Transition Metal Chemistry最新文献

This study employed the ball milling process to successfully craft nanostructures of Cu-doped ZnO/SnO₂ (ZOSn/Cu), which were thoroughly characterized through various methods. The X-ray diffraction (XRD) analysis revealed the presence of the Zn₂SnO₄ cubic spinel phase in the nanostructure samples, along with diffraction peaks corresponding to ZnO or SnO₂ phases. Notably, the photocatalytic degradation performance of the structured catalysts was greatly improved compared to undoped ZOSn/Cu nanostructures, achieving MB elimination rates of 60% and 80% after 120 min of irradiation, with an overall degradation of approximately 90%. The ZOSn/Cu electrode, designed for energy storage, demonstrated superior performance, boasting a specific capacitance of 380.0 Fg⁻¹, outperforming the pure ZOSn/Cu electrode. Its trimetallic composition of zinc, copper, and tin contributed to enhanced electrochemical properties. This electrode demonstrated excellent cyclic stability, maintaining around 90% of its capacity, along with key characteristics like corrosion resistance, high conductivity, and a wealth of active sites. These properties make it highly promising for advanced energy storage applications.

This research offers substantial insights into improving the hydrometallurgical processing of nickel ores, with a particular emphasis on minimizing impurities to meet the demands of modern industries, such as electric vehicle battery manufacturing. The study focuses on optimizing iron (Fe) removal from nickel laterite ore pregnant leach solution (PLS) using Response Surface Methodology (RSM), examining key variables including agitation speed, precipitation temperature, and precipitation duration. Employing a two-stage precipitation process with calcium carbonate (CaCO₃), this research concentrates specifically on second-stage Fe removal. This stage aimed to maximize Fe²⁺ removal efficiency while minimizing losses of valuable metals. Experimental results indicated an optimal Fe removal efficiency of 10.93% during the second stage and achieved under conditions of 450 rpm agitation, 90 min of precipitation, and a temperature of 90 °C, yielding a total Fe removal rate of 98.74%. Kinetic analysis across first-, second-, and third-order models suggests that the third-order model exhibits the highest R²; however, similar R² values across models prevented conclusive determination of the reaction order. The activation energy (Ea) derived from this study is 12.99 kJ/mol, indicating energy-efficient Fe precipitation. Characterization of the precipitate via X-ray fluorescence (XRF) and X-ray diffraction (XRD) confirmed hematite (Fe₂O₃) and goethite (FeOOH) as primary Fe compounds, along with calcium sulfate (CaSO₄), which may hydrate to form gypsum. These findings provide valuable insights into optimizing Fe removal in nickel laterite ore processing, demonstrating high Fe removal efficiency under controlled operational parameters.

In this work, one new heterometallic Cu(II)/Na(I) 3D coordination polymer [CuNa(Hhpmet)(H₂O)(OH)]_n (1) has been synthesized by using the Schiff base ligand namely, 2-[(E)-(2-hydroxyphenyl)methyleneamino]terephthalic acid [H₃hpmet], Cu(NO₃)₂.6H₂O and NaOH. Complex 1 was characterized by elemental analysis, FT-IR, UV–Vis, NMR spectroscopic measurements along with and single-crystal X-ray diffraction study. The single-crystal X-ray diffraction (XRD) analysis reveals that in complex 1, the copper (II) adopts a distorted square pyramidal geometry with the addition index parameter (τ) value 0.018 whereas Na(I) center possess tetrahedral geometry. Here, DFT study was carried out to give insight in HOMO–LUMO energy gap, MEP surface and topology analysis whereas Hirshfeld surface (HS) study further points toward packing interactions. In addition, complex 1 was investigated for its antibacterial efficacy toward Gram-positive and Gram-negative strains. Molecular docking assessed antibacterial potency of the complex 1 toward protein molecules.

Graphical Abstract

One new heterometallic Cu(II)/Na(I) 3D coordination polymer [CuNa(Hhpmet)(H₂O)(OH)]_n (1) has been synthesized and characterized. Complex 1 was characterized by elemental analysis, FT-IR, UV–Vis spectroscopic measurements and single-crystal X-ray diffraction study. The X-ray diffraction (XRD) analysis reveals that in complex 1, the copper (II) and Na(I) centers adopt a distorted square pyramidal and tetrahedral coordination geometry, respectively. The existence of vibrational structural distortion and intermolecular non-covalent interactions in complex 1 is well explained on the basis of Hirshfeld surface (HS) analysis. The high chemical reactivity of complex 1 was due to its very small HOMO–LUMO energy gap calculated by using density functional theory.

Researchers are increasingly studying and practicing advanced oxidation processes (AOPs) for micropollutant abatement in drinking water treatment and potable water reuse. This study conducted the comparison of the UV/chlorine, Fe (II)/UV/Chlorine, and Cu (II)/UV/Chlorine processes for the degradation of Ponceau S azo dye aqueous solution. The experimental study shows an enhancement in the degradation rate of PS dye in which complete degradation was obtained at 10 min reaction time when Fe²⁺ and Cu²⁺ were added to the solution. This improvement is due to catalyzing HOCl by ferrous and copper ions.

Using the density functional theory (DFT) with the hybrid method B3LYP by 6–311 + G(d,p) basis set, all theoretical calculations and optimum geometric parameters have been computed. We are able to identify Ponceau's electronic and energetic actions thanks to this investigation. Natural population analysis (NPA) and the Mulliken population method have both been researched. The parr function has been used to study the molecule's ({P}_{k}^{-}) and ({P}_{k}^{+}) local reactivity. To visualize the charge transfer between the lone pairs and localized bonds, natural bond orbital (NBO) analysis is performed. DFT is also used to examine molecular electrostatic potential (MEP) and to describe orbital hybridization. The study's findings suggest that both processes are viable for dye removal in water treatment, though further optimization of operating conditions, such as pH and metal ion concentration, could further improve performance.

Zirconium oxychloride (ZOC) is a valuable derivative product of zircon sand processing extensively used in applications such as ceramics, antiperspirants, and electronic components. However, challenges in ZOC synthesis arise from the limited data on the kinetics of critical processes, particularly acid leaching and high radioactivity in the final product. This study addresses these issues by evaluating the kinetics of the leaching process and synthesizing low-TENORM ZOC. The ZOC synthesis involves vital steps, including alkaline fusion, decantation, acid leaching, centrifugation, and crystallization. The results indicated that increasing the temperature and leaching duration improved the recovery, reaching a maximum of 78.06% at 90 °C for 120 min. An ash layer diffusion model best described the leaching process with an apparent activation energy (Ea) of 15.3922 kJ/mol, indicating a diffusion-controlled mechanism. Furthermore, the study successfully synthesized ZOC with alpha and beta radioactivity levels of 0.091 and 0.908 Bq/g, respectively, meeting the regulatory standards for TENORM in Indonesia. These findings provide important insights for improving ZOC synthesis while addressing radioactivity concerns.

A mononuclear square planar complex of [Ni(o-val)₂]·2H₂O (NiL₂) (where o-val is o-vanillin anion) has been synthesized by reacting nickel(II) chloride hexahydrate with o-vanillin followed by characterization of the complex by UV–Vis and FT-IR spectroscopic techniques and single-crystal X-ray diffraction analysis technique. Theoretically calculated IR frequencies well matched with the experimental data in solid state. HOMO–LUMO energy of the complex has been calculated in gas phase as well as in solvent phase (MeOH, EtOH and DMF) to predict the kinetic stability of the complex. Presence of H-bonding interaction within the complex with lattice water molecule was supported by Hirshfeld surface analysis, and the calculated H-bonding energy was found to be 7.5368 kJ/mol. Complex NiL₂ (L = o-val) was found to be active for catalysing the oxidation of 3,5-DTBCH₂ to 3,5-DTBQ under aerobic condition in methanol solvent with turnover number (k_cat) 230 h^‒1. Phenoxazinone synthase activity of the complex NiL₂ was also investigated using 2-aminophenol as a model substrate in methanol medium, and the k_catvalue was found to be 45 h^‒1.

The scientific community has long been intrigued by the potential practical applications of metal nanoparticles. In this research, we developed cost-effective and easily accessible palladium nanoparticle (Pd-NP)-supported biocatalysts using natural materials. Our main challenge was to ensure an even distribution of Pd-NPs on the bacterial surface while preventing their detachment during the reaction. We successfully addressed this challenge by employing a suitable synthesis method and covering the Pd-NP-coated bacteria with sericin. In our approach, we synthesized Pd-NPs using an in-situ method. In brief, we adsorbed Pd(II) ions onto the bacterial surface and then reduced them using sodium borohydride. Subsequently, we used a sericin solution to enhance the catalytic system’s resistance to leaching and mechanical forces (such as shaking and drying). We thoroughly characterized the morphology and structure of the heterogeneous biocatalysts prepared using FTIR, TGA, EDX, SEM, XRD, and TEM techniques. The catalytic efficiency of the bacteria-Pd-sericin nano-biocomposite was evaluated in the Heck coupling reaction. Our biocatalyst demonstrated high catalytic activity, rapid reaction times, and exceptional reusability, remaining active for up to four successive reaction cycles.

Nitroaromatic compounds are common toxic matters discharged as wastewater in varied industries. Reducing them into corresponding aromatic amines can not only decrease their contamination but also obtain value-added products, in which the preparation of catalysts with superior properties is the key. Herein, the spherical Cu-Ag architectures (ATs) are constructed via a two-step wet chemical method. First, the Cu microspheres are fabricated with the assistance of polyvinylpyrrolidone (PVP) in the mixed solution of ethylene glycol (EG) and water. Then, using them as templates, the spherical Cu-Ag ATs can be grown and constructed. The as-obtained Cu-Ag ATs have the spherical outlines assembled by many nanoparticles. The sliced Cu-Ag ATs show hollow structures and many nanothorns grow from the center to the around, combining the roughly spherical shell to build up the Cu-Ag ATs. In the reduction reaction of p-nitrophenol and p-nitroaniline, the spherical Cu-Ag ATs all exhibit excellent catalytic activities. Within 85 s and 80 s, the p-nitrophenol and p-nitroaniline can be converted completely. The prepared Cu-Ag ATs are expected to have potentials in other fields, such as electronics, sensors and so on.

Graphical abstract

The hierarchical Cu-Ag architectures are constructed successfully through a two-step wet chemical method, in which the rough Cu microspheres are first fabricated in aqueous EG solution, and are used as templates to direct the growth of Cu-Ag architectures. In both reduction of p-nitrophenol and p-nitroaniline, the Cu-Ag architectures exhibit high catalytic activities.

Sheet-like ZnO nanoparticles (SZNs) were synthesized using a microemulsion method and characterized by XRD, BET, DRS, and FESEM techniques. These nanoparticles were then utilized as selective ethanol sensors operating at temperatures between 300 and 450 °C. When precursor ZnO concentrations were high, the average particle size of the SZNs increased, which was reflected in the sharper diffraction peaks observed in the XRD results. The low band gap of SZNs, attributed to their 2D morphology, was confirmed by the Tauc diagram. The SZN sensors demonstrated a remarkable selectivity for ethanol, with response levels up to 77 times higher than for CO and 3700 times higher than for CH₄, achieving a limit of detection between 2.7 and 13.3 ppm. By fine-tuning the microemulsion conditions, the SZN4 sensor achieved an exceptionally high response to ethanol, about 106 times, and up to 30 times higher compared to TCE, toluene, and propane. Furthermore, the SZN4 and SZN5 sensors exhibited a relative insensitivity to humidity, with only a 26% and 17% reduction in ethanol response, respectively.

Graphical abstract

Ni extraction from laterite ore has progressively intensified via various hydrometallurgical methods. One of the by-products of the leaching process is Mn, which can increase the resilience of this metal supply on the market. By observing the effects of the laterite roasting temperature and the effects of the Mn leaching temperature and duration, we can obtain insight into the coextraction of Mn from laterite leaching. Roasting was carried out at 280 and 610 °C, whereas leaching experiments were conducted at 30–90 °C for 0–120 min. The leaching efficiency of Mn increased with increasing roasting temperature, leaching temperature, and leaching duration. The optimum leaching conditions were obtained using a 280 °C roasted sample at a leaching temperature of 90 °C for 90 min. Under these conditions, the Mn leaching efficiency reached 95.5%. Roasting also affects the Mn leaching kinetics parameters, and increasing the roasting temperature results in an increase in the Ea value of the leaching process.