CoSO4 Research Articles

Effect of Pre-treatment on Roughness and Hydrophobicity of Electro-Etched Steel with Improved Corrosion Resistance

A hydrophobic steel surface was created by a simple electro-etching technique using a cobalt sulfate bath. The effect of surface pre-treatment on the hydrophobicity and surface roughness was investigated. The wettability and roughness of the surface were determined by water contact angle (WCA) and atomic force microscopy (AFM), respectively. Accordingly, the sample abraded with 800 grit sandpaper followed by electro-etching process was selected as the optimum sample with the highest roughness and WCA (Sa = 28.4 nm, Ra = 35.4 nm, and WCA = 144 ± 1.6°, respectively). The morphology and cross-sectional images of the hydrophobic surface were investigated using field-emission scanning electron microscopy (FESEM). FESEM images showed a micro/nanostructured surface. The resulted hydrophobicity was attributed to the high roughness and overhanging structure obtained through this method. Furthermore, by using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests, the corrosion behavior of the samples was investigated. It was revealed that the surface hydrophobicity improved the corrosion resistance by increasing the polarization resistance (from 726 to 1598 Ω cm2) and decreasing the corrosion current density (from 0.025 to 0.012 mA cm−2). The simplicity of creating a hydrophobic surface with the improved corrosion behavior, the availability, and the low cost of the materials used to develop this approach makes it a proper candidate for large-scale and industrial applications.

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.

Volumes and Heat Capacities of Cobalt(II), Nickel(II), and Copper(II) Sulfates in Aqueous Solution

The densities and isobaric volumetric heat capacities of aqueous solutions of the sulfate salts of cobalt(II), nickel(II), and copper(II) have been measured at 298.15 K and 0.1 MPa using vibrating-...

Redox active polymer metal chelates for use in flexible symmetrical supercapacitors: Cobalt-containing poly(acrylic acid) polymer electrolytes

The novel polymer metal chelate electrolytes (polychelates) were prepared by incorporation of cobalt sulfate (Co) into poly(acrylic acid) (PAA) host matrix. Quasi-solid state supercapacitor devices were fabricated using polychelates, PAA-CoX (X: 3, 5, 7, and 10) where X represents the doping fraction (w/w) of Co in PAA. All polymer metal electrolytes were showed excellent bending-stretching properties, thermal stability and electrochemical durability with an optimum ionic conductivity of 3.15 × 10−4 S cm−1. Hierarchically porous activated carbon and nano-sized conductive carbon were used to form carbon composite symmetrical device electrodes. The electric double-layer capacitor (EDLC) and redox reactions of Co-incorporated polychelates at the interfaces of porous activated carbon provided an optimum specific capacitance of 341.33 F g−1 with a device of PAA-Co7, which is at least 15 times enhancement compared to the device of pristine PAA. The PAA-Co7 device also provided energy density of 21.25 Wh kg−1 at a power density of 117.69 W kg−1. A prolonged cyclic stability of the device exhibited superior capacitive performance after 10,000 charge–discharge cycles and the maintained 90% of its initial performance. In addition, the supercapacitor with a dimension of 1.5 cm × 3 cm containing PAA-Co7 successfully operated the red-blue-green (RGB) LED light.

Optimization of process parameters on the response of corrosion resistance of electroless Ni-Co-P coating using Box-Behnken Design (BBD)

Ternary Ni-Co-P alloy coating was chosen to improve the corrosion resistance of the Copper substrate. Box-Behnken Design (BBD) of experiment was utilized for the optimization of the effects of different process parameters such as Cobalt Sulphate, Sodium Hypophosphite, and temperature. Electrochemical Impedance Spectroscopy (EIS) was used to study the corrosion resistance behaviour of different samples by altering different parameters. Analysis of Variance (ANOVA) was done to determine the important process parameters and their significant interactions. The surface morphology, microstructures and elemental compositions of the as-deposited coatings were analyzed using Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and Energy Dispersive X-Ray Spectroscopy (EDX) respectively. Finally, 15g/L of Cobalt Sulphate, 25g/L of Sodium Hypophosphite, and 85°C of bath temperature were found out to be the optimum conditions for coating deposition in order obtain a corrosion resistance of 1165 ohm-cm2.

The influence of micronutrients on the productivity of corn during cultivation on green mass in the southern zone of Amur region

The following paper reviews the results of 2017-2019 studies of the influence of types and methods of micronutrient fertilizers application: zinc sulfate, cobalt sulfate and ammonium molybdate on the growth, development and productivity of corn. The studies were conducted in the southern agricultural zone of Amur region on the experimental field of Far Eastern State Agrarian University, located in the village of Gribskoye (Blagoveshchensk district). The object of research was a hybrid Mashuk 175MV (FAO 170) - an early-ripening three-linear hybrid of universal use. Treatment of seeds and plants of corn by microfertilizers was carried out using a solution with a concentration of 0.1%. As a result of studies, it was found that the use of microfertilizers during plants vegetation more effectively affects the accumulation of dry matter than seeds treatment and double treatment of seeds and vegetative plants. When seeds treatment, the most effective variant is the combined use of microelements and when treatment during vegetation is the variant with using cobalt. The use of microfertilizers showed a significant increase in leaf surface area for all variants relative to the background variant. The greatest effect was shown by the variant with the use of cobalt in the seeds treatment and spraying vegetation of plants. The combined use of microfertilizers in the seeds treatment and spraying during vegetation has shown a good increase the yield of green mass of corn. The greatest effect was shown in seeds treatment by cobalt and spraying the plants during vegetation.

Cobalt (II)-based open‐framework systems constructed on g-C3N4 for extraordinary enhancing photocatalytic hydrogen evolution

Developing a low-cost co-catalyst for hydrogen evolution reaction (HER) on a photocatalyst is a great challenge. An open-framework material, cobalt ethylenediammonium bis(sulfate) tetrahydrate, was initially used as an efficient co-catalyst to improve photocatalytic HER of g-C3N4. The unique open‐framework cobalt(II) sulfate (Co-S) lead to twice higher H2 evolution performance (10328.9 μmol g−1 h-1) compared to noble metal (Pt)-decorated g-C3N4 photocatalyst under simulated sunlight. The open network structure provides abundant active sites and excellent electron transport properties, properties and then promotes electron-hole separation, which play a synergistic role with g-C3N4 in the photocatalytic process. The loading of Co-S significantly changes the microenvironment of the catalyst surface of g-C3N4 and enhances its hydrophilicity, which benefits the release of the produced gas on the catalyst surface. The formation of the Co(Ⅰ) species in the open-framework material by the electron reduction of Co(Ⅱ) is proposed as a vital role in the extraordinary HER process.

Effects of Cobalt(II)Sulfate Addition on Structure and Corrosion Resistance of Alloy Micro-arc oxidation Coating on the ZL108 Aluminum

Effects of Cobalt(II)Sulfate Addition on Structure and Corrosion Resistance of Alloy Micro-arc oxidation Coating on the ZL108 Aluminum

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.

(Invited) Film Properties of Various Electroless Plated Co Alloy Films Formed on SiO2/Si Substrate and Its Interdiffusion Properties Against Cu

There is a serious problem of poor side wall coverage for the sputtered barrier metals in high aspect ratio TSVs. We have proposed electroless plated Co-alloy barrier metals for TSV. For this purpose, we prepared various CoB and CoWB alloys with different atomic compositions and crystalline structures. Furthermore, we evaluated interdiffusion properties of Cu/Co-alloy/Si stacked structure by SIMS analysis. It turned out that the electroless CoWB film containing larger amount of W has excellent diffusion barrier property than other CoWB films with smaller W content. We formed electroless barrier films of CoB and CoWB using Pd nanoparticle catalyst on SiO2/Si substrate [1]. For evaluation of Cu interdiffusion properties by SIMS, we deposited Cu and TiN thin films successively by sputtering on the barrier film. The ratio of the atomic composition was changed by adjusting the ratio of cobalt sulfate, tungstic acid, and some other contents of the plating bath. SIMS depth profiles of CoB (Fig.1-a) and CoWB films after annealing at 400 ℃ (Fig.1-b) are shown in Fig.1. There was a large interdiffusion between Cu and CoB after 400 ℃ annealing (Fig.1-a). Co-Silicide formation significantly occurred and Si atoms diffused into CoB layer. However, interdiffusion was significantly suppressed in the case of Co-20%W-B film (Fig.1-b). These results suggest that W atoms existed in CoWB have a strong effect of suppressing Cu diffusion in Co film, and CoWB with 20 atom % W showed a good diffusion barrier property. The present study suggests that the electroless plated CoWB having a larger W content has a high potential as a diffusion barrier film for the via last TSV process.[1] F. Inoue, T.Shimizu, F.Miyake, R.Arima, T.Ito, H.Seki, Y.Shinozaki, T.Yamamto, and S.Shingubara, Microelectronic Engineering, 106 (2013) 164–167.[2] T. Iseri, S.Shindo, Y.Miyachi, A.Hirate, S.Tanaka, T.Shimizu, T.Ito, S.Shingubara, Jpn. J. Appl. Phys. 57 (2018), 07MB02-1~6. Figure 1

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.

Electroplated NiCo Alloy with Low Residual Stress from the Sulfate Bath

NiCo alloys are electroplated in sulfate bath. The concentration of cobalt sulfate and current density were varied to optimize the surface hardness. The properties of NiCo deposits were analyzed using field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The surface hardness of the NiCo alloy was increased up to 500 Hv at 24 wt% Co in the deposits due to the grain refinement. The size of grain was reduced to 12 nm. The residual stress of the deposits was varied from tensile to compressive as the saccharin concentration increased. The zero residual stress was achieved at 0.05 g/L saccharin addition.

Frequency-Dependent Admittance Analysis of Au/n-Si Structure with CoSO4-PVP Interfacial Layer

A film of cobalt sulfate (CoSO4)-doped polyvinylpyrrolidone (PVP) blend was spin-coated on n-Si. Electrical measurements were conducted on the Au/n-Si structure with the CoSO4-PVP film sandwiched between them. The frequency dispersion of the main electrical and dielectric parameters and the corresponding mechanisms were evaluated. The extra capacitance originating from the contribution of interface states (Nss) resulted in a fairly large frequency dispersion in C–V plots. These states also influence the carrier transport and conduction mechanism, thus the determination of real Nss values is crucial to evaluate the nonideal behavior of such plots. The values of Nss were calculated using the Hill–Coleman method. The dielectric constant (e′) and dielectric loss (e″) exhibited higher values in the low-frequency region as a result of interface and dipole polarization, while the alternating-current (AC) electrical conductivity (σac) generally decreased. The variation of the loss tangent with increasing frequency of the applied field confirmed the effect of some internal field within the CoSO4-PVP film accompanied by the external AC field.

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.

Efficient Hydrogen Generation from the NaBH4 Hydrolysis by Cobalt-Based Catalysts: Positive Roles of Sulfur-Containing Salts.

Development of a simple and efficient strategy for improving the catalytic activity of cobalt-based catalysts toward hydrogen evolution from sodium borohydride (NaBH4) is paramount but remains challenging. Here, we reported a facile and efficient approach to tune the catalytic performance for NaBH4 hydrolysis with Co-based catalysts prepared by using cobalt sulfate as a precursor or a mixture of sulfur-containing sodium salts/cobalt salts as a raw material. With the use of cobalt sulfate as the precursor, the CoSO4-doped Co3O4 sample was formed and it exhibited excellent activity with the generation of ∼500 mL of hydrogen gas from NaBH4 hydrolysis under mild conditions. In terms of sulfur-free cobalt salts (e.g., cobalt chloride, cobalt nitrate, and cobalt acetate) as precursors, the obtained Co-based samples were found to be entirely ineffective for hydrogen production. Interestingly, during the cobalt-based catalyst preparation, the introduction of sodium sulfate or sodium sulfide can considerably accelerate hydrogen production. On the contrary, adding sulfur-bearing salts did not inspire any activity improvement only during the hydrogen generation reaction. Control experiments indicate that during catalyst preparation, the presence of Na2SO4 and Na2S is beneficial for the in situ transformation of Co3O4 into catalytically active Co-B alloys, accompanying a positive change in surface morphology during the NaBH4 hydrolysis, thereby inducing an excellent hydrogen generation rate of up to 4425 mL·min-1·gcat-1.

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.

Effect of Cobalt Precursors on Cobalt-Hydroxyapatite Used in Bone Regeneration and MRI

In clinical dentistry practice, supplemental bone surgery or jawbone defect after tooth extraction must be assisted by a bone-filling material. Cobalt-substituted hydroxyapatite (COHA) effectively promotes bone cell growth, reduces the inflammatory response, and is an antibacterial agent. COHA can therefore be used as an alveolar bone-filling material or guided bone regeneration membrane. Meanwhile, COHA can be used in magnetic resonance imaging (MRI) with negative contrast agents and targeting materials without causing metal interference with the image. Hence, COHA has received increasing amounts of attention in recent years. However, the influence of different cobalt precursors on the synthesized COHA is still unknown. Therefore, COHA synthesized from 3 cobalt precursors (cobalt chloride, cobalt nitrate, and cobalt sulfate) was compared in this study. The results show that COHA synthesized by the precursor with the smallest anion radius, cobalt chloride, has a larger particle size (239 nm) and a higher cobalt ion substitution rate (15.6%). When the cobalt ion substitution rate increases, the MRI has a stronger contrast. Bioactivity data indicate that COHAC is more susceptible to degradation and therefore releases more cobalt ions to contribute to the differentiation of bone cells. Based on these studies, COHAC prepared with the cobalt chloride precursor has a higher cobalt ion substitution rate, faster degradation rate, better image contrast, and better bioactivity. It is therefore the preferred choice of bone-filling material for alveolar bone regeneration.

Importance of the synergistic effects between cobalt sulfate and tetrahydrofuran for selective production of 5-hydroxymethylfurfural from carbohydrates

CoSO4/THF can selectively catalyze conversion of fructose to HMF, which is a cost-effective route for production and separation of HMF.

Electrochemical performance of a self-assembled two-dimensional heterostructure of rGO/MoS2/h-BN.

We report the preparation and electrochemical performance evaluation of a two-dimensional (2D) self-assembled heterostructure of graphene oxide (rGO), molybdenum disulphide (MoS2), and hexagonal boron nitride (h-BN). In the present study, the rGO–MoS2–h-BN (GMH) multi-layered GMH heterostructure is fabricated via an in situ chemical route. Based on material analysis, the composite consists of bond conformations of C–B–C, Mo–S, C–N, B–N, and Mo–C, indicating the layered stacks of rGO/h-BN/MoS2. In electrochemical analysis, the composite showed superior performance in the aqueous medium of cobalt sulphate (CoSO4) over other samples. CV measurements, performed over the range 10 to 100 mV s−1, showed a change in specific capacitance (Csp) from 800 to 100 F g−1. GMH showed almost no degradation up to 20 000 cycles @ 100 mV s−1. The calculated Csp, energy density (ED), and power density (PD) are discussed in light of Nyquist, Bode, and Ragone analysis. An equivalent circuit is simulated for the cell and its discrete electronic components are discussed. Due to its larger effective electron diffusion length > 1000 μm, broadly, the composite showed battery-like characteristics, as supported by radical paramagnetic resonance and transport response studies. The symmetric electrodes prepared in one step are facile to fabricate, easy to integrate and involve no pre or post-treatment. They possess superior flat cell character, are cost effective, and are favourable towards practicality at an industrial scale, as demonstrated on the laboratory bench. The details are presented.

Prediction and parametric optimization of surface roughness of electroless Ni-Co-P coating using Box-Behnken design

AbstractThe current study focuses on the parametric optimization of electroless Ni-Co-P coating considering surface roughness as a response using Box-Behnken Design (BBD) of experiment. The two bath parameters namely the concentration of cobalt sulphate and sodium hypophosphite were varied along with the bath temperature to predict the variation in surface roughness. Analysis of variance (ANOVA) method has been applied to determine the interactions of the substantial factors which dominate the surface roughness of the coating. The process parameters for surface roughness of the coating were optimized by successfully utilizing the statistical model of Box-Behnken Design (BBD) of experiment. From the BBD model, the optimum condition for the deposition of the coating has been evaluated. In that specific condition, the surface roughness of the as-deposited coating is found to be 0.913μm. Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), and X-Ray Diffraction (XRD) study have been utilized to characterize the electroless Ni-Co-P coating deposited in optimized condition.