Search Results (3,737)

A homogeneous photocatalyst on a stable substrate is required for photocatalytic reactors in wastewater treatment. ZnO films were synthesized on stainless steel prepared by the spray pyrolysis technique at different deposition temperatures (350 to 500 °C in steps of 50 °C). Scanning electron microscopy showed microflowers formed by nanopetals with an average size of 2 μm. The ZnO wurtzite structure and its defects were studied by Raman spectroscopy, X-ray diffraction, diffuse reflectance, and photoluminescence spectroscopy. A deposition temperature of 400 °C was chosen due to the presence of a higher number of vibrational modes, better distribution of microflowers, smaller crystallite size and a higher number of defects than the other options. Lanthanides were incorporated into ZnO by solution spraying, and then thermal treatment was performed at 600 °C. The photocatalytic evaluation of ZnO showed the best photocatalytic activity under UV light at 365 nm with a 69.34% degradation efficiency at 120 min. Photocatalytic activity toward methylene blue degradation was enhanced in ZnO:Ce³⁺ (2 and 4 atom%) and ZnO:Nd³⁺ (0.05 and 2 atom%) samples, achieving degradation efficiencies above 90% within 30 min of UV–visible light irradiation. Full article

The reverse water–gas shift (RWGS) reaction is a promising route for converting CO₂ into CO, an important feedstock for synthetic fuels and chemicals. In this study, Zn–Co zeolitic imidazolate frameworks (ZIFs), including ZIF-8, ZIF-67, ZIF-67-8, and the core–shell structures ZIF-8@67 and ZIF-67@8, were synthesized as catalyst precursors and thermally activated prior to catalytic testing. Transmission electron microscopy and elemental mapping confirmed the formation of well-defined core–shell architectures, while synchrotron X-ray diffraction verified the characteristic sodalite-type framework. Thermogravimetric analysis revealed substantial framework decomposition during activation at 700 °C. In situ time-resolved X-ray absorption spectroscopy (TR-XAS) showed that Zn remained predominantly in the Zn²⁺ state throughout heating, whereas Co²⁺ underwent progressive reduction to metallic Co⁰ at temperatures approaching 600 °C. Ex situ X-ray absorption spectroscopy confirmed the presence of Zn²⁺ species and metallic cobalt after activation. Catalytic testing of the activated ZIF-derived materials showed that Co-containing catalysts exhibited significantly higher RWGS activity than Zn-only ZIF-8-derived catalyst. Among the investigated samples, ZIF-67@8_C-500 achieved the highest performance, producing 2.50 μmol CO (equivalent to 50 μmol g⁻¹ catalyst) at 600 °C with a H₂/CO₂ ratio of 2:1. The strong dependence of activity on ZIF-67 core loading indicates that metallic cobalt generated from the Co-rich core plays a dominant role in CO₂ conversion. Thermal activation transformed the highly porous ZIF precursors into metallic Co-containing carbonaceous catalysts. The resulting structural evolution, rather than retention of the original porous MOF framework, governed the catalytic performance in the RWGS reaction. Full article

Effects of varying lanthanum (La) content on the melting characteristics, spreadability, mechanical properties of brazed joints, and microstructure of low-silver BAg5CuZn brazing filler metal were investigated. The results indicate that the addition of La has little effect on the solidus and liquidus temperatures of the filler metal, while an excessive amount of La slightly raises its liquidus temperature. An appropriate amount of La enhances the spreadability of the filler metal on both copper and stainless steel plates and simultaneously inhibits grain growth, refining the microstructure of the BAg5CuZn-xLa filler metal. When the La content in the filler metal reaches 0.3%, the shear strength of the 304 stainless steel/304 stainless steel joint brazed with BAg5CuZn-xLa filler metal reaches 492 MPa, which is 17.7% higher than that of the brazed joint without the La addition. Full article

Osteosarcoma is the third most common malignancy among children and adolescents, necessitating the development of effective therapeutic strategies. This study investigated the anticancer activity of green-synthesized zinc oxide nanoparticles (ZnO-NPs) fabricated using bark extract of Ficus benghalensis against the human osteosarcoma Saos-2 cell line. The synthesized ZnO-NPs were characterized using UV–Vis spectroscopy, Fourier Transform Infrared (FTIR), and X-ray Diffraction (XRD), confirming nanoparticle formation and a hexagonal wurtzite crystalline structure. Cytotoxicity evaluation revealed significant dosage-dependent inhibition of Saos-2 cell proliferation, with an IC₅₀ value of 75 μg mL⁻¹. Morphological alterations and 4′,6-diamidino-2-phenylindole (DAPI) staining confirmed apoptotic cell death following ZnO-NPs treatment. Furthermore, ZnO-NPs induced oxidative stress by increasing nitric oxide (NO) and lipid peroxidation (LPO) levels while significantly reducing antioxidant markers, including catalase (CAT), superoxide dismutase (SOD), and glutathione (GSH). Flow cytometry analysis demonstrated G0/G1cell cycle arrest, accompanied by elevated caspase-8 activity. Gene expression analysis showed upregulation of Bax and p53 and downregulation of Bcl-2, indicating activation of the mitochondrial apoptotic pathway. Collectively, these findings demonstrate that phytochemical-mediated ZnO-NPs exert potent anticancer effects against Saos-2 cells through oxidative stress-induced apoptosis and cell-cycle arrest, highlighting their potential for osteosarcoma therapy. Full article

The relationship between composition, structure, and electrical properties is essential for understanding charge transport in vanadate glasses. In this study, the influence of ZnO concentration and thermal treatment on the structure, electrical conductivity, and dielectric relaxation of xZnO–(35 − x)BaO–65V₂O₅ glasses (x = 0–20 mol%) was systematically investigated. Two series of glasses, as-quenched and annealed, were prepared by the melt-quenching technique and characterized by temperature-dependent direct current (DC) conductivity, broadband dielectric spectroscopy, and Raman spectroscopy. The DC conductivity exhibited Arrhenius behavior with two thermally activated conduction regions. Annealing reduced the activation energy at higher temperatures, indicating structural relaxation and stabilization of the glass network. Dielectric spectroscopy revealed two distinct relaxation mechanisms over the frequency range of 0.1 Hz–100 kHz, whereas thermal treatment had only a minor influence on the dielectric relaxation behavior. Raman spectra showed that ZnO progressively modifies the vanadate network through the formation of V–O–Zn linkages while preserving the characteristic terminal V=O bonds. Annealing enhanced the short-range structural ordering without altering the fundamental glass structure. Among the investigated compositions, the glass containing 7 mol% ZnO exhibited distinct structural and electrical characteristics, suggesting that this composition corresponds to a transition in the structural organization of the glass network. The combined structural and electrical analyses demonstrate a clear correlation between ZnO-induced structural modifications and the charge transport properties of ZnO–BaO–V₂O₅ glasses. Full article

This study evaluated potentially toxic element (PTEs) contamination (As, Cd, Co, Cr, Cu, Ni, Pb, and Zn) in soil and grapevine leaves across 36 sites in a historical vineyard near Iași, Romania, transitioning toward residential development. Soil samples were analyzed using energy-dispersive X-ray fluorescence (ED-XRF), while leaf tissues collected during the véraison stage (mid-August) underwent microwave-assisted acid digestion followed by inductively coupled plasma mass spectrometry (ICP-MS). Soil analyses revealed that average concentrations of Cr, Ni, and Pb exceeded national normal legal thresholds, while Cu and As surpassed alert permissible limits. Contamination factor ($CF$) and Geoaccumulation Index ($I_{geo}$) metrics confirmed significant anthropogenic Cu enrichment from historical viticultural treatments. Soil-to-leaf transfer factors ($TF$) approached or exceeded 1 for Cu and Zn, though grapevine was not identified as a hyperaccumulator. Spearman correlation modeling demonstrated a statistical decoupling between soil concentrations and foliar tissue levels for Cu ($r_s=-0.21$) and Zn ($r_s=0.075$), confirming that canopy accumulation is governed by historical agrochemical spraying and atmospheric deposition rather than root-driven uptake. Conversely, Pb ($r_s=0.43$) exhibited a moderate direct soil-to-leaf pathway. The potential ecological risk ($PER$) index indicated moderate-to-considerable cumulative risk, primarily driven by Cu ($E_{Cu}=68.64$) and Cd ($E_{Cd}=59.17$). Human health risk assessments established direct ingestion as the primary exposure pathway, with current non-carcinogenic hazards remaining within tolerable limits ($HI<1$). However, the proposed residential conversion increases exposure risks for vulnerable cohorts, underscoring the necessity of systematic soil screening and remediation prior to land redevelopment. Full article

Atmospheric PM₁₀ was investigated across Campania, southern Italy, during August 2024 to assess its elemental composition and probable sources. In total, 132 daily samples were collected at six ARPAC sites representing harbor, traffic, industrial, school, and regional-background conditions. PM₁₀ concentrations ranged from 2 to 72 µg m⁻³, with the highest and lowest values recorded at the traffic and background sites, respectively. Elemental composition was determined by particle-induced X-ray emission and complemented by SEM–EDS. Elemental-based Positive Matrix Factorization (PMF) resolved six profiles, tentatively assigned to S-rich secondary aerosol, Cl-rich marine aerosol, mixed combustion/industrial emissions, Cu-rich traffic emissions, Ca–Sr-rich road dust, and Pb–Zn-rich waste combustion. At the industrial site, the three anthropogenic profiles together represented 74% of the apportioned mass. Traffic-related, marine, and S-rich secondary aerosol represented 49%, 65%, and 30% at the traffic, harbor, and background sites, respectively. SEM–EDS identified representative irregular S–K-rich and Ca-rich particles, crystalline Na–Cl-rich particles, and fine spherical metal-rich particles. Conditional probability function and trajectory analyses indicated local and regional influences, including a possible secondary sulfate contribution from the Mount Etna region. As the PMF analysis relied exclusively on elemental data, these source assignments should be regarded as indicative rather than definitive. Full article

The aim of this study is to synthesize zinc oxide nanoparticles (ZnO NPs) using G. globosa aqueous leaf extract. The preliminary screening of the phytochemicals was performed with the G. globosa aqueous leaf extract. The physical and chemical characteristics of G. globosa-mediated ZnO NPs were evaluated using UV-Vis spectroscopy, Fourier-transform infra-red spectroscopy (FTIR), X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), nanoanalysis and thermogravimetry. The antibacterial activity of G. globosa-mediated ZnO NPs was assessed against Gram-negative bacteria. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) analyses were performed to evaluate the antibacterial efficacy of the G. globosa-mediated ZnO NPs. The heavy metal adsorption capacity of the synthesized ZnO NPs was evaluated using atomic adsorption spectroscopy (AAS). The UV-Vis spectrum of G. globosa-mediated ZnO NPs proved the excitonic absorption of the synthesized ZnO NPs. FTIR analysis determined the presence of metal oxide functional groups in the G. globosa-mediated ZnO NPs. The average size of 60 nm and the spherical shape of G. globosa-mediated ZnO NPs were confirmed by HRTEM and SEM analyses. The synthesized ZnO NPs had prominent antibacterial activity against Klebsiella pneumoniae and Escherichia coli. G. globosa-mediated ZnO NPs acted as an important adsorbent of heavy metals such as cadmium and lead. Adsorption kinetic studies (pseudo-first-order and pseudo-second-order kinetics) and isotherm analyses (Langmuir and Freundlich models) were performed. The kinetic studies and isotherm models revealed that the synthesized ZnO NPs showed higher adsorption efficiency for cadmium. Full article

Biogas slurry can enhance soil fertility, but the heavy metals it contains may pose potential ecological risks to soil-crop systems. To mitigate heavy metal pollution resulting from the application of biogas slurry to soil, this study investigated potential remediation strategies through the use of blended biochar application. In this study, soil incubation experiments were conducted to evaluate the immobilization performance of cow dung biochar (CB), corn straw biochar (SB), and blended biochar (cow dung + corn straw) (C3S7, C5S5, and C7S3) toward Pb, Zn, Ni, Cr, Cu, As, and Cd under different biogas slurry ratios (Z0, Z1:8, and Z1:4). The results concluded that immobilization efficiency consistently followed the order C7S3 ≥ C5S5 > C3S7 > CB ≈ SB, indicating that the blended biochar generally outperformed the two single biochar in the biogas slurry-irrigated soil system. Batch adsorption experiments showed that adsorption of all metals was better described by the pseudo-second-order model (R² > 0.94). Isotherm fitting further indicated that Zn, Ni, Cr, Cu, and Cd were better fitted by the Langmuir model, whereas Pb and As were better fitted by the Freundlich model. Physicochemical characterization, scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM–EDS), and Fourier transform infrared spectroscopy (FTIR) analyses collectively suggested that the superior performance of blended biochar was associated with the integration of mineral-related characteristics from CB and surface chemical properties from SB, which together enhanced the synergistic fixation of coexisting metals. Consistently, biochar application reduced the potential ecological risk index (RI) of bioavailable heavy metals in soil, with blended biochar showing lower RI values than CB and SB. C7S3 exhibited the best performance in all treatments, highlighting the potential of blended biochar as an effective amendment for mitigating multi-metal pollution risks with biogas slurry utilization. Full article

The interfacial reaction between solder and substrate is a critical factor governing joint reliability, making it essential to understand the formation and stability of interfacial reaction layers when developing new high-temperature lead-free solders. This study investigates the interfacial reaction layers formed in Zn-5Al-3Mg solder/Cu substrate joints soldered at 693 K under vacuum. With a binary Zn-Al solder, the Cu substrate is progressively consumed by Zn, and the intermediate phases CuZn₄, Cu₅Zn₈, and CuZn nucleate and grow concurrently at the solder interface. The addition of a minor amount of Mg to the Zn-Al alloy, however, fundamentally alters this reaction sequence. Transmission electron microscopy analyses, including scanning transmission electron microscopy–energy-dispersive X-ray spectroscopy (STEM-EDS), energy-filtered TEM (EF-TEM), and electron diffraction, reveal three distinct interfacial layers: an outer Mg₂Zn₁₁ layer, a middle two-phase mixture of CuZn₄/Mg₂CuZn₃, and an inner Cu₅Zn₈ layer adjacent to the Cu substrate. The biphasic CuZn₄/Mg₂CuZn₃ mixture layer is shown to form via a quasi-peritectic reaction governed by sequential four-phase equilibria in the Zn-Mg-Cu ternary system. These findings demonstrate that minor Mg additions redirect the interfacial reaction pathway between Zn-Al-based solders and Cu substrates, providing new insight for the design of high-temperature Pb-free solder systems. Full article

Jarosite-type residues generated during zinc hydrometallurgical processing represent a significant environmental liability and a latent source of valuable metals (Zn, Pb, Ag). In this study, the thermal decomposition and mineralogical evolution of an industrial ammonium jarosite residue were investigated to 600–1400 °C. The behavior of the as-received residue was compared against a designed flux-assisted formulation comprising 45 wt% jarosite, 40 wt% Na₂CO₃, and 15 wt% SiC. The conventional roasting of pure jarosite forms refractory zinc ferrite (ZnFe₂O₄) and releases SO₂ above 800 °C, while the flux-assisted route stabilized the sulfur as Na₂SO₄ and CaSO₄, decreasing toxic gas emissions. Concurrently, the reducing effect of the SiC significantly inhibited bulk zinc ferrite formation up to 1200 °C and favored the partial reduction of iron to magnetite (Fe₃O₄). Thermodynamic assessment using FactSage reasonably matches experimental results by X-ray diffraction and SEM-EDS measurements. The thermodynamic evaluation predicts the formation of elemental silver available for subsequent pickup by a collector metal and a liquid slag phase at approximately 1000 °C for the flux-assisted jarosite samples. The ammonium jarosite flux-assisted roasting strategy enhances the potential for metal recovery while increasing environmental sulfur fixation in the slag, aligning with sustainable circular economy principles in non-ferrous metallurgy. Full article

In this work, a comprehensive analysis of the relationship between photoluminescent, thermo-oxidative, and photocatalytic (upon simulated sunlight exposure) properties of ZnO powders is performed. The correlation between the X-ray diffraction and microscopic data is studied. ZnO powders of various sizes and morphologies were used: pseudo-spherical nanoparticles (30–50 nm), submicron faceted crystallites (100–500 nm), and plate- and rod-like microstructures (up to 20 μm). The mean specific surface area values were 32 m²/g, 3.8 m²/g, and 2.6 m²/g for pseudo-spherical nanoparticles, submicron faceted crystallites, and plate- and rod-like microstructures, respectively. According to the XRD data, microstresses and carbon-based impurities were present in ZnO nanoparticles, which is characteristic of nanomaterials synthesized at low temperatures. According to the photoluminescence spectroscopy data, the emission in ZnO was reduced due to high defectiveness, and characteristic emission bands indicated the presence of organic impurities. Upon long signal registration times, an intensive luminescence band with an effective maximum at 579 nm occurred, which indicated the presence of long-term components exhibiting decay times τ ~300 μs. According to the XRD data, the crystal structure parameters of ZnO submicro- and microparticles were close, with no impurities present. In their photoluminescence spectra, pronounced UV and defect-related bands were present with intensity ratios of 11.6 and 6.88, respectively. The decrease in the UV and defect-related luminescence band intensity ratios indicates deviation from the stoichiometry toward an increased Zn over oxygen content. At long signal registration times, in submicron ZnO particles, a luminescence band with maxima at 425 and 490 nm is present, which decays rapidly. An emission band in the 530 nm region is also present, which decays for ≤80 μs, and a weak long-wavelength emission decaying for ~100 μs. At long delay and strobe times (up to milliseconds), only an emission in the 460 nm region is observed, which we connect to the triplet–singlet transition of a defect center (F*, F⁺*). At lower intensities, an emission connected to the surface contamination by organic impurities is observed. In photoluminescence spectra of ZnO microparticles, no long-wavelength emission components are observed. However, upon immersing into methylene blue solution, a modification of the surface and UV region of the spectra is observed with signs of charge carrier recombination rate acceleration. It is shown that the catalytic action of ZnO powders in polyethylene thermo-oxidation processes is determined by a combination of factors. In addition to dispersity and concentration, which are the key parameters, the morphology of ZnO particles, the presence of impurities, the surface state, and the distribution of active sites have a significant influence on catalysis. It has been experimentally demonstrated that these secondary factors can markedly affect the rate of radical formation in polyethylene films and alter their resistance to oxidation. ZnO nanoparticles exhibited low catalytic activity in both photocatalysis (rate constant 0.146 min⁻¹) and thermocatalysis due to the high defect density of the crystallites and the presence of carbon-containing impurities. Submicron ZnO particles, owing to a high carrier generation rate and suppressed recombination (via trapping), demonstrated the highest photoactivity (rate constant 0.729 min⁻¹). Submicron ZnO particles exhibit a catalytic effect on the thermo-oxidation of polyethylene (PE films); however, at concentrations above 8 wt.% a transition to an inhibiting effect is observed. ZnO microparticles catalyzed the oxidation of PE films over a broader concentration range (1–12 wt.%), with oxidation inhibition observed only at 18 wt.%. At the same time, they demonstrated moderate photocatalytic activity (rate constant 0.256 min⁻¹). These characteristics of the samples correlate with data obtained by microscopy, photoluminescence spectroscopy, and X-ray diffraction analysis. Full article

The resource utilization of eutrophic cyanobacterial biomass provides a sustainable route for developing biochar-based catalytic materials for dye wastewater treatment. Herein, eutrophic cyanobacteria from Dianchi Lake, Kunming, were used as raw materials to prepare functional catalytic materials via pyrolysis-modification. A trimetallic photocatalyst, CuFeZnXBC₄₀₀ (XBC = cyanobacterial biochar), was fabricated for methylene blue (MB) degradation without hydrogen peroxide or other external oxidants. The samples were characterized by scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) analysis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), liquid chromatography–mass spectrometry (LC–MS), and three-dimensional fluorescence spectroscopy. At an initial MB concentration of 100 mg/L and pH 11, under UV irradiation, CuFeZnXBC₄₀₀ achieved nearly 99% MB removal within 60 min and retained over 90% activity after eight cycles. Transient photocurrent measurements and quenching experiments indicated that photogenerated holes (h⁺) were the dominant oxidative species, while superoxide radicals (·O₂⁻) contributed to the reaction and hydroxyl radicals (·OH) played a limited role. LC–MS analysis supported the chemical transformation of MB, and three possible degradation pathways were proposed. The development of CuFeZnXBC400 provides a new biochar-based material and a potential strategy for cyanobacterial biomass utilization and organic dye wastewater treatment. Full article

Geogenic processes and human activities are both major causes of soil pollution. Soils can get toxic transition metals from the materials they are formed from, but most pollution comes from industrial and farming activities. The presence of these transition metals in soil can be shown through changes in chemical, biochemical, and microbial properties, as well as how plants react. This research aims to remove transition metals like chromium (Cr), manganese (Mn), iron (Fe), zinc (Zn), tungsten (W), and cadmium (Cd) from soil using a boron nitride (BN) nanocage. The electromagnetic and thermodynamic properties of these metals when trapped in BN were studied using materials modeling. The metals are captured through chemisorption. The research looked at how Cr, Mn, Fe, Zn, W, and Cd are trapped by BN to detect soil metal cations. BN was designed in the presence of these transition metals. The covalent characteristics of these complexes show similar energy levels and a view of the partial density of states between the p states of boron and nitrogen in BN and the d states of Cr, Mn, Fe, Zn, W, and Cd in B(X)N complexes. Also, nuclear magnetic resonance (NMR) analysis showed clear peaks around Cr, Mn, Fe, Zn, W, and Cd when they were trapped in BN during atomic detection and removal from soil, although there were some variations in chemical shielding for isotropic and anisotropic tensors. Based on these results, the ability of BN (as an atom sensor) to adsorb toxic metals, metalloids, and nonmetals is ordered as: Cd > Zn > Fe > Cr > Mn ≈ W. This article suggests that elements absorbed by BN could be used to develop and improve the optoelectronic properties of BN, helping to create photoelectric devices for soil cleaning. Full article

Lung cancer remains a leading cause of cancer-related mortality worldwide, underscoring the need for safer and more effective therapeutic strategies. In this study, zinc oxide nanoparticles (ZnO NPs) were synthesized via a green, biogenic approach using Lantana camara L. flower aqueous extract and evaluated for their anticancer potential against human non-small cell lung cancer (NSCLC) NCI-H460 cells. The biosynthesized ZnO NPs were characterized using UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and particle size analysis, confirming the formation of nanocrystalline ZnO. LC-MS profiling of the Lantana camara flower extract revealed the presence of several bioactive phytochemicals, including phenolic compounds, terpenoids, fatty acids, and alkaloids, which may contribute to the reduction and stabilization of ZnO NPs during green synthesis. Cytotoxicity assessment of ZnO NPs using MTT and trypan blue exclusion assays revealed a dose-dependent reduction in cell viability, with an IC₅₀ value of 50 µg/mL. Mechanistic investigations demonstrated that ZnO NP exposure induced significant oxidative stress, evidenced by increased nitric oxide, lipid peroxidation, and reactive oxygen species levels, along with depletion of intracellular glutathione. Apoptotic cell death was further confirmed by nuclear DNA fragmentation, mitochondrial membrane depolarization, and G0/G1 phase cell cycle arrest. Quantitative real-time PCR analysis revealed upregulation of the pro-apoptotic genes Bax and p53, accompanied by downregulation of the anti-apoptotic gene Bcl-2, indicating activation of a mitochondrial-dependent intrinsic apoptotic pathway. Collectively, these findings suggest that Lantana camara L. flower-mediated ZnO nanoparticles induced apoptotic responses associated with oxidative stress in NSCLC cells, highlighting their ability as an eco-friendly nanoplatform for further anticancer investigations. Full article