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The presence of cobalt ions Co(II) in wastewater poses major threats to both humans and the environment. The effectiveness of the adsorption of modified quartz rock particles (MQRP) adsorbent with calcium hydroxide solution Ca(OH)2 for eliminating Co(II) from a water solution was examined. MQRP had a maximum ability to adsorb 47.112 mg g−1 for Co(II) at pH 6.0 and a contact time of 2 h. The HCl stripping agent offered the highest desorption efficiency to regenerate the adsorbent for use again for a new cycle of adsorption. The equilibrium isotherms of the adsorption characteristics were experimentally identified, and the results of adsorption aligned with the principles of the Langmuir model. Under the examined temperature conditions, thermodynamic evaluation proved that Co(II) adsorption on adsorbent vacancies was spontaneous and exothermic. The outcomes of the kinetic process demonstrated that the process closely conformed to a pseudo-secondorder pattern. Therefore, the high silica content of MQRP makes it an important adsorbent, and it could be applied as a cost-effective and efficient adsorbent to control the release of Co(II) ions in industrial wastewater. [ABSTRACT FROM AUTHOR]

Ion-imprinting methodology was used to fabricate a new cobalt ion-imprinted polymer as a cross-linked copolymer consisting of fumaric acid and 4-vinylpyridine as monomers. Different techniques were used to investigate all of the chemical and morphological changes that occurred during the cobalt ion imprinting process. Furthermore, extraction experiments for cobalt ions using controlled and imprinted polymers were carried out to obtain the essential isotherm, kinetic and thermodynamic parameters. The controlled and imprinted resins had the best agreement with the pseudo-second-order and Langmuir models, with maximum retention capacities of 14.7 ± 2 and 42.0 ± 0.5 mg/g, respectively. In comparison to non-imprinted polymer, the imprinted polymer showed greater affinity for cobalt ions in the presence of other metal ions like Cd2+, Cu2+, Ni2+, La3+, and Y3+. In addition, after the fifth adsorption-desorption cycle, resin regenerates with about 96% of its initial activity, demonstrating its high economic value. [ABSTRACT FROM AUTHOR]

This study is focused on the application of the ultraviolet/peroxymonosulfate/cobaltous cation (UV/PMS/Co2+) (cobalt II ion) system for the successful degradation of bromocresol green (BCG) dye in an aqueous solution. The influences of different variables like initial PMS concentration, pH of the media, and catalyst dose in terms of BCG degradation were studied. Furthermore, the effectiveness of the UV/PMS/Co2+ system for the degradation of BCG was performed in different water systems (i.e., deionized water, tap water, and industrial wastewater). UV and UV–PMS systems alone contributed 13 and 67%, respectively, in the degradation of BCG with the kapp values of 0.006 and 0.0297 min−1, respectively. It was observed that by the incorporation of Co2+ in the UV–PMS system, the degradation of BCG was significantly increased from 67 to 98% with the corresponding increase in kapp values to 0.0931 min−1. The scavenger results revealed the SO4•- and •OH radicals are the dominant species involved in the BCG removal. The toxicity data showed that the UV/PMS/Co2+ method considerably reduced the toxicity of textile effluent. In addition, seven BCG degradation products (DPs) have been identified experimentally using gas chromatography–mass spectrometry (GC-MS). In conclusion, the UV/PMS/Co2+ procedure can be used to effectively cleanse and detoxify wastewater. HIGHLIGHTS To the best of our knowledge, this is the first article on photocatalytic elimination of BCG by the UV/Co2+ process.; The addition of the green oxidant, peroxymonosulfate, synergistically improved the degradation process.; The mechanistic approach was conducted for the photocatalytic elimination of BCG by the UV/Co2+ process.; The toxicity evaluation was performed.;

Purpose: Due to the multilayered structure of the skin tissue, the architecture of its engineered scaffolds needs to be improved. In the present study, 45s5 bioglass nanoparticles were selected to induce fibroblast proliferation and their protein secretion, although cobalt ions were added to increase their potency. Methods: A 3-layer scaffold was designed as polyurethane (PU) - polycaprolactone (PCL)/ collagen/nanoparticles-PCL/collagen. The scaffolds examined by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), tensile, surface hydrophilicity and weight loss. Biological tests were performed to assess cell survival, adhesion and the pattern of gene expression. Results: The mechanical assay showed the highest young modulus for the scaffold with the doped nanoparticles and the water contact angle of this scaffold after chemical crosslinking of collagen was reduced to 52.34±7.7°. In both assessments, the values were statistically compared to other groups. The weight loss of the corresponding scaffold was the highest value of 82.35±4.3 % due to the alkaline effect of metal ions and indicated significant relations in contrast to the scaffold with non-doped particles and bare one (P value

The spectroscopic properties of cobalt ions in Ca3(VO4)2 crystals doped via thermal diffusion and during synthesis are investigated. The diffusion doped crystal shows the potential for higher cobalt doping while maintaining its high initial optical quality. The redistribution of several absorption and fluorescence lines intensities with cobalt concentration is attributed to the formation of Co2+ optical centers with sufficiently different local environments. The fluorescence decay times of Co2+ optical centers are measured to differ by an order of magnitude (95 and 13 μs) and are attributed to centrosymmetric M1 and low symmetry M2 types of Co2+ optical centers, possibly corresponding to Ca(4) and Ca(1) positions of Ca3(VO4)2 crystal, respectively. Nonlinear transmission of Co2+ M2 centers is measured, and efficient absorption cross‐sections of 1.4 × 10−19 and 2.4 × 10−19 cm2 are evaluated at 1300 and 1500 nm, respectively. The narrow fluorescence line of cobalt ions peaking at about 1170 nm, detected in both Ca3(VO4)2 crystals doped via thermal diffusion and during synthesis, is attributed to Co ions in a trivalent state. [ABSTRACT FROM AUTHOR]

Nitrogen, boron co-doped carbon quantum dots (gCQDs), and a coloration probe (PPD-NPs) with response to cobalt ions (Co2+) were prepared by using 4-hydroxyphenylboric acid as the common precursor, with ethylenediamine and p-phenylenediamine (PPD) adopted as nitrogen-doped reagents, respectively. A noticeable brown-to-purple color change can be observed with the addition of Co2+, and a broad absorption band emerges at 535 nm. At the same time, gCQDs, which is introduced as the fluorescence signal source, will be significantly quenched due to the enhanced inner filtration effect, induced by the overlap between the emission spectrum of gCQDs and the emerging absorption band. Therefore, a colorimetric/fluorescent dual-mode sensing probe for Co2+ is constructed by combining the recognition unit PPD-NPs and the fluorescent gCQDs into PPD-NP/gCQD. Under the optimized experimental conditions, the calculated limits of detection are 1.51 × 10−7 M and 3.75 × 10−7 M for the colorimetric mode and the fluorescence mode, respectively, well qualified for the determination of Co2+ maximum permitted level in drinking water. The feasibility of the proposed method has been verified in tap water, lake water, and black tea samples. [ABSTRACT FROM AUTHOR]

Herein, the effect of changing the alkaline earth metal cations type on the structure-properties of cobalt zinc borate glass was demonstrated. A series of spectroscopic analyses such as X-ray diffraction (XRD), Fourier transform infrared (FT-IR), optical absorption, electron spin resonance (ESR) spectra, and mass density were carried out to scrutinize these effects. The glass structure was confirmed using XRD. The mass density and molar volume increased in the order of Ca < Sr < Ba, increasing the densification and connectivity of glass network. FT-IR analysis exhibited that the increased number of B O 4 units and decreased number of nonbridging oxygen (NBO) are attributed to the decrease in cation field strength in the order of Ca > Sr > Ba. Optical absorption spectra showed a single optical transition of Co 2 + cations in octahedral sites at ⁓ 502 nm, which is owing to 4 T 1 g (F) → 2 T 1 g H , and two transitions at ⁓ 572 nm and 1577 nm, which are owing to 4 A 2 (4 F) → 4 T 1 4 P and 4 A 2 (4 F) → 4 T 1 g 4 F of Co 2 + cations in tetrahedral sites, respectively. These optical transitions were exploited to evaluate the effect of changing the type of alkaline earth cations using ligand field theory. The crystal field strength (Dq) and inter-electronic repulsion (B and C) suggest that the ionic environment around the cobalt cations increases from Ca to Ba. Finally, ESR spectra indicated that cobalt ions exist in divalent states with more domination of tetrahedral sites than octahedral ones, in good accordance with the increase in mass density, the conversion to tetrahedrally-coordinated boron atoms ( BO 4 ), the decrease in NBOs, and the increase in optical band gap energy. The obtained values of covalency parameter ( K 0 ) increased from 0.833 for Ca, 0.878 for Sr, and 0.893 for Ba confirm the ionic nature. These obtained findings render these glasses a decent contender as optical material in the optics realm. [ABSTRACT FROM AUTHOR]

A facile hydrothermal approach was applied for synthesizing single crystalline Sm vanadate nanowires without any surfactants, and the formation mechanism of the Sm vanadate nanowires was analyzed in detail. The Sm vanadate nanowires possess a tetragonal SmVO4 phase, smooth surface, length of tens of micrometers, and a diameter of 30–100 nm, respectively. The Sm vanadate nanowires can be applied as the electrode materials with excellent electron transfer interface, exhibiting good electrocatalytic performance for Co2+ detection by square wave voltammetry (SWV) technique. A well-defined potential at + 0.60 V exists at the Sm vanadate nanowire–modified electrode in KCl electrolyte with 1 mM Co2+. Electrolyte pH value, deposition time, deposition potential, and standing time are optimized to be pH = 6, 90 s, − 1.5 V, and 60 s, respectively. Sm vanadate nanowire–modified electrode indicates a linear detection range of 0.01–1000 μM, detection limit of 0.23 nM, good stability, reproducibility, and selectivity for Co2+ detection. The Sm vanadate nanowires provide promising electrode materials and are applicable for the detection of Co2+ in real water environment. [ABSTRACT FROM AUTHOR]

Purpose: Due to the multilayered structure of the skin tissue, the architecture of its engineered scaffolds needs to be improved. In the present study, 45s5 bioglass nanoparticles were selected to induce fibroblast proliferation and their protein secretion, although cobalt ions were added to increase their potency. Methods: A 3-layer scaffold was designed as polyurethane (PU) - polycaprolactone (PCL)/ collagen/nanoparticles-PCL/collagen. The scaffolds examined by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), tensile, surface hydrophilicity and weight loss. Biological tests were performed to assess cell survival, adhesion and the pattern of gene expression. Results: The mechanical assay showed the highest young modulus for the scaffold with the doped nanoparticles and the water contact angle of this scaffold after chemical crosslinking of collagen was reduced to 52.34±7.7°. In both assessments, the values were statistically compared to other groups. The weight loss of the corresponding scaffold was the highest value of 82.35±4.3 % due to the alkaline effect of metal ions and indicated significant relations in contrast to the scaffold with non-doped particles and bare one (P value<0.05). Moreover, better cell expansion, greater cell confluence and a lower degree of toxicity were confirmed. The up-regulation of TGF β1 and VEGF genes introduced this scaffold as a better model for the fibroblasts commitment to a new skin tissue among bare and nondoped scaffold (P value<0.05). Conclusion: The 3-layered scaffold which is loaded with cobalt ions-bonded bioglass nanoparticles, is a better substrate for the culture of the fibroblasts. [ABSTRACT FROM AUTHOR]

Sulfate radical (SO4•−)–based advanced oxidation processes (AOPs) from sulfite activation have recently received attention for abatement of microorganic pollutants in the aquatic environments. Trace-level Co(II) has been demonstrated to be effective for promoting sulfite activation (simplified as the Co(II)/sulfite system) and the corresponding radical formation, yet this process is challenged by the limited valence inter-transformation of Co(II)/Co(III). In order to enhance this valence inter-transformation, a novel Co(II)/HPO42−/sulfite system is developed in this work, because HPO42−, as a typical radical scavenging agent, has the advantage of complexing with Co(II) without quenching effect. In this work, complexation of Co(II) with HPO42− can regulate the electronic structure of Co(II), accelerate electron transfer, and promote valence inter-transformation of Co(II)/Co(III) during the sulfite activation process. The Co(II)/HPO42−/sulfite system exhibits superior iohexol abatement performance under circumneutral conditions. For pH 8.0 and Co(II) dose of 1 μM, the iohexol abatement efficiency is as high as 98%, which is considerably higher than that of the Co(II)/sulfite system (50%). SO4•− is identified as the predominant reactive radical contributing to iohexol abatement. The presence of HPO42− broadens the pH adaptability of the Co(II)/sulfite system for iohexol abatement. In addition, the coexisting Cl− exerts an inhibitory effect on iohexol abatement while the other cations and anions show negligible effect. The Co(II)/HPO42−/sulfite system displays good reusability and adaptability towards various organic pollutants. This study highlights the important role of complexation of Co(II) with HPO42− in sulfite activation and provides a feasible idea for abatement of the microorganic pollutants. [ABSTRACT FROM AUTHOR]

This study aimed to utilize synthesized graphene oxide (GO) for adsorptive removal of cobalt ions and investigate the adsorption mechanism using advanced techniques such as X-ray absorption spectra (XAFS). The GO was synthesized via an improved Hummers method, resulting in high surface area (93.7 m2/g) and abundant oxygen-containing functional groups. Various characterizations, including SEM, TEM, Raman, FT-IR, TG, potentiometric titrations, and N2 sorption–desorption measurements, were employed to characterize the GO. The adsorption behavior of GO towards Co2+ was investigated, and the results showed that the adsorption process followed a pseudo-second-order kinetic model and the Langmuir model, with a maximum sorption capacity of 93.7 mg/g. The adsorption process was chemisorption and endothermic, with GO showing adsorption selectivity order of Co2+ > Sr2+ > Cs+. Based on various characterizations such as X-ray absorption near-edge spectroscopy (XANES), extended X-ray absorption fine structure (EXAFS), FT-IR, and XPS, the sorption mechanism of Co2+ onto GO was discussed, with the results indicating that coordination and electrostatic interaction were the primary adsorption mechanisms, with oxygen-containing functional groups playing a vital role. The first coordinating atom for Co2+ was O, and the coordination environment was similar to that of cobalt acetate and CoO. Overall, this study provides comprehensive understanding of the adsorption behavior and mechanism of Co2+ onto GO, highlighting its potential as an effective adsorbent for removing nuclides from aqueous solution. [ABSTRACT FROM AUTHOR]

In this study, activated carbons derived from walnut shells (CA-N) and apple wood (CA-M) were used as adsorbents to remove cobalt(II) and strontium(II) ions from aqueous solutions. The novel materials were obtained using nitric acid (CA-Mox) and nitric acid/urea mixture (CA-Mox-u, CA-Nox-u) as oxidizing agents. The physical–chemical characteristics of activated carbons were determined from nitrogen sorption isotherms, SEM-EDX, FTIR, pH metric titrations, the Boehm titration method and elemental analysis. The results of batch experiments indicate that maximum adsorption can be achieved in broad pH ranges: 4–8 for Co(II) and 4–10 for Sr(II). The maximum adsorption capacities of Co(II) and Sr(II) on oxidized activated carbons at pH = 4 are: CA-Mox, 0.085 and 0.076 mmol/g; CA-Mox-u, 0.056 and 0.041 mmol/g; and CA-Nox-u, 0.041 and 0.034 mmol/g, respectively. The mathematical models (pseudo-first-order, pseudo-second-order and intraparticle diffusion kinetic models, and Langmuir, Freundlich, Dubinin–Radushkevich, and Temkin–Pyzhev isotherm models) were used to explain the adsorption kinetics, to study the adsorption mechanism and predict maximum adsorption capacity of the adsorbents. The adsorption mechanisms of toxic metal ions on activated carbons were proposed. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) are considered potential electrode materials for lithium‐ion batteries (LIBs) in the future because of their structural diversity and high controllability. However, due to poor electrical conductivity and few exposed active sites caused by structural stacking, MOFs material is difficult to use as electrode material directly. Therefore, herein, a new preparation method is proposed. Specifically, vapors containing organic ligands reacted with porous carbon fibers loaded with metal ions under high temperature and pressure to prepare porous carbon nanofibers loaded with nanoscale Co‐MOF particles (Co‐MOF/Pcnf). Compared with the solvothermal method, the gas‐solid reaction method can limit the growth of MOFs to a certain extent. Nanoscale MOFs particles have a larger specific surface area, exposing more active sites. The introduction of porous carbon fibers enhances electrical conductivity. These properties have a positive effect on improving the performance and stability of the corresponding batteries. When used as an anode of LIBs, the Co‐MOF/Pcnf composite exhibits a specific capacity of 1036.9 mAh g−1 after 150 cycles at 0.5 A g−1 and an excellent long‐term cycling capability (820.33 mAh g−1 at 1 A g−1 after 300 cycles). This novel preparation method can provide ideas for future research on electrode materials for MOFs. [ABSTRACT FROM AUTHOR]

This study evaluated nanocellulose derived from discarded palm leaves for its ability to remove cobalt ions from industrial wastewater. The process involved extracting cellulose nanocrystals (CNCs) from date palm leaves through a series of repeated chemical treatments. The study examined the adsorption rates of cobalt ions under various conditions using different techniques. Two equilibrium models, the Langmuir and Freundlich models, were employed, and the Langmuir model was found to be consistent with the experimental data. The maximum amount of cobalt ions adsorbed at room temperature was 5.98 mg/g. Furthermore, several kinetic models were used to gain insight into the adsorption mechanism, including the pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion models. The pseudo-second-order model provided an accurate description of the adsorption process, while the Elovich equation suggested a chemical reaction between cobalt ions and nanocellulose, involving multiple chemical reactions and mass-transfer processes. Kinetic parameters were critical in interpreting the results, and the study's findings were in agreement with the pseudo-second-order and intraparticle models, indicating general chemical reactions and diffusion resistance. [ABSTRACT FROM AUTHOR]

Coal from Aduunchuluun deposit was pre-treated by pyrolysis at 600°C, and semi-coke was activated at 800°C under a steam flow of 2 ml/min for 120 and 240 minutes to obtain activated carbons. The maximum weight loss of activated carbon was 64.7% with relatively high adsorption capacity, i.e. iodine and methylene blue absorption was 615 mg/g and 762 mg/g, surface area was 894 m² /g, respectively. The activity of Fe3+ and Co2+ ion adsorption of activated carbon was investigated depending on the pH of aqueous solution, initial concentration of metal ions, adsorption time and temperature. The removal of Fe3+ ions was 93.2-93.7%, for Co2+ ions was 95.1-95.2%. According to the adsorption isotherms and thermodynamic studies, the adsorption process was leading to the multilayer coverage with the metallic ions on the heterogeneous surfaces )micro- and meso-) of the activated carbons )A3 and A-7) and the adsorption process was spontaneous. [ABSTRACT FROM AUTHOR]

Zirconium oxide nanoparticles (ZrO2NPs) were green synthesized for the first time using an aqueous peppermint extract as a precipitating and capping agent. Addition of the extract to Zr4+ solution was followed by calcination of the resulting precipitate at 570 and 700 °C to form ZrO2NPs570 and ZrO2NPs700, respectively. These oxides were characterized using X-ray diffraction, transmission electron microscopy, and BET surface area analysis, and used as adsorbents for cobalt ions (Co2+) in water. The effects of pH, initial Co2+ concentration, ZrO2NPs mass, and contact time on adsorption efficiency were studied. Characterization results showed formation of cubic ZrO2 with average crystallite sizes (XRD data) of 6.27 and 7.26 nm for ZrO2NPs570 and ZrO2NPs700, respectively. TEM images of the two oxides exhibited nearly spherical nanoparticles and BET surface area measurements indicated the formation of mesoporous oxides having surface areas of 94.8 and 62.4 m2/g, respectively. The results of the adsorption study confirmed that the synthesized ZrO2NPs can be efficiently used for the adsorption of Co2+ from water. The uptake of Co2+ from the treated solution is favored at pH values higher than its point of zero charge (6.0). In addition, the adsorption of Co2+ by ZrO2 follows a pseudo-second order kinetics (R2 = 1.0) and can be explained by the Langmuir adsorption isotherm (R2 = 0.973). [ABSTRACT FROM AUTHOR]

This study investigates the influence of CoO doping on concentration and characteristics of nano-sized cavities in Li₂SO₄-MgO-P₂O₅ glasses using positron annihilation lifetime spectroscopy (PALS). These defects are known to significantly impact the physical properties of glasses. Glasses with compositions of 20 Li₂SO₄-20MgO-(60- x) P₂O₅: x CoO (0 ≤ x ≤ 1.0 mol%), were prepared using melt-quench technique. PALS analysis revealed a strong dependence of positronium (e⁺- e⁻ pair) lifetime on CoO concentration. The analysis of the results further indicated that the fraction of free volume Δ f/f 0) and cavity radius (R) reached minimum values between 0.6 and 0.8 mol% CoO, but increased with further CoO doping. This suggests that cobalt ions prefer O h sites, act as network modifiers, and create a larger concentration of free volume defects when CoO is increased beyond 0.8 mol%. Notably, the PALS-derived free volume defect concentration with CoO concentration is found to follow nearly same trend exhibited by the results of optical absorption and AC conductivity studies. [ABSTRACT FROM AUTHOR]

[Display omitted] • The ionic liquid [HOEmim][NTf 2 ] can strengthen the extraction performance of TBP for Co2+. • The extraction efficiency of TBP/kerosene/[HOEmim][NTf 2 ] system for Co2+ is up to 99.6 %. • DFT calculations and FT-IR analysis indicate that Co2+ mainly binds to P=O in TBP. • A theoretical basis for removing Co2+ from waste water based on ionic liquids was laid. • ABSTRACT In order to achieve effective removal of radioactive Co(II) from the primary circuit wastewater of nuclear power plants and promote the safe use of nuclear energy, an efficient and eco-friendly method using ionic liquid as a co-extractant was proposed. The effects of ionic liquids 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C 2 mim][NTf 2 ]) or 1-(2-hydroxyethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([HOEmim][NTf 2 ]) as co-extractants on the extraction of Co(II) using tributyl phosphate (TBP) as an extractant were investigated in this work. The results reveal that the optimal extraction conditions for Co(II) are as follows: V TBP : V kerosene : V [HOEmim][NTf2] = 18:1:1, R(O/A) = 1, pH=4. Under these conditions, the extraction efficiency of Co(II) (E Co) reaches 99.6 %, with a distribution ratio (D Co) of 257. Notably, a single TBP or ionic liquid exhibits minimal ability to extract Co2+, while adding only 5 % (v/v) ionic liquid based on TBP/kerosene system can increase D Co by 104 times. The slope method and FT-IR analysis demonstrate that the TBP/kerosene/[HOEmim][NTf 2 ]/ system extracted Co2+ by a cation exchange mechanism. In addition, density functional theory (DFT) calculations were employed to explain the influence of different ionic liquid systems on the E Co , and further elucidate the extraction mechanism of Co2+. The striping results indicate that 92.2 % of Co2+ is stripped with 1.0 mol L−1 HNO 3. The extraction efficiency of Co(II) from the TBP/kerosene/[HOEmim][NTf 2 ] system remained at 98 % after 6 cycles. Therefore, the extraction system exhibits great practical potential in removing Co(II) from contaminated water. This work not only proposes an extraction system with excellent reusability and stability, but also lays a theoretical foundation for the ionic liquid-based cobalt extraction process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesis of PEDOT in aqueous solutions by chronoamperometry. • Cobalt incorporation inside PEDOT by cyclic voltammetry. • Activation of inserted cobalt by lithium incorporation. • PEDOT(aCo) characterization by hyphenated techniques. Cobalt ions were inserted into poly(3,4-ethylenedioxythiophene) by cyclic voltammetry in a 0.1 M C o N O 3 2 aqueous solution (PEDOT(Co)). After activation of the inserted cobalt, the PEDOT(aCo) system was investigated by cyclic voltammetry, digital video electrochemistry, spectroelectrogravimetry, and coupled impedance techniques (ac-electrogravimetry) to elucidate the key role of inserted cobalt ions in the altered electrochemistry of PEDOT. The incorporation of C o 2 + involves slow transfer of cations for charge compensation during Co 2 + ⇄ Co 3 + conversion inside the PEDOT. This fact explains the enhanced charge storage showed by PEDOT(aCo) compared with pristine PEDOT at similar potentials. Finally, the stability of PEDOT(aCo) was investigated by cyclic voltammetry measuring at the same time current, mass and motional resistance variation during 100 cycles offering high stability at all times. [ABSTRACT FROM AUTHOR]

Heavy metals that enter the environment due to natural processes or industrial activities, when accumulated, have a negative impact on organisms, including microorganisms. Microorganisms have developed various adaptations to heavy metal compounds. The aim of our work was to investigate the influence of ferric citrate and cobalt (II) chloride on biomass accumulation, indicators of free radical damage and activity of enzymes of the antioxidant defense system of bacteria Rhodopseudomonas yavorovii IMV B-7620, that were isolated from the water of Yavorivske Lake (Ukraine, Lviv region), which was formed as a result of flooding of a sulfur quarry. We used cultural, photometric methods, and statistical processing of the results was performed using two-way ANOVA and factor analysis. It was found that ferric citrate at a concentration of 1–12 mM causes inhibition of the accumulation of biomass of bacteria Rh. yavorovii IMV B-7620 up to 44.7%, and cobalt (II) chloride at a concentration of 1–15 mM – up to 70.4%, compared with the control. The studied concentrations of ferric citrate and cobalt (II) chloride cause free radical damage to lipids and proteins of Rh. yavorovii IMV B-7620. As a result of two-way ANOVA we found that under the influence of ferric citrate statistically significant changes in biomass accumulation, lipid hydroperoxides and thiobarbiturate reactive species content, superoxide dismutase activity were predetermined by increasing the concentration of metal salts as well as increasing the duration of cultivation of bacteria, while the content of diene conjugates and catalase activity changed with increasing duration of cultivation. Under the influence of cobalt (II) chloride, statistically significant changes in all studied indicators were found both due to the increase in the concentration of metal salts and with increasing duration of bacterial cultivation. The studied parameters of Rh. yavorovii IMV B-7620 cells under the influence of ferric citrate and cobalt (II) chloride are combined into two factors, that explain 95.4% and 99.2% of the total data variance, respectively. Under the influence of ferric citrate, the first latent factor included diene conjugates, thiobarbiturate reactive species, carbonyl groups in proteins, which are closely linked by a direct bond and inversely related to the content of lipid hydroperoxides and catalase activity. The second latent factor included duration of cultivation of bacteria, biomass accumulation, and superoxide dismutase activity, which are inversely related to lipid hydroperoxide content and catalase activity. Under the influence of cobalt (II) chloride, the first latent factor included the content of lipid hydroperoxides, carbonyl groups in proteins, as well as catalase and superoxide dismutase activities, which are inversely related to bacterial biomass.

Using Ag-coated Au nanobipyramids as a sacrificial template, a novel and exquisite morphologically adjustable Au@AuAg yolk-shell heterogeneous nanostructure with asymmetrical pyramidal core is prepared. And this nanostructure is used as multi-information spectral sensor to sensitively detect Co2+ based on shell etching. [Display omitted] In this paper, a novel Au@AuAg yolk-shell heterogeneous nanostructure is designed as plasmonic spectroscopic sensor based on surface etching for ultrasensitive detection of trace cobalt ions (Co2+). Due to the surface diffusion of gold atoms, the Ag at one end of the core gold nanobipyramids (Au NBPs) is retained, and Au@AuAg yolk-shell nanostructure with asymmetric core is prepared. The alloy shell is coupled to Au NBPs and the interface of asymmetric Ag respectively, the two local surface plasmon resonance bands will have obvious reverse changes depending on the surface morphology of the shell. By using this distinct plasmon response generated by Co2+ induced surface etching, which is driven by discrepancy of double-peaks, a sensing method has been established to realize multi-information spectral detection of Co2+. There is a good linear relationship between the intensity ratio and the Co2+ concentration in the range of 1–100 nM, in which the limit of detection is 0.2 nM. This method further improves the sensing capability by combining multiple pieces of strongly changing spectral information, and demonstrates great advantages and potential of Au@AuAg yolk-shell heterogeneous nanostructure as a multi-information plasmonic sensor based on etched shell surface for trace detection. [ABSTRACT FROM AUTHOR]

In this study, activated carbons derived from walnut shells (CA-N) and apple wood (CA-M) were used as adsorbents to remove cobalt(II) and strontium(II) ions from aqueous solutions. The novel materials were obtained using nitric acid (CA-Mox) and nitric acid/urea mixture (CA-Mox-u, CA-Nox-u) as oxidizing agents. The physical–chemical characteristics of activated carbons were determined from nitrogen sorption isotherms, SEM-EDX, FTIR, pH metric titrations, the Boehm titration method and elemental analysis. The results of batch experiments indicate that maximum adsorption can be achieved in broad pH ranges: 4–8 for Co(II) and 4–10 for Sr(II). The maximum adsorption capacities of Co(II) and Sr(II) on oxidized activated carbons at pH = 4 are: CA-Mox, 0.085 and 0.076 mmol/g; CA-Mox-u, 0.056 and 0.041 mmol/g; and CA-Nox-u, 0.041 and 0.034 mmol/g, respectively. The mathematical models (pseudo-first-order, pseudo-second-order and intraparticle diffusion kinetic models, and Langmuir, Freundlich, Dubinin–Radushkevich, and Temkin–Pyzhev isotherm models) were used to explain the adsorption kinetics, to study the adsorption mechanism and predict maximum adsorption capacity of the adsorbents. The adsorption mechanisms of toxic metal ions on activated carbons were proposed.

Photochemical vapor generation (PVG) of germanium (Ge) was first reported in this work. The synergistic effect from cobalt/chloride ions and air-liquid interfaces was found for the PVG of Ge. No obvious signal response was observed from the standard solution of Ge in 10% (v/v) formic acids (FAs) under UV irradiation. The addition of 300 mg L−1 of Co2+ and 30 mmol L−1 of Cl− resulted in enhanced photochemical reduction for Ge, and the introduction of air-liquid interfaces proceeding and succeeding the sample solution caused another 4.6 folds of enhancement in signal response of Ge. Under the selected condition, the limit of detection (LOD, 3σ, n = 11) was obtained to be 0.008 ng mL−1 with inductively coupled plasma mass spectrometry (ICP MS) measurement. A good precision, expressed as a relative standard deviation (RSD, n = 7) of 2.0%, was found from replicated measurements of 2 ng mL−1 of Ge. The generation efficiency was found to be no better than 9 ± 2%. The PVG mechanism of Ge was investigated in this work. The new finding is useful for understanding the principle of PVG, and further exploring the analytical and environmental application of PVG. [ABSTRACT FROM AUTHOR]

This study evaluated nanocellulose derived from discarded palm leaves for its ability to remove cobalt ions from industrial wastewater. The process involved extracting cellulose nanocrystals (CNCs) from date palm leaves through a series of repeated chemical treatments. The study examined the adsorption rates of cobalt ions under various conditions using different techniques. Two equilibrium models, the Langmuir and Freundlich models, were employed, and the Langmuir model was found to be consistent with the experimental data. The maximum amount of cobalt ions adsorbed at room temperature was 5.98 mg/g. Furthermore, several kinetic models were used to gain insight into the adsorption mechanism, including the pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion models. The pseudo-second-order model provided an accurate description of the adsorption process, while the Elovich equation suggested a chemical reaction between cobalt ions and nanocellulose, involving multiple chemical reactions and mass-transfer processes. Kinetic parameters were critical in interpreting the results, and the study’s findings were in agreement with the pseudo-second-order and intraparticle models, indicating general chemical reactions and diffusion resistance.

Benzotriazole UV stabilizers (BUVs) have gained popularity, due to their absorption properties in the near UV range (200–400 nm). They are used in the technology for manufacturing plastics, protective coatings, and cosmetics, to protect against the destructive influence of UV radiation. These compounds are highly resistant to biological and chemical degradation. As a result of insufficient treatment by sewage treatment plants, they accumulate in the environment and in the tissues of living organisms. BUVs have adverse effects on living organisms. This work presents the use of peracetic acid in combination with d-electron metal ions (Fe2+, Co2+), for the chemical oxidation of five UV filters from the benzotriazole group: 2-(2-hydroxy-5-methylphenyl)benzotriazole (UV-P), 2-tert-butyl-6-(5-chloro-2H-benzotriazol-2-yl)-4-methylphenol (UV-326), 2,4-di-tert-butyl-6-(5-chloro-2H-benzotriazol-2-yl)phenol (UV-327), 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (UV-328), and 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol (UV-329). The oxidation procedure has been optimized based on the design of experiments (DoE) methodology. The oxidation of benzotriazoles follows first order kinetics. The oxidation products of each benzotriazole were investigated, and the oxidation mechanisms of the tested compounds were proposed. [ABSTRACT FROM AUTHOR]

The use of raw white eggshells (WES) as a catalyst, and promoted WES with acetic acid as a promoted catalyst for study the adsorption of cobalt (CO+2) and lithium (Li+) ions from polluted soils was investigated in this paper. The selection of a treated chemical substance was achieved after performing several experiments under controlled laboratory conditions using three chemical substances covering different range of pH: acidity (acetic acid), neutral (potassium iodide), and alkalinity (baking soda) media to determine the optimal conditions for improving CO+2 and Li+ recovery from soil contaminated samples. Several operating factors were examined in order to detect their corresponding effects on the catalyst behavior. These factors were: pH, incubation time, the initial concentration of CO+2 and Li+ ions, the dose of the WES, and the ambient temperature. The maximum adsorption efficiency of CO+2 and Li+ions were 94 and 85% for promoted WES at the incubation time of 21 and 7 days, pH of 5 and 4, temperature of 50 and 45 °C, and WES dose of 2.5 and 3 g, respectively. A regression equation was developed to investigate the removable percentage for both pollutants at different dosage of ordinary WES. This method introduces an innovative idea for promoting the process of remediation of light and heavy metals using a low-cost adsorbent under controlled laboratory conditions.

In the present study, an adsorption method exploiting synthetic and natural adsorbents was utilized for removing cobalt ions from aqueous solutions. First, the nanocomposite synthetic adsorbent containing Fe3O4 magnetic particles stabilized by cetyltrimethylammonium bromide (CTAB) was synthesized and then, the sample was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen adsorption and desorption isotherms (BET). The impacts of various operating parameters (adsorbate concentration, pH, adsorbent dose, contact time, and stirring speed) were also investigated. The results indicated that the pseudo-second order kinetic model can well fit the experimental values of cobalt ion removal from aqueous solution for both adsorbents. Gibbs free energy, enthalpy and entropy were also calculated which revealed that the adsorption behavior for both adsorbents is chemical, endothermic and spontaneous. Moreover, the equilibrium data were fitted with Langmuir, Freundlich, Temkin and Dubinin-Radushkevich equilibrium isotherms. Accordingly, CO2+ adsorption on both nanocomposite and Typha latifolia L. followed the Langmuir isotherm model. The maximum amount of the cobalt ion removal by nanocomposite and Typha latifolia L. adsorbents was evaluated to be 196.07 and 107.52 mg/g of adsorbent, respectively. [ABSTRACT FROM AUTHOR]

Zirconium oxide nanoparticles (ZrO2NPs) were green synthesized for the first time using an aqueous peppermint extract as a precipitating and capping agent. Addition of the extract to Zr4+ solution was followed by calcination of the resulting precipitate at 570 and 700 °C to form ZrO2NPs570 and ZrO2NPs700, respectively. These oxides were characterized using X-ray diffraction, transmission electron microscopy, and BET surface area analysis, and used as adsorbents for cobalt ions (Co2+) in water. The effects of pH, initial Co2+ concentration, ZrO2NPs mass, and contact time on adsorption efficiency were studied. Characterization results showed formation of cubic ZrO2 with average crystallite sizes (XRD data) of 6.27 and 7.26 nm for ZrO2NPs570 and ZrO2NPs700, respectively. TEM images of the two oxides exhibited nearly spherical nanoparticles and BET surface area measurements indicated the formation of mesoporous oxides having surface areas of 94.8 and 62.4 m2/g, respectively. The results of the adsorption study confirmed that the synthesized ZrO2NPs can be efficiently used for the adsorption of Co2+ from water. The uptake of Co2+ from the treated solution is favored at pH values higher than its point of zero charge (6.0). In addition, the adsorption of Co2+ by ZrO2 follows a pseudo-second order kinetics (R2 = 1.0) and can be explained by the Langmuir adsorption isotherm (R2 = 0.973).

The adsorption of cobalt ions was evaluated using sediment samples from water bodies to investigate the adsorption properties of sediment and the behavior of these natural materials in the presence of nuclear and industrial waste. The two sediments (S1 and S2) were treated to eliminate humic and fulvic acids and then they were characterized by several techniques. The minerals found in both the sediments (X-ray diffraction) were quartz and albite; plus, goethite and muscovite in S1, and kaolinite and montmorillonite in S2. Point of zero charge (PZC) of S1 and S2 was 6.00 and 5.22, respectively. The specific area of S1 (63.3 m2/g) is higher than S2 (1.5 m2/g). Adsorption kinetics data for S1 and S2 were best fitted to the pseudo second-order model. The removal efficiency of S1 for cobalt was 96% with an adsorption capacity (q e) of 0.93 mg/g, and for S2 was 45% with a q e of 0.40 mg/g. The experimental data of the adsorption isotherms were adjusted to Langmuir and Freundlich models for S1 and S2, respectively. The thermodynamic parameters (enthalpy, entropy, and Gibb's free energy) indicated that the adsorption processes were endothermic, spontaneous, and chemisorption mechanism. The results show that the adsorption capacities of the sediments depend on their composition. These water sediments have important adsorption properties for cobalt, and they can be used in the treatment of nuclear and industrial aqueous wastes. [ABSTRACT FROM AUTHOR]

In this research, batch adsorption of cobalt ions (Co(II)) from wastewater onto NaOH-treated rice husk (TRH) was studied at room temperature. Several techniques such as Fourier transform infrared, scanning electron microscopy, and energy diffraction X-rays were used to prove adsorption of Co(II) onto TRH. The percentage discharge of Co(II) was increased with the contact time, amount of TRH, and temperature whereas decreased with an initial concentration of Co(II) solution. Nonlinear isotherms such as Langmuir, Freundlich, and Dubinin–Radushkevich were utilized to study experimental data for adsorption of Co(II) onto TRH. Results showed that experimental data fitted well to nonlinear isotherms. The value of Langmuir constant Qm was 9.35 × 10–5 mol/g. Adsorption kinetics was studied by using pseudo-first-order model, pseudo-second-order model, Elovich model, liquid film diffusion model, modified Freundlich equation, and Bangham equation. Results exhibited that experimental data for adsorption of Co(II) fitted well to pseudo-second-order model having k2 numerical value of 0.45 g/mg min. Thermodynamic analysis revealed that adsorption of Co(II) from wastewater was endothermic with a change in enthalpy (ΔH°) value of 15.406 kJ/mol and spontaneous process. Desorption of Co(II) from TRH was also investigated. Hence, TRH could be used as an excellent adsorbent for the discharge of Co(II) from wastewater. [ABSTRACT FROM AUTHOR]

A novel fluorometric method based on bipyridine-linked three-dimensional covalent organic frameworks (COFs) was developed for the determination of Co2+. The COFs were synthesized by the polyreaction of tetrakis(4-aminophenyl)methane (TAPM), 2,2′-bipyridine-5,5′-diamine (Bpy), and 4,4′-biphenyldicarboxaldehyde (BPDA) under solvothermal conditions. The fluorescence of the COFs, with excitation/emission peaks at 324/406 nm, is quenched by Co2+. Under the optimal conditions, the fluorescence quenching degrees (F0–F) of the resulted COFs linearly enhance as the concentrations of Co2+ increase in the range 0.01 to 0.25 μM, and a limit of detection of 2.63 nM is achieved. The fluorescence response mechanism was discussed in detail. This proposed approach has also been successfully employed to determine Co2+ in complex samples (shrimp and tap water), and satisfactory recoveries (88.1 ~ 109.7%) was obtained. The relative standard deviations are below 4.9%. [ABSTRACT FROM AUTHOR]

Benzotriazole UV stabilizers (BUVs) have gained popularity, due to their absorption properties in the near UV range (200–400 nm). They are used in the technology for manufacturing plastics, protective coatings, and cosmetics, to protect against the destructive influence of UV radiation. These compounds are highly resistant to biological and chemical degradation. As a result of insufficient treatment by sewage treatment plants, they accumulate in the environment and in the tissues of living organisms. BUVs have adverse effects on living organisms. This work presents the use of peracetic acid in combination with d-electron metal ions (Fe2+, Co2+), for the chemical oxidation of five UV filters from the benzotriazole group: 2-(2-hydroxy-5-methylphenyl)benzotriazole (UV-P), 2-tert-butyl-6-(5-chloro-2H-benzotriazol-2-yl)-4-methylphenol (UV-326), 2,4-di-tert-butyl-6-(5-chloro-2H-benzotriazol-2-yl)phenol (UV-327), 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (UV-328), and 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol (UV-329). The oxidation procedure has been optimized based on the design of experiments (DoE) methodology. The oxidation of benzotriazoles follows first order kinetics. The oxidation products of each benzotriazole were investigated, and the oxidation mechanisms of the tested compounds were proposed.

Conditions were determined for the formation of a ternary complex of polyethylenimine with copper and cobalt ions, ensuring the predominant binding of the metal ions with the macromolecule of the polyethylenimine stabilizer. Metal particles were prepared under the conditions of different binding of metal ions with the stabilizer. The reduction of cobalt and copper ions in the presence of polyethylenimine yields Cu and Co metal nanoparticles irrespective of the mode of metal ion binding with the stabilizer. The metal particles obtained using the preliminarily prepared ternary complex of polyethylenimine with Cu2+ and Co2+ ions have approximately spherical shape and smaller characteristic size compared to the particles prepared without this complex. In the latter case, the particles are anisometric aggregates elongated in one direction. [ABSTRACT FROM AUTHOR]

Cultivation of Azotobacter vinelandii D-08 in media with molasses and distillery waste was shown to increase levansaccharase activity and levan biosynthesis. Levansaccharase also exhibited maximal activity when grown in a molasses medium, which correlated with the highest level of the polysaccharide synthesis. An additional fraction of high molecular weight levan (more than 1000 kDa) with a modified molecular structure (reduced contribution of double bond oscillations and decreased molecule hydration) was synthesized by bacteria, which resulted in a higher capacity for the binding of Na, Mg, S, Ca, and Fe in the cultivation medium. Cryogels based on polyvinyl alcohol and levan were capable of efficient maximal absorption of different ions at different times: copper (1 h), zinc (24 h), and cadmium (10 min), radioactive plutonium (4 h), and uranium (168 h). This suggests that they can be used as sorbents for wastewater treatment to eliminate heavy metals and radionuclides. [ABSTRACT FROM AUTHOR]

This work continues a series of studies devoted to complex formation of ions of biogenic metals with the flavonoid dihydroquercetin (DHQ). The interaction of Со2+ ions with DHQ in aqueous solutions has been investigated. It has been found that, at different pH of a solution, complex compounds (CC) with different stoichiometry are formed; a variation of the pH value of a solution from 6.0 to 7.0 results in the formation of compounds (1)–(3) with the metal : flavonoid ligand ratio (Met : L) from 1 : 2 at рН 6.0 (1), through 2 : 3 at pH 6.4–6.7 (2), to 1 : 1 at рН 6.8–7.0 (3). By using the thermogravimetric method and the data of the elemental analysis, the most probable composition of the compounds with the determination of the amount of bound water has been proposed: [CoL2(H2O)4] for (1), [Co2L3(ОН)(H2O)4] for (2), and [CoL(ОН)(H2O)2] for (3). Conditions for the optimization of product yield in the complexation reaction of Со2+ ions with DHQ in an aqueous solution have been determined for compound (2): the рН value of solution 6.7; the reaction time 15 min; the temperature of the reaction solution 90°С; the molar ratio of the initial reagents DHQ : Со2+ 1 : 1.5; the initial concentration of DHQ 0.020 mol/L and that of Со2+ 0.030 mol/L; and the use of CoSO4 ⋅ 7H2O as a source of cobalt ions. The yield of the product is 81.8%. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Fuzhou University is the property of Journal of Fuzhou University, Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The immobilization effect of 1 and 3 mass % of Ni2+ or Co2+ ions on the hydration reaction of ordinary Portland cement (OPC) and ordinary Portland cement blended with 5 and 15 mass % pumice was investigated. This was done by studying the bulk density, total porosity, compressive strength as well as identifying the phase composition of the formed hydrates using X-ray diffraction (XRD) technique. In addition, leaching behaviour of Ni2+ and Co2+ ions was examined up to 90 days using static leaching technique. The results indicated that the incorporation of these ions causes a notable retardation for the early hydration of the OPC. This effect is more noticeable in presence cobalt ions. Besides, the retarding effect was increased by increasing the percentage of heavy metal ions incorporated in the hydrated matrix. However, for OPC-pumice blended cement pastes, the existence of Ni2+ or Co2+ ions resulted in an enhancement in the compressive strength values during the hydration period from 3-28 days to be comparable with the values of neat OPC pastes. This enhancement is attributed to the interaction of these ions with pumice which increases the heavy metal fixation.

This work presents facile preparation processes of multiphosphonic acid functionalised multi‐walled carbon nanotubes (HEDP‐MWCNTs and ATMP‐MWCNTs), which have been characterised by FT‐IR, XPS, X‐ray diffraction, TGA, and SEM, and have employed for heavy metal ions adsorption. The adsorption properties of MWCNTs, HEDP‐MWCNTs, and ATMP‐MWCNTs for gold ions, cadmium ions, copper ions, lead ions, nickel ions, cobalt ions, zinc ions, and chromium ions have been investigated, the experimental results reveal that the functionalised samples HEDP‐MWCNTs and ATMP‐MWCNTs have excellent adsorption properties for Pb(II) and Au(III), respectively. The investigation results on their adsorption selectivity represent that in the binary heavy metal ion systems, HEDP‐MWCNTs/ATMP‐MWCNTs has displayed a strong affinity for Pb(II)/Au(III) and even could exhibit 100% selectivity while coexisting with copper ions, nickel ions, cobalt ions, zinc ions, chromium ions, or cadmium ions. Furthermore, the adsorption kinetics of HEDP‐MWCNTs for Pb(II) and ATMP‐MWCNTs for Au(III) have also been studied at different solution temperatures. All these research work results show that two novel functionalised adsorbents HEDP‐MWCNTs and ATMP‐MWCNTs have shown excellent adsorption properties for heavy metal ions and they can be used in wastewater treatment, especially for lead/gold ions removal. [ABSTRACT FROM AUTHOR]

An easy and quick spectrophotometric method was developed and employed for detection and quantification of cobalt using ammonium pyrollidine dithiocarbamate (APDC) in presence of anionic surfactant sodium dodecyl sulfate aqueous micellar solution. The cobalt forms bis(ammonium pyrollidine dithiocarbamato) cobalt complex reacting with ammonium pyrollidine dithiocarbamate. The prepared complex was used for the detection of Co(II) ions spectrophotometrically in different types of samples of practical nature and developed methods shows high sensitivity and selectivity toward Co(II) ions and the coefficient of molar absorption (ε) and Sandell's sensitivity were 2.35 × 104 L mol−1 cm−1 and 2.73 ng/cm2 at λmax 322.2 nm, respectively. A linear relationship with concentration was observed in the range of 0.12–4.0 μg/ml and 1:2 metal to ligand ratio was found best for the complex Co–[APDC]2 formation. Using developed material and method, cobalt ions in pharmaceutical, tap water and reference material was recovered up to 99.81, 99.0, and 99.14 (%), respectively. The developed methods has potential for Co(II) estimation and could possibly be used for Co(II) quantification in practical samples. [ABSTRACT FROM AUTHOR]

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[Display omitted] • A facile and eco-friendly approach was developed for preparing CuNCs without hyperpyrexia. • The synthesis strategy endowed CuNCs with prominently enhanced stability. • PEI-CuNCs could realize Co2+ sensing specifically in living cells in neutral condition. • The colorimetric detection of Co2+ was realized with a handily paper strip. • PEI-CuNCs could act as reversible response thermometers. Excessive uptake of Co2+ is harmful to one's physical health and should not be ignored. Herein, a polyethylenimine (PEI) protected hydrophilic copper nanoclusters (PEI-CuNCs) with strong green fluorescence emission around 510 nm was apace synthesized employing a one-pot method without hyperthermia. Interestingly, the as-prepared water-soluble PEI-CuNCs can be specifically quenched by Co2+ at pH 6.0, with a wide detection range (0–500 μM) and a sensitive detection limit of 14.9 nM, which was lower than the maximum level in the body. Besides, the colorimetric detection of Co2+ could be additionally realized based upon the typical yellow color of PEI-CuNCs changed to baby-pink color of the PEI-Co2+ complex. Furthermore, the PEI-CuNCs was employed in fabrication portable test strip for visual detection of Co2+ by capturing the change in fluorescence color, which can be ascribed to the coordination interaction between Co2+ and amine groups in PEI, and also the aggregated quenching of large PEI-CuNCs-Co2+ particles formation. Moreover, the PEI-CuNCs displayed excellent reversible thermo-responsive within a temperature range of 20–65 °C. It is worth mentioning that the PEI-CuNCs exhibited low bio-toxicity and excellent cell permeability when selectively detecting Co2+ in living cells by fluorescence microscopy imaging. Armed with these engaging properties, the sensing system paved a new avenue for the effective development of a convenient fluorescence colorimetry sensor for general assessment of potential risks and specific assessment of human security. [ABSTRACT FROM AUTHOR]

Gd vanadate nanowires were synthesized by a facile one-step hydrothermal route and characterized by X-ray diffraction, electron microscopy and X-ray photoelectron spectroscopy. The obtained nanowires consist of single crystalline tetragonal GdVO 4 phase. The length and diameter of the nanowires with smooth surface are longer than 20 µm and 20–100 nm, respectively. The formation mechanism of the Gd vanadate nanowires was analyzed by the structural and morphological evolution of the intermediates obtained from various conditions. The Gd vanadate nanowires modified glassy carbon electrode (GCE) shows fast electron transfer and efficient electro-catalytic behaviour between Co2+ and Gd vanadate nanowires modified electrode. By square wave voltammetry (SWV) technique, the electrochemical detection of Co2+ using the Gd vanadate nanowires modified electrode was investigated. The buffer solution pH value, deposition time, deposition potential and standing time were optimized to be pH = 6, 60 s, −1.5 V and 30 s, respectively. A linear working range of 0.01–1000 μM was established between the anodic current and Co2+ concentration with the detection limit of 0.32 nM. Under optimized measurement parameters, the proposed Gd vanadate nanowires modified GCE demonstrates low detection limit, wide linear range, good stability, repeatability, selectivity and reproducibility for Co2+ detection. The Gd vanadate nanowires modified electrode shows promising application potential for Co2+ detection in real samples. [Display omitted] • Gd vanadate nanowires were synthesized by a facile one-step hydrothermal route. • The morphology and size of the Gd vanadate nanowires can be adjusted by controlling the growth conditions. • Gd vanadate nanowires can be used as the electrode materials for monitoring Co2+ ions. [ABSTRACT FROM AUTHOR]

We used the gill (Na+, K+)-ATPase as a molecular marker to provide a comprehensive kinetic analysis of the effects of Co2+ in vitro on the modulation of K+-phosphatase activity in the Blue crab Callinectes danae. Co2+ can stimulate or inhibit K+-phosphatase activity. With Mg2+, K+-phosphatase activity is almost completely inhibited by Co2+. Co2+ stimulates K+-phosphatase activity similarly to Mg2+ although with a ≈4.5-fold greater affinity. At saturating Mg2+ concentrations, Mg2+ displaces bound Co2+ from the Mg2+-binding site in a concentration dependent manner, but Co2+ cannot displace Mg2+ from its binding site even at millimolar concentrations. Saturation by Co2+ of the Mg2+ binding site does not affect p NPP recognition by the enzyme. Substitution of Mg2+ by Co2+ slightly increases enzyme affinity for K+ and NH 4 +. Independently of Mg2+, inhibition by ouabain or sodium ions is unaffected by Co2+. Investigation of gill (Na+, K+)-ATPase K+-phosphatase activity provides a reliable tool to examine the kinetic effects of Co2+ with and without Na+ and ATP. Given that the toxic effects of Co2+ at the molecular level are poorly understood, these findings advance our knowledge of the mechanism of action of Co2+ on the crustacean gill (Na+, K+)-ATPase. [Display omitted] • Without Mg2+, cobalt ions stimulate gill (Na+, K+)-ATPase activity. • Co2+ has a 4.5-fold greater affinity for the gill (Na+, K+)-ATPase than does Mg2+. • Mg2+ displaces Co2+ from the Mg2+-binding site in a concentration dependent manner. • Inhibition by ouabain with Co2+ or Mg2+ is identical. • Saturation by Co2+ of Mg2+-binding sites does not affect substrate recognition. [ABSTRACT FROM AUTHOR]