ni2+, and Co2+). Surfactin, at a molar ratio of 1:3, has been shown to float 75.2%, 94.7%, and 98.2% of initial 100 mu M solutions of copper nickel and cobalt, respectively. Increasing the gas flow rate modifies the float by increasing the carryover of water into the overflow. A pH of 5 was found to be ineffective (due to surfactin precipitation), while a pH of 10 was less effective than pH 7, likely due to the ionic speciation of the metals in solution tending to hydroxyl precipitates at a high pH. This work demonstrates an opportunity for the recovery of metals (at low concentrations) using biosurfactant-based froth flotation.

Influence of coexisting EDTA, citrate, and chloride ions on the recovery of copper and cobalt from simulated wastewater using fluidized-bed homogeneous granulation process

Copper and cobalt from industrial operations build up in the environment, posing a substantial health risk. This study examined how ethylenediaminetetraacetic acid (EDTA), citrate, and chloride ions affected the fluidized bed homogeneous granulation process' (FBHGP) ability to recover both individual and combination of copper and cobalt ions from simulated waste streams. A 99% copper removal and 95% granulation efficiency were attained in copper-based solutions. The soluble copper still present in the solution caused a 4% variation in the removal and granulation efficiencies. There were 99% removal and 99% granulation efficiencies in cobalt-based solutions. When EDTA was present in a copper-based solution, 95% removal and 86% granulation were reached, and for cobalt-based solutions, 95% and 91% were the removal and granulation efficiency, respectively. The presence of citrate in the copper-based solution obtained the removal of 83% and granulation efficiency of 54% at 0.1 MR of citrate to copper. No copper phosphate precipitate was formed when the MR was greater than 0.1. There were 96% removal and 92% granulation efficiency when citrate was present in cobalt-based solutions. The presence of chloride ions in copper solution achieved a 99% removal and 91% granulation efficiency, while in cobalt solutions, 99% removal and 98% granulation efficiency were attained. Solutions with combined copper and cobalt with chloride ions achieved 99% removal and 95% granulation efficiency for copper and 99% removal and 95% granulation efficiency for cobalt. The granule sizes decreased as the MR of the complexing agents to metal, and the concentration of chloride ions increased. The peaks on the XRD pattern exactly matched the peaks of cobalt phosphate hydrate (Co3(PO4)2·8 H2O). FBHGP has effectively recovered copper and cobalt from the waste streams of simulated metals.