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The production of critical metals for emerging clean technologies also requires more sustainable, cleaner and cost-effective processing options. The recovery of cobalt (Co) via pyrometallurgical or hydrometallurgical methods has proved to be successful and practicable; nevertheless, these processes are difficult to manage, have a high operating cost, and produce secondary waste products. In recent years, bioleaching has increasingly gained favor as a method for extracting Co from ores, concentrates, and tailings. The availability of Co in primary and tailings resources, as well as the bioleaching approaches from these deposits are discussed in this paper. Bioleaching of Co has been investigated from primary sources such as Cu-Co deposits, polymetallic Ni-Co-Cu deposits, Co sulfides and arsenides, Ni-Co laterites, and secondary sources including tailings materials. The microorganisms and methods utilized in Co bioleaching from these sources, as well as parameters influencing the bioleaching process, and ways for improving Co bioleaching efficiency, have all been thoroughly discussed in this review. This study examines the potential of different microorganisms to solubilize Co from sulfide and laterite deposits by performing an in-depth meta-analysis of the individual research findings to enable inter-study comparisons and identify research gaps. The reviewed laboratory studies and existing industrial practices for Co bioleaching in this paper intend to offer some inspiration for further research into innovative technologies that may be used to sustainably extract Co, mainly from ores, concentrates and tailings resources. [ABSTRACT FROM AUTHOR]

Cobalt- and nickel-based superalloys are being extensively used in aerospace, automotive and medical applications due to their specific properties, which include working at high temperatures and stresses, good corrosion and oxidation resistance. This paper incorporates a review on the machinability aspects of nickel- and cobalt-based superalloys in turning operations. The machinability aspects like tool wear and surface integrity are critically reviewed for turning operation. Also, the effect of parameters, such as coating, cooling methods, cutting speeds and feed rate on tool wear, is reviewed critically. The different tool wear mechanisms that occur during machining of these superalloys are studied along with surface integrity, which include surface roughness and microstructures. Lastly, conclusions drawn are based on parameters that need to be improved for sustainable machining of nickel- and cobalt-based superalloys. This review will guide researchers and manufacturers for proper understanding of parameters selection. [ABSTRACT FROM AUTHOR]

This paper considers the surprising, tentative emergence of the London Metal Exchange as a quasi-labour regulator following persistent scandals over cobalt mined by child labour in the Democratic Republic of the Congo (DRC). It argues that this case offers us a useful window into the limits to financialization. The 'financialization' of cobalt here refers to the process by which cobalt has come to be traded as a speculative asset. Such processes have often been understood in terms of a 'divorcing' of value from the underlying material form. The persistence of controversies around child labour and cobalt highlights clearly how fraught a process any such divorce is. Theoretically, the paper develops these arguments through engagements with Marxian and science and technology studies (STS) literatures on commodification. [ABSTRACT FROM AUTHOR]

This paper explains and demonstrates the capabilities of Metal Additive Manufacturing (MAM) technology in producing intricate stent structure with a customise design by using ASTM F75 Cobalt-Chromium (CoCrMo) powder. Current commercialise stent in the market is rigid in size and geometries and the cost of tooling and manufacturability are increased once the other stent production is replaced. The design, process parameter, powder characterisation, part density and microstructure were investigated and thus exploring the potential area of MAM process for future proof stent manufacturing. Average density achieved for the seven (7) additive-manufactured stents was within 92– 97%, whereas the shrinkage is in between 0.31% and 0.61% (diameter) and 0.03–0.05% (height) respectively. The average surface roughness achieved are 4.1 µm (highest peak) whereas the lowest peak was 365.1 nm. The suggested model of the stent was taken from the third-party vendor and fabrication was carried out using EOSINT M280 metal printer with the aid of Materialise Magics 19.0 software for support generation. [ABSTRACT FROM AUTHOR]

Cobalt-rich crust has attracted increased attention due to their economic value. Studies have indicated that seamounts in the Western Pacific Ocean are rich in cobalt-rich crust resources. The Caiwei Guyot in Western Pacific Ocean is one of the cobalt-rich crust exploration areas contracted between China and the International Seabed Authority. A large volume of research has been conducted to elucidate the tectonic evolution, basement type, sediment type, gravity and magnetic anomaly characteristics, and geochemical characteristics of shallow surface sediments at Caiwei Guyot. However, a research gap exists on the sedimentary strata below the pelagic deposits and above the volcanic basement of the Caiwei Guyot. This paper summarizes that two main types of sediments existing on the top of Caiwei Guyot. The deposition thickness on the top of Caiwei Guyot is characterized by three sedimentary centers and exposed periphery. Pelagic sediments are difficult to form at the northeastern portion and edge area of Caiwei Guyot due to the strong bottom current environment, which makes these areas suitable for crust growth. This paper delineated three cobalt-rich crust prospective areas at the Caiwei Guyot with of significant implications for exploration and mining-lease-block selections at Caiwei Guyot. [ABSTRACT FROM AUTHOR]

Cobalt is a key element of the lithium-ion batteries that supply energy and continuous power to several electronic equipments such as cellphones, computers, and electric vehicles. Due to the depletion of primary sources of metal extraction and limited supply, countries are now focusing on recycling secondary resources for economic and sustainable management. Though the majority of the technologies involved are focused on industrial-scale development, they lack eco-friendliness and efficiency. The dead lithium-ion batteries containing several valuable metals such as cobalt, lithium, manganese and nickel are regarded as an appealing secondary resource. Battery recycling is required not only to reduce energy consumption but also to alleviate the scarcity of rare resources and eliminate pollution from hazardous components, as the world moves toward more sustainable industries such as consumer electronics and electric vehicles. The significance of cobalt recovery from secondary resources is emphasized in this paper. From the research, it is found that the amount of cobalt is more in the spent LIBs. Hence, focus is given on the green method of leaching of the spent Lithium-ion batteries (LIB) and extracting the valuable metals such as cobalt, nickel and lithium using organic acids. The method of using organic acids as leachant is environmentally friendly, cost-effective, and has the potential to provide sustainable development in the battery industry. This initiative is aimed to stimulate people's interest in wasted LIBs recycling with organic acids and raise awareness of the benefits. [ABSTRACT FROM AUTHOR]

In this paper, we employed Density Functional Theory (DFT) to study structural and mechanical stability, electric, magnetic and electronic properties of cubic Co-based new quaternary half-Heusler alloys CoZrCrZ (Z = Al, Ga, In) using WIEN2k. Volume optimisation suggests that these alloys are stable in the Y1 structure and show ferromagnetic behavioTAur. Generalised Gradient approximation calculations confirm the half-metallic nature of the reported alloys, which show metallic nature, and semiconducting band gaps exist in spin-up and spin-down channels, respectively. From the calculated cubic elastic constants, the reported Heusler alloys shows ductile nature. The calculated spin-magnetic moments of CoZrCrZ (Z = Al, Ga, In) are consistent with the Slater-Pauling rule. The very fine narrow band gap in the spin-down channel enhances the thermoelectric properties. The reported ferromagnetic half-metals with good thermoelectric parameters suggests that these alloys have possible applications in spin-based electronics and green energy technology. [ABSTRACT FROM AUTHOR]

Cobalt demand has witnessed tremendous growth in recent years due to its wide utilization in many critical industries. However, more than half the world's demand for cobalt is supplied only by one country, raising concerns about the potential future supply. Considering the status of cobalt as a critical raw material, recycling is viewed as an option to provide an alternative stream of supply by recovering cobalt from secondary resources. In this paper the importance of cobalt recovery from secondary resources is highlighted. The current state of research on Co recovery from secondary resources such as catalysts, magnets, superalloys, cemented carbides, rechargeable batteries, and metallurgical wastes are discussed. The industrial-scale cobalt recycling has also been reviewed to give a better overview of the overall progress. This review provides insights into the future outlook and challenges associated with cobalt recovery from secondary resources. Despite the challenges, cobalt recovery technologies from secondary resources should be further developed. [ABSTRACT FROM AUTHOR]

In this paper, we studied the adsorption and desorption characteristics of cobalt, nickel, and copper in nitrite–sulfuric acid system, and their adsorption mechanism was also explored. The results showed that the adsorption capacity of cobalt and copper on the anion exchanger is 206 and 175 mg/g, respectively. However, the nickel adsorption capacity was very weak, exhibiting almost no adsorption. When the concentration of sodium nitrite was 1 mol/L, IRA-900 resin showed the best adsorption selectivity to cobalt. The FT-IR, UV absorption spectrometry, and XPS analysis results indicated that the adsorption mechanism of cobalt and copper could be attributed to the formation of anionic nitro-complexes in the solution, which could be exchanged with the anions on the resin to achieve the adsorption of metal ions. After a series of investigations, 1 mol/L sulfuric acid and ammonia were selected as desorption agents for cobalt and copper. [ABSTRACT FROM AUTHOR]

This paper concerns children's relations with the geological aspects of digital media technologies. Using ideas from media theory, I develop a new conceptual framework for childhood studies research on digital media that goes beyond the dominant focus on children's use of technology. I argue that studies of use would benefit from being linked up with analyses of the technicality and physicality of technology. Following recent debates concerning the Anthropocene, the planetary nature of digital media require analyses that link local and global scales, and address the politics of the specific materialities of digital media. As an example of the analytical potential of this approach, I discuss the issue of child labour in cobalt mining in the Democratic Republic of Congo. [ABSTRACT FROM AUTHOR]

A major concern in cobalt electrowinning is the generation of H2 along with cobalt deposition on the cathode, which results in current efficiency drop, specific energy consumption increase, as well as poor deposit quality. In this paper, the influence of initial pH, temperature, current density, and Co2+ ions concentration on current efficiency and specific energy consumption for cobalt electrowinning in a batch cell for 24-h electrolysis was investigated through a two-level factorial design. Preliminary analysis from cyclic voltammograms and current-time curves indicated a current efficiency of 86.2%, with 60 g/L of Co2+ at pH 4.0. The statistical study indicated that temperature presented the greatest significant contribution for the response variables. The best result was achieved with initial pH 4.0, 70°C 100 A/m2 and 60 g/L of Co2+, leading to a current efficiency of 78.8% and a specific energy consumption of 2.3 kWh/kg. As the pH drops considerably during the tests, its influence demands further studies. [ABSTRACT FROM AUTHOR]

This paper evaluates and demonstrates the methods for additively manufactured stent and the use of material ASTM F75 Cobalt-based superalloy (CoCrMo) by evaluating the chemical content, hot isostatic pressing process, mechanical properties, and electrochemical polishing. The commercialise stent available had cause issues in the like of unmatch fitting in the blood vessel, with highly dependent on surgeon guessing during angioplasty; thus, the risk of restenosis or thrombosis can occur. By SLM technique, it creates complex products with high geometric accuracy while allowing the design freedom to produce patient-specific stent. The heat treatment for additively manufactured stent has been done through a series of Hot Isostatic Pressing (HIPing) cycle 1200°C and 14,150 PSI. The sample preparation by chemical etching method was delivered to assess the effect of as-built sample and HIPing where it showed the change pattern of the microstructure. The chemical composition has been assessed by Energy-Dispersive X-ray spectroscopy (EDX) and showed the presence of element Cobalt, Chromium, Molybdenum, and Carbon content. The compressive, flexural, and hardness testing has been conducted to determine the behaviour for an as-built sample and HIPing where the stiffness is drastically improved by 10%. [ABSTRACT FROM AUTHOR]

Cobalt blue pigments, which mainly comprise CoAl2O4, are widely synthesized as nano-scale particles using the coprecipitation method. Such ultrafine powders are necessary for the ceramics industry because of their significant effect on the color of glaze and bulk tiles. In this paper, cobalt blue pigments have been prepared using the coprecipitation method and then subjected to supercritical fluid drying. The differences in their physicochemical and optical properties are characterized using a series of analysis including X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive spectrometer (EDS), and CIE-L*a*b*colorimetry analysis. The results indicate that the CoAl2O4 pigments subjected to supercritical fluid drying exhibit a fine-scale structure, a crystallite size of approximately 52 nm at 1400°C, and an excellent stability at high temperatures. They also present a vivid blue color, with improved brightness and hue than those of other cobalt blue pigments. Furthermore, this study elucidates the promising potential of supercritical fluid drying for fabricating nano-sized CoAl2O4 pigments with excellent optical and physicochemical properties. [ABSTRACT FROM AUTHOR]

Phenylethynyl-terminated polyimide resin/carbon fiber composites become ideal structure materials for aerospace vehicle because of excellent mechanical properties and high-temperature thermal stability. However, the curing temperature of the polyimide resin/carbon fiber composite was higher than 370 °C, which caused much thermal stress that would inevitably deteriorate the performance of the composite and restrict its application. In this paper, a compound catalyst of isopropyl peroxide and cobalt naphthenate was used to catalyze the cross-linking reaction of phenylethynyl-terminated polyimide resin and decrease the curing temperature of the polyimide/carbon fiber composite. The result showed that the phenylethynyl characteristic absorption peak at cm−1 was still existed in the polyimide resin without catalyst and disappeared for the catalystic polyimide resin when curing temperature was 300 °C, in which the spectrum was the same as that of the polyimide resin cured at 370 °C without catalyst. The inter-laminar shear strength and flexure strength of the catalytic polyimide/carbon fiber composite were 96.8 MPa and 2080.0 MPa, there were increases of 28.8% and 23.8% compared to that of the composite without catalyst cured 370 °C. All these results demonstrate that the compound catalyst of radical initiator and coordination catalyst could efficiently decrease the curing temperature of phenylethynyl terminated polyimide resin and increase the mechanical properties of the polyimide resin/carbon fiber composite. [ABSTRACT FROM AUTHOR]

The suitable electrochemical performance of lithium-ion batteries (LIBs) led to an increase in demand and the use of LIBs in electrical and electronic equipment. Naturally, increased demand will be accompanied by an enhancement in the supply of metals from mineral resources. On the other hand, the lithium metal supply scenario will not be able to meet market demand over the next few years. Spent LIBs include valuable metals like lithium, cobalt, nickel, manganese, etc., which can be considered as a secondary source for the recovery of valuable metals. LIBs also contain toxic and organic compounds whose lack of attention, causes irreparable damage to the public health and the environment. Therefore, two important perspectives on the recycling of spent LIBs are the recovery of valuable metals as secondary sources and compliance with environmental regulations. Among the recycling process of spent lithium-ion batteries, hydrometallurgical processes are a suitable technique for recovery of valuable metals from spent lithium-ion batteries, due to their advantages such as the high recovery of metals with high purity, low energy consumption, and very low gas emissions. In this paper, the main aspects of spent LIBs recycling (environmental and economic) and hydrometallurgical processes (pre-treatment, leaching by organic and inorganic acids with various reducing agents, precipitation, solvent extraction, electrochemical methods, ion exchange resin, and regeneration) used to recover valuable metals, have been investigated. [ABSTRACT FROM AUTHOR]

Polyoxometalates containing titanium (Ti-POMs) related to semiconductor TiO2 have potential applications in photocatalysis, photovoltaics and semiconducting materials. In this paper, we synthesized a Ti-POM, Na2H10[Co4(H2O)2(TiW9O34)2]·48H2O (1), by one-pot self-assembly reaction. In its crystal architecture, sodium ions connect multiple monomer units to form a layered structure. The electrochemical properties of 1 were investigated by cyclic voltammograms. The semiconductor band gap (Eg) value of 1 was calculated through diffuse reflection UV-vis spectroscopy. Furthermore, 1 was used as a semiconductor material and applied to photoelectrochemical sensing to detect dopamine with different concentrations in aqueous solution. The above-mentioned results open up an opportunity to develop polyoxometalate-based, titanium-containing coordination complexes with functional properties and lay the foundation for detection of other biological targets. [ABSTRACT FROM AUTHOR]

Since many decades material plays major role in all fields. In recent years, materials are more useful in specific field of science and engineering. This paper deals with micro-strip patch antenna designed using FR-4 and magneto dielectric substrate. To compare these results, CSTMWS Suite (Computer Simulation Technology Micro-Wave Studio) software is used. The results show that different substrate produce different gain and directivity based on their properties. Here, two different materials namely FR-4, Cobalt metal with fluoropolymer matrix are used as a substrate for same structure. [ABSTRACT FROM PUBLISHER]

Cobalt substituted Nickel ferrites, Ni1-xCoxFe2O4 where x = 0, 0.6, one were successfully synthesized by sol-gel auto-combustion method. With the help of the XRD machine, the phase formation and structural analysis of the samples have been carried out. The surface morphology has been studied using Transmission Electron Microscopy. The magnetic properties of the synthesized samples were carried out using Vibrating Sample Magnetometer. The lattice parameter was found to be in the range of around 8 Å it is noted that the lattice parameter is varied sample to sample and have been mentioned in this research paper. [ABSTRACT FROM AUTHOR]

Introduction:Dicobalt edetate is one of a number of cobalt compounds that have been studied in the treatment of cyanide poisoning, their efficacy being based upon the fact that cyanide combines with cobalt to form relatively non-toxic complexes. Inorganic cobalt salts are quite toxic (cyanide and cobalt antagonise one another's toxicity) and complexes such as dicobalt edetate were studied with the aim of identifying compounds that were less acutely toxic, but which retained the antidotal properties of cobalt salts. The proprietary preparation, Kelocyanor™, contains free cobalt and glucose as well as dicobalt edetate. Objective:The aim of this study was to evaluate the published evidence for the efficacy and adverse effects of dicobalt edetate. Methods:A Pubmed search was undertaken for the period 1961–September 2015. The search terms were “dicobalt edetate”, “cobalt edetate” and “Kelocyanor”, which produced 24 relevant citations. A review of the references in four relevant books (L'intoxication cyanhydrique et son traitement,Clinical and Experimental Toxicology of Cyanides,Antidotes for Poisoning by CyanideandAntidotes) produced three further relevant papers, making a total of 27 papers. Efficacy of dicobalt edetate:There is evidence from animal pharmacodynamic studies that dicobalt edetate is an effective cyanide antidote in experimental animals. Some 39 cases of human poisoning treated with dicobalt edetate have been reported, but in only nine cases were blood cyanide concentrations measured, although administration of dicobalt edetate procured survival in four of the seven patients with concentrations in the lethal range (>3.0 mg/L). It is unlikely that death in any of the adequately documented fatal cases was attributable to treatment failure with dicobalt edetate, as it is probable that they all had suffered anoxic brain damage before treatment could be initiated. Furthermore, in one case, acute gold toxicity contributed substantially to death. Adverse effects of dicobalt edetate:Adverse effects reported have included hypertension, tachycardia, nausea, retrosternal pain, sweating, palpebral, facial and laryngeal oedema, vomiting, urticaria and/or a feeling of impending doom. Such effects appear to be more prevalent where the antidote has been administered without evidence of substantial systemic poisoning or where other antidotes have been used which might have been expected also to combine with cyanide. Although the adverse effects observed were doubtless unpleasant, and some were severe, no fatal reactions were found. Conclusions:Dicobalt edetate is an effective cyanide antidote when given to patients with systemic cyanide poisoning, but it has the potential to give rise to adverse reactions, particularly when administered in the absence of intoxication. [ABSTRACT FROM AUTHOR]

This paper deals with the systematic investigation of microstructure, optical and magnetic properties of Co doped CaSnO3 nanostructures prepared by hydrothermal route. Detailed structural analysis using XRD, FTIR and Raman analysis reveals the formation of orthorhombic CaSnO3 with pnma space group. Optical absorption studies authenticates the tuning of optical band gap upto 1eV was achieved by varying Co concentration in Ca-Sn-O lattice. Presence of oxygen vacancies and defects in the grown nanostructures were supported by PL and EPR studies. Room temperature M-H loops implies clear occurrence of room temperature ferromagnetism in all the Co doped nanostructures and the saturated magnetization (Ms) increases with increase Co doping. The magnetization behaviour was explained based on F-centre exchange interactions mediated by oxygen vacancies. The overall findings open up a pathway to tune the ferromagnetism as well as bandgap of stannate systems by varying the concentration of transition metal dopant's. [ABSTRACT FROM AUTHOR]

In this paper, we produced spinel structure nanometre cobalt blue powder pigment by chemical coprecipitation. We also modified it through element doping and analysed the spinel structure and colouring mechanism of the pigment. We discussed the process conditions of coprecipitation reaction, the influence of doping element and its content on the properties of cobalt blue pigments spectral reflection effect. The morphology and particle size of powders were characterised through scanning electron microscopy and energy dispersive spectroscopy. The doping element type and content have great influence on the spectral curve of the cobalt pigment. High temperature in sintering contributes to the performance of the products. The sample produced at 1250°C sintering possesses good reflection characteristics, which is similar to chlorophyll. [ABSTRACT FROM AUTHOR]

Electropolishing is a common method for decreasing surface roughness and removing surface irregularities. In this paper the electropolishing of nickel and cobalt are successfully demonstrated in a deep eutectic solvent, comprising a 2:1 molar mixture of ethylene glycol and choline chloride. Voltammetric and electrochemical impedance studies were used to characterise the polishing mechanism and show that film formation occurs prior to polishing. Scanning electron microscopy and atomic force microscopy were used to characterise the morphology before and after polishing and 3D optical microscopy was used in-situ to observe film formation during polishing. This study shows that the impact of film formation and subsequently mass transport are responsible for electropolishing of both metals in the choline chloride-based ionic liquid. [ABSTRACT FROM AUTHOR]

The rose petal effect (large apparent contact angles accompanied by high affinity to water) has greatly inspired researchers recently. In this paper, the rose-petal surfaces with tunable high water adhesion have been prepared successfully via a facile electroless galvanic deposition process as well as the subsequent modification with stearic acid on zinc substrates. We have regulated the concentration of CoSO4solution in the process of electroless galvanic deposition to control the surface topography. After being modified with stearic acid, the as-prepared cobalt coated films showed similar apparent contact angles larger than 150° but contrast high water adhesion. To the best of our knowledge, the fabrication of rose petal surfaces with tunable water adhesion is still scarce. The largest water droplet volumes suspended on the tunable rose petal surfaces were 8, 24 and 28 μL, respectively. In addition, based on the different water adhesion on the rose petal surfaces, the selective transportation of microdroplets with different volumes has been demonstrated. We believe that these tunable adhesive rose petal surfaces would have great potential in the droplet-based microreactors. [ABSTRACT FROM PUBLISHER]

In this paper, we elucidated the synthesis, characterization, and investigation of catalytic activity studies of new metallophthalocyanines4and5as the catalyst for phenolic compounds oxidation by trying different types of oxygen sources. The structural characterization of the products was made by a combination of elemental analysis, FT-IR, LC-MS/MS (for phthalonitrile derivative 3), MALDI-TOF mass spectral data (for metallophthalocyanines4–7), UV–vis spectroscopy (for metallophthalocyanines4–7),1H NMR and13C NMR spectroscopies (for compounds3and6). The synthetic routes for the (trans-3,7-dimethyl-2,6-octadien-1-ol) substituted phthalonitrile derivative3and corresponding metallophthalocyanines4–7are outlined in Scheme1. The MPc complexes4–7were synthesized via cyclotetramerization of compound3in the presence of the corresponding anhydrous metal salts (CoCl2for4, CuCl2for5, Zn(CH3COO)2for6and MnCl2for7) in dryn-pentanol as solvent and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as strong base at reflux temperature under nitrogen gas. Phthalocyanines and their metal complexes, in general, display poor solubility in most of the organic solvents, however, the synthesized metallophthalocyanine complexes4–7were highly soluble in common organic solvents because of the introduction of the methyl groups on alkyl chains of peripheral arms. The catalytic activity of compounds4and5was evaluated for the oxidation of phenolic compounds such as 4-nitrophenol,o-chlorophenol, 2,3-dichlorophenol, andp-methoxyphenol. CoPc4displayed good catalytic performance with a full oxidation of 4-nitrophenol into the corresponding benzoquinone and hydroquinone with the highest TON and TOF values within 3 h. [ABSTRACT FROM PUBLISHER]

Two novel CoII metal–organic frameworks {[Co(BIMB)2(H2O)2](SO4)·EG·3 H2O}n (I) and {[Co(TIMB)2](SiF6)}n (II) were hydrothermally synthesized by corresponding metal salt with organic ligands 1,3,5-tris[(1H-imidazol-1-yl)methyl]benzene (TIMB) or 1,4-bis((1H-imidazol-1-yl)methyl)benzene (BIMB). Crystal structural analysis reveals that they exhibit varied structures. Compound I contains two crystallographically unique CoII centers, each lying on an inversion center and having a slightly distorted octahedral environment. The BIMB ligands link the CoII cations to generate a three-dimensional porous framework with a 4-connected uninodal (65.8) topology. Compound II exhibits a two-dimensional sheeted metal-organic structure running parallel to the (0 0 1) plane, in which TIMB ligands join Co2+ centers having a six-coordinated octahedral structure. In the solid state, adjacent sheets are further bridged by guest SiF6- anions via C–H...F hydrogen-bonding interactions, giving rise to a three-dimensional supramolecular network structure with a 2-nodal (3-c)2(6-c) net. The topological analysis suggests that the point Schläfli symbol of compound II is (43)2(46.66.83). In addition, their thermal stabilities have also been investigated. [ABSTRACT FROM AUTHOR]

In this paper, a process is reported for the recovery of cobalt and nickel from copper raffinate solutions using partially saponified Cyanex 272 and D2EHPA as the extractants. The aqueous feed contains 1.65 g/L cobalt and 16.42 g/L nickel. More than 99.9% cobalt separation was achieved with 0.13 M Cyanex 272 (60% neutralized with alkali) in two counter-current stages at an aqueous to organic phase ratio of 1.1:1. Co-extraction of nickel was 0.18% only. Stripping of cobalt from a loaded organic phase was carried out with synthetic spent electrolyte solution at an organic to aqueous phase ratio of 2.5 in two counter-current stages to generate a pregnant electrolyte solution to produce cobalt metal by electrowinning. Similarly, optimum conditions for nickel extraction with 60% neutralized 1 M D2EHPA at O/A ratio of 1.4 in 2 two stages and stripping of metal with synthetic spent electrolyte at O/A ratio of 1.6 in two stages were standardized. Extraction and stripping efficiencies were >99% and the flowsheet of the process is demonstrated. [ABSTRACT FROM AUTHOR]

Cobalt disulfide (CoS2) is a highly sophisticated metal chalcogenide that has garnered significant attention due to its distinctive properties such as its electrical, optical, catalytic, and magnetic capabilities and potential for use in a range of applications. In this work, pure CoS2 nanoparticles were synthesized using the economical and facile hydrothermal method. The X-Ray diffraction (XRD) method was used to characterize the synthesized sample, confirming that it has a cubic crystal structure with space group P a −3. The Debye-Scherrer's formula was implemented to determine the average crystallite size of nanoparticles and found to be 24.24 nm. Through the use of Field Emission Scanning Electron Microscopy (FESEM), the morphology and effective grain size of the obtained sample was determined. FTIR spectrophotometry was used to examine the vibrational stretching of the various bonds in CoS2. UV-Vis spectroscopy is employed to measure the optical property of the sample. The optical bandgap calculated from the Tauc Plot is around 1.90 eV reflecting the presence of photovoltaic properties in the sample. The change in dielectric permittivity and loss have been observed for the sample in the frequency range of 100 Hz to 10KHz at different temperatures between 303K and 423K. The frequency-dependent electrical conductivity of CoS2 is also explained. The observations revealed the presence of unique electrical and structural properties in the synthesized sample. [ABSTRACT FROM AUTHOR]

Using the spray pyrolysis technique, CoSe-doped erbium, and pure cobalt selenide (CoSe) thin film was successfully examined with the influence of deposition temperature. The XRD results revealed that CoSe and CoSe: Er are crystalline materials and as the deposition temperature is increased, the peak intensity is found to decrease. Clusters of sizeable nanoparticles may be seen on the surface micrograph of the synthesised films. They are evenly dispersed and do not exhibit pinholes. The optical studies revealed that CoSe: Er has high absorbance, transmittance, and low reflectance. The obtained energy bandgap ranged from 1.52 to 2.35 eV. It was noticed that doping cobalt selenide with erbium enhances the structural and optical properties of the synthesised films for photovoltaic devices. [ABSTRACT FROM AUTHOR]

Recent experimental observations show thattwin boundaries in hexagonal close-packed (hcp) metals are frequently faceted. The objective of this paper is to investigate the influence of this faceting on the strain produced by twinning. We show that basal–prismatic (BP) facets are terminated by opposite disclinations and the migration of these facets along a straighttwin boundary produces ordinary twinning shear. On the other hand, joining conjugate twins gives rise to BP facets terminated on the parent twin boundaries by identical disclinations. In this case, the strain produced by the migration of BP facets is an average between the strains produced by the individual conjugate twins. These theoretical studies are complemented by two EBSD measurements on cobalt that is closely related to magnesium. The misorientation profiles measured across two conjugate twin boundaries yield a misfit of approx. 7° consistent with the theoretical prediction that the corner of a twin embryo is terminated by two identical disclinations, each accommodating a misfit of 3.7°. [ABSTRACT FROM AUTHOR]

Carbon-encapsulated cobalt nanoparticles (Co@C) are prepared by the chemical vapour deposition of methane at 773-1073 K. This paper investigates the graphitisation and microstructure transformation of Co@C governed by synthesis temperature. The results show that carbon shells consisting of amorphous carbon or small graphite fragments begin forming on Co nanoparticles from 773 to 873 K. The products transform into onion-like carbon-encapsulated cobalt nanoparticles at 973 K. At 1073 K, a higher graphitisation of Co@C is achieved, with the appearance of carbon nanotubes. With a rising synthesis temperature, the carbon shells undergo the transformations from amorphous carbon to graphite fragments and finally to onion-like carbon. The microstructural transformations are demonstrated by scanning electron microscope, transmission electron microscope and Raman characterisations. Therefore, controlling the synthesis temperature is a feasible and easy approach one can take to adjust the structure and graphitisation of Co@C in the chemical vapour deposition process. [ABSTRACT FROM AUTHOR]

Simpleand validated ultrasound-assisted dispersive microsolid-phase extraction (UA-DMSPE) approach for separation, and preconcentration of trace cobalt (Co(II)) and nickel (Ni(II)) ions in various water, juice, food and tobacco samples prior to their flame atomic absorption spectrometry determination (FAAS) was developed. The proposed method based on using oxidized multiwalled carbon nanotubes (ox-MWCNTs) as adsorbent and 3-(2-hydroxy-5-acetylphen-1-ylazo)-1,2,4-triazole (HAPAT) as complexing agent at pH 7.0. The effect of different parameters has been investigated and optimised. The calibration curves were linear in the ranges of 1.0–300 and 2.0–400 μg L−1 and the limits of detection were 0.30 and 0.60 μg L−1 for Co(II) and Ni(II) ions, respectively, under the optimum conditions.The preconcentration factor was 200. Co(II) and Ni(II) havemaximum sorption capacities of around 300 and 370 mg g–1, respectively. The recovery rates of the analytes ranged from 96.0 to 101%. Furthermore, relative standard deviation (RSD%) for intra-day (1.40 and 1.90%) and inter-day (1.70 and 2.10%) as repeatability for Co(II) and Ni(II), respectively. Certified reference materials (SRM 1570A spinach leaves and TMDA-52.3 fortified water) were used to verify the accuracy of the proposed preconcentration protocol. The proposed method was successfully used to determine the content of Co(II) and Ni(II) ions in a variety of real water, juice, food and tobacco samples yielding satisfactory results. [ABSTRACT FROM AUTHOR]

Magnetic hydroxyapatite incorporated cobalt (Co/HAp@Fe3O4) was fabricated by introducing both Co2+ and Fe3O4 into the hydroxyapatite (HAp) matrix. HAp@Fe3O4 and Co/HAp@Fe3O4 were characterised by IR, XRD, EDX, SEM and TG/DTA. The adsorption efficiency of La(III) and Sm(III) was compared on both HAp@Fe3O4 and Co/HAp@Fe3O4 using several factors, such as solution pH, contact time, initial metal concentrations and reaction temperature. It was found that the appropriate factors for the highest adsorption were at pH 5 and the equilibrium time was 60 min. The Co/HAp@Fe3O4 exhibited enhanced adsorption efficiency compared to HAp@Fe3O4 due to the existence of additional adsorption sites. The equilibrium adsorption isotherms for both Sm(III) and La(III) were fitted well with Langmuir model.The adsorption capacity was found to be 259.06 and 200.80 for La(III) and 413.22 and 476.19 mg/g for Sm(III) on Co/HAp@Fe3O4 and HAp@Fe3O4respectively. Thermodynamic parameters (∆G°, ∆S°, ∆H°) of La(III) and Sm(III) equilibrium with Co/HAp@Fe3O4 indicated a non-spontaneity and endothermic nature. The positive ΔSo suggested an entropy un-favoured or disorder at the solid/liquid interface. [ABSTRACT FROM AUTHOR]

Cobalt-substituted magnetite CoxFe3-xO4 nanoparticles were synthesized using a sol-gel auto-combustion method using citric acid as a fuel. The samples were characterized by X-ray diffraction (XRD), fieldemission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR) spectroscopy, optical ultraviolet-visible (UV-Vis) spectroscopy, and vibrating sample magnetometer (VSM). XRD studies revealed cobalt replacing iron, forming a single phase with a crystalline size of 17-25 nm. FESEM and FTIR spectra showed a metal-oxygen bond, while UV-Vis spectra showed absorbance spectra and Kubelka-Munk theory. Magnetic properties were studied using VSM, revealing increased saturation magnetization and a constant squareness ratio, confirming the single domain of cobalt-doped Fe3O4 nanoparticles. These nanoparticles have potential applications in spintronics, nanoscale devices, and supercapacitors. [ABSTRACT FROM AUTHOR]

The influence of cobalt (Co) on the as-cast microstructure of an Ni-based single crystal superalloy and its chemical segregation, incipient melting temperature and stress rupture properties was investigated. The results show that the dendrite arm spacing in the alloy did not vary with the addition of Co. The γ′ size in the as-cast microstructure decreased with increasing Co content. The segregation ratio of the γ′-forming elements titanium (Ti) and tantalum (Ta) became higher in alloys with high Co content (5%, 10%), while the segregation ratio of the γ-forming elements chromium (Cr) and molybdenum (Mo) first increased then decreased with increasing Co content, attaining the minimum around 10% Co. The incipient melt temperature decreased with increasing Co content. The stress rupture life under 1010°C/248 MPa increased with the increasing of Co content up to 10%, but decreased at 15% Co. The related mechanisms are also discussed in this paper. [ABSTRACT FROM AUTHOR]

The paper demonstrates the filling of cobalt nanoparticles into the multiwalled carbon nanotube buckypaper by the dispersion and filtration method to study microwave absorption. Synthesised buckypaper samples were subject to characterisation by using X-ray diffraction, scanning electron microscope, atomic force microscope and four probe techniques to measure the size of the cobalt particles, morphology and low temperature electrical resistivity of the buckypaper, respectively. We used two different sizes of cobalt particles (14·54 and 33·04 nm, respectively) for doping in the buckypaper. Microwave-absorbing properties were examined by measuring the transmission coefficient (S21) in a frequency range of 1-20 GHz with the buckypaper as an absorber. Variations in the resistivity value, with different particle sizes of cobalt were attained by the low temperature resistivity measurements. The observed maximum of S21 indicates that the cobalt-buckypaper displays good microwave absorption (90%) properties for a potential application as wideband electromagnetic wave absorbers. [ABSTRACT FROM AUTHOR]

The paper demonstrates the filling of cobalt nanoparticles into the multiwalled carbon nanotube buckypaper by the dispersion and filtration method to study microwave absorption. Synthesised buckypaper samples were subject to characterisation by using X-ray diffraction, scanning electron microscope, atomic force microscope and four probe techniques to measure the size of the cobalt particles, morphology and low temperature electrical resistivity of the buckypaper, respectively. We used two different sizes of cobalt particles (14·54 and 33·04 nm, respectively) for doping in the buckypaper. Microwave-absorbing properties were examined by measuring the transmission coefficient (S21) in a frequency range of 1-20 GHz with the buckypaper as an absorber. Variations in the resistivity value, with different particle sizes of cobalt were attained by the low temperature resistivity measurements. The observed maximum of S21 indicates that the cobalt-buckypaper displays good microwave absorption (90%) properties for a potential application as wideband electromagnetic wave absorbers. [ABSTRACT FROM AUTHOR]

Open pit optimisation and scheduling tasks are an important part of mining ventures that have attracted considerable attention in the mining industry in the past couple of decades. The process of determining the optimum pit significantly impacts the calculation of mine life, which involves huge capital investment. This paper addresses the application of a heuristic algorithm for optimising the pit size and then life of mine scheduling for a copper-cobalt deposit in the Central African copper belt. The resource model was generated using a traditional geostatistical algorithm, specifically the kriging method. The methodology used was to generate a series of optimised nested pits by artificially varying the commodity price and applying a graph closure algorithm. The mine scheduling was generated by combining the solutions of different sub-problems. The deposit is optimised to 9.1 Mt with an average copper grade of 2.03% and cobalt grade of 0.47%. The total NPV generated from the pit is around 495 million US dollars. The results of our proposed algorithm were compared with linear relaxation of the mine scheduling problem. They demonstrated that our proposed algorithm is 30 times more efficient than the linear relaxation problem with an optimality gap of 7.4%. [ABSTRACT FROM AUTHOR]

Introduction. There has been some recent concern regarding possible systemic health effects resulting from elevated blood cobalt concentrations in patients with cobalt containing hip implants. To date there are no blood cobalt criteria to help guide physicians when evaluating an individual hip implant patient's risk of developing systemic health effects because historically there was little or no concern about systemic cobalt toxicity in implant patients. Objective. Our purpose is to describe recently completed research regarding the relationship between blood cobalt concentrations and clinical health effects. We discuss the possibility of systemic health effects in patients with metal containing implants and propose various blood cobalt concentrations that are not associated with an increased risk of developing certain adverse effects. Methodology. The primary literature search was conducted using PubMed and Web of Science using the following search terms: cobalt AND (toxicity OR health effects OR cardiotoxicity OR hematological OR endocrine OR immunological OR reproductive OR testicular effects OR neurological OR case report OR cohort OR Roncovite). The searches identified 6786 papers of which 122 were considered relevant. The Agency for Toxic Substances and Disease Registry toxicological profile for cobalt and the U.S. Environmental Protection Agency Office of Research and Development's National Center for Environmental Assessment's documentation on the provisional peer-reviewed toxicity value for cobalt were also utilized to identify secondary literature sources. Results. Our review of the toxicology and medical literature indicates that highly elevated blood cobalt concentrations can result in certain endocrine, hematological, cardiovascular, and neurological effects in animals and/or humans. These studies, in addition to historical clinical findings involving the therapeutic use of cobalt, indicate that significant systemic effects of cobalt will not occur below blood cobalt concentrations of 300 μg/L in most persons. Some individuals with specific risk factors for increased susceptibility (e.g., severe and sustained hypoalbuminemia) may exhibit systemic effects at lower cobalt blood concentrations. This review also describes several cobalt dosing studies performed with human volunteers that consumed cobalt for 15, 30, or 90 days. Overall, the results of these dosing studies indicate that sustained blood cobalt concentrations averaging 10-70 μg/L for up to 90 days cause no significant clinical effects (maximum concentrations approached 120 μg/L). Some proposed blood criteria for assessing implant wear and local tissue damage have been suggested by several medical groups. For example, the UK Medicines and Healthcare Products Regulatory Agency has proposed a blood cobalt guidance value of 7 μg/L, and the Mayo Clinic has suggested serum cobalt concentrations greater than 10 μg/L, but both of these values are primarily intended to address implant wear and to alert physicians to the possibility of an increased incidence of local effects. There is a clear lack of consensus regarding how to identify a specific numerical blood concentration of concern and whether whole blood or serum is a better matrix to assess total cobalt concentration. Conclusions. Based on currently available data, only under very unusual circumstances should a clinician expect that biologically important systemic adverse effects might occur in implant patients with blood cobalt concentrations less than 300 μg/L. Patients with metal-containing hip implants who exhibit signs or symptoms potentially related to polycythemia, hypothyroidism, neurological, or cardiac dysfunction should be clinically evaluated for these conditions. Polycythemia appears to be the most sensitive endpoint. [ABSTRACT FROM AUTHOR]

Cobalt (Co) is an essential element with ubiquitous dietary exposure and possible incremental exposure due to dietary supplements, occupation and medical devices. Adverse health effects, such as cardiomyopathy and vision or hearing impairment, were reported at peak blood Co concentrations typically over 700 µg/L (8-40 weeks), while reversible hypothyroidism and polycythemia were reported in humans at ∼300 µg/L and higher (≥2 weeks). Lung cancer risks associated with certain inhalation exposures have not been observed following Co ingestion and Co alloy implants. The mode of action for systemic toxicity relates directly to free Co(II) ion interactions with various receptors, ion channels and biomolecules resulting in generally reversible effects. Certain dose-response anomalies for Co toxicity likely relate to rare disease states known to reduce systemic Co(II)-ion binding to blood proteins. Based on the available information, most people with clearly elevated serum Co, like supplement users and hip implant patients, have >90% of Co as albumin-bound, with considerable excess binding capacity to sequester Co(II) ions. This paper reviews the scientific literature regarding the chemistry, pharmacokinetics and systemic toxicology of Co, and the likely role of free Co(II) ions to explain dose-response relationships. Based on currently available data, it might be useful to monitor implant patients for signs of hypothyroidism and polycythemia starting at blood or serum Co concentrations above 100 µg/L. This concentration is derived by applying an uncertainty factor of 3 to the 300 µg/L point of departure and this should adequately account for the fact that persons in the various studies were exposed for less than one year. A higher uncertainty factor could be warranted but Co has a relatively fast elimination, and many of the populations studied were of children and those with kidney problems. Closer follow-up of patients who also exhibit chronic disease states leading to clinically important hypoalbuminemia and/or severe ischemia modified albumin (IMA) elevations should be considered. [ABSTRACT FROM AUTHOR]

The necessity to reduce time and maintenance costs in electrical energy generation turbines promotes the development of new materials and processes to recover cavitated areas. Nowadays, different automated welding process have been studied, mainly plasma-transferred arc welding (PTA) in substitution of fluxed core arc welding (FCAW). The PTA process presents as its main advantages: low dilution, a narrow heat-affected zone and excellent arc stability; however, few cavitation resistant alloys are developed for this process. This paper aims to compare three cobalt cavitation resistant alloys deposited with the PTA process. The first alloy is a cobalt stainless steel alloy developed for the FCAW process, the second is a cobalt stainless steel alloy developed for the PTA process and the third is a national developed stainless steel alloy with cobalt. The samples were analysed by optical and electronic microscopy, microhardness and accelerated cavitation testing, ASTM G32-95. Results show that a refined austenitic microstructure was observed in all samples. The commercial alloys, developed for PTA welding, presented a better arc stability and lower quantity of defects. The national alloy demonstrated good results during deposition while the FCAW alloy presented better cavitation resistance. [ABSTRACT FROM PUBLISHER]

In this paper, carbon-supported Ir-Co, Ir-Ni, and Ir-Cr catalysts (Ir-Co/C, Ir-Ni/C, and Ir-Cr/C) were synthesized and characterized for the oxygen reduction reaction (ORR). Compared to both Pt/C and Pd/C catalysts, these Ir alloy catalysts demonstrated much higher formic acid tolerance capabilities during the ORR process in a 0.5 M H2SO4 solution containing both oxygen and formic acid. Rotating disk electrode measurements confirmed that if formic acid was present, these Ir alloy catalysts could still catalyze a complete 4-electron transfer ORR from O2 to H2O, while the Pt/C catalyst could only catalyze a reaction contributed by both 2- and 4-electron transfer processes, producing both H2O2 and H2O. These results strongly suggest that Ir alloy catalysts should be promising candidates for direct formic acid fuel cell applications. [ABSTRACT FROM AUTHOR]

A review of the literature dealing with the effect of cobalt on lead-based anodes for oxygen evolution during electrolysis of sulfuric acid solutions verifies that the presence of cobalt at the anode-electrolyte interface, either as constituent of the anode material or as ions in the electrolyte, catalyzes the evolution of oxygen and reduces the corrosion of the anodes and the contamination by lead of metal cathodes produced during electrowinning. However, due to harmful effects of cobalt ions on the cathodic reaction in some processes, these benefits are limited to the electrowinning of copper. Efforts to develop a way of introducing cobalt at the anode-electrolyte interface without interfering with the cathodic reactions are reviewed in this paper. The use of lead-cobalt alloy anodes has had limited success due to issues arising from the low solubility of cobalt in lead, segregation during casting of the alloys, and nonuniform distribution of cobalt which affects the integrity of the anodes. This has been overcome in part lately by inclusion of cobalt into only the surface layer of a lead or lead alloy substrate, by thermal treatment of a cobalt salt to form a catalytic cobalt oxide surface species, or by electrodeposition of composite lead-cobalt oxide anodes. The last approach in particular has been actively investigated by several groups, but to our knowledge it is yet to find application in the industry. The review also critically examines the likely reaction mechanisms involved. [ABSTRACT FROM AUTHOR]

The present paper describes Raman studies of chemically synthesized nanocrystalline cobalt-substituted (up to 10%) ZnO samples exhibiting room temperature ferromagnetism. These studies were carried out using Laser excitation wavelengths -457.9, 532 and 785 nm. The Raman spectra of the samples excited with 457.9 nm show predominantly lattice modes of ZnO because of pre-resonance enhancement. In the Raman spectra of cobalt added ZnO samples excited with 532 and 785 nm, clear evidence is seen for the presence of Co3O4 (an impurity phase not detectable in XRD) in the samples with cobalt exceeding 3%. The presence of Co3O4 in the samples having higher concentration of cobalt explains the nonmonotonic increase in magnetization with Co-concentration in the ZnO1 - xCox samples. [ABSTRACT FROM AUTHOR]

Despite the wide use of nanoscale materials in several industrial applications as well as in biology and medicine, very little research has been carried out on the potential toxicity of nanoparticles. We had previously obtained 10 differentially expressed mRNAs in BALB3T3 fibroblasts exposed to different forms of cobalt, i.e., microparticles, nanoparticles, and ions. Those genes represented candidate biomarkers for indicating specific cellular effects after cobalt nanoparticle exposure. In the present paper, we have further evaluated the expression of those genes by real-time RT-PCR after exposure to different forms of cobalt. Moreover, we also tested some genes associated with cobalt toxicity, such as VEGF, HIF-1α, and Bnip3. We identified biomarkers that are sensitive to cobalt ions that we think to be the reactive form. Our data, in fact, are consistent with the possibility that Co-nano, due to their large surface area, once inside the cell dissolve and act as ions. [ABSTRACT FROM AUTHOR]

The ability to couple two or more materials, exhibiting distinct properties, into a single geometry, such as core-shell nanocables, may lead to the realisation of novel multi -functional materials for applications such as spin valve systems. We discuss in this paper the use of supercritical fluid inclusion techniques for the growth of cobalt/magnetite and magnetite/cobalt core/shell nanocables within the pores of anodic aluminium oxide (AAO) membranes. These nanowires exhibit tunable magnetic properties which are dominated by the core material. [ABSTRACT FROM AUTHOR]

Metallic magnetic nanoparticles synthesized via an organometallic route are interesting candidates for nanoscale magnetic applications. Due to exposure to air they are often covered by passivating oxide overlayers following synthesis. For technological applications the influence of this layer on the macroscopic properties needs to be understood as, to a large extent, it governs the properties of nanoparticle systems. In this paper we show that the thin oxidic layer covering highly monodisperse Co/CoO core-shell nanoparticles with diameters of 10-13 nm gives rise to interesting magnetic effects. We discuss the influence of the oxide overlayer on the orbital magnetic moment at the interface to the metallic core and its importance for the occurrence of exchange bias effects. Moreover, the oxide layer manifests itself as a time-dependent reduction of the effective magnetic anisotropy field (magnetic aging) from which an estimate of the magnetically active volume of the nanoparticles as a function of time can be obtained. The investigations were carried out using ferromagnetic resonance supported by superconducting quantum interference device magnetometry. The ferromagnetic resonance results are compared with X-ray magnetic circular dichroism measurements. The latter are, in the case of total electron yield detection, surface sensitive, thus providing a direct probe of the interface between the Co core and the CoO shell. [ABSTRACT FROM AUTHOR]

In this short review, the application of powder X-ray diffraction to the study of heterogeneous catalysis is described. Within the literature, most applications of powder diffraction in heterogeneous catalysis have centred on its use as a fingerprint technique for phase identification/confirmation. However, there is wealth of additional information potentially available, and in this review some studies, which have gone beyond fingerprint applications, are described. Brief descriptions of selected papers detailing the application of in-situ measurements, the determination of catalyst stoichiometry in-situ, the determination of coke location in ZSM-5 catalysts, line profile analysis, Debye Functional Analysis and combined X-ray absorption and diffraction are given. Many, but not all, of these studies have been performed with standard instrumentation, illustrating some of the range of information available in laboratory studies. [ABSTRACT FROM AUTHOR]

Metallophthalocyanine (MPc) and its derivatives are well known as electrocatalysts to catalyze oxidation or reduction of some species, such as cysteine, nitric oxide. Their nanosized particles may display the potential optics, electronic, catalytic, and structural properties. In this paper, carbon paste electrodes (CPE) modified with nanosized cobalt phthalocyanine (Nano-CoPc) particles (Nano-CoPc-CPE) are fabricated. The electrocatalytic oxidation of theophylline (THP) on the Nano-CoPc-CPE is investigated by means of differential pulse voltammetry. The Nano-CoPc particles perform better electrocatalytic activity to THP, the response current enhanced about 3.4 times compared to bulk CoPc-modified CPE (B-CoPC-CPE). On optimal conditions, there is a good linear relationship between anodic peak current and THP concentration in the range of 4.0 × 10−7–1.0 × 10−4 mol L−1 with the detection limit of 1.4 × 10−7 mol L−1 (S/N = 3). The current responses of successive 40 measurements at the identical surface and at the renewed ones of Nano-CoPc-CPE are examined with relative standard deviation of 2.1% and 3.5%, respectively. It indicates that the electrode shows a good stability and reproducibility. It can be used to determine THP in tea and drug without separation from the matrix. The possible electrocatalytic mechanism is investigated by means of electrochemical method and UV/VIS spectroscopy. [ABSTRACT FROM AUTHOR]