Search Results (348)

In this study, we report the development of a novel magnetized coal fly ash-supported nano-silver composite (AgNPs/MCFA) for dual-functional applications in wastewater treatment: the efficient degradation of methyl orange (MO) dye and broad-spectrum antibacterial activity. The composite was synthesized via a facile impregnation–reduction–sintering route, utilizing sodium citrate as both a reducing and stabilizing agent. The AgNPs/MCFA composite was systematically characterized through multiple analytical techniques, including Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and vibrating sample magnetometry (VSM). The results confirmed the uniform dispersion of AgNPs (average size: 13.97 nm) on the MCFA matrix, where the formation of chemical bonds (Ag-O-Si) contributed to the enhanced stability of the material. Under optimized conditions (0.5 g·L⁻¹ AgNO₃, 250 °C sintering temperature, and 2 h sintering time), AgNPs/MCFA exhibited an exceptional catalytic performance, achieving 99.89% MO degradation within 15 min (pseudo-first-order rate constant k_a = 0.3133 min⁻¹) in the presence of NaBH₄. The composite also demonstrated potent antibacterial efficacy against Escherichia coli (MIC = 0.5 mg·mL⁻¹) and Staphylococcus aureus (MIC = 2 mg·mL⁻¹), attributed to membrane disruption, intracellular content leakage, and reactive oxygen species generation. Remarkably, AgNPs/MCFA retained >90% catalytic and antibacterial efficiency after five reuse cycles, enabled by its magnetic recoverability. By repurposing industrial waste (coal fly ash) as a low-cost carrier, this work provides a sustainable strategy to mitigate nanoparticle aggregation and environmental risks while enhancing multifunctional performance in water remediation. Full article

In sharp contrast to photocatalysis and other prevalent catalytic technologies, tribocatalysis has emerged as a promising technology to degrade high-concentration organic dyes in recent years. In this study, BaTiO₃ (BTO) nanoparticles were challenged to degrade methyl orange (MO) solutions with unprecedentedly high concentrations through magnetic stirring. With BTO nanoparticles and home-made PTFE magnetic rotary disks in 50 mg/L MO solutions, 10 h of magnetic stirring resulted in 91.4% and 98.1% degradations in an as-received glass beaker and in a beaker with a PTFE disk coated on its bottom, respectively. Even for 100 mg/L MO solutions, nearly complete degradation was achieved by magnetic-stirring-stimulated BTO nanoparticles in beakers with the following four kinds of bottom: 97.3% degradation in 30 h for a glass bottom, 97.4% degradation in 20 h for a PTFE coating, 97.9% degradation in 42 h for a Ti coating, and 97.4% degradation in 74 h for an Al₂O₃ coating. Electron paramagnetic resonance (EPR) analyses revealed that the generation of reactive oxygen species (ROS) by magnetic-stirring-stimulated BTO nanoparticles is dramatically affected by the bottom material of beakers. These findings suggest an appealing prospect for BTO nanoparticles to utilize mechanical energy for sustainable water remediation. Full article

Free-standing copper oxide (Cu₂O)-copper hydroxide (Cu(OH)₂) nanocomposites with enhanced catalytic and antibacterial functionalities were synthesized on copper mesh using a green method based on spinach leaf extract and glycerol. EDX, SEM, and TEM analyses confirmed the chemical composition and morphology. The resulting Cu2O-Cu(OH)₂@Cu mesh exhibited notable hydrophobicity, achieving a contact angle of 137.5° ± 0.6, and demonstrated the ability to separate thick oils, such as HD-40 engine oil, from water with a 90% separation efficiency. Concurrently, its photocatalytic performance was evaluated by the degradation of methylene blue (MB) under a weak light intensity of 5 mW/cm², achieving 85.5% degradation within 30 min. Although its application as a functional membrane in water treatment may raise safety concerns, the mesh showed significant antibacterial activity against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria under both dark and light conditions. Using the disk diffusion method, strong bacterial inhibition was observed after 24 h of exposure in the dark. Upon visible light irradiation, bactericidal efficiency was further enhanced—by 17% for S. aureus and 2% for E. coli. These findings highlight the potential of the Cu₂O-Cu(OH)₂@Cu microfibers as a multifunctional membrane for industrial wastewater treatment, capable of simultaneously removing oil, degrading organic dyes, and inactivating pathogenic bacteria through photo-assisted processes. Full article

To successfully prepare cellulose hydrogels through a dissolution–regeneration process, 60 wt% LiBr aqueous solution was used as a green solvent. Carboxyl groups were precisely introduced onto the surface of the cellulose hydrogels through a TEMPO-mediated oxidation reaction, while the three-dimensional network structure and open pore morphology were completely retained. This modification strategy significantly enhanced the loading capacity of the hydrogels with copper nanoparticles (Cu NPs). The experimental results show that the LiBr aqueous solution can efficiently dissolve cellulose, and the TEMPO oxidation introduces carboxyl groups without destroying the stability of the hydrogels. Cu NPs are uniformly dispersed and highly loaded on the surface of the hydrogel because of the anchoring effect of the carboxyl groups. Cu NP-loaded hydrogels exhibit excellent catalytic activity in the NaBH₄ reduction of 4-nitrophenol (4-NP). Cu NP-loaded hydrogels maintain their complete structure and good catalytic performance after five consecutive cycles. Moreover, Cu NP-loaded hydrogels demonstrate high efficiency in degrading organic dyes such as methyl orange and Congo red. This study successfully developed efficient, low-cost, and environmentally friendly Cu NP-loaded hydrogel catalysts through the synergistic effect of LiBr green solvent and TEMPO oxidation modification, providing a feasible alternative to noble metal catalysts. Full article

Environmental contamination from industrial dyes, particularly Methylene Blue (MB), presents a growing challenge due to their toxicity and persistence in aquatic systems. This study explored the catalytic potential of cellulose acetate-stabilized nickel (CA/Ni) nanoparticles for the degradation of MB in aqueous solutions. CA/Ni was synthesized and characterized using FTIR and SEM, confirming its successful incorporation into the cellulose acetate matrix and uniform distribution across the membrane. UV-Vis spectrophotometry was employed to monitor the catalytic degradation of MB, revealing a significant decrease in absorbance at 665 nm over 28 min, indicating 68% degradation efficiency. Kinetic analysis showed that the degradation followed pseudo-first-order kinetics, with an apparent rate constant of 0.0348 min⁻¹ and an R² value of 0.9851, confirming excellent catalytic performance. The effects of temperature and pH on MB degradation were investigated, with the highest efficiency observed at 35 °C and a pH of 7. A room temperature (25 °C) and acidic conditions (pH 5) reduced the degradation rate to 52%. In comparison, a higher temperature (45 °C) and an alkaline pH (pH 9) resulted in a slight decline to 55%, likely due to changes in catalyst efficiency and MB solubility. These findings highlight the potential of Ni NP-stabilized membranes for wastewater treatment applications, providing a scalable and efficient approach to dye removal. Full article

This study presents a one-step electrospinning method to fabricate polyacrylonitrile (PAN) nanofibers embedded with green-synthesized silver nanoparticles (AgNPs) for efficient catalytic dye reduction and real-time monitoring. Utilizing avocado seed extract for AgNP synthesis, the resulting composite nanofibers exhibit uniform nanoparticle dispersion and enhanced surface area, significantly improving adsorption and catalytic properties. The membranes demonstrated outstanding catalytic activity, achieving over 95% degradation of methyl orange within 45 min when paired with sodium borohydride, and maintained structural integrity and performance over ten reuse cycles. The integration of a novel 3D-printed support enabled scalability, allowing a 60-fold increase in treatment volume without compromising efficiency. Additionally, the composite’s electrical conductivity changes enabled the real-time monitoring of the dye reduction process, highlighting its dual functionality as both catalyst and sensor. These results encourage the potential of PAN/AgNPs supported on a 3D-printed structure nanofiber membranes for scalable, sustainable wastewater treatment and in situ reaction monitoring. Full article

Spherical Cu₂O nanoparticles were obtained by reducing copper acetate in N,N-dimethylformamide (DMF) system using glucose as the reducing agent and polyvinylpyrrolidone (PVP) as the surfactant, with which spherical PdCu nanocatalysts were thus synthesized by disproportionation. The catalyst was used for the activation of peroxymonosulfate (PMS) and showed an excellent degradation effect on rhodamine B and methylene blue-contained printing and dyeing wastewater with good stability. Additionally, the surface morphology analysis of the catalyst was carried out by SEM and TEM. The structure was characterized by XRD and FT-IR. The valence state and composition of the catalyst were characterized by XPS. The catalytic performance of the prepared catalysts was investigated with methylene blue and rhodamine B used as target pollutants. The results showed that the catalytic reduction efficiency of PdCu nanocatalyst for the two pollutants could reach 99% at 20 °C, when catalyst concentration was 60 mg/L and PMS concentration was 1.0 g/L and 0.6 g/L, respectively. The degradation efficiency of the catalyst was significantly reduced when Cl⁻, ${\mathrm{H}\mathrm{C}\mathrm{O}}_3^{-}$ and HA were present in the water. The degradation efficiency was above 90% when the pH was in the range of 5–11. The excellent performance of the PdCu/PMS system in the treatment of RhB-contained wastewater was further confirmed by taking into account of the data of free radical quenching experiment and the results of electron paramagnetic resonance (EPR) experiment. After three cycles, the removal rate of MB and RhB could still be maintained at more than 90%, which proved its excellent recyclability due to its remarkable stability and efficiency. Full article

With the rapid advancement of industrialization, dye-containing wastewater has emerged as one of the primary pollution sources in aquatic environments, posing a significant threat to ecosystems and human health. S-scheme heterojunction photocatalysis technology, known for its high efficiency and environmental compatibility, is considered a strategic solution for addressing environmental pollution challenges. In recent years, significant progress has been made in the development of S-scheme heterojunction photocatalysts based on graphitic carbon nitride (g-C₃N₄). However, systematic summaries and in-depth analyses of these advancements remain limited. This study provides a comprehensive review of the research progress of g-C₃N₄-based S-scheme heterojunction systems in the field of photocatalytic dye degradation. It elaborates on the fundamental concepts, operational mechanisms, and representative applications of these systems while exploring the latest advancements in synthesis strategies, catalytic performance optimization, and the underlying mechanisms. Finally, this review discusses the existing challenges and future prospects of g-C₃N₄-based S-scheme heterojunction photocatalytic materials, aiming to offer valuable insights and guidance for further research in this area. Full article

Efficient photocatalysts based on composite materials are essential for addressing environmental pollution and enhancing water purification. This study presents a novel BiOI/V₂O₅ nanocomposite (BVNC) with a flower-like layered structure, synthesized via a low-temperature solvothermal process followed by high-pressure annealing for visible light (VL)-driven dye degradation and antibacterial activities. Compared to individual BiOI nanoparticles (BOINP) and V₂O₅ nanoparticles (VONP), under VL, the BVNC demonstrated significantly enhanced photocatalytic and antibacterial activity. The best-performing BVNC achieved a remarkable methylene blue degradation efficiency of 95.7% within 140 min, with a rate constant value 439% and 430% of those of BOINP and VONP, respectively. Additionally, BVNC exhibited high photocatalytic efficiencies for rhodamine 6G (94.0%), methyl orange (90.4%), and bisphenol A (69.5%) over 160 min, highlighting the superior performance of the composite materials for cationic and anionic dyes. Furthermore, BVNC established outstanding antibacterial capability against Staphylococcus aureus and Escherichia coli, demonstrating zones of inhibition of 12.24 and 11.62 mm, respectively. The improved catalytic and antibacterial capability is ascribed to the presence of a robust p-n heterojunction between BOINP and VONP, which broadens the photo-absorption range, reduces bandgap energy, and facilitates the significant separation of excitons and faster release of reactive oxygen species. Full article

In this work, Guar gum and copper oxide-nickel oxide (GG-CuO-NiO) hydrogel were produced with the help of formaldehyde solution to display an efficient catalytic performance toward the catalytic degradation of selected dyes (Methylene Blue (MB), Methyl Orange (MO), and Eosin Yellow (EY)) in the presence of NaBH₄. The morphological and structural properties of the prepared hydrogel were thoroughly analyzed using SEM, EDX, XRD, and FT-IR techniques. According to the results, the GG-CuO-NiO hydrogel was able to reduce MB by 95% in one minute, 90.0% in four minutes, and 80.0% in 10 min for MO and EY, respectively. The catalytic efficiency of the hydrogel for MB was studied by adjusting its concentrations, varying reducing agent concentrations, and altering the amount of gel used. Using the recyclability method, which involved testing the GG-CuO-NiO hydrogel multiple times for the reduction of MB, the stability, reusability, and loss of catalytic activity of the hydrogel were examined. As a result, the designed GG-CuO-NiO hydrogel was stable for up to four times toward the reduction of MB. Lastly, the efficiency of the GG-CuO-NiO hydrogel was evaluated for MB removal in real samples and displayed exceptional reduction capabilities. Full article

Aloe vera is effectively utilized to synthesize zinc oxide nanoparticles (Av-ZnO NPs), providing an alternative to traditional chemical and physical methods. This sustainable approach minimizes the environmental impacts and enhances their compatibility with herbal ecosystems. We comprehensively analyzed the optical, structural, morphological, and catalytic properties of Av-ZnO NPs using various analytical methods. The results indicated that the nanoparticles primarily exhibited a spherical shape. X-ray diffraction (XRD) revealed the successful formation of a highly crystalline hexagonal wurtzite structure, with an average size estimated at 12.2 nm. The antimicrobial properties of the Av-ZnO NPs indicated moderate antibacterial effectiveness. Using the DPPH free radical scavenging method, we evaluated the antioxidant properties, where the Av-ZnO NPs exhibited improved the radical scavenging efficiency, reflected by a lower IC₅₀ value compared to the plant extract. Additionally, we assessed the photocatalytic functionality through the degradation of methylene blue (MB) dye, finding that the Av-ZnO NPs achieved approximately 82.43% degradation in 210 min, demonstrating their potential for environmental remediation. These findings suggest that green-synthesized ZnO NPs could play a noteworthy role in various nanotechnology applications and biomedical fields, while also promoting environmental sustainability. Full article

Wastewater containing triphenylmethane dyes such as malachite green (MG), discharged by textile and food industries, poses significant carcinogenic risks and ecological hazards. Conventional physical adsorption methods fail to degrade these pollutants effectively. To address this challenge, we focused on two-dimensional SnSe₂ semiconductor materials. While their narrow bandgap and unique structure confer exceptional optoelectronic properties, prior research has predominantly emphasized heterojunction systems. We synthesized SnSe₂ with well-defined hexagonal plate-like structures via a one-step hydrothermal method by precisely controlling precursor ratios (Sn:Se = 1:2) and reaction temperatures (120–240 °C). Systematic investigations revealed that hydrothermal temperature modulates the van der Waals forces between crystal planes, enabling selective exposure of (001) and (011) facets, as confirmed by XRD, SEM, and XPS analyses, thereby influencing the exposure of specific crystal facets. Experiments demonstrated that pure SnSe₂ synthesized at 150 °C achieved complete degradation of MG (40 mg/L) within 60 min under visible light irradiation, exhibiting a reaction rate constant (k) of 0.099 min⁻¹. By regulating the exposure ratio of the active (001)/(011) facets, we demonstrate that crystal facet engineering directly optimizes carrier separation efficiency, thereby substantially enhancing the catalytic performance of standalone SnSe₂. This work proposes a novel strategy for designing noble-metal-free, high-efficiency standalone photocatalysts, providing crystal facet-dependent mechanistic insights for the targeted degradation of industrial dyes. Full article

In this work, we have reported a simple synthesis method for a hollow porous organic nanosphere-supported ZnO composite photocatalyst (HPON@ZnO) through a combination of a hyper-crosslinking-mediated self-assembly method and a “ship-in-bottle” strategy. The obtained HPON@ZnO possesses a large specific surface area and hierarchically porous structures, which exhibited exceptionally high catalytic activity in the adsorption and degradation of crystal violet, with the reaction proceeding under mild conditions. Additionally, the catalyst demonstrated degradation activity towards other dyes and featured a good stability and recyclability. This simple strategy provides a new approach for the large-scale synthesis of efficient heterogeneous photocatalysts, and offers an effective dye wastewater treatment technique. Full article

Decatungstate (DT) is a highly promising photocatalyst for dioxygen (O₂)-based reactions but has hardly been applied in the photocatalytic degradation technology of dye. Here, we synthesized hydrophilic DT–SO₃H salts by incorporating tetra-alkyl cations with sulfonic acid groups, aiming to enhance both the water solubility and catalytic efficiency of DT under visible light. Comprehensive characterization of DT–SO₃H using ultraviolet–visible spectroscopy (UV–Vis), Fourier Transform Infrared Spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), Photocurrent (PTC), and Electrochemical Impedance Spectroscopy (EIS) confirmed its improved properties. DT–SO₃H demonstrated outstanding photocatalytic performance, achieving 90% degradation of methyl orange within 25 min under continuous visible light irradiation. This study presents a cost-effective and efficient method for degrading methyl orange, representing a significant advancement in the development of high-performance photocatalysts and opening new avenues for the study and application of photocatalytic dye degradation technologies. Full article

This study investigates the catalytic potential of silver nanoparticles (AgNPs) synthesized using aqueous Cymbopogon citratus (lemongrass) extract for the degradation of toxic textile dyes, offering an eco-friendly solution to industrial wastewater treatment. The green-synthesized AgNPs demonstrated remarkable degradation efficiency (>94%) for multiple dyes, such as rhodamine B, methyl red, methyl orange, methylene blue, eosin yellow, and Eriochrome black T, in the presence of sodium borohydride. Optimization studies employing a one-factor-at-a-time approach revealed the critical influence of AgNPs and reductant concentration, temperature, and pH. Kinetic analysis confirmed pseudo-first-order degradation behavior. Reactive species scavenging experiments established that hydroxyl radicals and holes played dominant roles in the degradation mechanism. Notably, the AgNPs retained catalytic activity across eight reuse cycles with negligible performance loss, demonstrating strong potential for repeated application. Comparative analysis with data from the literature highlights the superior performance of C. citratus-derived AgNPs in terms of reaction rate and efficiency. This work underscores the value of plant-extract-mediated AgNPs synthesis not only for its environmental compatibility but also for its catalytic effectiveness. The study advances the practical applicability of green nanotechnology in wastewater remediation and supports its integration into sustainable industrial practices. Full article