Search Results (4,263)

Given the increasing environmental degradation, this study investigates advanced zinc oxide (ZnO)-based materials for the mineralization of toxic compounds through the combined action of photo- and piezocatalysis. Two complementary strategies were employed to enhance catalytic efficiency. First, ZnO_1−xN_x thin films were deposited by reactive high-power impulse magnetron sputtering (R-HiPIMS) to reduce the band gap energy. Second, flower-like ZnO nanostructures were synthesized using the pulsed thermionic vacuum arc (p-TVA) technique to increase the specific surface area. Both systems were further modified by decoration with Ag₂O nanoparticles to improve charge separation. The R-HiPIMS technique offers significant advantages in terms of precise control over processing parameters, enabling accurate tuning of film properties, including microstructure, chemical composition, and electronic structure. However, films produced via R-HiPIMS generally exhibit lower photo-piezocatalytic activity compared to nanostructured counterparts, primarily due to their comparatively reduced effective surface area and limited charge separation efficiency. In contrast, the p-TVA technique enables the synthesis of nanostructured thin films with substantially enhanced photo-piezocatalytic performance. This improvement is attributed to the increased effective surface area and the promotion of more efficient electron–hole pair separation. The materials were comprehensively characterized in terms of optical properties (UV–Vis spectroscopy), chemical composition and bonding (XPS), crystalline structure (XRD), surface morphology (FE-SEM), and photo-piezocatalytic performance. Catalytic activity was evaluated via the degradation of methylene blue (MB) under visible light irradiation and mechanical vibrations. Nitrogen incorporation in ZnO_1−xN_x thin films led to an increase in photocatalytic efficiency from 20% to 28.7%, while the simultaneous application of light and mechanical stimulation increased efficiency to approximately 50%. Under identical irradiation conditions, Ag₂O-decorated ZnO and Ag₂O-decorated ZnO_1−xN_x exhibited photo-degradation reaction rate constants up to 65% higher than bare counterparts, attributed to reduced electron–hole recombination. ZnO nanostructures achieved degradation efficiencies of 59%, rising to 88.3% with Ag₂O decoration under solar illumination for 120 min. When combined with mechanical vibrations, after 60 min, the degradation efficiencies reached 93% for ZnO and 98% for Ag₂O/ZnO systems. A photodegradation mechanism of Ag₂O NPs-decorated ZnO heterostructures was proposed. Full article

Infection urinary stones account for approximately 10–15% of all urinary stones worldwide, with a rising incidence observed in recent decades, particularly in countries with a high Socio-Demographic Index (SDI). This trend has been partially attributed to dietary changes, including increased consumption of processed foods. Heavy metals belong to a group of substances, the source of which can be both food and the human environment. Among many heavy metals, in this study, we focus on copper and investigate its influence on the nucleation and growth of struvite crystals, the primary component of infection urinary stones. Experiments were conducted in artificial urine, both in the presence and absence of Proteus mirabilis, a urease-producing bacterium commonly associated with infection urinary stones. In a bacteria-free system, bacterial urease activity was mimicked by the addition of aqueous ammonia solution. Our results demonstrate that the presence of copper in artificial urine induces a slight shift in the struvite crystallization toward lower pH values, indicating that crystal formation initiates earlier compared to a control test. Additionally, the amount of precipitated struvite increases modestly in the presence of copper. Struvite crystals formed in copper-containing artificial urine are larger and exhibit altered habit and morphology. Energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) analyses confirm that copper does not incorporate into either the bulk or surface structure of the struvite crystals. X-ray diffraction (XRD) data show that struvite remains the sole crystalline phase, consistent with the control samples. Microbiological assays reveal that copper, at the concentrations tested, does not affect the viability of P. mirabilis, indicating an absence of bacteriostatic or bactericidal effects. To elucidate the physicochemical mechanisms underlying copper’s influence on nucleation and growth of struvite, speciation analysis of chemical complexes was performed. This revealed the formation of various copper complexes in artificial urine, including Cu(OH)⁺, CuCit⁻, CuC₂O₄, Cu(OH)₂, CuHPO₄, Cu(NH₃)²⁺, Cu(NH₃)₂²⁺, and Cu(NH₃)₃²⁺. These chemical complexes modulate the equilibrium and formation of complexes with Mg²⁺ and PO₄³⁻ (e.g., MgHCit, MgCit⁻, MgOH⁺, MgC₂O₄, MgSO₄, MgHPO₄), contributing to the observed shift in struvite crystallization to lower pH values. Full article

In zinc electrowinning, industrial Pb-Ag anodes have inherent limitations, including high oxygen evolution overpotential and rapid corrosion. This study constructs Ti-Ti₂N-PbO₂-CeMnO_x composite anodes to overcome these shortcoming, Electrochemical characterization revealed enhanced performance with a reduced overpotential (725 mV 50 mA cm⁻²) and lower Tafel slope (102.92 mV dec⁻¹) in the standard zinc electrowinning electrolyte, indicating faster oxygen evolution kinetics compared to commercial benchmarks. Analysis of the XPS test revealed an increase in the content of Mn³⁺, which helps enhance the OER catalytic activity of the electrode. The Ti/Ti₂N/α/β-PbO₂-CeMnO_x (abbreviation: CMO) composite anode exhibited superior corrosion resistance with an extended service life of 53 h under accelerated polarization at 2 A cm⁻². This durability enhancement is attributed to the combined effects of the Ti₂N interlayer and CMO incorporation, which effectively mitigate anode degradation through passivation inhibition. The developed fabrication strategy enables the production of dimensionally stable anodes (DSAs) with balanced electrocatalytic activity and operational stability, showing promising potential for industrial zinc electrowinning applications. Full article

In this study, we used CTS and DMDAAC as raw materials and prepared a novel chitosan graft copolymer, CTS-g-PDMDAAC, through UV initiation in the presence of the photoinitiator VA-044. The synthesis process was systematically optimized, and its structural characteristics and performance in water treatment were evaluated. A single-factor experiment determined the optimal synthesis conditions to be a mass ratio of chitosan to DMDAAC of 1:4, total reactant concentration of 15.5%, ultraviolet light exposure for 5 h, and concentration of VA-044 of 0.2%. CTS-g-PDMDAAC demonstrated superior performance overall to CTS according to various characterization methods, such as FTIR, XPS, XRD, and BET. The coagulation experiment showed that at a dosage of 6.0 mg/L, the removal rates of residual turbidity and chlorophyll a reach 0.58 NTU and 99.37%, respectively, and the generated flocs have a dense structure and exhibit strong shear resistance. Finally, the flocculation mechanism was explored. Compared with traditional flocculants, CTS-g-PDMDAAC has the advantages of efficient algae removal, lower sludge production, no secondary pollution, and potential for the utilization of microalgae. This research provides theoretical support and suggests technical pathways for the development of biobased, environmentally friendly flocculants with broad pH adaptability. Full article

Nanoplastics (NPs) have emerged as pervasive aquatic pollutants due to their small size, high surface activity, and potential ecological and health risks. Although sludge-derived biochar is a sustainable adsorbent for NP removal, the relative importance of coexisting adsorption mechanisms remains poorly quantified. Here, iron-modified sludge biochar (FeBC) was synthesized and evaluated for NP removal from water. Batch experiments showed that FeBC significantly outperformed pristine biochar, achieving a maximum removal efficiency of 96.09%. Adsorption was strongly pH-dependent, with enhanced removal under acidic conditions due to surface protonation and strengthened electrostatic attraction toward negatively charged NPs. SEM, BET, FTIR, and XPS analyses indicated that electrostatic interactions, hydrogen bonding, π–π interactions, and pore adsorption jointly contributed to NP capture. Importantly, structural equation modeling quantitatively disentangled these mechanisms, revealing electrostatic interactions as the dominant driver (52.6%), followed by hydrogen bonding (23%), pore adsorption (16.6%), and π–π interactions (7.9%), and further identified synergistic and antagonistic relationships among them. These results demonstrate that surface charge regulation governs NP adsorption efficiency, providing a quantitative mechanistic basis for the rational design of biochar-based adsorbents. This study advances a multi-mechanistic framework for understanding and optimizing NP removal while promoting sludge resource valorization. Full article

One-step hydrothermal synthesis of zeolites is a common synthesis technology for zeolites. Las-NaP1 zeolite was synthesized with fly ash (FA) as the silica-alumina source under low-alkalinity conditions for aqueous adsorption. Furthermore, H-NaP1 modified zeolite, a high-efficiency chloride ion (Cl⁻) adsorbent, was fabricated using hollow glass microspheres (HGMs) and FA as a silica-alumina source. The structure of the material was characterized by XRD, SEM, TEM, BET, XPS, FT-IR, Zeta, and other techniques. Effects of the synthesis process and adsorption conditions on the adsorption performance of Cl⁻ and its mechanism were systematically studied. The maximum adsorption capacity of H-NaP1 for Cl⁻ (193.57 mg/g) is 12 times that of Las-NaP1 (15.48 mg/g). The adsorption process conformed to the pseudo-second-order kinetic model and the Freundlich isotherm model. The addition of HGMs effectively inhibited the agglomeration of zeolite particles. This research provided a new idea for the synthesis of efficient dechlorination materials with low alkali and realized the high-value-added utilization of FA. Full article

Bacterial biofilms remain a major challenge in clinical infections due to their dense extracellular polymeric substance (EPS) matrix and strong resistance to conventional antibiotics. This study reports manganese dioxide (MnO₂) nanoparticles capable of autonomous navigation toward bacterial clusters, mechanical penetration of biofilm structures, redox-driven membrane disruption, and synergistic oxidative stress. The nanoparticles exhibit directional movement attributed to a combination of negatively charged surface potential, asymmetric topology, and catalytic reactivity toward bacterial metabolites. MnO₂ demonstrates potent antibiofilm activity against MRSA and MDR E. coli (>98% eradication) and partial activity against Pseudomonas aeruginosa. Time-lapse microscopy, EPR spectroscopy, XPS analysis, and SEM imaging reveal that MnO₂ disrupts both EPS and cell membranes while maintaining structural integrity throughout treatment. Cytotoxicity assays confirm ≥85% viability in human fibroblasts and keratinocytes at therapeutic concentrations. MnO₂ shows controlled biodegradation into Mn²⁺ ions, which participate in physiological pathways and undergo renal clearance. These findings support MnO₂ nanoparticles as promising biofilm-targeting agents for topical formulations, wound care, and implant coatings. Full article

Adjusting the Schottky barrier height is an important approach to enhancing the gas-sensing performance of TiO₂ Schottky sensors. In this study, micro TiO₂ nanotube Schottky sensors were fabricated via magnetron sputtering and anodic oxidation, with their Schottky barrier height adjusted by varying the annealing temperature. The morphology, phase composition, oxygen vacancy concentration, band structure, and Schottky junction of the samples were investigated using SEM, GIXRD, EPR, Hall effect measurements, XPS, I-V curves, and AC impedance. The sensor annealed at 500 °C demonstrated the highest gas-sensing response, outperforming sensors treated at other temperatures by over 100 times. Its response value to 1 ppm H₂ was 242. The annealing temperature significantly affects the TiO₂ phase and oxygen vacancy concentration, resulting in the highest Schottky barrier height in the 500 °C-annealed sensor, which contributes to its superior sensing performance. AC impedance measurements revealed no significant Fermi-level pinning in TiO₂. Based on the gas-sensing mechanism analysis, the response of the TiO₂ sensor can be divided into three regimes: Schottky junction control, TiO₂ resistance control, and co-control. Full article

Fruit spoilage caused by fungal pathogens jeopardizes food safety and inflicts significant economic damage. Cyclic lipopeptides (CLPs) have been applied as biofungicides by disrupting the cell membrane and intracellular components; however, the first target for antifungal action is the fungal cell wall. This study elucidates the molecular mechanism by which CLPs compromise cell wall integrity using molecular dynamics simulation and experimental validation. Among Surfactin C, Iturin A, and Fengycin A, Surfactin C exhibited the strongest binding to β-glucan (ΔE = −1970.536 kcal/mol) and the lowest free volume (7.302%), with enhanced effects at higher concentrations. Key interaction sites were identified at C=O of D-Leu3, -N-H of Leu2, and -COOH of Glu1 by Radial distribution function. In vivo assays with Aspergillus niger confirmed a MIC of 40 µg/mL and Surfactin-induced β-glucan exposure. FTIR and XPS analyses revealed structural reorganization and hydrogen bonding, while SEM/TEM showed spore deformation and wall rupture. These findings demonstrate that Surfactin disrupts fungal cell walls via direct complexation with β-glucan, leading to structural collapse and cell death, supporting its potential as a targeted biofungicide. Full article

Amorphous calcium phosphate (ACP), a key calcium-phosphorus compound, has been widely applied in fields such as dentistry, orthopedics, and biomedicine. However, its potential for removing copper ions from aqueous solutions remains largely unexplored. In this study, sodium citrate-stabilized amorphous calcium phosphate (Cit-ACP) and its calcined derivatives at various temperatures were successfully synthesized as adsorbents for copper ions. The adsorption behavior of Cit-ACP was best described by the Langmuir isotherm, with kinetics following a pseudo-second-order model. Under conditions of pH 5.5 and an initial copper ion concentration of 200 mg/L, Cit-ACP exhibited a maximum adsorption capacity of 323.96 mg/g. Thermodynamic analysis confirmed that the adsorption process was spontaneous and endothermic. Comprehensive characterization via XRD, XPS, and zeta potential measurements before and after adsorption revealed a two-stage adsorption mechanism. At low initial copper concentrations, adsorption occurred predominantly through surface complexation between copper ions and sodium citrate molecules on Cit-ACP nanoparticles. At higher concentrations, the mechanism extended to include co-precipitation of copper ions with hydroxyl groups, which promoted the transformation of Cit-ACP into copper-substituted calcium phosphate phases, such as copper-containing hydroxyapatite. Owing to its straightforward synthesis, high adsorption capacity, and inherent biocompatibility, Cit-ACP presents a promising, cost-effective, and efficient adsorbent for the removal of copper ions from aqueous environments. Full article

Magnesium alloys require protective surface coatings for widespread application, with micro-arc oxidation (MAO) being a prominent technique. However, conventional MAO coatings are typically gray or light-colored, necessitating secondary treatments for specific colors like black, which complicates the process. This study aims to develop a one-step method for fabricating black MAO coatings on AZ31 magnesium alloy by introducing cupric pyrophosphate (Cu₂P₂O₇) as a colorant into a silicate-based electrolyte. As the Cu₂P₂O₇ concentration increased from 0 to 5 g/L, the coating color transitioned from grayish-white to pink, then brownish-black, achieving a uniform black appearance at 4–5 g/L. XPS and EDS analyses confirmed the incorporation of copper as CuO, identified as the primary coloring agent. XRD indicated that the phase composition remained MgO, MgSiO₃, and Mg, although the MgO content decreased. Microstructural analysis showed that an optimal concentration of 4 g/L enhanced coating compactness by thickening the dense layer and reducing pore size. However, electrochemical tests revealed that the incorporation of CuO significantly increased the corrosion current density, thereby reducing the coating’s corrosion resistance compared to the unmodified coating. This work successfully demonstrates the one-step fabrication of black MAO coatings, elucidates the coloration mechanism involving CuO formation, and provides insights into the trade-off between aesthetic functionalization and corrosion performance. Full article

Understanding the environmental pathways and surface modification of beach sand grains is essential for reconstructing coastal dynamics and assessing the suitability of natural sands for engineering applications. This study applies a multiproxy approach—integrating grain roundness classification, SEM microtextural analysis, and XPS surface chemistry—to beach sediments from four coastal sectors of Latvia: Liepaja, Ventspils, Riga, and Salacgrīva. The results reveal clear spatial differences in grain maturity, abrasion signatures, biological imprinting, and nanoscale surface composition. Liepaja is characterised by sub-rounded to rounded grains with abundant percussion pits and abrasion surfaces, indicating prolonged high-energy wave reworking. Ventspils retains angular grains with fresh conchoidal fractures, reflecting rapid sediment renewal from glacial and coastal sources. Riga exhibits weak abrasion and hydrated particulate coatings typical of low-energy brackish environments. Salacgrīva displays strong fluvial influence, including persistent diatom and algal microtextural features and elevated oxygenated carbon and metal-associated XPS signals. These findings demonstrate strong coupling between grain-surface microtextures and surface chemistry and reveal distinct sedimentary fingerprints linked to environmental setting. The multiproxy framework presented here improves understanding of Baltic coastal sediment pathways and provides a preliminary basis for future evaluation of natural sands in filtration and other environmental engineering applications. Full article

This study introduces an electrochemical sensing platform based on bimetallic CoAg/rGO and CuAg/rGO nanocomposites for the detection of 1,3-dinitrobenzene (DNB), a highly toxic nitroaromatic compound commonly encountered in industrial effluents and contaminated water systems. The prepared nanocomposites were characterized using SEM, TEM, AFM, XPS, and electrochemical techniques, providing detailed insight into their structural, morphological, and surface properties relevant to electrochemical sensing. The electrochemical behavior of DNB was investigated in phosphate buffer solutions using cyclic voltammetry under optimized experimental conditions. Both CoAg/rGO and CuAg/rGO electrodes exhibited pronounced electrocatalytic activity towards the reduction in DNB, characterized by well-defined reduction peaks. The developed sensors exhibited good analytical performance, with limits of detection of 2.21 µM and 2.47 µM for the CuAg/rGO and CoAg/rGO electrodes, respectively, both showing linear responses in the concentration range of 5–50 µM. Moreover, a clear response to DNB was obtained in the presence of phenols as interferents as well as in spiked real water samples. The integration of characterization results with electrochemical measurements and validation in real water samples supports process-oriented research in environmental monitoring and electrochemical process control. These results confirm that bimetallic rGO-based nanocomposites represent efficient and cost-effective electrode materials for the electrochemical detection of 1,3-dinitrobenzene. Full article

As a fission product of ²³⁵U or ²³⁹Pu, ⁹⁰Sr is a β-emitting radionuclide with a relatively long half-life (t_1/2 = 28.9 years). Due to its high solubility, easy environmental mobility, and propensity for bioaccumulation within the food chain, the development of efficient materials for the selective capture of ⁹⁰Sr²⁺ is critical for the safe disposal of nuclear waste and environmental protection. In this study, a layered metal sulfide, K_1.36Cd_1.12Bi_2.80S₆ (denoted as KCBS), was synthesized via the high-temperature solid-phase method using K₂CO₃ as the potassium source. KCBS demonstrates high adsorption performance towards Sr²⁺, achieving a maximum adsorption capacity (q_m^Sr = 77 mg·g⁻¹). Moreover, it can maintain high adsorption efficiency (R^Sr > 84.15%) across a broad pH range of 2.98–12.01. In addition, KCBS exhibits the outstanding selectivity for Sr²⁺ removal in the presence of excessive Na⁺ ions and even in actual water samples. KCBS also possesses regenerability, maintaining its superior adsorption capacity for Sr²⁺ ions over three cycles. The mechanism study by energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) analyses indicates that the efficient Sr²⁺ capture is attributed to the ion exchange between Sr²⁺ and interlayer K⁺ ions in KCBS. This research further highlights the potential of layered metal sulfide ion exchange materials for radionuclide remediation. Full article

Ultrasmall near-infrared (NIR)-responsive quantum dots (QDs) are highly promising for deep-tissue phototherapy but often face challenges with biocompatibility and clearance. In this study, Cu₂ZnSnS₄ quantum dots (CZTS QDs) were synthesized via a non-injection method and surface-functionalized with glutathione (GSH) to create water-dispersible and biocompatible CZTS@GSH QDs. Comprehensive characterization using XRD, TEM, DLS, XPS, and UV-Vis spectroscopy confirmed a sphalerite-type ZnS crystal structure, an average hydrodynamic diameter of ~6.2 nm, and a band gap of 1.47 eV (843.5 nm). The CZTS@GSH QDs demonstrated effective photothermal conversion under 808 nm laser irradiation, achieving a temperature increase sufficient for photothermal therapy (PTT). Furthermore, using a DPBF assay, the QDs were shown to generate singlet oxygen, confirming their photodynamic therapy (PDT) capability. Owing to their ultrasmall size, strong NIR absorption, and demonstrated dual PTT/PDT functions, the CZTS@GSH QDs are established as a nanoplatform with potential for combined cancer treatment. Full article