Cobalt Sulfate Solution Research Articles

Separation of trace amount of nickel from cobalt sulphate solutions using a synergistic solvent extraction system consisting of dinonylnaphthalene sulfonic acid (DNNSA) and decyl 4-picolinate (4PC)

The current methods for separation of nickel from cobalt sulphate solutions have drawbacks of long flowsheets, release of large volumes of wastewater and incomplete separation of two metals. A synergistic solvent extraction (SSX) system consisting of dinonylnaphthalene sulfonic acid (DNNSA) and decyl 4-picolinate (4PC) is proposed in this work to extract nickel from cobalt sulphate solutions selectively. The extraction of nickel reached 99.7% after five-stage counter current extraction with an A/O volume ratio of 1/6 at 30 °C, resulting in a large increase of Co/Ni mass ratio to 25,700 in raffinate from 56 in feed. The loaded organic phase can be easily stripped using a dilute H2SO4 solution. Application of this process in industry is expected to make an important impact on the production of high-purity cobalt sulphate solutions and to deliver economic benefits.

Process monitoring of cobalt carbonate precipitation by reactions between cobalt sulfate and sodium carbonate solutions to control product morphology and purity

Recovering critical elements from EV batteries is challenging as the separation is a complex process which involves different processing parameters. Cobalt (Co) is one of the metals which ensures the life of EV batteries and here we have successfully precipitated cobalt carbonate (CoCO3) by semi-batch precipitation using cobalt sulfate and sodium carbonate as reactant solutions. The precipitation of cobalt carbonate was investigated by offline Raman spectroscopy, Powder X-ray diffraction analysis, inline Focused Beam Reflectance Measurement (FBRM), and pH measurements. In addition, the effects of various factors including pH, aging time, reactant addition time, mixing speed, and temperature on cobalt carbonate precipitation and the properties of the precipitated solids were investigated. In the process of precipitation, the carbonate ions in the initial electrolyte solution were converted to bicarbonate ions during the addition of acidic cobalt sulfate solution, which consequently decreased the pH in the suspension. When the pH was lower than 8, the carbon mainly existed as bicarbonate and the cobalt carbonate started to precipitate at a high efficiency. Cobalt initially precipitated as cobalt carbonate hydroxide (Co2CO3(OH)2) at a higher pH (9–11) and converted to cobalt carbonate at a lower pH (6.5–8). The crystallite size of cobalt carbonate calculated for the different reaction conditions shows that the growth response is high at longer reactant addition time and high temperature. The morphology of the final cobalt carbonate precipitate was small single spherical crystals and their aggregates. The purity of precipitates could be increased by reducing the aggregation tendency during the precipitation.

Extraction kinetics of cobalt and manganese with D2EHPA from lithium-ion battery recyclate

The separation of manganese from cobalt sulfate solutions is crucial in the field of spent lithium-ion battery recycling. A membrane-based microreactor is used to reveal required mass transfer characteristics as is diffusion and chemical reaction. The dependence of di-(2-ethylhexyl)phosphoric acid (D2EHPA) concentration, pH, and metal ion concentration on the extraction efficiency are investigated. A back-reaction term is introduced giving a significant influence on the effective extraction rate even at small metal complex concentrations as initial extraction rates proved to be inaccurate to describe the system. It is shown that the extraction of manganese at a pH of 3.0 is mainly diffusive while the cobalt extraction is strongly kinetically controlled. At a separating pH of 3.9 a good agreement between the model and experimental data is only given if the equilibrium back-extraction rate is considered (deviation less than 5%).

Kinetic Study of the Elimination of Nickel from Cobalt Sulfate Solutions by Sulfur Cementation on Cobalt in the Presence of Sulfur Dioxide and Elemental Sulfur

Kinetic Study of the Elimination of Nickel from Cobalt Sulfate Solutions by Sulfur Cementation on Cobalt in the Presence of Sulfur Dioxide and Elemental Sulfur

Synthesis of Cobalt-Nickel Nanoparticles via a Liquid-Phase Reduction Process

Cobalt-nickel nanoparticles (Co-Ni-NPs) show promising electrochemical performance in oxygen and hydrogen evolution reactions (OER and HER) due to their physicochemical properties such as electronic configuration and great electrochemical stability. Therefore, developing new economically and environmentally friendly methods of synthesizing Co-Ni-NPs has become a practical requirement. Co-Ni-NPs were produced by employing the liquid-phase reduction method. Nickel and cobalt sulfate solutions in hydrazine monohydrate with various mixing ratios were used as raw materials. Nickel plays an important role in the nucleation process via increasing the reduction reaction rate throughout the formation of Co-Ni-NPs. Furthermore, the acceleration of the Co-Ni-NPs formation process may be attributed to the partial dissolution of Ni(OH)2 in the presence of N2H4 and/or citrate-anions and the formation of the Ni-N2H4 or Ni-Cit complexes in contrast to Co(OH)2.

Application of Artificial Neural Network as a nonhazardous alternative on kinetic analysis and modeling for green synthesis of cobalt nanocatalyst from Ocimum tenuiflorum

The present paper is dedicated to analyze non-hazardous kinetic behaviour and modelling of green synthesized cobalt nanocatalyst (CoNCs), using an Artificial Neural Network (ANN). In order to supplement the trace metal in other applications, CoNCs were rapidly synthesized with a Cobalt sulphate solution at room temperature between 30 and 35 ºC at pH 7.2 under less reaction time. The Levenberg – Marquardt algorithm (LM) is used to investigate the experimental values by applying ANN. The results of variance using logistic ANN model depicts that the maximum nanoparticles were synthesized at its optimized stipulation of 0.5 h stirring time, 25 mL volume of extract and 20 mL volume of cobalt sulphate. The developed ANN model proved to be an efficient size determining tool in the biosynthesis of cobalt nanocatalyst. Experimental behavior using potentiometric analysis confirms that the linearity in CoNCs formation and size coincides (5–38 nm)with the predicted values of the ANN model. Techno economic analysis proved that, green synthesis reduced 30–40% in raw material cost and 60% in energy consumption.

Evaluating the antibacterial effect of cobalt nanoparticles against multi-drug resistant pathogens.

This study aimed to estimate the effect of cobalt nanoparticles (Co NPs) with different concentrations against multidrug-resistant (MDR) pathogenic bacteria. Three isolates of Staphylococcus aureus (gram-positive), Proteus spp. (gram-negative), and Escherichia coli (gram-negative) bacteria were extracted from various clinical examples utilizing routine methods on bacteriological culture media. The antibacterial sensitivity of commercial antibiotics such as Ciprofloxacin, Cefotaxime, Gentamycin, and Amoxicillin was broken down on a Muller Hinton agar plate and evaluated using the disk diffusion method. The study results demonstrated the antibacterial effect of the Co NPs against the bacterial isolates with three different concentrations utilized in the study. The results indicated that the Co NPs showed the highest antibacterial activity when utilizing 100 μg/ml against Escherichia coli followed by Proteus spp and Staphylococcus aureus with zones of inhibition measured as 22.2±0.1 mm, 20.3±0.15 mm, and 15.8±0.1 mm; respectively. Co NPs at a 100 μg/mL concentration showed higher inhibition zones than several common antibiotics except for Ciprofloxacin, which demonstrated better antibacterial activity against the bacterial isolates employed in this study. Scanning Electron Microscope (SEM)and X-Ray diffraction (XRD)studies confirmed that Cobalt nanoparticles (Co NPs) were synthesized from cobalt sulphate solution with a size ranging from 40 nm to 60 nm. The nanoparticles showed a crystalline structure with a round shape and smooth surface. The antibacterial resistance of Co NPs against three common bacteria such as Staphylococcus aureus, Proteus spp, and Escherichia coli was assessed in this study. The optimum concentration of the Co NPs was identified as 100 μg/ml, which could provide a similar or higher antibacterial effect.

Catalytic potential of cobalt oxide and agar nanocomposite hydrogel for the chemical reduction of organic pollutants

In this study, cobalt oxide nanoparticles (Co3O4 NPs) were synthesized by precipitation method from cobalt sulphate solution with basic pH, followed by calcination. The ex-situ synthesized Co3O4 NPs were mixed with hot agar (AG) aqueous solution. The preparation of AG- Co3O4 nanocomposite hydrogel was carried out by self-association method promoted by thermal denaturation. The quenching of hot suspension from 80 °C to room temperature resulted in the formation of AG-Co3O4 nanocomposite hydrogel. The as-synthesized AG-Co3O4 was characterized by FTIR, XRD and SEM techniques. In order to test the catalytic activity, AG-Co3O4 was used as a heterogeneous catalyst for the reduction of methylene blue (MB), congo red (CR) and 4-nitrophenol (4-NP). The excellent performance of the AG-Co3O4 was shown by the reaction rate constant (kapp) values of 0.3623, 0.2114 and 0.2893 for MB, 4-NP and CR, respectively. All these results were obtained with R2 above 94 and utilization of an AG-Co3O4 catalyst. Furthermore, the catalytic reduction was studied with varying dye concentration and catalyst dose. This study showed that AG-Co3O4 catalyst has high potential for remediation of environmental pollutants in wastewaters.

Extraction of Cobalt and Lithium from Sulfate Solution Using Di(2-ethylhexyl)phosphoric Acid/Kerosene Mixed Extractant

The solvent extraction behavior of cobalt and lithium from mixed sulfate solution using di(2-ethylhexyl)phosphoric acid (D2EHPA)/kerosene as extractant system has been investigated. The effect of different process parameters such as pH of feed solution, extractant concentration, cobalt and lithium ion concentrations in the feed solution have been studied. Extraction equilibrium constants have been calculated and found to be log Kex Co = –2.01 and log Kex Li = –2.42. The highest separation factor of 292 was achieved using 1.59 M D2EHPA at pH 1.85 from mixed sulfate solution. 93.9% of cobalt and 11.4% lithium was co-extracted from 0.01 M cobalt and lithium sulfate solution. Extraction of cobalt-lithium by D2EHPA is affected by cation exchange mechanism, cobalt is extracted as [Co(HA2)2] and [CoA2] depending on the metal concentration in the feed solution while the lithium is extracted as [Li(A2H)]. Quantitative extraction of cobalt was achieved in two-stage counter-current batch extraction (with McCabe–Thiele plot) using 0.477 M D2EHPA at an O : A phase ratio of 1. The data obtained from loaded organic and raffinate indicate a composition which reveals nearly complete extraction of cobalt and rejection of lithium resulting significant separation of these elements from mixed sulfate solution.

Hydrothermally Synthesized Spherocobaltite Nano-Particles

Spherocobaltite, CoCO3, or cobalt carbonate is a mineral of calcite group. It finds applications in high-performance Li-ion batteries, as an animal feed trace elements, and also used as a precursors to synthesize cobalt oxide. In this study, spherocobaltite nano-particles are synthesized by hydrothermal method using cobalt sulphate solution and ammonium carbonate solution in the ratio of 1:3.The mixture was then transferred into a 100 ml Teflon-lined autoclave and heated at 140 °C for 4 h. The final sample is recovered by centrifugation redispersion cycle. The hexagonal crystal structure is confirmed by powder XRD, and the average crystallite size is determined by Scherrer’s formula and Williamson-Hall method, which is found to be within 14 nm. The presences of Carbon, Oxygen and Cobalt were confirmed by EDAX analysis. The TEM image suggests spherical morphology of the nano-particles. The FT-IR spectrum confirms the presence of functional groups such as O-H and C-O. The TGA curve suggests that the material starts dehydrating first and then decomposes in to cobalt oxide at 390o C temperature. The impedance and dielectric studies are carried out within 20 Hz to 2 MHz range at room temperature. The complex impedance and modulus plots are drawn and exhibiting the grain effect only. The VSM data taken at room temperature and low temperatures from 20 K to 300 K suggests a paramagnetic nature of the sample.

Preparation of spherical cobalt carbonate from cobalt sulfate solution

Abstract A precursor of cobaltous dihydroxycarbonate was firstly prepared by precipitation reaction of cobalt sulfate solution and ammonium carbonate solution, and then a hydrothermal process for the precursor was conducted to obtain the spherical cobalt carbonate with low sulfur content. The experimental results show that the feeding method, final pH value of the precipitation reaction slurry and the concentration of the cobalt sulfate solution have obvious effects on the sulfur content, morphology and particle size distribution of the precursor. The sulfur content of the precursor is 0.0115 wt.% under the optimized conditions. The hydrothermal treatment with temperatures of 125−150 °C can transform the precursor of cobaltous dihydroxycarbonate into spherical cobalt carbonate and decrease the sulfur content to 0.0030 wt.% in the obtained product.

Optimisation & minimisation of corrosion rate of electroless Ni-Co-P coating

ABSTRACT Electroless Ni-Co–P alloy coatings were deposited to decrease the corrosion rate of the copper substrate. Central Composite Design (CCD) was employed through Design Expert Software to establish optimised deposition parameters, which produces a coating having high corrosion resistance. CCD has also been employed to determine the effect of various process parameters namely concentration of cobalt sulphate (CoSO4.7H2O) solution (10–20 gm/cc), concentration of sodium hypophosphite (NaH2PO2.H2O) solution (20–30 gm/cc) and bath temperature (80-90°C). The corrosion rate was determined by the Potential Dynamic test in 3.5% NaCl solution and the Tafel plot was used to determine the corrosion current density for each coated substrate. On the corrosion response of the coatings, the most significant interactions and important factors were identified using ANOVA analysis. The regression analysis showed a good fit of the experimental data through the second-order polynomial model with a coefficient of determination (R2) value of 0.9531 and a model F-value of 22.57. 15 g/L of Cobalt Sulphate, 30 g/L of Sodium Hypophosphite and 80°C of bath temperature were found out to be the optimum conditions of bath deposition to obtain a corrosion rate of 0.535 µm/Y.

Electrodeposition of cobalt nanoparticles: An analysis of the mechanisms behind the deviation from three-dimensional diffusion-control

Electrochemical nucleation and growth of cobalt nanoparticles on aluminium was investigated by potentiostatic electrodeposition from cobalt sulphate solutions buffered with boric acid. At sufficiently low overpotential, the experimental current transients could be fairly reproduced by a mathematical model describing nucleation and growth under mixed kinetic-diffusion control, yielding an estimated number of particles per surface area in agreement with the SEM analysis of the deposits. However, the model gave estimates for the charge-transfer kinetic constant several orders of magnitude lower as compared to the Tafel analysis of cobalt electrodeposition on a previously electrodeposited cobalt film. This deviation can be explained by the inhibition of the direct attachment of metal ions, which can be induced by the adsorption of hydrogen onto cobalt particles and/or the formation of stable nanocluster aggregates. The implemented model failed to reproduce the current transients generated at larger overpotential values. A revision of the implemented mathematical model overcoming this limitation is proposed.

Wear-corrosion response of Cerium oxide reinforced Cobalt hybrid composite layers in biological solution

The research work aims at improving biomaterials surface properties by Co/nano-CeO2 composite layers obtained by electro-codeposition method from a cobalt sulphate solution containing CeO2 dispersed nanoparticles. The thicknesses of pure cobalt and Co/CeO2 hybrid nanocomposite layers are measured versus applied current density and time of the plating process. The tribocorrosion properties of Co/nano-CeO2 hybrid nanocomposite layers and pure Co layer obtained were comparatively investigated friction sliding tests in a unidirectional tribometer in lubricating conditions using biological solution (Hank). During the tribocorrosion test, the normal force, tangential force, coefficient of friction, number of cycles as well as the electrochemical parameter (potential), were continuously monitored. The results show that the wear - corrosion (tribocorrosion) behavior of Co/nano-CeO2 hybrid nanocomposite layers are closely related with dispersed reinforcing nano-CeO2 content. The hybrid nanocomposite layers with all CeO2 content shows increased wear - corrosion resistance as compared with pure Co layer, by decreasing wear volume loss with increasing nano-CeO2 particles dispersed into plating electrolyte.

Cobalt recovery from the stripping solution of spent lithium-ion battery by a three-dimensional microbial fuel cell

Cobalt (Co) recycling from the spent LIBs not only favors the ecological protection also meets the supply chain of Co in the international market. In this research, a three-dimensional microbial-fuel-cell (3D-MFC) two-chamber system with granular activated carbon (GAC) microelectrodes was constructed to remove and recover Co from the stripping cobalt sulfate solution. The 3D bio-electrochemical (BE) system exhibited the largest voltage output and power production at 12th day during the acclimation, achieving the maximum power densities (W/m3) of 6.24, 10.29, 14.52, 12.59, and 8.78, respectively. The GAC prepared at 500 °C achieved highest removal and recovery efficiencies of Co in the 3D-MFC system. The maximum removal efficiency of 98.47%, the recovery efficiency of 96.35%, the power density of 11.34 W/m3, and the columbic efficiency of 28.74% were obtained in the orthogonal experiments. The influence of the operating time on the removal and recovery of Co was more obvious than the electro-output of the system. The addition of ammonium carbonate to the 3D-MFC systems clearly increased the precipitation of Co. The stacking of GAC particles in MFC had strengthened the adsorption of Co ions by intensifying the acidic-alkaline pathways during the 3D BE process. The removal and recovery of Co ions from the stripping solution in the 3D-MFC experiments were mainly achieved by the electromigration, electrostatic adsorption of GAC, and chemical precipitations of cobalt hydroxide and cobalt carbonate. A continuous process was suggested for the 3D-MFC application integrating to the traditional recovery procedure of Co from the spent LIBs at the pilot scale.

Removal of Cadmium from Cobalt Sulfate by Solvent Extraction Using Cyanex 301

A variety of reagents, including P204, P507, and Cyanex 301, were used for extraction of cobalt and cadmium from cobalt sulfate solution. It was found that Cyanex 301 exhibited the best separation efficiency for cadmium and cobalt from solution containing 90 g L−1 Co and 3 g L−1. The effects of initial pH, extractant concentration, phase ratio, extraction time, and temperature on the cadmium and cobalt extraction ratios were examined. The results showed that the extraction ratios of cadmium and cobalt were 99.95% and 2.45% under the optimal conditions of pH 1.8, 10% Cyanex 301, O/A = 1:1, T = 25°C, and t = 10 min. The species of Cyanex 301 chelated with cadmium or cobalt were proposed to be Cd[Cyanex 301]2.5 and Co[Cyanex 301]2. The stripping ratios of cadmium and cobalt were 99.9% and 95% using 7 mol L−1 hydrochloric acid, respectively, indicating effective separation of cadmium from high-concentration cobalt sulfate solution.

A novel two-step approach to fabricating nanofibrous nickel cobaltite for high performance supercapacitors

A novel two-step approach, electrochemical deposition in a cobalt sulfate solution followed by hydrothermal treatment in a nickel sulfate solution, is used to fabricate nanofibrous NiCo2O4 on carbon fibers for binder-free supercapacitor electrodes. The obtained NiCo2O4 consists of nanofibers and nanoflakes which are connected with each other to form open nanopores in the active material. The material exhibits excellent pseudocapacitive performance with a specific capacitance as high as 1807 F g-1 at a current density of 1 A g−1 and a rate capability of 75% at 40 A g−1. The remarkable electrochemical properties are attributed to the porous structure created by the hydrothermal reaction between oxyhydroxide and Ni2+ ions. Compared to the conventional method based on hydrothermal decomposition of cobalt and nickel nitrates, this approach is more environment-friendly, and when used for preparation of binder-free electrode, it is more effective in confining nanostructred NiCo2O4 growth to a conductive substrate and ensuring good contact between the active material and the substrate.

Cobalt electrowinning – A systematic investigation for high quality electrolytic cobalt production

The process of Minera y Metalúrgica del Boleo recovers cobalt from a complex oxide and sulfide ore by solvent extraction and electrowinning after the recovery of copper and zinc (as copper cathode and zinc sulfate monohydrate). As part of the process development, cobalt electrowinning was systematically studied with respect to temperature, pH, pitting behavior, deposit morphology, deposition stress and interfacial tension. Electrowinning test work was conducted in a bench scale diaphragm cell in a sulfate medium with control of the catholyte pH. Cobalt was deposited on a coated stainless-steel mandrel cathode with exposed circles to allow plating of disk shaped deposits over the surface of the cathode that could be easily stripped after 5–7 days of deposition. Limiting the area of plating prevents the detachment of the cobalt deposit from the cathode due to high deposition stress. The morphology and pitting behaviour varied for different commercial cobalt raw materials used for making cobalt sulfate solution as they contained different impurities or additives. The deposition behaviour changed after the solutions had an activation carbon treatment as some impurities (mainly organic compounds) were removed. In the temperature range from 50 to 65 °C, a higher temperature resulted in a brighter deposit with more pits and smaller lateral dendrites. The cobalt deposition current efficiency was around 98% at pH 3.0 and was not sensitive to temperature. With decreasing catholyte pH from 3.5 to 2.0, the cobalt current efficiency decreased from 99 to 88% and the growth of lateral dendrites were significantly suppressed. The formation of pits resulted from the adhesion of hydrogen bubbles on the cobalt deposit. The adhesion of hydrogen bubbles was determined by the prevailing surface and interfacial tensions. Anti-pitting agents were used to change the interfacial and surface tensions in such a way that the detachment of bubbles was facilitated, resulting in a pit-free cobalt deposit. The anti-pitting agents affected the deposit morphology and internal stress. The impact of the anti-pitting agents on the disengagement of organic and aqueous phases during cobalt solvent extraction was also investigated. The internal stress of the cobalt deposit as a function of temperature and anti-pitting agent dosage and the conductivities of the CoSO4-Na2SO4-H2SO4 system are reported.

A thermodynamic and kinetic study of trace iron removal from aqueous cobalt sulfate solutions using Monophos resin.

High purity cobalt has many important applications, such as magnetic recording media, magnetic recording heads, optoelectronic devices, magnetic sensors, and integrated circuits, etc. To produce 5N or higher purity cobalt in an electro-refining process, one of the challenges is to effectively reduce the Fe content of aqueous cobalt salt solution before electrolysis. This paper describes thermodynamic and kinetic investigations of the Fe adsorption process of a new sulfonated monophosphonic resin with the trade mark Monophos. Five cobalt sulfate solutions of different Co concentrations were prepared. Fe ions were removed from the solutions by ion exchange method using Monophos resin. Chemical analysis was carried out using a Perkin Elmer ICP-OES. The initial Fe concentrations of about 0.9-2.0 mg/L can be reduced to about 0.3-0.8 mg/L, which is equivalent to an Fe removal rate of 60-67%. The Langmuir isothermal adsorption model applies well to the Fe removal process. A second-order type based on McKay equation fits better with experimental data than other kinetic models. The kinetic curve can be divided into two sections. For t < 30 min, particle diffusion may act as the controlling step, whereas chemical reaction may control the Fe adsorption process in the section t > 30 min. Monophos resin is effective for the removal of trace Fe from cobalt sulfate solution. This ion exchange process obeys the Langmuir isothermal adsorption model and the McKay equation of second-order kinetics.

Effect of Waveform and Heat Treatment Processes on the Performance of Electrodeposited Co-P Coating

Cobalt-phosphorus (Co-P) alloy is a promising material for the replacement of traditional hard chromium alloy of high hardness. In this paper, the cobalt-phosphorus alloy layer with high phosphorus content was formed by electrodeposition in a cobalt sulfate solution system under direct current (DC), single pulse (SP) current and double pulse (DP) current, separately. Surface morphology, structure and properties of the deposited layer were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), Vickers microhardness and a neutral salt spray test, respectively. The results showed that the dense Co-P coatings could be obtained by DC, SP and DP with P content of 9.6, 8.9 and 9.1 wt %, respectively. After 30 min heat treatment at 400 °C, coatings deposited under DC, SP and DP currents transformed from an amorphous to a nanocrystalline state, while the grain size was 12–13 nm, 10–12 nm and 8–10 nm, respectively. Among all these conditions, the microhardness of coatings deposited under DP current was the highest, which was 1211 HV, while the microhardness of coatings deposited under DC current was the lowest but higher than that of hard chromium. The wear rate of Co-P coatings was 4 × 10−6–5 × 10−6 mm3/N m with Si3N4 ball as bearing material, which was lower than that of hard chromium. In coatings deposited under different currents with a thickness of ca. 40 μm, no visible corrosion area appeared after 1000 h of a neutral salt spray test. Coatings heated at 300 and 400 °C reached the corrosion grade 7 and grade 4–5, respectively after 1000 h of a neutral salt spray test, so the wear resistance of Co-P coatings was better than that of hard chromium.