Search Results (82)

This study assessed elemental exposure and health risks in 35 prepared livestock and poultry dishes from Zhejiang Province using inductively coupled plasma mass spectrometry (ICP-MS). Aluminum (Al) showed the highest concentrations, while strontium (Sr) and barium (Ba) were moderate; other elements (molybdenum (Mo), chromium (Cr), lead (Pb), cadmium (Cd), thallium (Tl), cobalt (Co), arsenic (As)) were low; and nickel (Ni) was undetected. All dishes complied with GB 2762-2022 limits. Although seven dishes showed mild-to-moderate single-factor contamination, Nemerow indices confirmed safe levels (P_c < 0.7). Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) indicated that processing methods drove contamination profiles, with deep-fried products accumulating higher metal levels than stir-fried or boiled ones. While non-carcinogenic risks were acceptable for adults, children showed higher susceptibility with Total Target Hazard Quotients (TTHQ) values nearly double those of adults, exceeding safety thresholds in certain dishes primarily due to As and Cr. Carcinogenic risks for hexavalent chromium (Cr(VI)) and inorganic arsenic (iAs) were acceptable (1 × 10⁻⁶ to 1 × 10⁻⁴) for 32 dishes. After speciation-based recalibration, the remaining three dishes also fell within safe limits. Overall, exposure risks are low, though specific deep-fried products warrant monitoring. Full article

A study on the selective solvent extraction (SX) of molybdenum (Mo) and rhenium (Re) from two industrial pregnant leach solutions (PLSs) was carried out using Alamine 336 as the extractant and the ionic liquid (IL) 1-octyl-3-methyl Imidazolium bis (trifluoromethylsulfonyl) imide [Omim][Tf₂N] as the diluent. One industrial PLS was rich in Mo (VI) (PLS-Mo) and the second one rich in Re (VII) (PLS-Re). Experiments were carried out in open vials in which the concentration of Alamine336 in the diluent, the aqueous-to-organic ratio (A/O), and the stripping with ammonium carbonate (${\left(\mathrm{N}{\mathrm{H}}_4\right)}_2\mathrm{C}{\mathrm{O}}_3$) were carried out systematically. Results indicate that decreasing the aqueous-to-organic (A/O) ratio led to an enhancement in the extraction performances of both Mo (VI) and Re (VII), reaching recoveries of 95%–98% at an A/O ratio of 1:1. However, differences between PLSs became evident at higher ratios, as Re extraction declined more sharply than Mo. Third-phase formation was observed only in the Mo-containing PLS. The PLS–Re system did not exhibit the formation of a third phase due to a lower concentration of metal (1 g/L Mo). The use of ammonium carbonate for stripping led to enhanced recoveries, achieving 84.4% for Re and 46.8% for Mo. A total of 50 extraction-stripping cycles were carried out in this work. These demonstrated nearly total initial extraction, but performance decreased over the cycles because of insufficient stripping and solvent loading. Overall, [Omim][Tf₂N] proved to be an effective and environmentally friendly alternative to conventional diluents for Mo and Re separation and recovery from industrial leach solutions. Full article

In this study, molybdenum disulfide (MoS₂)-based water nanofluids were prepared and stabilized using two surfactants with opposite charges: the cationic cetyltrimethylammonium bromide (CTAB) and the anionic sodium lauryl sulfate (SLS). Different MoS₂:surfactant ratios (1:1, 1:2, and 1:3) were examined to identify the optimal formulation ensuring stable dispersion. Stability was evaluated through dynamic light scattering (DLS), zeta potential, and UV–Vis spectroscopy analyses. The results showed that the MoS₂:SLS (1:3) nanofluid achieved the highest stability, characterized by a zeta potential of −38 mV and a mean particle size of approximately 290 nm. Thermophysical properties were then investigated for nanoparticle concentrations of 0.05, 0.1, and 0.2 wt%. The 0.1 wt% nanofluid exhibited the best performance, showing a thermal conductivity enhancement of about 49% and an increased specific heat capacity compared with pure water. This improvement is attributed to uniform nanoparticle dispersion and enhanced phonon transport. Overall, the results demonstrate that the anionic SLS surfactant at a 1:3 ratio effectively enhances the stability as well as the thermal performance of MoS₂–water nanofluids, making them promising candidates for thermal management and energy systems applications. Full article

This study reports the successful fabrication and characterization of two-dimensional (2D) vertical heterostructures composed of a semiconducting molybdenum disulfide (MoS₂) layer stacked with semimetallic platinum dichalcogenides (PtSe₂ and PtTe₂). The heterostructures were created using a versatile fabrication method that combines chemical vapor deposition (CVD) to grow high-quality MoS₂ nanolayers with thermally assisted conversion (TAC) for the synthesis of the Pt-based layers. The final MoS₂/PtSe₂ and MoS₂/PtTe₂ heterostructures were then assembled via a dry transfer process, ensuring high structural integrity. The quality and properties of these heterostructures were investigated using a range of advanced spectroscopic techniques. Raman spectroscopy confirmed the presence of characteristic vibrational modes for each material, validating successful formation. X-ray photoelectron spectroscopy (XPS) analysis further confirmed the elemental composition and oxidation states, though it also revealed the presence of elemental Pt⁰ and oxidized Te⁺⁴ in the PtTe₂ layer, suggesting an incomplete conversion. Importantly, the photoluminescence (PL) spectra showed a significant quenching effect, a clear sign of strong interlayer charge transfer, which is essential for optoelectronic applications. Finally, UV-Vis-NIR spectrophotometry demonstrated the combined optical properties of the stacked layers, with the Pt-based layers causing broadening and a blue-shift in the MoS₂ exciton peaks, indicating altered electronic and optical behavior. This research provides valuable insights into the synthesis and fundamental properties of MoS₂/PtX₂ heterostructures, highlighting their potential for next-generation electronic and optoelectronic devices. Full article

The efficient separation of chalcopyrite from molybdenite is crucial for the utilization of copper–molybdenum ores and is inevitably influenced by the presence of metal ions in the pulp. However, the underlying impact mechanisms remain unclear. This study systematically investigated the influence of Cu²⁺ on the flotation separation of chalcopyrite and molybdenite, with sodium thioglycolate (STG) as a depressant. Flotation experiments revealed that Cu²⁺ in the STG system significantly reduced molybdenite recovery and hindered selective separation. Characterization using contact angle, zeta potential, and UV–Vis analysis demonstrated that the presence of Cu²⁺ triggered STG adsorption on the molybdenite surface, thereby increasing its hydrophilicity. XPS analysis showed that Cu²⁺ adsorbed onto the molybdenite surface as Cu(I), creating reactive sites for the –SH or –COO⁻ groups in STG. This interaction forms a stable molybdenite–Cu(I)–STG complex through chemisorption, significantly suppressing molybdenite flotation. DFT calculations further demonstrated that Cu²⁺ enhanced the reactivity between STG and molybdenite. These findings provide a comprehensive understanding of the influences of Cu²⁺ on the flotation separation between chalcopyrite from molybdenite, providing valuable insights into further optimizing copper–molybdenum flotation separation processes. Full article

The widespread presence of pesticides—especially malathion—in aquatic environments presents a major obstacle to conventional remediation strategies, while the ongoing global energy crisis underscores the urgency of developing renewable energy sources such as hydrogen. In this context, photocatalytic water splitting emerges as a promising approach, though its practical application remains limited by poor charge carrier dynamics and insufficient visible-light utilization. Herein, we report the design and evaluation of a series of TiO₂-based ternary nanocomposites comprising commercial P25 TiO₂, reduced graphene oxide (rGO), and molybdenum disulfide (MoS₂), with MoS₂ loadings ranging from 1% to 10% by weight. The photocatalysts were fabricated via a two-step method: hydrothermal integration of rGO into P25 followed by solution-phase self-assembly of exfoliated MoS₂ nanosheets. The composites were systematically characterized using X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) spectroscopy. Photocatalytic activity was assessed through two key applications: the degradation of malathion (20 mg/L) under simulated solar irradiation and hydrogen evolution from water in the presence of sacrificial agents. Quantification was performed using UV-Vis spectroscopy, gas chromatography–mass spectrometry (GC-MS), and thermal conductivity detection (GC-TCD). Results showed that the integration of rGO significantly enhanced surface area and charge mobility, while MoS₂ served as an effective co-catalyst, promoting interfacial charge separation and acting as an active site for hydrogen evolution. Nearly complete malathion degradation (~100%) was achieved within two hours, and hydrogen production reached up to 6000 µmol g⁻¹ h⁻¹ under optimal MoS₂ loading. Notably, photocatalytic performance declined with higher MoS₂ content due to recombination effects. Overall, this work demonstrates the synergistic enhancement provided by rGO and MoS₂ in a stable P25-based system and underscores the viability of such ternary nanocomposites for addressing both environmental remediation and sustainable energy conversion challenges. Full article

The short-term mechanical properties of commercial corrosion-resistant nickel alloys based on Ni-Cr (Hastelloy^® G-35^® or UNS N06035), Ni-Mo (Hastelloy^® B-3^® or UNS N10675), and Ni-Cr-Mo (VDM^® Alloy C-4 or UNS N06455, VDM^® Alloy 59 or UNS N06059, and KhN62M-VI) systems were analyzed in the as-received state and after long-term (up to 5000 h) aging at 500–700 °C. All alloys exhibited moderate strength and high ductility in the as-received state. Under the influence of high temperatures, these alloys showed a tendency toward the decomposition of Ni-based FCC solid solutions and a change in mechanical properties. It was shown that the difference in chromium and molybdenum content in Ni-Cr-Mo alloys leads to the formation of secondary phases of various composition and morphology, which had varied influence on the short-term mechanical properties of the materials. Grain boundary precipitates had a negligible effect on the strength properties of the investigated alloys, while intragranular precipitates embrittled nickel-based alloys, reducing their possible application at high temperatures. Full article

A novel method for the spectrophotometric determination of trace amounts of molybdenum has been developed. This method utilizes a centrifuge-less cloud point extraction (CL-CPE) in a mixed micellar (MM) system containing a nonionic surfactant (Triton X-114) and an ionic liquid (Aliquat^® 336, A336). The chromophore chelating reagent employed was 4-nitrocatechol (4NC, H₂L). This work marks its first application as a CPE reagent. Under the optimal conditions, Mo(VI) forms a yellow ternary complex with 4NC and A336, which can be represented by the formula (A336⁺)₂[MoO₂L₂]. The method possesses the following characteristics: limit of detection (LOD) of 3.2 ng mL⁻¹, linear range of 10.8–580 ng/mL, absorption maximum of 435 nm, molar absorptivity coefficient of 3.34 × 10⁵ L mol⁻¹ cm⁻¹, and Sandell’s sensitivity of 0.29 ng cm⁻². The method has been successfully employed for the determination of molybdenum in reference standard steel samples, bottled mineral water, and a molybdenum-containing dietary supplement. Full article

Previous studies have demonstrated that underwater low-temperature plasma is effective for synthesizing nanomaterials by generating plasma discharges between metal electrodes submerged in water. This study extends this approach to the one-step synthesis of MXenes containing titanium, molybdenum, and titanium–molybdenum composites through pulsed discharges in carbon tetrachloride, an oxygen-free, non-flammable solvent characterized by a high boiling point and low permittivity. By employing titanium and molybdenum electrodes in various configurations, three MXene samples were synthesized: Ti₂CT_X, Mo₂CT_X, and Mo₂TiC₂T_X. Characterization techniques, including UV-Vis spectroscopy, X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy, confirmed the successful synthesis of high-purity MXenes with distinct structural and optical properties. Notably, the bandgap values of the synthesized MXenes were determined as 1.71 eV for Ti₂CT_X, 1.42 eV for Mo₂TiC₂T_X, and 1.07 eV for Mo₂CT_X. The photocatalytic performance of the synthesized MXenes was evaluated, showing a removal efficiency of 65% to 98% for dye mixtures, with methylene blue showing the highest degradation rate. This plasma-assisted method offers a scalable, precursor-free route for the synthesis of MXenes with potential applications in energy storage, environmental remediation, and optoelectronics due to their tunable bandgaps and high catalytic activity. Full article

Green diesel is a high-quality biofuel obtained through the transformation of triglycerides into linear alkanes. In order to obtain green diesel, this study investigates the impact of impregnation pH on the surface species of NiMo/Al₂O₃ catalysts in the hydroprocessing of soybean oil. NiMo catalysts supported on Al₂O₃ were synthesized at different pH values (pH = 7 and 9). In the oxide state, solids were characterized by UV-Vis diffuse reflectance, Raman, and FT-IR spectroscopies, and, in the sulfide state, they were characterized by HR-TEM. The results show that the pH of impregnation significantly determines the surface species formed. An impregnation at pH = 7 favors the formation of Ni²⁺_(Oh) and Ni²⁺_(Oh-dis) interacting with non-crystalline molybdenum trioxide, while the formation of Ni²⁺/Al₂O₃, Ni_2+(Oh-dis), and MoO₃ species is favored at pH = 9. These surface species play a fundamental role in the hydrogenolysis and deoxygenation steps. Catalyst impregnated at pH = 7 shows higher activity due to the formation of shorter MoS₂ slabs. This study emphasized the importance of controlling impregnation conditions for optimizing catalyst performance. Full article

The design and preparation of advanced hybrid nanofibers with controllable microstructures will be interesting because of their potential high-efficiency applications in the environmental and energy domains. In this paper, a simple and efficient strategy was developed for preparing hybrid nanofibers of zinc oxide–molybdenum disulfide (ZnO–MoS₂) grown on polyimide (PI) nanofibers by combining electrospinning, a high-pressure hydrothermal process, and in situ growth. Unlike simple composite nanoparticles, the structure is shown in PI–ZnO to be like the skeleton of a tree for the growth of MoS₂ “leaves” as macro-materials with controlled microstructures. The surface morphology, structure, composition, and photocatalytic properties of these structures were characterized using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and UV–vis spectroscopy. The ultra high-volume fraction of MoS₂ can be grown on the brush-shaped PI–ZnO. Decorating ZnO with nanosheets of MoS₂ (a transition metal dichalcogenide with a relatively narrow band gap) is a promising way to increase the photocatalytic activity of ZnO. The hybrid nanofibers exhibited high photocatalytic properties, which decomposed about 92% of the methylene blue in 90 min under visible light irradiation. The combination of MoS₂ and ZnO with more abundant surface-active sites significantly increases the spectral absorption range, promotes the separation and migration of carriers, and improves the photocatalytic characteristics. Full article

Regarding photocatalytic oxidative desulphurization (PODS), titanium oxide (TiO₂) is a promising contender as a catalyst due to its photocatalytic prowess and long-term performance in desulphurization applications. This work demonstrates the effectiveness of double-doping TiO₂ in silver (Ag) and molybdenum (Mo) for use as a novel catalyst in the desulphurization of light-cut hydrocarbons. FESEM, EDS, and AFM were used to characterize the morphology, doping concentration, surface features, grain size, and grain surface area of the Ag/Mo powder. On the other hand, XRD, FTIR spectroscopy, UV-Vis, and PL were used for structure and functional group detection and light absorption analysis based on TiO₂’s illumination properties. The microscopic images revealed nanoparticles with irregular shapes, and a 3D-AFM image was used to determine the catalyst’s physiognomies: 0.612 nm roughness and a surface area of 811.79 m²/g. The average sizes of the grains and particles were calculated to be 32.15 and 344.4 nm, respectively. The XRD analysis revealed an anatase structure for the doped TiO₂, and the FTIR analysis exposed localized functional groups, while the absorption spectra of the catalyst, obtained via UV-Vis, revealed a broad spectrum, including visible and near-infrared regions up to 1053.34 nm. The PL analysis showed luminescence with a lower emission intensity, indicating that the charge carriers were not thoroughly combined. This study’s findings indicate a desulphurization efficiency of 97%. Additionally, the promise of a nano-homogeneous particle distribution bodes well for catalytic reactions. The catalyst retains its efficiency when it is dried and reused, demonstrating its sustainable use while maintaining the desulphurization efficacy. This study highlights the potential of the double doping approach in enhancing the catalytic properties of TiO₂, opening up new possibilities for improving the performance of photo-oxidative processes. Full article

1,2,3,4,5-pentathiepines (PTEs) are naturally occurring polysulfides of increasing scientific interest based on their identified pharmacological activities. Artificial PTEs with N-heterocyclic backbones are efficiently synthesized via mediation by a molybdenum–oxo-bistetrasulfido complex. A common feature of all precursor alkynes successfully used to date in this reaction is the presence of a –CH(OEt)₂ group since the previously postulated mechanism requires the presence of one OEt^– as the leaving group, and the second must become a transient ethoxonium moiety. This raised the question of whether there really is a need for two, maybe only one, or possibly even zero ethoxy substituents. This research problem was systematically addressed by respective variations in the precursor-alkyne derivatives and by employing one related allene species. It was found that the total absence of ethoxy substituents prevents the formation of PTEs entirely, while the presence of a single ethoxy group results in the possibility to distinctly functionalize the position on the resulting N-heterocyclic pyrrole five ring in the target compound. This position was previously exclusively occupied by an –OEt for all products of the molybdenum-mediated reaction. The allene was applied with similar success as precursor as with the related alkyne. The now-employable significant change in precursor composition gives access to a whole new PTE subfamily, allowing further modulation of (physico)-chemical properties such as solubility, and provides additional insight into the mechanism of PTE formation; it comprises a merely partial validation of the previous hypothesis. The new alkyne precursors and pentathiepines were characterized by a variety of instrumental analyses (NMR, mass spec, UV–vis) and in six cases (one alkyne precursor, one unexpected side product, and four PTEs) by single-crystal X-ray diffraction. Syntheses, isolation procedures, analytical data, and the impact of the findings on the previously proposed mechanism are described in detail herein. Full article

In this work, we report on the development of a computational algorithm that explores the configurational isomer space of bimetallic decametalates with general formula ${\left[{\mathrm{M}}_{\mathrm{x}}{\mathrm{M}}_{10-\mathrm{x}}^{\prime }{\mathrm{O}}_{28}\right]}^q$. For x being a natural number in the range of 0 to 10, the algorithm identifies 318 unique configurational isomers. The algorithm is used to generate mixed molybdenum(VI)–vanadium(V) systems ${\left[{\mathrm{Mo}}_{\mathrm{x}}{\mathrm{V}}_{10-\mathrm{x}}{\mathrm{O}}_{28}\right]}^{8-}$ for $x=0,1,2,$ and 3 that are of experimental relevance. The application of the density functional theory (DFT) effectively predicts stability trends that correspond well with empirical observations. In dimolybdenum-substituted decavanadate systems, we discover that a two-electron reduction preferentially stabilizes a configurational isomer due to the formation of metal–metal bonding. The particular polyoxometalate structure is of interest for further experimental studies. Full article

Molybdenum trioxide (MoO₃) is an attractive semiconductor. Thus, bandgap engineering toward photoelectronic applications is appealing yet not well studied. Here, we report the incorporation of sulfur atoms into MoO₃, using sulfur powder as a source of sulfur, via a self-developed hydrothermal synthesis approach. The formation of Mo-S bonds in the MoO₃ material with the synergistic effect of sulfur doping and oxygen vacancies (designated as S-MoO_3−x) is confirmed using Fourier-transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR). The bandgap is tuned from 2.68 eV to 2.57 eV upon sulfur doping, as confirmed by UV-VIS DRS spectra. Some MoS₂ phase is identified with sulfur doping by referring to the photoluminescence (PL) spectra and electrochemical impedance spectroscopy (EIS), allowing significantly improved charge carrier separation and electron transfer efficiency. Therefore, the as-prepared S-MoO_3−x delivers a sensitive photocurrent response and splendid cycling stability. This study on the synergistic effect of sulfur doping and oxygen vacancies provides key insights into the impact of doping strategies on MoO₃ performance, paving new pathways for its optimization and development in relevant fields. Full article